Custom Leaf Spring Shims

Contents:

• Introduction
• Custom Shims
• Ordering
  • Shims:
    • Standard 2" Width Shims
    • Custom Width Shims
  • Lift Blocks:
    • Standard 2" Width Steel Lift Blocks (3/4" and 1" tall)
    • Custom Width Steel Lift Blocks (1" tall only)
    • Custom Flat and Tapered Aluminum Lift Blocks
  • Axle Relocation Plates:
    • Standard 2" Width Axle Relocation Plates
    • Custom Width Axle Relocation Plates
  • Toyota Front Axle Spring Perch Spacers
  • Longer Center Bolts (a.k.a. center pins)
  • Toyota Emergency Brake Extensions
  • Ordering Notes
• Frequently Asked Questions
• References
• Installation Notes
• Contact Info.

Introduction

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.

Custom Shims:

Below, you can see a few versions that 4Crawler Offroad has produced over the years:

• 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.
• 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.
• 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
  • Longer center bolts and for Toyota rear axles emergency brake extensions are available if needed.
• Photo D: A pair of tapered lift blocks in billet aluminum with pressed in locating pins
• Photo E: A pair of shims with offset center holes for use with relocated axles via offset spring perch holes
• 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.
• The maximum length of the steel shims will depend upon the angle and the material used:
  • At 12°, 4-1/8" long is about the limit on shim length using my thickest 1" stock
  • At 10°, 4-3/4" long is about as long as can be cut
  • Shims can be extended the above lengths about 1" with a welded on extension piece or laminated up in thickness.
    • Shims above 12° can also be fabricated with this technique
    • Contact 4Crawler Offroad for details
  • Or shims can be cut from billet aluminum

A: 3° Bolt-On Shim	B: 8° Weld-On Shim	C: 2° Bolt On 3" Wide
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.

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.

Ordering:

4Crawler Offroad can machine solid steel axle shims, custom angles, 1°-12°, made to your specifications:

• Note: Due to material limitation, there are certain angle vs. length limits for the steel shims as noted below:
  • 12° = 4-1/8" long maximum
  • 10° = 4-3/4" long maximum
    • 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.
    • With welded-on extensions, 12° angle can be cut up to 5-1/8" long and and 10° up to 5-3/4" long
    • Laminated steel shims allow for shims up to 6" long and/or angles above 12° to be made
  • 8° or less can be cut up to 6" in length
    • Steeper angles can be cut as well, using the billet aluminum material which is available in greater thicknesses
    • 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.
  • To find out what size shim you need, measure the length and width of the spring perch on the axle before ordering.
    • 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.
  • Shims exceeding the above sizes/angles will incur additonal cost, inquire for an estimate before ordering.
  • 1" thick is the maximum steel material thickness, resulting in a shim with a ~1/2" center thickness.
    • 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.
    • Order both the shim and the desired thickness spacer and the shim will be supplied welded to the spacer.
• Shipping world-wide (for most countries) is included in all the on-line ordering buttons below.
  • Please, PLEASE be sure to include a valid shipping address capable of receiving US mail deliveries.
  • The tapered lift blocks are custom-ordered and shipping will depend on weight and destination.
  • Alternate shipping arrangements are possible, please contact 4Crawler Offroad before ordering.
• Most items below are priced per pair (pr.).
  • So when you see "Qty. 1" in the order form, that is "1 pair" or 2 shims.
    • Unfortunately, it is not possible to alter the order form to reflect the per pair quantity.
  • If you want 2 shims of the same dimensions, order 1 pair (Qty. 1).
  • If you want 2 (or more) pair of shims, order quantity 2 or more as needed.
• Please refer to the ordering notes for other options...

Standard 2" wide steel shims:

• Any length up to 6" and 2" wide (only)
  • If you want a shim wider (or narrower) than 2", order the CUSTOM WIDTH shim, below...
  • Note for high angle shims (greater than 8°) or shims longer than 6":
    • 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
    • Or order 2 shims and the material will be laminated/welded to increase the thickness for a single shim.
• 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.
• 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.
• Cost: US$25/pr. plus shipping and applicable sales tax:

• Use the buttom below to order a high angle shim longer than length/angle limits listed above or for angles steeper than 12°:
• Cost: US$40/pr. plus shipping ($7.00 - worldwide) and applicable sales tax:

Custom width steel shims:

