

Custom Leaf Spring Shims
Visitor #
82323
since 13.AUG.2001
NOTE: 4Crawler Offroad/MissingLinkZ will be on reduced operations until 29.MAY.2008. New orders may not be processed until that date and e-mail response may be delayed. Stay tuned to this page for updates.

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On leaf-sprung vehicles, shims (or wedges) are often used to modify the
angle between the spring perch on the axle and the leaf spring itself.
The correction may be needed because of longer spring shackles tilting
the pinion out of alignment, or to change from a single-cardan to a
double-cardan drive shaft (for increased drive line angle capability),
or to correct steering geometry (so your trucks handles better). An
alternative to shims is to cut off the spring perches and re-weld new
ones on at the corrected angle, but this is a lot of work and requires
careful measurement to get things lined up properly.
Anyway, for whatever reason you need a shim, you do need one. And if
you need one you probably need an exact angled one, not just the angle
or two the shop has. When I needed shims, I found one shop that had
3° and 6°, and another that had 4° and 8°. All of
these shims were aluminum, and not the nice strong billet aluminum, no
they were cheap cast aluminum. Cast aluminum can be brittle, and it
tends to fatigue or deform over time, and ultimately break. On the rear
axle, this can be a pain if it happens on the trail, if it happens on
the front axle, this can be downright dangerous.
Since I had only been able to find low quality cast alloy shims
available and only in limited angles, I decided to make my own shims
from a solid piece of mild steel, cut to the desired angle. Then a flat
seat for the center bolt head is cut into the base to eliminate stress
at that critical point. These shims are much more resistant to breakage
than cast alloy shims. After locating a material source, developing the
mfg. process, and forming a company to produce them, 4Crawler Offroad
can now make these made-to-order shims available to others. If you want
to "roll your own", click here
for a VRML model of my shim design (5°). These shims are used
to correct drive line and steering angles on leaf-sprung vehicles. Feel
free to read my article on measuring drive
line angles here before ordering. Finally, for permanent mounting,
steel shims can easily be welded to the spring perch. No worries about
shims breaking, twisting or falling out on the trail.
Lift blocks are similar to shims, except they are designed to add lift
(to a spring over axle) or drop (to a spring under axle) and optionally
may have a bevel cut in the top for pinion angle correction. Common
aftermarket blocks use extruded aluminum sections. The thin wall
material is prone to fatigue and cracking. 4Crawler Offroad can also
make solid billet aluminum lift blocks with built-in angles. With the
solid material, the blocks will hold up to the heaviest vehicles and
loads.
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Below, you can see a few versions that 4Crawler Offroad has produced
over the years:
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Photo A: Is a typical bolt-on shim, it is drilled for the center bolt
to go through, there is a bolt head relief flat ground or milled to
allow the bolt head of the center bolt to rest flat, then the shim is
bolted to the rest of the spring pack. With aluminum shims, this is
your only option.
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Photo B: In the center is a picture of an 8° weld-on shim. Since
the shim is steel and the spring perch is steel, one way to ensure the
shim stays put is to weld it to the spring perch. Then, the head of the
center bolt goes into the hole in the shim, so you don't need to remove
or replace your old center bolt.
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Photo C: On the lower right is a custom width 2° bolt-on shim,
3" wide, 5-3/8" long cut from 3/8" stock for minimum
thickness
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Photo D: A pair of tapered lift blocks in billet aluminum with pressed
in locating pins
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Photo E: A pair of shims with offset center holes for use with
relocated axles via offset spring perch holes
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Photo F: A pair of axle relocation plates, locating pin locks the plate
into the perch, new holes allow spring to be moved forward or back as
desired.
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The maximum length of the steel shims will depend upon the angle and
the material used:
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At 12°, 4-1/8" long is about the limit on shim length using
my thickest 1" stock
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At 10°, 4-3/4" long is about as long as can be cut
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Shims can be extended the above lengths about 1" with a welded on
extension piece or laminated up in thickness.
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Or shims can be cut from billet
aluminum
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| A: 3° Bolt-On Shim |
B: 8° Weld-On Shim |
C: 2° Bolt On 3" Wide |
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| D: 10° tapered AL block |
E: Offset Center Holes |
F: Spring Relocation Plates |
Below is a closeup of some of the design details 4Crawler Offroad
incorporates in the shims. First is the above mention center bolt head
relief pocket. Also, each shim is stamped in 1 or 2 places with the
angle it was cut to. This will come in handy down the road when you
need to change angles for whatever reason. On several occasions,
customers have run into trucks with existing shims (of unknown angle)
where it is needed to add or subtract a few degrees. Without pulling
the shim out, its very difficult to get an accurate angle off it. With
the angle stamped into the end and the face, it should be visible in
most situations.
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| Closeup of shim details |
Weld-on vs. Bolt-on shim |
In the image above-right, is pictured a weld-on and bolt-on shim with a
spring center bolt in the middle. The weld-on shim has a center bolt
hole large enough for the head of the center bolt to fit. The shim
itself is designed to be welded to the spring perch, in effect becoming
a permanent part of the perch. The bolt-on shim has a center bolt hole
only large enough for the shaft of the center bolt to fix. The head of
the center bolt then fits into the machined pocket in the shim and then
engages the hole in the spring perch as normal. In this case, the shim
becomes part of the spring pack.
