Doesn't it seem strange that most places only offer 3" longer
spring shackles? For example, most stock Toyota 4Runner (and
mini-truck) spring shackles measure approximately 3.5" center to
center (T-100 shackles are approx. 4.5"). I wanted longer shackles
but not 3" longer, so I decided to make my own. The first ones I
made involved buying a 3" longer "Rubicon"
shackle from Downey Offroad,
redrilling one hole in the desired location and cutting off the excess.
While this worked fine for shorter shackles, it was somewhat expensive
and time consuming.
The Downey Rubicon shackle design used two, unbraced
side plates with straight 18mm through bolts and nylon lock nuts to
hold the shackle together. This design allows the side plates to move
independently, which reduces stress on the suspension and allows for
greater articulation. However, I found the Downey design has one fatal
flaw, that is that the bolt tends to remain fixed inside the
spring/frame bushing, thereby forcing the shackle side plate to rotate
on the bolt. Over time this metal-to-metal contact leads to wear,
opening up the hole in the side plate, leading to sloppy handling on
the road. But worse yet, the back and forth rotation of the side plate
under the nut can cause it to work its way loose, ultimately leading to
a loss of the nut (I know, it happened to me) and possibly the entire
In fact, if you run the Downey Rubicon shackles, be sure to check
the tightness of the nuts periodically!
One nice feature of the Rubicon shackle design that I do like is that
removal is very easy, since you can pull each bolt out separately. If
you've ever struggled with trying to pull out a one-piece shackle out
of the frame and the spring at the same time, you can appreciate this
In light of the above problems, I decided I could make a better
shackle, taking the good features of the Rubicon design, and correcting
the weaknesses. My first attempt was to tack weld the bolt head to the
side plate. It worked for a while, but it made shackle removal
difficult as now you could not pull one bolt at a time. So, I ground
out the welds and decided to come up with a better solution.
I then came up with a retainer (photo above) to hold the bolt (and thus
the nut) fixed to the side plate without restricting the inherent
flexibility of the design. While this retainer works well it takes a
fair amount of time to make and I figured there had to be an even
My final solution was even simpler, I basically combined the two
previous ideas into one. By welding tabs on the shackle to prevent the
bolt from turning, yet still allowing it to move independently, I think
I've solved all the problems with the original Downey Rubicon shackle
design and I've given up none of the benefits. Also, as an unexpected
side benefit, the tabs help to protect the head of the lower shackle
bolt from damage scraping over rocks. The tabs take most of the abuse
and leave the head of the bolt fairly unscathed.
For the shackle side plates themselves, to ensure perfect alignment
between the bolt holes, all 4 shackle side plates are tack welded
together prior to drilling. After the holes are drilled, through all 4
side plates, to the proper size for the bolts, the side plates are
separated and then any final work such as bending or welding in bracing
is done. For unbraced shackles, you can use the "witness
marks" on the side of the plates to put the plates back together
as they were drilled. THe plates will have from 1 to 4 dots stamped
into the side, and if you keep 1 next to 2 and 3 next to 4, the plates
for each shackle will be next to the one they were drilled with.
The shackles use stock size hardware to provide the proper fit in the
stock Toyota spring and frame bushings. Since the side plates are cut
from lengths of 3/8" x 2" steel flat bar, any length shackle
from stock length to 3.5" over stock length can be made to suite
your needs. Pictured below are some examples of custom 4Crawler
spring shackles for Toyota pickups (2WD and 4WD), 4Runner, T-100,
(A) 3" longer rear shackle
'84-89 4Runner, '79-'88 Pickup
Available in stock length on up
(B) 2" longer wide body shackle
'84-85 pickup/4Runner'89-95 Pickup,
Available in stock length on up
(C) 2" longer '89-'95 Pickup
w/ stock shackle for reference
Available in stock length on up
(D) Wide body unbraced front shackle,
2" over stock length,
w/ drilled polyurethane spring bushings
(E) Wide body braced shackle
3.5" over stock length w/
18mm hardware for stock bushings
(F) Braced rear (3rd gen p/u)
5.5" over stock length (9" c-c)
For a rear Chevy spring install
(G) Tacoma Rear Shackle
(H) Tacoma Shackle Installed
Note: The shackles match the factory
offsets on inner and outer plates
(I) Shackle Spacers to make
your own wide body shackles,
thickness/hole made to order
(J) Greaseable Shackle Bolts
(K) Load Sensing Prop Valve
Bracket - For Toyota/Leaf Spring
(L) Load Sensing Prop Valve
Bracket - For Toyota/Coil Spring
Spring Shackle Examples
Note that the 2nd generation Pickups ('89-'95) have a shackle hanger
that is wider than the spring itself. We offer two options for this,
one is a wide body shackle (A) with welded-in-place spacers, or a
stepped-down shackle similar to stock (B). You can compare the size of
the stock shackle to the longer units. Note, with stock rubber spring
bushings, it is necessary to remove the steel sleeve in the spring eye
to install the 18mm bolt directly. It is also possible to get the
shackles set up with a bolt to fit inside the stock steel spacer if
Also available, custom front shackles. Same basic options as the rear
shackles, braced or unbraced, wide body or bent
side plates. Also available is custom widths, top and bottom. An
example is the Tacoma ('95.5-'04) shackle shown in pictures (G) and (H)
above. The factory shackle hanger is not centered directly above the
spring for some reason. Instead, the factory shackles have a different
offset on the inner and outer shackle plates. By exactly duplicating
the factory offsets, the 4Crawler Tacoma shackle ensures that the rear
springs are not put under the added stress caused by a symmetrical
shackle (as many common shackle designs use) and ensures that the rear
axle alignment is preserved.
Also available, custom machined shackle spacers (I) for making your own
wide-body shackles. Simplifies shackle fabrication since no bending is
required. Common thicknesses are:
0.375" for the '89-'95 Toyota pickup rear shackles
0.70" for the '79-'85 Toyota front shackles w/ Toyota leaf springs
0.56" for the '79-'85 Toyota front shackles w/ Wrangler leaf
springs (67mm width)
0.375"/0.50" for the Tacoma rear shackles with Toyota leaf
springs (60mm width)
Turned from 1.75" OD billet steel, they cam be made with nearly
any thickness and center hole size.
And now available are greaseable shackle bolts (J). Bolts are
gun-drilled through the head, cross-drilled with a center groove to
allow for grease insertion into the bushings or OrbitEye/Johnny Joint
type spring end. Then the hole in the head is tapped for 1/4-28 thread
low-profile grease zerks. Use of this size thread allows the zerks to
be removed and replaced with a short, flat-headed screw to prevent the
zerk from being scraped off by a rock on the trail.