Note the difference between the thin shims and the thick tapered
blocks. In the shims, there is only a hole in the middle. In the
blocks, there is a hole on one side and a pin on the other side. So,
can shims be made with a hole/pin combination? Unless the center of the
shim is thicker than 3/4" - 1", there is simply not enough
room for a hole deep enough for the head of the center bolt (they can
be up to 1/2" tall) and the pressed in pin, which needs to be
3/8" or so deep. Since all the "shims" are made under
1/2" thick, they can only be had in the thru-hole design. If the
hole/pin design is desired, then a tapered block will be required.
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NOTE: 4Crawler Offroad/MissingLinkZ will be on reduced operations until 29.MAY.2008. New orders may not be processed until that date and e-mail response may be delayed. Stay tuned to this page for updates.
4Crawler Offroad can machine solid steel axle shims,
custom angles, 1°-12°, made to your specifications:
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Note: Due to material limitation, there are certain angle vs. length
limits for the steel shims as noted below:
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12° = 4-1/8" long maximum
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10° = 4-3/4" long maximum
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For longer high angle shims, extensions can be welded on; order the custom width shim for 2"
wide high angle shims or aff $10.00 to the cost for custom width shims.
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With welded-on extensions, 12° angle can be cut up to 5-1/8"
long and and 10° up to 5-3/4" long
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Laminated steel shims allow for shims up to 6" long and/or angles
above 12° to be made
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8° or less can be cut up to 6" in length
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Steeper angles can be cut as well, using the billet aluminum material
which is available in greater thicknesses
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Or in steel, order 2 pair of shims and the 2 pieces of steel will be
laminated/welded into one thicker piece of stock and a single shim will
be cut.
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To find out what size shim you need, measure
the length and width of the spring perch on the axle before ordering.
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Ordering a shim longer than required is not "better", it will
only make the shim thicker than needed and the extra shim length will
likely just be bent over the end of the spring perch.
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Shims exceeding the above sizes/angles will incur additonal cost, inquire
for an estimate before ordering.
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1" thick is the maximum steel material thickness, resulting in a
shim with a ~1/2" center thickness.
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If thicker lift shims are needed in steel, 1/2" and 1" thick
spacers can be welded to the bottom of the shim at an
additonal cost.
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Order both the shim and the desired thickness spacer and the shim will
be supplied welded to the spacer.
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Shipping world-wide (for most countries) is included in all the on-line
ordering buttons below.
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Most items below are priced per pair (pr.).
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So when you see "Qty. 1" in the order form, that is "1
pair" or 2 shims.
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Unfortunately, it is not possible to alter the order form to reflect
the per pair quantity.
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If you want 2 shims of the same dimensions, order 1 pair (Qty. 1).
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If you want 2 (or more) pair of shims, order quantity 2 or more as
needed.
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Please refer to the ordering notes for
other options...
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NOTE: 4Crawler Offroad/MissingLinkZ will be on reduced operations until 29.MAY.2008. New orders may not be processed until that date and e-mail response may be delayed. Stay tuned to this page for updates.
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Any length up to 6" and 2" wide (only)
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If you want a shim wider (or narrower) than 2", order the CUSTOM WIDTH shim, below...
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Note for high angle shims (greater than
8°) or shims longer than 6":
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If you want a shim of longer length that permitted to be cut from a
single piece of stock, with order the custom length shim (see order
button below) for up to 1" longer
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Or order 2 shims and the material will be laminated/welded to increase
the thickness for a single shim.
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The shim design minimizes the length of the center bolt, but if your's
is near the end of its length, you may need to use a longer center
bolt. It needs to be long enough to pass through all the leaves of your
spring pack, the shim and any blocks you may have as well leaving
sufficient threads exposed for the retaining nut. The shim thickness
will vary with the angle, a 3° shim adds about 3/16" to the
bolt length, 5° about 1/4", 8° about 3/8", etc.
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Specify the angle desired, the length of the shim (standard shims use
2" wide shim stock), and the location and size of the center bolt
hole in the Note To Seller field of the order form.
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Cost: US$25/pr. plus shipping and applicable sales tax:
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| US delivery - $7.00 |
International delivery - $12.00 |
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| US delivery - $7.00 |
International delivery - $12.00 |
NOTE: 4Crawler Offroad/MissingLinkZ will be on reduced operations until 29.MAY.2008. New orders may not be processed until that date and e-mail response may be delayed. Stay tuned to this page for updates.
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Any width other than 2" wide (more or less), up to 3" wide
and 6" long
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Note for high angle shims (more than 8°)
or shims longer than 6":
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If you want a shim of longer length that permitted to be cut from a
single piece of stock, with order the custom length shim (see order
button below):
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Or order 2 shims and the material will be laminated/welded to increase
the thickness for a single shim.
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Shims cut from 1/2" or 1" thick stock, ideal for higher angle
shims
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Specify the angle desired, the length and width of the shim, and the
location and size of the center bolt hole in the Note To
Seller field of the order form.