For Toyota pickups and 4Runners, a bracket to raise the sensing rod on
the axle for the Load Sensing Proportioning Valve (LSPV-BV) is also
available (K, L). Bracket is made to order, it is sized to match the
Also, if looking for shackles to use with non-stock springs, for
example, the popular Rancho 44044 springs are 1/4" wider than the
stock Toyota springs and therefore cause problems when used with
shackles built for the stock width spring. If you can provide the
specifications of the spring and hanger setup you are using, 4Crawler
Offroad can probably make a shackle to fit your exact needs.
All our spring shackles are proudly designed and manufactured in
For shackle and hardware dimensions, see the
information in the table in this link. We'll use those
dimensions as the basis for the custom shackles unless you advise us
otherwise. For example if you have aftermarket springs or bushings that
use different size hardware, let us know so we can adjust the design
for your shackles. Also, some vehicles may have variations in hardware
dimensions that may affect the design of your shackles.
Typical compression-style spring shackle, built to order (specify the
length over stock desired, +0" = stock length):
Priced from $95.00, per pair, unbraced,
or $65.00 per pair, unbraced w/o hardware (i.e. side plates only)
A pair of shackles includes 2 sets of shackles, one for each spring on
Price applies to shackles up to 6.5" long, center-center
(typically 2"-3" longer than stock)
Toyota Pickup/4Runner stock length is ~3.5", T-100 is ~4.5"
For lengths greater than 6.5", add $10.00/in. (or fraction
thereof) over that length
For shackle side plates only, indicate the bolt hole sizes for the
shackles and whether you want the bolt head tabs welded in place, as
they are designed to fit the bolt head sizes that we use. We can also
send you the loose tabs that you can weld on yourself to exactly match your bolt heads.
For greater installation flexibility, shackles are available with
additional sets of bolt holes pre-drilled
Add $15.00 for each set of additional bolt holes
Minimum offset for the extra holes is approx. 1.5" for 18mm /
3/4" hardware and 1" for the 14mm / 9/16" hardware
Prices above are per pair (i.e. two shackles, one for each side of a
Single shackles are also available, starting at $60.00/ea. w/ hardware.
If you want to build your own shackle plates or replace existing
shackle or spring hanger bolts, replacement bolts are available:
Grade 8.8 M18x120/130mm or 150mm bolts and M14 or 9/16" bolts with
nylock nuts are available separately:
$12.00 ea. or $45.00 for a set of 4 (includes nylock nuts)
Bolts have ~2"/50mm of threaded length and can be cut down to
shorter lengths is needed.
Spare nylon lock nuts are available separately for $3.00/ea.
Also available at the same cost are the 14mm or 9/16" bolts often
used for the forward spring hanger bolts or for later model sleeved
spring eye bushings, 100mm/4" or 125mm/5" long. Same cost as
Spring hanger bolts with a flange that bolts to the frame are not available.
The small 30mm OD bushings are used in the shackle hangers and rear
springs eyes on the early trucks
These are plain bushings, no sleeve, inside or outside, 18mm (or
Cost, per pair of bushings (as in two bushings - each bushing comes in
2 halves) enough to do two spring eyes or two shackle hangers - i.e.
one per side of the truck, is:
$16.00/pr. for the narrow bushings (can be used in the spring eye or
rear shackle hanger)
$22.00/pr. for the wider front "through-the-frame" shackle
hanger bushing or the wider 3rd gen pickup or Tacoma shackle hangers. Bushings may need trimming to length.
Add $8.00/pr. for bushing drilled to accept 3/4" hardware
The large 40mm OD bushings are used in some spring eyes on the later
In OEM form, these bushings have an inner and outer sleeve and are
pressed into the spring eye and need to be cut or pressed out to
The bushings have a removable inner sleeve to allow use of either 14mm
(9/16") or 19mm (3/4") hardware.
For a tighter 18mm bolt fit, like with the OEM front spring hanger
pins, we can supply a heat
shrink sleeve (PVC) for the pin ($2/sleeve),
that you can heat shrink over the OEM spring pin to bring it's OD up
from 18mm to 19mm to better fit a 40mm spring eye bushing w/o the
internal sleeve. This lets you re-use the stock solid axle spring
hanger pin (which is not a normal bolt) by putting the heat shrink
tubing over the 18mm section of the pin.
Cost is $25.00/pr.
T-100 pickups use the long 30mm OD bushings on the rear frame hanger
(see above). The spring eyes may use a 36mm OD / 18mm ID bushing or they may use a 30mm OD / 18mm ID
bushing, similar to the earlier pickups. The bushings are typically
not sleeved and instead make use of an 18mm dia. pin with a 14mm dia.
shoulder that is threaded. We now have a poly bushing solutions for both these sizes
vehicle, with several options, depending on application. All the options are
equally good, it all depends on what you want as a finished solution.
For OEM replacement, we can machine custom 36mm OD spring eye bushings, which
normally come with a 19mm OD / 14mm ID steel sleeve. That sleeve can't be used
with the OEM 18mm shackle pin or spring hanger bolt. Instead we can supply a heat shrink
sleeve that can fit over the 18mm pin and fill up the 1mm space inside
the poly bushing. This option costs $54.00/pair of bushings + heat shrink sleeves, enough to
replace one spring eye on each side. Order two sets if you want to
replace both pairs of spring eye bushings on both sides.
For 30mm OD spring eye bushings, just order the 30mm / narrow bushings. We can also build
spring shackles for this size bushing that use 18mm dia. bolts top and bottom.
For replacement spring shackle + bushing applications, we can supply
the 36mm dia. bushing with the 19mm dia sleeve and then make the
shackles with a 14mm dia. lower bolt to fit inside the steel sleeve that fits the bushings.
This bushing setup (for the rear spring eye only) costs $50.00 for the
pair. This is how the pickup and Tacoma shackle bushings are setup.
For the forward spring eye, the 36mm OD. bushing needs the heat shrink sleeve if
you're planning to use the factory spring hanger and 18mm bolt. Another option is
to drill out the holes in the spring hanger on the frame to 3/4" or 19mm and then
use that size hanger bolt. We can supply that bolt in both greaseable and non-greasable versions,
let us know the approximate length of the existing bolt so we can try to match that length.
This should not be too hard to do if you have access to a 1/2" low speed drill and a suitable
stepped down, Silver-Deming type drill bit with 1/2" shank and 3/4" cutting diameters.
Drill bit link.
The existing holes will guide the drill bit and you're only taking out a small amount of metal.
Sorry the T-100 bushing options are so complicated. Blame Toyota for using one-of-a-kind
bushings on the T-100 springs. For decades before and after, they used either 30mm or 40mm OD bushings,
then out of the blue, they use 36mm for this one model. Unfortunately, with this small market size,
aftermarket bushing mfgs. don't see enough volume to justify the cost of tooling up to make a special
size bushing. Also, 36mm doesn't match any imperial size bushing, like 1-1/2" which is commonly used on domestic trucks.
On the T100 shackles, we can build the shackles as pictured here.
By adding a pair of sleeves, either 18mm or 19mm outer diameter, this setup can work with the stock bushings (18mm) ID
or the 36mm poly bushings if you later decide to swap to those. Simply add a pair of steel sleeves to the shackle
order and let us know which diameter sleeve you want.
Steel bushing sleeves are available to step the 18mm or 3/4"
bushings down to accept 14mm or 9/16":
Cost is US$7.50/sleeve:
Specify length and Outer Diameter and Inner Diameter of sleeve(s)
Standard size for Toyota Pickup/4Runner/Tacoma spring eyes is 14mm ID,
18mm OD and 70mm (2.75") length.
T-100 uses 18mm bolts in most cases
For OME springs/bushings, we can supply the sleeves for the 18mm ID
bushings to step them down to fit stock size 14mm or 9/16" hanger
bolts. OME doesn't seem to supply new sleeves with their bushings and expect
that you'll be re-using the original ones, so be advised.
We can also supply sleeves in 19mm or 3/4" OD which fits into many
aftermarket poly spring bushings. Energy Suspension bushings will often have a
19mm or 3/4" ID on the bushings and that needs a similar sized sleeve if you
want to run a 14mm or 9/16" bolt.
We can also supply a complete shackle/bushing/sleeve setup if you want
to replace an unsleeved shackle setup with a sleeved setup, or vice
Just let us know what you currently have and what you want to end up
with and we can help you do that.
Ordering/payment options below:
Shipping is additional, based upon weight and destination
Add 9.0% sales tax for shipments to a California address:
Automatically added if using the Buy Now buttons below
If you live outside of California, no sales tax applies
US Delivery: $15.00 for regular or $18.00 for insured Priority Mail shipping on
shackles, or $9.00 for smaller items like bushings or bolts
International shipping options below:
US$35.95 for smaller items like bushings or bolts (subject to size and
4 pound USPS flat rate weight limits)
US Mail shipping to Canada/Mexico: US$54.95 for all the above kits
US Priority Mail shipping to Europe/Central and South America: US$79.95
for most items
US Priority Mail shipping to Asia/Australia/New Zealand: US$81.95 for
For total weight up to 20 pounds
Typical shipping time is 6-10 days
Purchase w/ small US shipping
- Adds US$9.00 shipping automatically
- For bushings, bolts, sleeves, etc. that
- fit in a small envelope/box
Purchase w/ uninsured US shipping
- Adds US$15.00 shipping automatically
- For shackles, etc.
Purchase w/ insured
- Adds US$18.00 shipping automatically
- For shackles, etc.
Purchase w/ other shipping option
- Add custom shipping cost to order total
In the Payment For field, enter the vehicle and length
For example: 2" longer than stock rear shackle for 19xx
Toyota Tacoma pickup or whatever specifics appropriate to
In the Price field, enter the parts total and shipping
if using the custom shipping button
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In the Note To Seller field, enter any specific options
you want in the order.
Vertical bolt style for leaf-sprung Toyota rear axles (1st gen
4Runner/Surf, Pickup and T-100 w/ ~24mm bolt hole spacing))
Due to the factory bolt hole spacing, the minimum height bracket is
approx. 1-3/4" in this style.
Horizontal bolt style for coil-sprung Toyota rear axles typical on the
Order the size bracket to match your rear axle lift, so for a 2"
lift, order a 2" bracket, etc.
How much lift do I have?
Well, if lifting a stock truck, measure the stock height, say from the
top of the wheel to the fender before and after the lift, difference =
suspension lift height.
And you want to judge the lift from stock height if at all possible as
the stock LSPV rod attachment was designed for the factory height, so
if your rear end was sagging 2" below stock height before you
lifted the truck and you ended up 2" above stock height, you only
need a bracket to handle the 2" above stock height, not the full
4" of lift.
Forgot to measure the "before" height, well then make an
educated "guess" at the lift.
For an estimate on stock height on '86-'95 pickups and 4Runners, the
stock height up front is 13.5" - 14" from the top of a
15" wheel to the highest point of the wheel well arch (with no
body lift). If a body lift is installed, adjust that distance for the
height of the lift. Then to translate that to height at the rear axle,
measure up from the ground to the frame rails, behind the front wheels
and in front of the rear wheels. Select a flat area of the frame as far
apart as possible. Then take the difference in those two heights and
multiply by the wheel base divided by the distance between the two
point you measured the frame heights at. Then add/subtract that number
from the front height determined above. So for example, if you measured
15" wheel-fender height this says you have about 1"-1.5"
of lift over stock. Then if you measure two points on the frame
52" apart and find the rear of the frame is 1/2" higher than
the front and assuming a 104" wheel base, you have 1/2" x 104
/ 52 = 1" higher in the back then the front. So adding 1" -
1-1/2" front lift and 1" higher in back you have about
2" - 2-1/2" of rear lift, so order an LSPV bracket in that
size range. The exact size bracket is up to you, if you expect the lift
to settle a bit over time (i.e. you installed new springs), then go for
the shorter size, if you installed some used springs from another
vehicle, then they may not settle much, so order the taller size
One other option is to unbolt the LSPV rod from the axle and lift it up
until the sensing rod at the LSPV valve on the frame is approx. in the
center of it's up-down range, then measure the distance between the
bolt holes on the sensing rod and the bracket on the axle.
Since the sensing rod is adjustable, no need to get the LSPV bracket
measurement to the nearest 0.001", just to the nearest 1/2"
or so is fine.
Note that a body lift or taller than stock tires make no difference in
LSPV bracket size, it is only the rear suspension lift height that
Cost is $15.00+shipping and includes the bracket and mounting hardware:
Adjustable LSPV Bracket:
We can also build LSPV brackets with multiple holes in there to allow
for adjustability. The series of holes can be spaced at about 1"
increments from about 1" up to the maximum lift you specify, so a
3" bracket would have holes for 1" and 2" and 3" of
lift, while a 4" bracket would have holes for approx. 1",
2", 3", 4" lifts. This is a good option if you have just
installed new springs and/or are unsure of the total lift you have. New
springs will tend to settle with time and use, so your 2" lift
springs may start out with 4" or more of lift then settle down to
the 2" height after a year or so, as they settle, lower the LSPV
sensing rod on the bracket to compensate.
Spring shackles are designed to accommodate the lengthening and
shorting of a semi-elliptical leaf spring as it compresses and relaxes.
Leaf springs have a built-in arch and when relaxed have a certain
eye-eye distance then is somewhat less than the eye-eye distance when
they are flattened out. In geometrical terms, this is the chord length
vs. the circumferential length of the arc (a.k.a. arc length). So, the
shackle is designed to rotate back and forth to make up the difference
between the fixed distance from the front to back spring mounting
points on the frame and the variable distance between the spring eyes.
If you want to get really technical, James Stevenson has an excellent
analysis of Shackle
Tech. One approach to setting shackle length is to shoot for a
vertical shackle with the springs at full droop and about a 45°
angle at full compression. Here
is an article on how to mathematically determine a good shackle length
for a given spring.