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Cost: US$40/pr. plus shipping and applicable sales tax:
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| US delivery - $7.00 |
International delivery - $12.00 |
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Use the buttom below to order a high angle shim longer than length/angle limits listed above or for
angles steeper than 12°:
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Cost: US$50/pr. plus shipping and applicable sales tax:
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| US delivery - $7.00 |
International delivery - $12.00 |
NOTE: 4Crawler Offroad/MissingLinkZ will be on reduced operations until 29.MAY.2008. New orders may not be processed until that date and e-mail response may be delayed. Stay tuned to this page for updates.
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Note, spacer is flat, no taper, also known as a "zero rate
leaf"
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2" width, length up to 6" long, and heights of 3/4" or
1" tall
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Choice of mounting options:
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Bolt-on spacer has a hole for the center bolt (3/8") or as
specified
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The weld-on spacer has a hole for the center bolt head (5/8") or
as specified
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| US delivery - $7.00 |
International delivery - $12.00 |
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Want a taller block?
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Order as many 1" blocks as needed to make the height you want and
they will be welded together into a single piece.
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So, for a 2" solid steel block, order qty. 2 of the 1" tall
blocks above or below:
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Bolt-on w/ pressed in locating pin ($35/pr.):
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| US delivery - $7.00 |
International delivery - $12.00 |
NOTE: 4Crawler Offroad/MissingLinkZ will be on reduced operations until 29.MAY.2008. New orders may not be processed until that date and e-mail response may be delayed. Stay tuned to this page for updates.
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Note, spacer is flat, no taper, also known as a "zero rate
leaf"
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Width up to 3", length up to 6" long, 1" tall
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Choice of mounting options:
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Bolt-on spacer has a hole for the center bolt (3/8") or as
specified
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The weld-on spacer has a hole for the center bolt head (5/8") or
as specified
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| US delivery - $7.00 |
International delivery - $12.00 |
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Want a taller block?
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Order as many 1" blocks as needed to make the height you want and
they will be welded together into a single piece.
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So, for a 2" solid steel block, order qty. 2 of the 1" tall
blocks above or below:
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Bolt-on w/ pressed in locating pin ($45/pr.):
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| US delivery - $7.00 |
International delivery - $12.00 |
NOTE: 4Crawler Offroad/MissingLinkZ will be on reduced operations until 29.MAY.2008. New orders may not be processed until that date and e-mail response may be delayed. Stay tuned to this page for updates.
2" wide, 1/2" thick
5/8" locating pin and 5/8" holes offset 3/4" and 1"
from center standard
Custom offsets and sizes available, as well as length (up to 6"),
specify in the order Note field
Cost: $25/pr. plus shipping and applicable sales tax.
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| US delivery - $7.00 |
International delivery - $12.00 |
NOTE: 4Crawler Offroad/MissingLinkZ will be on reduced operations until 29.MAY.2008. New orders may not be processed until that date and e-mail response may be delayed. Stay tuned to this page for updates.
Over 2" wide, 1/2" thick
5/8" locating pin and 5/8" holes offset 3/4" and 1"
from center standard
Custom offsets and sizes available, as well as width (up to 3")
and length (up to 6"), specify in the order Note field
Cost: $40/pr. plus shipping and applicable sales tax.
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| US delivery - $7.00 |
International delivery - $12.00 |
NOTE: 4Crawler Offroad/MissingLinkZ will be on reduced operations until 29.MAY.2008. New orders may not be processed until that date and e-mail response may be delayed. Stay tuned to this page for updates.
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For vehicles with Toyota front axles who want to run equally arched
springs. If you run equally arched springs without this spacer, you can
see 3/4" or more tilt in your vehicle.
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Note: Use of this spacer with stock push-pull steering is not
recommended due to draglink/u-bolt clearance issues
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Bolt-on or weld-on spacers for the driver's side spring perch, raises
it to the level of the passenger side perch (3/8")
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Can also incorporate this offset into shims, blocks, etc.
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A 2" wide spacer (5-1/4" perch length assumed) costs US$7.50
plus shipping and applicable sales tax.
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| US delivery - $7.00 |
International delivery - $12.00 |
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A custom width spacer (2-3/8" spring or 2-1/2" perch width,
5-1/4" perch length assumed) costs US$12.50 plus shipping and
applicable sales tax.
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| US delivery - $7.00 |
International delivery - $12.00 |
NOTE: 4Crawler Offroad/MissingLinkZ will be on reduced operations until 29.MAY.2008. New orders may not be processed until that date and e-mail response may be delayed. Stay tuned to this page for updates.
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May be needed with bolt on axle shims.
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Bolts are threaded approx. 4" long, so can be cut to length as
needed.
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3/8" center bolts with nuts (will also replace 10mm import center
bolts)
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3/8" seems to be the most common size, but 5/16" and
7/16" are other sizes available
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All but the 3/8"x5" bolts have approx. 1.25"-1.5"
of threaded length, allow for approx. 1" longer than your spring
pack is thick plus the thickness of the shim or block
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The 3/8"x5" pin has approx. 4" of threaded length and
can be cut down to length as needed (currently out of stock, expect
delivery by early May).
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Cost is US$9.50/pr. plus shipping and applicable sales tax:
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| US delivery - $3.00 |
International delivery - $12.00 |
NOTE: 4Crawler Offroad/MissingLinkZ will be on reduced operations until 29.MAY.2008. New orders may not be processed until that date and e-mail response may be delayed. Stay tuned to this page for updates.