Note that by installing a longer shackle, you'll be transferring a bit
more of the vehicle's weight to the axle where the shackle is
installed. Its similar to the way the stock car racers "jack"
or "add wedge to" one corner of the car to change the weight
distribution. This added weight will tend to cause the leaf spring to
flatten a bit more. If the spring was already close to its load limit,
you may find you need to beef up the springs a little with an
add-a-leaf spring. You can use a commercial kit (be sure to get one
with one or more long, thin leaves, not a short, thick leaf) or pick up
a set of similar springs at a junkyard and use one or more of those
leaves to add to your spring pack.
And, if all you are interested in is replacing the stock
shackles, we are more than happy to make you a set of heavy duty, stock
length spring shackles.
If you assume that the vehicle's engineers/designers spent a lot of
time designing the stock shackles to work well with the stock springs,
then this makes a good baseline on which to work from.
If you keep the stock springs and only want longer shackles for more
lift, see information on that topic below.
When an aftermarket spring manufacturer builds a new spring (usually a
lift spring) for a vehicle, there are a couple of basic design
strategies that can be used:
1. Keep the stock spring geometry and just use thicker and stiffer
leaves to gain lift.
This does give the desired lift but the ride quality is reduced and
suspension compliance is reduced.
2. Retain the stock arc-length (see above) but use more free arch to
gain lift (an arched leaf will be stiffer than a similar flat leaf).
The advantage of this design is that it will work fine with stock
3. Keep the stock chord length and instead use a longer free-arch which
results in a longer arc-length.
For this type of spring, you must use a longer spring shackle or else
you may find the stock length shackle will bottom out on the frame and
cause excessive stress.
For example I had problem #3 with the NWOR 3.5" lift front
springs, but did not with the same maker's rear springs, which used a
combination of options #1 and #2 above.
A good rule of thumb is to add 1" of extra shackle length for each
extra inch of arc-length. For example, when I installed 47" long
rear springs in place of my 45" long front springs, I used a
2" longer (5.5" overall) shackle and it works perfectly. Note
this rule of thumb applies if you are retaining the stock spring and
shackle hanger locations. If you move those, adjust the shackle length
as needed. And you still need a shackle long enough to accommodate the
length change in the spring as it flattens.
Basic rule is they should be long enough to accommodate the change in
length of the spring. Ideally, a shackle should swing from about
vertical at full droop to kicked back 30-45° at full compression.
A shackle that is longer than necessary won't move as far and can lead
to a less supple suspension. I found the following on-line calculator
handy for working out shackle lengths:
Just measure the spacing of the spring mounts, the length of the spring
and shackle and work out the angles. It'll help if you enter your data
such that it somewhat matches the on-screen diagram. So make A be the
shackle hanger location, C be the spring hanger and B the bottom end of
the shackle. So A-B is the shackle length, A-C is the straight line
distance between A and C and B-C is the flattener length of your
Or see James's Shackle
Tech page for the nitty gritty details.
If you want to skip to the "Executive Summary", do so now.
Otherwise, here is the explanation, and realize there is no exact
answer to this question... Given a spring with the axle located about
midway on the leaf, every 2" of extra shackle will equate to
1" extra height at the axle. Usually, you'll get a bit more than
that, since the longer shackle won't be kicked back as far. So,
for a rule of thumb, figure between 1/2 and 2/3 of the extra shackle
length will be seen as lift at the axle. Why is this?
Look at the springs, one end is fixed to the frame, the axle is
connected to the spring about in the middle and the shackle is
connected to the spring at the other end. So every 1" of change at
the shackle, make 1/2" of change at the axle and 0" change at
the fixed hanger. And since it is frame to axle separation that defines
suspension lift, you only see about 1/2 of the additional shackle
length in the form of suspension lift. If in doubt, draw a simple
sketch of a triangle with the shackle being the short end. Make one
version with a short shackle and one with a long one. See how the axle
moves away from the frame as the shackle length changes.
As an aside, the following will illustrate some of the pitfalls people
make in measuring spring shackles (a compression shackle assumed in the
following discussion). So, I was once contacted to make a 7" lift
shackle like the person saw on another truck! I replied that this would
be a very long shackle (see above) and was the person sure it was
7" of lift? Yes, was the reply, that shackle is 7" long!
Ah, I replied, and how is the length being measured? I found out that
the shackle side plate length was being measured, from one end to the
other. Since the only dimension that matters on a shackle is the center
to center distance between the two bolts, one must ignore the ends of
the shackle, so assuming 1" overhang on each end, the 7" long
shackle is actually only 5" center to center (7-1-1=5). So then
is this a 5" lift shackle? No, see above note, so then this is a
2.5" lift shackle, right? Wrong again, lift and length is measured
relative to something, you can't have a 0" shackle, see FAQ #1. So what is the shackle length measured
relative to? Logically, if you want to describe a lift relative to
stock vehicle height, you should also measure the shackle length
relative to the stock length. So, assuming a stock Toyota spring
shackle in the above discussion (which is ~3.5" center to center)
the above shackle is actually 1.5" longer than stock
(5-3.5=1.5) or a simply a 1.5" longer shackle. And referring to
the beginning of this FAQ answer, we see that a
1.5" longer shackle gives between 3/4" and 1" (1/2 of
1.5"=3/4", 2/3 or 1.5" = 1") of lift. So the point
of this rather long discussion was to illustrate how measuring and
interpreting the wrong dimensions can make someone believe a 1"
lift shackle is a 7" lift shackle!
So, back to the original question, how much lift will I get? Assuming
the spring is a simple rigid beam and the axle is locate mid-way along
its length, then the above rule of thumb applies, 1" of extra
shackle length = 1/2" of lift. However, a number of factors can
complicate the issue. First, the axle may not be at the center of the
spring. If its located closer to the fixed end, the lift/length ratio
is reduced, if closer to the shackle end, it is increased accordingly.
Then the spring is not a rigid beam, its a flexible member. So the lift
gained will be influenced by the weight distribution on the vehicle
(front to rear) and the relative spring rates at both ends. If the
longer shackle is placed on a relatively light end of a vehicle or on
the end with a relatively stiff spring, you may see more that the
simple lift/length ratio of lift, since after all, the end of the
spring attached to the shackle is pushed down the full amount of the
added length so in the limit, you may see up to that much lift at that
end of the vehicle then proportionately less as you move to the other
end. To further complicate matters, you also need to account for the
relative stiffness of the leaf spring in terms of front and rear
halves. If the spring is not perfectly symmetric, you'll find that the
longer side is softer than the shorter side.
Anyway, given all the above, there is really no 100% accurate way to
predict how much lift a given shackle will provide. If you find some
place selling "2 in.lift shackles", you should really ask
them if they can guarantee that lift. The only thing 4Crawler Offoad
can guarantee is that the shackle will be so many inches longer than
stock, your lift may vary. When we make a set of shackles, we
start by taking a piece of steel and measure out so many inches of
length and make a cut there. We have yet to find a "lift"
tape measure, all the ones we have found just measure length.
Also, realize that any lift you get will be off what height your
suspension currently is at. So it you are starting 1" below stock
(due to sagging springs), you would need 1" of lift just to get
back to stock. Likewise, if you already have some sort of suspension
lift, say from lift springs, your height change would be based off of
your current suspension lift height.
Using the above rule of thumb, figure the lift you
want will be about 1/2 to 2/3 the additional shackle length. So you'll
need to decide that if the lift comes out more or less than you wanted,
which way would you "be happy"? That is, if you want at
most 1.5" lift, then choose a shackle in the
2"-2.5" longer range. If you want at least
1.5" lift, then go for a shackle in the 3" longer range. Why
might this matter? Well, maybe you need to fit your vehicle into a
garage and the garage door opening might limit the overall height. Or
you may want to level the vehicle, especially one with an IFS type
front end. So if, for example, the front is lifted 1.5", then you
would want the rear lifted at least 1.5" and a little more is OK.
The basic difference is the wide body shackle maintains the width of
the widest bushing and uses two long bolts, while the bent side plate
tries to duplicate the stock shackle design and configuration. Wide
body shackles work well in the front, where they provide enough
clearance to avoid hitting the frame under compression. For
applications where clearance is not an issue the bent side plates are
Sure, many do and often for less money, too. If they have what you
need, length and design wise, then by all means get the lower cost
shackle. Although do your research, too often inexpensive shackles will
use SAE style hardware that won't fit the metric bushings used on
standard Toyota leaf springs. If you do get a set of these shackles, I can supply bushings to fit them. Also,
if you are looking at an unbraced shackle design, be aware of the
problem of having the nuts back off the shackle bolts. Make sure the
shackle has a design feature to prevent this from happening.
Yes, greaseable bolts are available, the cost is $13.00/bolt or
$50.00/set of 4 in addition to the cost of the bolt itself. For
example, for a set of 4 shackle bolts, parts cost is $35.00, add $50.00
to the cost, for all 4 bolts in greaseable versions). You can also send
in your own shackle bolts to have them made "greaseable" if
you wish, at a cost of $15.00/bolt. Also available are selected spring
hanger bolts. These would include the 14mm bolts for the forward spring
hangers on vehicles using the sleeved 40mm OD bushings. Hanger bolt
pricing and options are the same as shackle bolts.
The bolts are "gun-drilled" from the head end to the middle,
then cross-drilled to allow the grease to exit the bolt. The bolt head
is tapped for a 1/4-28 thread zerk.
1. This allows the zerk to be replaced with a 1/4-28 screw for use on
the trail, preventing the problem of a rock or log scraping the zerk
off the shackle bolt.
2. These button head allen screws are available for purchase at a cost
of $1.00/screw, typically you only need to plug the lowest holes on
shackles, the upper zerks are typically close enough to the frame to
A couple of things to consider with greaseable bolts:
1. You need to replace stock rubber bushings with
polyurethane, since petroleum-based grease will attack rubber. Also
note that with stock rubber bushings, grease is really not needed
anyway. The carbon black in rubber helps to lubricate the bolt and
often rubber bushings have steel sleeves bonded inside and there is
thus no sliding contact that needs grease anyway. Simple rule of thumb:
poly=grease, rubber=no grease.
2. For maximum effectiveness, the bushings should not have a
steel sleeve installed, since the idea of the greaseable bolt is to get
grease in between the bolt and the bushing. If a sleeve is present then
the grease can't get out of the sleeve.
3. For example, on Toyota bushings, the sleeves have an ID
of 14mm and an OD of 18mm and in the poly bushings, the sleeve is
easily removable. So, if you want a greaseable bolt in a normally
sleeved bushing, simply order the poly replacement bushing, omit the
sleeve when installing it and specify that the bolt for the shackle be
made in 18mm instead of the stock 14mm size.
The biggest issue with adding a shackle lift is that you are working
with a triangle. One side is the frame, the 2nd side is the spring and
the 3rd side is the shackle. The frame stays the same and if the
shackle gets longer, the angle of the spring must therefore tilt. The
axle is attached to the spring and it therefore tilts and since the
differential is attached to the axle, it too tilts, changing the angle
of the pinion flange. On typical Toyota spring lengths (i.e..
48"), you can figure about 1° tilt for each extra inch of
shackle, more or less. So, adding a 3" longer shackle can tilt the
pinion flange of the differential up 3° in back or down 3° in
front. But it is hard to give exact figures, best to measure the
angles and then correct
the difference. It is hard to give exact formulas or advice
here, as adding a longer shackle, while changing the pinion flange
angle, also raises the height of the rear pinion (drops the front one),
which in turn lessens (increases) the angle of the driveshaft.
Depending on the style of driveshaft you are running all these changes
may either be good or bad. You may even need
to add shims under the springs to correct the angles.
Also, while a longer shackle will give your vehicle some lift, it won't
make up for an overloaded leaf spring. That is it won't increase the
spring rate, so if the springs were sagging because of too much load,
they will still be sagging after installing a longer shackle. The only
difference is they will be sagging "higher" than before. Also
a longer shackle can allow for more negative arch under compression,
unless a taller bump stop is used. As such this can contribute to
fatiguing a marginal spring pack faster than normal.
Finally, on many 4x4 vehicles, like Toyota, the rear axle has a
"Load Sensing Proportioning Valve" (LSPV) that attaches to
the rear axle to sense the ride height and by inference, the load or
weight on the rear axle. It uses this "Load Sense" to adjust
the front-rear brake pressure "proportioning" to keep the
brakes balanced. With a rear axle shackle lift, for each inch of lift,
you'll want to adjust the LSPV upward 1" to compensate for the
lift. If not done, the LSPV "thinks" there is less load in
the rear of the truck and it reduces the rear brake pressure. A relocating bracket is available for Toyota
trucks, or you can make your own.
If you can provide us the dimensions of the shackles, we can take a
look at the specifications and give you an estimate. What 4Crawler
Offroad will need to know are the following:
The length, center to center on the stock shackle bolts (dimension A).
The inner width of the top (dimension B) and bottom (dimension C) of
the stock shackle.
The diameters of the shackle bolts, i.e. the ID of the bushings in the
spring eye (dimension E) and shackle hanger (dimension D)
Note, these dimensions may be different than the size of the nut on the
end of the bolt in the case of a shouldered shackle pin or bolt.