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Click
here for installed image
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Click here for installation
instructions
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Lengthens the e-brake arms to clear taller spring packs, or when
running blocks and/or thick shims
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Can be drilled to raise the e-brake lever attachment point between
1" and 2"
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With the spring over axle configuration, it is possible that adding a
thick shim or spacer between the axle and springs can lift the top of
the spring pack high enough that the e-brake cable rubs on the springs.
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This can reduce e-brake effectiveness and can cause damage to the
cable.
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The extensions include a hardware to attach them to the e-brake arm and
are shipped without a top hole drilled.
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This allows you to raise the e-brake cable just enough for your needs.
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Also suitable for use in a horizontal orientation to lengthen the
e-brake cables for use on a wider rear axle
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For example when upgrading from an '85 or earlier to an '86 or later
rear axle that is 3" wider, the existing e-brake cables will be
1.5" short on each side.
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For rear axles US$12/pr. plus shipping and applicable sales tax:
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| US delivery - $3.00 |
International delivery - $12.00 |
NOTE: 4Crawler Offroad/MissingLinkZ will be on reduced operations until 29.MAY.2008. New orders may not be processed until that date and e-mail response may be delayed. Stay tuned to this page for updates.
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Machined out of billet T6061 aluminum (solid block, no cast or extruded
material used).
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Price varies with height/width/length but generally ranges from
US$40/pair to US$85/pair depending on size, plus shipping (varies with
weight) and applicable sales tax.
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US shipping typically $11for regular or $15 for insured shipping
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Internation shipping: $25 to Canada/Mexico and $40 to most other
countries
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Standard mounting with center bolt hole, optionally a pressed in
locating pin is available for US$10 additional.
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Contact
4Crawler Offroad with your specifications.
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Unless otherwise specified, center bolt holes will be drilled
for 3/8" hardware (bolt -on shims) and 5/8" bolt head (for
weld on shims) and the hole will be centered in the shim.
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Note 5/16", 10mm and 7/16" center bolts are also used,
likewise, head sizes can range from 1/2" up to 3/4"
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If you are unsure of what size hole to specify, you can order shims w/o
center holes
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You can also specify off-center (e.g. 3/8" hole offset 1"
toward the thick edge of the shim) or multiple holes.
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"Buy Now" buttons above:
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These buttons will take you the PayPal secure web server.
If you already have a PayPal account, you may directly access it via
these buttons. If you do not have an account set up, or have an
unverified account, you may want to consult the following PayPal
HELP information before proceeding. And if you don't want
to set up a Paypal account, you may choose to simply enter your credit
card and address information to place the order w/o setting up a Paypal
account. Some advantages of having a Paypal account are:
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Only need to enter your information once
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You'll be able to check the status of your oder on-line, including a
direct link to package tracking information
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And with verified address and account information, your orders and
shipments will be more secure
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For oversize shim orders shipped outside the US, additional shipping
charges may apply:
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Regular shipping ($12.00) covers shimpents up to 4 lbs., this is
sufficient to cover most shim/block orders
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However, for extra thick/large shims, weighing over 4 lbs., additional
shipping charges may apply:
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You will be notified once the items are ready to ship if this applies
to your order.
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For an estimate on whether this applies to your order, a shim/block
volume larger than 12 cu.in. will tend to exceed the 4 lb. limit;
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e.g. a 2.5" wide, 5" long, 8 degree shim would probably
exceed 4 lbs. and incur an additional $10.00 shipping charge.
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For shipments to California, add applicable state sales tax
(automatically added by PayPal).
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Local pickup (for orders from the SF Bay Area) is possible, shipping
charge will be refunded upon pick up.
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Below are some commonly asked questions along with answers. Please take
a minute to browse this list and see if it answers your questions. If
not, feel free to contact me...
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How do I know what angle to make my shims or
if I even need shims?
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How do I figure out how long to make my
shims?
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How do I figure out what width to make my
shims?
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What's the difference between bolt-on and
weld-on shims?
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How accurate are the shims?
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Which way do the shims go?
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How long will it take to get my shims after I
order?
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What if I measure wrong, am I stuck with the
shims?
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Is there any "volume" discount on
shims?
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How do I order the shims and specify options?
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I only need a single shim, can I order just
one?
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Are there any drawbacks to lift blocks?
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Do you make shims for other applications?
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1. How do I know what angle to make my shims
or if I even need shims?
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You may get lucky and find someone else (on a web forum or mailing
list) who has done a similar modification to their vehicle (that is
similar to yours) and find out what angle shim they used for their
application. Or you might contact the lift supplier and ask them what
angle shim they reccommend for your type of vehicle with their lift
installed. Spring manufacturers should be more than happy to supply
this information to you.
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Short of finding out from someone else what angle shim is needed, the
only real way to know is to measure the angles. Since you are even
considering adding shims means you have somehow modified your vehicle.
Either you have added lift, changed springs, installed longer shackles,
moved spring hangers, etc. You need to get some simple measurements to
determine if shims are needed and if so, what angle shim is required.
For rear axles, you only have the worry about the angle of the pinion
in relation to the driveshaft.
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How to measure the driveshaft angles:
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Depending on the type of driveshaft you are running, the
information on how to measure may be found here.