See image below for a typical spring shackle and an illustration of the
sort of data that is needed. Note the use of metric dimensions, since
it was an import (Toyota pickup) shackle, but 4Crawler Offroad is
perfectly capable to work with imperial units as well (in fact, its
best to use imperial units when measuring domestic shackles):
And for example, the leaf-sprung Mitsubishi vehicles use the same size
and design shackle as Toyota. So, many Mitsubishi Montero, Pajero, or
Dodge Raider or D50 pickup would be included (coil-sprung vehicles
excluded). The table below has some typical shackle dimensions for
various vehicles that 4Crawler Offroad has specifications for:
Toyota Hilux Pickup
Toyota Pickup Hilux
Mitsubishi Montero, Gen1
Mits MityMax, Dodge D50
Mazda B-series 2WD Pickup
(*) Offset side plates, ~12mm on the outside and ~20mm on the inside
(**) Bushings with sleeves from the factory
Some later model 2WD pickups will use a 30mm outer/18mm inner diameter spring eye bushing at the rear
of the spring and an 18mm dia. bolt or pin. If you have this arrangement, please let us know when ordering
so that we can build shackles to match.
Some T-100 models may use 18mm lower pins stepped down to a 14mm threaded end instead
of 14mm pins with 18mm sleeves, so be sure to check which you have. You can't tell just by the size of the nuts,
as both the stepped down 18mm and the 14mm pins will both have 19mm wrench size nuts, see the above photo.
You may need to remove the nuts and side plate in order to look at the diameter of the pin where it fits in the bushing.
With the stepped down or shouldered bolt, you'll see the bolt with the machined shoulder inside the bushing.
With the bolt + sleeve version, you'll see the sleeve on the outside with the bolt in the middle.
There also seems to be 2 styles of shackle hanger, one is the standard
below the frame type and the other is a through the frame type, let us
know which style you have.
Thus there are 3 options on the T-100:
1. 18mm bolts top and bottom if you know you have 18mm bolts in the
2. 18mm top and 14mm bottom if you have a sleeved bushing in the spring
eye with a 14mm bolt like our poly bushing option.
3. If you don't know which you have and want to cover all the bases,
specify 14mm bottom bolts and add a pair of 18mm sleeves ($15.00 for
the pair) and then you can for with all spring eye bushing
We can make the shackles for sleeved or unsleeved pins and can supply
sleeves in cases where it's desired to replace a stepped down pins with
(***) May also be 16mm, so best to measure before ordering.
Usually the 1st gen Monteros use 18mm top and bottom bolts
The pickup models often use 16mm bolts, best to check what is on your
vehicle prior to ordering
On the Mazda B-series pickups, 1 inch over stock length is a good fix for trucks with lowering springs
that are longer than stock. This helps prevent the shackle from inverting up onto the frame.
The Toyota shackle pins/bolts will typically have am M14-1.25 thread on
the ends, regardless of bolt diameter.
That is the 18mm bolts will have a shoulder and smaller diameter on the
end that sticks though the inner shackle plate.
Also, 4WD Toyota shackle dimensions shown above, but the same vehicle
w/ 2WD will typically have the same sizes, but best to check.
If different, supply that information along with the shackle order
For example, some of the 1-ton 2WD pickups use 40mm bushings on both
end of the shackle and 14mm bolts.
Pictured above are examples of unbraced and braced shackles. In the
braced version, a steel support is welded in between the two side
plates to reinforce them. Generally, we find that for more than 2"
longer than stock up front and more than 3" longer than stock in
back, a braced shackle is a bit more stable on the road. Unbraced has
the advantage of increased flex in the springs, since the two side
plates can move independently as the spring compress and extend. Your
choice, the bracing adds $15 to the cost of the shackles. Due to the
size of the bracing material, we typically can't add bracing to
shackles that are less than 2" longer than stock. And if you want
to add additional bolt holes to the shackle, that may affect the
ability to brace the shackles.
Changing the spring shackle length will change the angle of the springs
and anything attached to them such as the axle. One end of the spring
is attached to the frame, the other end is attached to the shackle. A
triangle is formed by the leaf spring, the shackle and the section of
frame between the front and rear attachment points. Since the spring
and frame are fixed in length, changing the shackle length will change
the angle between the spring and frame. By how much? It depends on the
length of the spring and the length of the shackle. Simple trigonometry
will give you the answer, divide the added shackle length by the spring
length and take the inverse sine function. For example, on a 48"
long spring and a 1" longer shackle, the approx. angle change is
1.2°, a 3" longer shackle on the same spring would make a
3.6° change. What this means is that your pinion angle will also
change by the same angle. Whether that is an issue depends on what type
of driveshaft setup you have and where the angles are currently. I have
a full discussion of the ramifications of pinion angle changes on the
Driveshaft-101 page. Information on leaf spring degree shims
may be found on the 4Crawler Offroad shim page.
All shackles are built to order. Typically allow 1-2 weeks for
fabrication, depending on order backlog and material availability.
Allow a few extra days for greaseable bolts. Once ready to ship, a
tracking number for the shipment will be sent via e-mail.
NOTE: Due to high order volume and supply chain issues, it may take some time for deliveries, production and shipments to catch up. Order backlog could be up to 12 weeks.
All the above options will provide a suspension lift (blocks assume a
spring over axle setup). There are benefits and drawbacks to all the
above lift options.
Lift blocks are probably the least
expensive lift option (again in a spring over axle setup). However,
there can be hidden costs with lift bolts, like a new set of u-bolts.
Also lift blocks can also lead to increased axle wrap/wheel hop under
hard acceleration. Consider a lift block as a "passive" form
of lift. You get the added height but no increase in wheel travel or
load capacity on the lifted axle. If you are otherwise happy with the
current springs and just need a little more height to level a vehicle,
then a block is a good option. Note that "lift blocks" only
apply to "spring-over-axle (SOA)" suspensions. That is the
spring sits atop the axle and thus a block between the axle and the
spring would add to the ride height of the vehicle. In a
spring-under-axle setup, a block would actually lower the ride height
of the vehicle. If considering a lift block, be sure to factor in the
cost of new u-bolts, which may be required, depending on the amount of
exposed thread on the existing u-bolts. In a coil spring suspension,
the equivalent of a "lift block" would be a coil spring spacer. In a
torsion bar suspension, an equivalent of a lift block would be
something like a "dropped spindle" or a ball joint spacer.
Spring shackles can provide lift with increase wheel travel
to boot, assuming the rest of the suspension will allow that to happen.
Down sides are the change in pinion angle that can be corrected with shims. If you are otherwise happy with the
current springs and just need a little more height to level a vehicle,
then a longer spring shackle is a good option. Spring shackle
"lifts" only apply to vehicles with "compression"
shackles, that is where the leaf spring pushes up on the spring shackle
that in turn pushes up on the frame to support the weight of the
vehicle. The other type of spring shackle setup is a tension shackle
where spring pulls up on the shackle that in turn pulls up on the frame
to support the weight of the vehicle. In a tension shackle setup, a
longer shackle actually reduces the vehicle's ride height. A spring
shackle lift is a good option when looking for an inch or maybe 2
inches of lift.
Add-a-leaf springs are a good option to consider if you need
to increase the load capacity on a given axle. A good option on the
Toyota springs is the Rancho
Soft-Ride-AAL kit which has 2 pair of leaves (one long thin
pair and one shorter thicker pair) that you can mix-n-match with your
existing leaves to make up the ride height and quality you are looking
for. With an AAL, avoid kits with just a single pair of short thick
leaves, they can damage the existing springs where they rest on the end
of the heavy AAL. With an AAL, consider 1"-2" lift about all
you will reasonably get. The ride may be a little bit stiffer than
before, but if you carry heavy loads frequently, then this is a decent
low cost option. And for add-a-leaves, another option to consider is
finding some used springs from a vehicle with a similar with and length
of spring pack as you have. Might find those at a 4WD shop that
installs suspension lifts or a junkyard or you might have a buddy that
recently installed a lift. Simply measure your spring width and an
approximate length of leaf that would fit your spring pack, forward and
back from the center pin location, and start digging through the pile
of used springs. Basically you just need a leaf that will fit into your
current spring pack and be a little shorter than the leaf on top of it
and a little longer than the leaf below it (if there is one). The AAL
will generally go between the overload leaf (that is on the bottom) and
the first regular thickness (or load) leaf on the spring pack.
Helper Springs are like the add a leaf spring but often take
the form of a coil spring that "helps" the leaf spring carry
the load on it. Some are in the form of air-filled shocks that you can
adjust the pressure inside to adjust the "spring rate".
Others are air bags that sit between the spring and frame to add lift.
Others are like small coil springs installed over the shock absorbers.
The final type is a coil spring installed between the leaf springs and
the frame; here
is a write-up on that option.
Lift springs are of course the best option in terms of
performance, but likely the most expensive option as well. There are a
wide variety of off-the-shelf lift spring options as well as a wide
variety of custom spring mfgs. to consider. With custom springs, best
to get your vehicle weighed (each axle separately) and then provide
that weight as well as the lift and load requirements to the spring
mfg. in order to get exactly what you need.
So which option is best for you? Depends on your needs and
your budget. Also, you may find a combination of several lift options
may work for you. For example, if you are looking for 3" of lift,
you might try to put on an Add-A-Leaf kit which might net you 2"
of lift, then if you need say an inch more lift, add a 2" longer
than stock (~1" lift) shackle on the spring. Or you could use a
lift spring to get the bulk of the lift and then add a longer shackle
to pick up any extra lift height you need or you may find the lift
spring needs a longer spring shackle to handle it's
added length. Trying to get more than an inch or two of lift
from shackles alone is probably not a good idea.
Typically not. Many stock spring shackles are built with thin side
plates and the "pins" are pressed or welded into one side
plate. The pins are typically not a proper bolt as they lack a hex head
and often have a stepped down shoulder and smaller nut on the other
end. And since the 4Crawler shackle side plates are made from 3/8"
thick steel, the added thickness likely makes the stock hardware too
short to fit. Here is a photo of a
typical Toyota shackle pin and side plate to illustrate the above.
Different years of Toyota mini trucks used different sized bushings
(30mm or 40mm OD and narrow or wide) and also these varied by which
spring (F=Front Spring, R=Rear spring) as follows:
'89-'95 Pickup/2WD *
30mm or 36mm/narrow
30mm or 36mm/Narrow
(*) On some later model 2WD pickups, the rear spring hanger will be a 30mm inner diameter.
Easy way to check is to compare the dia. of the shackle hanger bushing under the frame to
that of the spring eye. If both are the same 30mm dia., then you need the 30mm/narrow bushing
instead of the 40mm/narrow size.
(***) On the T-100 bushings, best option is to check the dimensions of
your existing bushings before ordering bushings. The T-100s seem to use
a variety of bushing sizes. We can supply them all, but the sizes are not interchangeable.
Also, front and rear spring eye diameters may be different.
Of course, with a solid axle swap (SAS) on the later model vehicles,
the bushings needed for the front springs will depend on what year
vehicle the springs came from and whether the front shackle hanger is
OEM style (through-the-frame / 30mm/Wide) or under the frame like the
rear springs (i.e. 30mm/Narrow). And by all means, if you want to
ensure that you order the proper sized bushings for your vehicle and
application, feel free to measure the bushing sizes you need on your
vehicle. The bushing outer diameter should of course match the inner
diameter of the spring eye or shackle hanger (30mm = ~1-3/16" and
40mm = ~1-9/16"). And the width should match the width of the
same; narrow means the bushing is just as wide as the spring is wide
(~2-3/8" wide). The wide bushings are of course wider than the
width of the spring (typically 3/4" to 1-1/2" wider). It is
possible to use a narrow bushing in a wide shackle hanger either as-is,
or by cutting the flange off an old bushing and using that to fill the
center of the shackle hanger with a new bushing on either side. The
center of the bushings really does not do a whole lot to support the
shackle bolt, it is mainly the outer ends of the bushings that do all
the work. So if you want to save a little money, use the narrow
NOTE: Bushings are sold in pairs, as in two bushings (each 2 halves),
enough to do two spring eyes or two shackle hangers, as in one per side
of the truck.
The above table is put together listing what size bushings were used on
the factory Toyota leaf springs for a given vehicle year.
Aftermarket springs may or may not follow the Toyota bushing sizing
scheme - some may use a different bushing/sleeve setup:
OME springs often use sleeves in both the 30mm and 40mm bushings, be
sure to check before ordering.
So it is best to measure the ID and OD of the spring eye bushings you
have on your vehicle and go with what will fit them. So, if your spring
eyes measure 30mm ID, then you need a 30mm OD bushing to fit inside the
Spring eyes will always be of the narrow variety, as that is what
defines the narrowest component in the system.
The spring hangers will either be the same width as the spring eyes, or
they will be wider.
SuperLift springs tend to use 30mm ID spring eyes and bushings
OME springs can use a mix of 30mm and 40mm ID spring eyes and bushings,
so be sure to check with you need.
Rancho springs will use a different diameter spring eye bushing that
the OEM springs do, and they typically require use of Rancho-specific
So how many spring shackles are on a vehicle? Generally, assuming a
leaf sprung suspension, you'll have one spring shackle on one end of
each spring on a given axle. So for one axle, you'll typically have one
spring on each side, so 2 springs = 2 shackles or 1 pair of shackles.
If you have 2 leaf-sprung axles, then you have 2 pair of axles and thus
2 pair of shackles.
A related question; can you put 2 shackles on one spring, as in one
shackle on each end of the spring? Generally not, since there would be
nothing to locate the axle fore-aft. Normally, the fixed spring eye at
one end of the spring provides the axle location front-back and the
shackle at the other end lets the spring length changes as it moves
In some cases, folks will run a "double-shackle" on a rear
spring for increased wheel travel. The idea is that you have two
shackles linked end to end. The upper shackle normally stays flat
against the bottom of the frame while the lower shackle works normally.
Then when the suspension unloads and the axle drops away from the
vehicle, the upper shackle can swing down and increase the wheel
travel. While this does work in theory, that added wheel travel is
basically "unweighted", in that the only weight on that wheel
is the weight of the axle, wheel and tire. Since the traction the tire
can generate is proportional to the weight it puts onto the ground, the
"unweighted" tire will provide little added traction. So
while you have several extra inches of wheel travel, if it does you no
good, what is the point?