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Front axle pinion and caster angle considerations:
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For a leaf-sprung front axle, you can use the above measurements, but
they only consider the pinion/driveshaft angles. IMHO, you really want
to first address steering angles up front (unless you have a trail-only
rig) first then worry about pinion angles. So how do you measure the
steering caster angle? Best bet is to go to an alignment shop and have
them put your truck on the alignment machine and give you a printout of
the angles. You'll get a list of toe-in, camber and caster as-measured
and they may tell you what the angles should be. If not, consult your
owners manual or a good repair manual for your vehicle. As far as what
angle to use, its a direct relationship between the number of degrees
your caster angle is off and the angle of the shim. For example if your
vehicle specs +2° of caster and you are at +5° or -1°,
you'll need a 3° shim, and just install it in the proper
orientation to correct the angle.
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Here is a link to Toyota
solid front axle steering alignment specifications. On the
Toyota front axle, an angle of approx. 6° up (front of perch
higher than the back)on the spring perch provides a decent caster
angle.
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It is not uncommon for the caster angle to be off different amounts on
each side of the axle. If so, this means that the axle housing itself
is not quite aligned side to side or that it is slightly bent. Best bet
is to get a shim to correct the average of the two angle errors. Short
of cutting off one steering knuckle and turning it to align with the
opposite side, its unlikely that you'll be able to "twist"
the housing by using two different angle shims.
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CV or double cardan driveshafts:
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One complication arises if you are correcting the pinion angle on a CV
or double-cardan driveshaft. This is because as you change the pinion
angle, the driveshaft angle is also changing. Luckily, it is relatively
easy to determine the relationship of the two angles. Basically the
angles change by the ratio of the respective lengths of the driveshaft
and the pinion extension from the axle center line. Lets say that you
measure the distance from the center of the axle to the pinion flange
or u-joint yoke and find it is 11" (as measured on a Toyota
8" axle). And lets say the driveshaft measures 55" long from
the t-case output flange to the pinion flange. This results in a 1 in 5
ratio, meaning that for every 5° of pinion angle change, the
driveshaft angle will change 1/5 of that or 1°. This is easy to
see if you sketch out the driveshaft and pinions to scale. Since the
shim is tilting the axle at it's center line and the pinion sticks out
away from that center line, it moves up and down as the angle changes.
This means the bottom end of the driveshaft moves up and down by the
same amount. But since it is much longer than the pinion length, the
angle change is reduced by the ratio of the two lengths.
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For a practical example, assume a 20° driveshaft angle and a
10° pinion angle, with a pinion length of 11" and a
driveshaft length of 55", again your measurements will likely be
different. So this gives a 1:5 ratio of angle changes. So, starting
with the 10° difference, we want to end up with the pinion angle
1° - 2° less than the driveshaft angle. So, installing a
7° shim, we would find that the pinion angle would increase from
10° to 17°. But at the same time, the driveshaft angle would
decrease by 7°/5 or 1.4°, so it would end up at 18.6°
(20° - 1.4°). This leaves an angle difference of 1.6°,
which is within the 1° - 2° target we were shooting for.
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2-piece driveshafts (i.e. center support bearing):
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For applications with 2-piece driveshafts (i.e ones with a Center
Support Bearing - CSB), there is often confusion about what to do about
the CSB. Some folks think it is necessary to shim the CSB to correct
the driveshaft angle. This is generally not something you want to do.
Why? Look at the way the driveshaft is set up. The part from the
transmission/transfer case output to the CSB is generally a
signle-cardan shaft, It has one or maybe two u-joints on it and
generally is run straight at both ends. And since it is a single cardan
shaft, the angles at both ends must stay equal for smooth operation.
So, if you shim or lower the CSB, you are changing the angle of that
shaft and that can lead to alignment issues and vibration. The proper
place to shim is at the axle. Only look at the bottom half of the
shaft, it is either a single-cardan (u-joint) or double-cardan (CV
joint) shaft and you just measure and correct the angles on that part
of the shaft. So just treat the bottom half of the 2-piece shaft like
any other driveshaft and forget the upper half.
[return to the FAQ section]
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2. How do I figure out how long to make my
shims?
-
You'll want the shims to be about the same size as your spring perch.
One way to measure that is to get the distance between the u-bolts
(length and width). If the axle is separated from the springs, just
measure the spring perch directly. On rare occasions, spring perches
can be difference lengths (especially on front axles). Shims can be
made different lengths if requested. 4Crawler Offroad does not have a
master database of all possible vehicle and axle combinations. By the
very fact that you need to add a shim, you have a modified vehicle, the
axle may or may not be stock, the perches may or may not be original,
and the axle itself may be a hybrid of several different axle
components.
-
So why does the length of the shim matter? It should match the length
of the spring perch. If it is too short, the spring may not make
contact with the shim along it's full length, since it may hit the end
of the perch sticking out past the end of the shim. If the shim is much
longer than the perch, the thin end of the shim will likely just bend
down around the end of the spring perch and be ineffective. Likewise,
for any given angle, the longer the shim, the thicker the material it
must be cut from is. Since most applications desire as thin a shim as
possible (especially in a spring-under-axle situation), specifying a
6" long shims, for example, where a 4" shim would be
sufficient may in fact double the thicknes of the shim.