We have 2 shackle options for the B-series pickups running the Belltech lowering springs.
Both are 1" longer than stock, similar to the T-100 shackles, but feature the proper offset
sides to match the Mazda spring hanger width.
One set uses full sized 18mm dia. bolts, cost US$95.00.The other set uses 18mm dia. sleeves, cost US$125.00.
The shackles with sleeves are easier to install as you fit the short sleeves inside the bushings then slide the
shackle bolts through the sleeves. They also allow you to torque down the bolts onto the sleeves.
These longer spring shackles are needed to handle the longer than stock Belltech springs and prevent the shackles
from hitting the frame. One downside is tha added length will result in added lift height. To counter that and
also to re-center the rear wheels in the wheel well arch and restore the original driveshaft length,
we have a combined 1" lowering / relocation block.
This block is US$85.00, add $9.00 for a pair of longer center bolts. This block is designed to bolt to the Belltech
spring pack using the center bolts.
There's recesses in the block for the head of that bolt at either 3/4" or 1" offset
The block then has a 9/16" center pin that fits into the spring perch on your axle.
Safety First! Before you undertake any suspension modifications,
remember that such mods may change your vehicle's handling
characteristics and stability. Raising your vehicle's center of gravity
with extended shackles, body lifts, etc., may increase the likelihood
of a rollover, especially at high speed or on uneven terrain. Hence,
all 4Crawler Offroad products are designed and intended for off-road
use only. It is entirely your responsibility to determine the fitness
and suitability of this 4Crawler Offroad product for your application.
4Crawler Offroad will accept no responsibility for any unsafe
condition, damage or personal injury arising from your use of this
product. 4Crawler Offroad products should only be installed by those
knowledgeable and experienced with leaf sprung suspensions. Your safety
depends on it!
Park your vehicle on a hard, flat surface and apply the parking brake.
Chock both sides of rear tires if you're working on the front or chock
front tires if you're working on the rear. Be sure the vehicle can't
Use floor jack under the axle to lift working end until both tires are
3-to-4 inches off the floor. It is not necessary to remove wheels and
tires. Place jack stands under frame rails, close to the spring hangers
you'll be working on. Lower vehicle onto jack stands, but leave floor
jack under axle. You'll use it to raise and lower axle during shackle
installation. Make sure jack stands holds the vehicle securely.
Be sure axle is again supported by floor jack. Un-bolt and remove old
shackle bolts and shackles. Slowly release floor jack pressure until
tires rest on floor or work surface.
Inspect shackle mounting places, including perches, frame mounts and
bushings, for excessive wear or damage. Damaged or worn parts must be
replaced with new ones or repaired to as-new condition before the
shackles are installed.
Install shackles into upper mounts, probably easiest to install the
bolt from the outside, placing the nut on the inside. Apply nuts, but
do not tighten all the way yet. The shackle plate with the
anti-rotation tabs should ideally be on the same side as the head of
the bolt, but it can be placed on the side with the nut if desired.
Use floor jack to raise axle until spring eyes and bushings fit into
shackles and insert the bolts. You may want to apply grease to bolts to
ease installation and reduce squeaking from poly bushings. Do
not grease bolts if using rubber bushings, the petroleum base of the
grease will attack and destroy the rubber bushings, so if you want to
lubricate the rubber bushings, use a silicone-based lubricant.
You may need to tap bolts with a rubber mallet during installation. Do
not force a bolt if it catches or there is excessive resistance. Use
floor jack to realign holes correctly. Excessive hammering can ruin
bushings and deform shackles.
Tighten nuts on the shackle bolts.
If using a plain bolt and lock nut, do not over tighten nuts until
bushings bulge or shackles bend. Over tightening can "freeze"
your suspension and prevent it from cycling properly. The ideal
tightness with polyurethane shackle bushings is to just tighten the nut
until the bushings just start to compress. With the locking tabs on our
shackles, the bolt will not move and with the nylon locking ring on the
lock nut, the nut will not move, so you don't have to use a specific
torque on the shackle bolts, just tighten until you see the bushings
just start to compress and that is enough.
If using a sleeved bushing or a factory-style shouldered bolt, then you
can use the Factory torque specification of 67 ft.lbs. of torque on the
bolt and nut, as the sleeve or shoulder on the factory shackle pin
prevents the bushing from being over-compressed.
Recheck all fasteners for proper tightness and inspect periodically for
Ideally you want the front brakes to lock up slightly before the rear
brakes do. To test this, find a vacant parking lot (wet) or a dirt or
gravel road. Drive up to about 15-20 MPH and brake hard to try and lock
up the tires. Make sure the front tires lock up first. If the rears
lock up too soon, shorten the adjustment on the LSPV sensing rod to
lower the arm on the valve. Likewise, if the rear braking is too weak,
lengthen the sensing rod to raise the arm on the valve and increase
rear braking effort.
One is a split bushing without a sleeve, to replace these, simply pry
each half of the old bushing out of the spring eye or hanger.
The second type is usually a one piece bushing with a sleeve bonded
into the center and often a sleeve on the outside of the bushing.
These bushings are typically pressed into the spring eye and will need
to be pressed out.
Lacking a press, you can often use a small drill and drill a series of
holes around the rubber between the inner and outer sleeves. The idea
is to remove the center sleeve by cutting it free from the rubber. Then
you can try using a SawZall to cut outward from the middle through the
outer sleeve in one or two places to loosen it up.
You can also try using a pry bar at the closing gap of the spring eye
to open that up a bit. The idea is to loosen the grip of the spring eye
on that pressed in bushing.
And a final option is to use a hammer drill (that you can set to
hammer-only mode) or an air hammer to drive out the old bushing. Use a
blunt ended adapter in the drill or hammer and put something heavy
behind the spring to push against. Then use the drill or air hammer to
drive the bushing out with repeated blows. Note that a regular hand
hammer probably won't work for this task as the spring and bushing will
have time to "spring" back between hammer blows. But with a
hammer drill or air hammer, you are putting in thousands of blows per
second and that does not allow the spring or bushing to
"spring" back between impacts. One advantage of this
technique is that you can do it with the springs still attached to the
vehicle. All you need to do is drop the spring eye out of the shackle
or hanger far enough to get a straight shot at the bushing.
The important considerations with replacing these one piece bushings is
to be sure you need to replace them and if you need to replace them,
figure out how you are going to do so before you order the bushings.
The replacement poly bushings are of the split variety and easy to
insert the replacement bushings, one half from each side.
With the polyurethane material you can use any sort of lubricant you
wish, silicone grease works well, or you can also use something like a
graphite loaded wheel bearing grease to help reduce friction and
squeaking with the new bushings. Over time, the graphite in the grease
will build up on the surface of the bushings and provide lubrication
for a longer period of time.