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For example on the Toyota mini-truck axles, the rear spring perch is
approx. 4-3/4" long, so the shims would be cut 4-3/4" long
for the rear axle. However, some folks replace the stock spring perch
with a u-bolt eliminator kit, such as the one AllPro Offroad makes.
That kit uses a 6" long spring perch, so that is how long the
shims should be.. The front Toyota mini-truck axle spring perches are
approx. 5-1/4" long, so that would be the proper length for the
front mini-truck axle. Other vehicles probably have varying length
spring perches, so don't use the above numbers, grab a tape measure and
find out for yourself.
-
There is no "standard length" for a spring
shim. Shims have been made in lengths from 3-3/4" to over 6"
long. So bottom line, how long is the spring perch (front-back) on your
vehicle's axle (rear or front) to the nearest 1/4". Then see the
following question and answer about shim width vs. spring vs. perch
width.
[return to the FAQ section]
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3. My springs are more (or less) than 2"
wide, what width shim do I need?
-
You really have 2 options, one is to run the standard 2" wide
shim, the springs really won't "know" the difference. If you
look at the spring perch itself, it probably has rounded edges
resulting in a flat area that is only about 2" wide. However,
4Crawler Offroad can make shims to the match the width of the springs
and/or perch if desired. There is an additional cost for shims over
2" wide due to the additional material and labor required to
manufacture them.
-
For example, my Toyota 4Runner has springs that are 2-3/8" wide. I
run 2" wide shims and they work just fine. A full width shim might
resist twisting a bit better since it would be trapped in between the
u-bolts, or I can even fit a 2-1/2" wide shim in between the
u-bolts as the perch itself is 2.5" wide. So what is the
"correct" width to use? That's why this is an option, you
order what you want.
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On a vehicle like the Toyota Landcruiser that uses 2-3/4" springs
or a full size rig with 3" wide springs, a full width shim
probably makes sense. To put it another way, if its worth the
additional cost (to you), get the custom width shim, if not, get the
standard width.
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Also, some vehicles have spring perches much wider than the spring. For
example, some early 1990s model Toyota pickups use a rubber lined metal
clamp around the springs (the purpose of which is not known) and thus
have a perch that is perhaps 1" wider than the actual springs. To
add shims to this vehicle, you generally need to remove the clamp and
then use a regular width shim. It would not really make sense to use a
3-1/2" wide shim on a 2-3/8" wide spring. Same story with
some of the u-bolt eliminator kits, they have a perch that is much
wider than the spring to allow room for the clamping bolt nuts to ride
below the perch.
-
On a related note, why do the custom width shims cost more than the
standard width shims? There is more material (and waste) involved in
the production of the custom width shims and also more labor. The
standard width shims are cut from lengths of 2" wide flat bar to
the exact length needed. On the custom width shims, they are cut to
width out of 6" wide flat bar then cut to length. Any excess is
scrap. The extra time and labor to make a 6" x 1" cut in
steel is significant as well. Finally, with the standard width shims,
4Crawler Offroad often will make several copies of the shim if the
length and angle are common. With the custom widths, the extra variable
means its unlikely that exact combination will come up again, so each
pair of shims is made to order.
[return to the FAQ section]
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4. What's the difference between bolt-on and
weld-on shims?
-
Both types of shims are made of mild steel. There are three main
differences:
-
1. Bolt-on shim has a small center bolt hole (typically 3/8" or
10mm) for the shaft of the center bolt, the weld-on shim has a larger
hole (typically 5/8"or 17mm) for the head of the center bolt.
-
2. Bolt-on shim will have a pocket machined into the bottom side to
eliminate the angle for the center bolt head to sit flat, the weld-on
does not have this.
-
3. Bolt-on shim is painted to prevent rust, the weld-on is shipped
unpainted to allow welding it to the spring perch.
-
A bolt-on shim can always be converted to weld-on at a later time.
Simply drill out the center bolt hole to accommodate the head of the
center bolt and weld it to the perch.
-
Click here of a picture showing the
differences, weld-on to the left, bolt-on to the right.
[return to the FAQ section]
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5. How accurate are the shims?
-
4Crawler Offroad can machine the shims to within +/` 0.5 degrees,
typically. Shims are checked after machining with a digital angle gauge
to ensure they are within this tolerance. Both shims from one block of
material so the angles are identical between the pair (this is an
important design issue). On thickness, 4Crawler Offroad tries to get
the two shims within 1/16" of each other, normally. 4Crawler
Offroad can also make shims for Toyota front axles where the 10mm
offset in spring perch heights can be built into the shim, making the
driver's side shim 10mm thicker than the passenger side shim. If
concerned about the slight difference in thickness, measure the ride
height of both sides of the vehicle and place the slightly thicker shim
on the low side for a spring-over-axle or on the high side for a
spring-under-axle application.
-
If your application depends a high accuracy shim, you can order the
item below along with your shims to get shims custom machined to be
typically within 0.010" in thickness of each other, and the angle
within +/- 0.2 degrees (whole angles only). Cost is $15.00 to cover the
additional machining and setup time:
[return to the FAQ section]
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6. Which way do the shims go on the axle?
-
It all depends on which way you want the axle to rotate and how your
axle sits on the springs. Its easiest to think of the springs as being
rigid and fixed. Then visualize the axle being separate from the
springs and one solid part, that pivots about the springs. Then,
depending on which way you need to rotate the pinion to correct the
driveline angle, think of grabbing the axle and turning it (and the
pinion) to the correct the pinion angle. You should now be able to
"see" a gap between the spring perch and axle on one end or
the other, that's the side that the thick end of the shim goes in (i.e.
the shim fills this "gap). One other trick I've found to help
visualize this is to exaggerate the angles involved. Its hard to
"see" 3° but if you imagine 30° its a lot easier.
[return to the FAQ section]
NOTE: 4Crawler Offroad/MissingLinkZ will be on reduced operations until 29.MAY.2008. New orders may not be processed until that date and e-mail response may be delayed. Stay tuned to this page for updates.
-
7. How long will it take to get my shims after
I order?
-
These shims are custom made to order to *your* specifications. As such,
they are generally not "in stock", since there would need to
be thousands of different combinations of angle, length, width, bolt
hole size and mounting style shims stocked to meet each and every
possible order.
-
Shims can usually be custom machined and shipped within 48-72 hours
after receipt of order, although it can take up to a week depending on
backlog. Normal shpping is via Priority Mail shipping which has 2-3 day
delivery time in most of the US and Priority Mail International (to
many countries, check the USPS.COM
web site for service info.) which takes 6-10 days internationally.
Express handling and delivery (in the US, 1-2 day typical shipping
time) is also available starting at US$15.00 additional for the shims
and other parts, except for the larger custom tapered blocks. Please
inquire on exact shipping costs for the larger items like
that...
-
Order this item to upgrade the shipping on an previously
ordered set of shims or center bolts.
[return to the FAQ section]
NOTE: 4Crawler Offroad/MissingLinkZ will be on reduced operations until 29.MAY.2008. New orders may not be processed until that date and e-mail response may be delayed. Stay tuned to this page for updates.
-
8. What if I measure wrong, am I stuck with
the shims?
-
No problem, you can return the shims for credit against a new set. For
custom width the credit is equal to the cost of standard width shims
(or US$25), and for standard width the credit is US$5.00 less than the
standard cost (or US$20). For the new set, pay the difference in cost
plus shipping and send back the old shims to 4Crawler Offroad. For
shims/blocks with non-centered holes, or other modifications, contact
4Crawler Offroad for return/credit information.
[return to the FAQ section]
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9. Is there any "volume" discount on
shims?
-
For 2 (or more) pair of shims made to the same specification, there is
a US$5.00 discount on the 2nd (and subsequent) pairs of shims, since
there is a savings on setup time for the machining. This discount will
be refunded upon shipment for on-line orders upon request, simply set
the order quantity to 2 (or more) pair of the desired shims, specify
the length, width and angle for the combined order. On multiple pairs
of shims (of differing specifications) shipped to the same address,
there is often a savings on shipping, over shipping them separately.
You can also use the mutliple
item order link at the top level web page.
[return to the FAQ section]
-
10. How do I order the shims and specify
options?
-
You can click on the "Buy Now" buttons above to oerder
on-line using the PayPal service. If you have an account already set up
on PayPal, you can just use it as-is, if you don't have an account
set-up, you can do so on-line while ordering. You can use credit cards,
electronic funds transfers and other sources for the funds as desired.
-
You can specify any details on the parts order in the NOTE TO
SELLER field in the PayPal order form, things such as the
width and length of the shim, the angle, mounting style, etc. Be sure
to select a good delivery address and double check that its correct. If
you want the goods shipped to an alternate address, specify that CLEARLY
in the note section. If
you want to order multiple items or prefer another payment option,
please contact 4Crawler Offroad via e-mail. And also, PLEASE
BE SURE to give a working e-mail address to reply to. All
too often 4Crawler Offroad is sent questions with invalid reply-to
addresses, if we can't reply, you won't get an answer.
[return to the FAQ section]
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11. I only need a single shim, can I order
just one?
-
Sure, 4Crawler Offroad can make single shims, cost depends on width, a
2" wide standard width single shim costs $15, a custom width
single shim costs $25, add $7.00 for US shipping or $12.00 for
international shipping and applicable sales tax (or order on-line
below). Common use is on Dana 44 front axles with relocated long side
spring perch, short side perch is cast into the diff. housing. Contact
4Crawler Offroad for details.
-
--
-
Order a single standard width (2" wide) shim:
|
|
|
| Single 2" wide shim; US delivery |
Single 2" wide shim; International delivery |
-
--
-
Order a single custom width shim:
|
|
| Single custom width shim; US delivery |
Single custom width shim; International delivery |
[return to the FAQ section]
-
12. Are there any drawbacks to lift blocks?
-
In a spring-over-axle configuration, adding lift blocks does move the
center of the axle farther away from the leaf springs. Since one of the
leaf springs jobs is to resist the torque reaction of the axle to the
tires in contact with the ground, moving the axle farther from the
springs will increase the leverage of the axle on the springs. This can
increase the likelyhood of axle wrap, which is a condition where the
axle causes the springs to twist into an "S" shape, arching
up in front and down in back, due to the axle torque. Whether this is a
problem or not depends on the weight and engine power of the vehicle,
the stiffness of the springs and the presence or absence of some sort
of torque-countering device like a traction bar, kicker shocks or
anti-wrap leaves. The taller the block the more likely wrap will occur.
[return to the FAQ section]
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13. Does 4Crawler Offroad make shims for
other applications?
-
Sure, if you need a tapered shim for another application, feel free to
contact 4Crawler Offroad for a quote. For example, tapered blocks/shims
have been designed and machined for bumper and radiator mounting
applications. Cost will depend on complexity and size of the part
needed.
[return to the FAQ section]
If this is all too confusing to figure out, I'd be more than happy
to consult with you on your specific application.
[Return to the top of this page]
U-bolts need to be properly torqued. You should consult your vehicle
manufacturers recommendations, if that is not possible, then the
following can be used as a general guideline.
U-bolt Torque (from Rancho)
| U-bolt Dia. |
Torque (ft.lbs.) |
| 5/16" |
15-18 |
| 3/8" (10mm) |
28-32 |
| 7/16" |
30-35 |
| 1/2" (12mm) |
65-80 |
| 9/16" (14mm) |
75-90 |
| 5/8" |
85-110 |
 |
| U-Bolt Dimensions |
In the above image, you can see how u-bolts are specified.
-
A is the inner diameter of the u-bolt itself (not measured at the
center of the bolt ends).
-
It corresponds to the maximum size axle tube it can fit over.
-
D is the diameter of the threaded bolt end.
-
Note that since most u-bolts use rolled threads, the unthreaded portion
is likely to be a bit smaller in diameter than the threaded portion,
due to the thread forming process pushing metal out to form the
threads.
-
L is the length of the u-bolt, measured from the inside of the
"U" to the end of the bolts.
-
It usually needs to be longer than the total of the axle tube diameter,
the height of the spring perch, the thickness of the spring pack and
spring plate and still leave enough length for the washer and nut to
fit on top. U-bolts usually have an extra long threaded portion (which
is often specified) that allows them to fit a wide variety of heights
and then be cut to length.
-
If you find the nuts bottoming out on the u-bolt threads, you can stack
a few hardened Grade 8 washers under the nut to gain some height.
-
Finally, the shape of the end of the u-bolt can be specified, the two
common types are round and square.
If needed, 4Crawler Offroad can special order a selection of
replacement Grade 8 u-bolts. They include lock nuts and washers and run
approx. US$20.00/ea. depending on size. Contact 4Crawler
Offroad for more information.
Block the wheels and jack up the frame and put jackstands under it.
Remember safety first. This will take the weight of the truck off the
axles. You have to unbolt both sides before adding the shims. Unbolt
the u-bolts carefully. If you did not take enough weight off the axle,
the springs will ride down the u-bolts as you turn them. If that is
ocurring, jack the frame up a bit higher. Once the nuts are off the
bolts, pull the bolts and plate. Now your springs are connected to the
frame at the rear perch and the front shackle. The springs are
disconnected from the axle.
For a spring-under axle setup, if you lower the frame, the axle will
stay put because it is resting on the tires, and the springs will pull
away from the axle a few inches. For spring-over axle, you can raise
the frame a bit for added clearance.
 |
| Clamping Leaf Springs |
For a bolt-on shim, you can put a C-clamp on your springs ahead and
behind the spring perch (see image above), clamping all the leaves
securely. This will keep the spring pack from fanning out when you take
the center pin out. Next, remove the nut on the bottom or top of the
center pin. If the center pins are damaged, you might have to replace
yours, or if there is insufficient excess length to accomodate the new
shim. Put the shim in between the springs and perch (make sure the head
of the center bolt is in the machined pocket in the shim) then install
the old (or new) new center pin in and put the nut on. Pull it tight,
but make sure your shim and spacer stay lined up.
For a weld-on shims, place the shim on top of the perch, align the
center bolt holes with a spare center bolt head or something of similar
diameter. Then place weld beads on the thick end and sides as needed.
-
Note:
-
If installing a single shim, for example on a Dana44 front axle w/
rotated knuckles, you should try to align the hole in the shim with the
hole in the other spring perch (that has been relocated on the axle
housing) to ensure the center holes remain lined up. If you just align
the center hole on the cast perch with the center hole on the shim, the
angle of the shim will "push" the hole forward or back,
depending on the shim orientation.
For tapered blocks, slip the block in between the springs and perch,
ensuring the pressed in pin engages the hole in the spring perch and
the head of the center pin engages the hole in the block.
Jack the frame back up (or down) until the center pin pops into the
hole in the perch. You may have to push and pull on the tires/axle a
bit to line up correctly. Then, put the spring plate back on with the
u-bolts back in. You should inspect your u-bolts and if the threads are
damaged or the bolt appear stretched or fatigued, consider replacing
them. You may also need to replace them with longer bolts depending on
the thickness of the shim/block. New u-bolts are relatively inexpensive
and reusing them is often recommended against. After re-installing the
u-bolts, torque to the factory specifications (or use the table above).
Check to make sure everything is lined up. Push and pull on the axle to
make sure it is secure. Lower your frame back off the jackstands. Take
it for a test drive. Go slow and listen for odd noises and then
re-check the u-bolt torque after approx. 100 miles.
[Return to the top of this page]
(Contact 4Crawler
Offroad if interested in more information on any of these items)
[Return to the main 4Crawler Offroad page... ]
Questions? -->
<-- Comments?
email: sales@4Crawler.com
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[Last updated: 12.May.2008]