• Any width other than 2" wide (more or less), up to 3" wide and 6" long
• Note for high angle shims (more than 8°) or shims longer than 6":
  • 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):
  • Or order 2 shims and the material will be laminated/welded to increase the thickness for a single shim.
• Shims cut from 1/2" or 1" thick stock, ideal for higher angle shims
• 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.
• Cost: US$40/pr. plus shipping and applicable sales tax:

• Use the buttom below to order a high angle shim longer than length/angle limits listed above or for angles steeper than 12°:
• Cost: US$50/pr. plus shipping and applicable sales tax:

Steel lift blocks (3/4" and 1" tall, standard 2" width) in bolt-on or weld-on lift blocks.

• Note, spacer is flat, no taper, also known as a "zero rate leaf"
• 2" width, length up to 6" long, and heights of 3/4" or 1" tall
• Choice of mounting options:
  • Bolt-on spacer has a hole for the center bolt (3/8") or as specified
  • The weld-on spacer has a hole for the center bolt head (5/8") or as specified

• Want a taller block?
  • Order as many 1" blocks as needed to make the height you want and they will be welded together into a single piece.
  • So, for a 2" solid steel block, order qty. 2 of the 1" tall blocks above or below:

• Bolt-on w/ pressed in locating pin ($35/pr.):

Steel lift blocks (1" tall, custom width) in bolt-on or weld-on lift blocks.

• Note, spacer is flat, no taper, also known as a "zero rate leaf"
• Width up to 3", length up to 6" long, 1" tall
• Choice of mounting options:
  • Bolt-on spacer has a hole for the center bolt (3/8") or as specified
  • The weld-on spacer has a hole for the center bolt head (5/8") or as specified

• Want a taller block?
  • Order as many 1" blocks as needed to make the height you want and they will be welded together into a single piece.
  • So, for a 2" solid steel block, order qty. 2 of the 1" tall blocks above or below:

• Bolt-on w/ pressed in locating pin ($45/pr.):

2" Wide Axle Relocation Plates (specify length in the Note field):

Custom Width Axle Relocation Plates:

Toyota Spring Perch Spacers:

• 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.
  • Note: Use of this spacer with stock push-pull steering is not recommended due to draglink/u-bolt clearance issues
• 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")
  • The spacer is the proper thickness to make both perches the same height
  • The bolt-on spacer has a hole for the center bolt (3/8" or 10mm typical)
  • The weld-on spacer has a hole for the center bolt head (5/8")
• Can also incorporate this offset into shims, blocks, etc.
• A 2" wide spacer (5-1/4" perch length assumed) costs US$7.50 plus shipping and applicable sales tax.

• 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.

Longer center bolts:

• May be needed with bolt on axle shims.
• Bolts are threaded approx. 4" long, so can be cut to length as needed.
• 3/8" center bolts with nuts (will also replace 10mm import center bolts)
  • 3/8" seems to be the most common size, but 5/16" and 7/16" are other sizes available
  • 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
  • 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).
• Cost is US$9.50/pr. plus shipping and applicable sales tax:

Toyota e-brake lever extensions:

• Click here for installed image
• Click here for installation instructions
• Lengthens the e-brake arms to clear taller spring packs, or when running blocks and/or thick shims
• Can be drilled to raise the e-brake lever attachment point between 1" and 2"
  • 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.
  • This can reduce e-brake effectiveness and can cause damage to the cable.
  • The extensions include a hardware to attach them to the e-brake arm and are shipped without a top hole drilled.
  • This allows you to raise the e-brake cable just enough for your needs.
• Also suitable for use in a horizontal orientation to lengthen the e-brake cables for use on a wider rear axle
  • 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.
• For rear axles US$12/pr. plus shipping and applicable sales tax:

Made to order custom taper lift blocks:

• Machined out of billet T6061 aluminum (solid block, no cast or extruded material used).
• 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.
  • US shipping typically $11for regular or $15 for insured shipping
  • Internation shipping: $25 to Canada/Mexico and $40 to most other countries
  • Standard mounting with center bolt hole, optionally a pressed in locating pin is available for US$10 additional.
• Contact 4Crawler Offroad with your specifications.

Ordering Notes:

• 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.
  • Note 5/16", 10mm and 7/16" center bolts are also used, likewise, head sizes can range from 1/2" up to 3/4"
  • If you are unsure of what size hole to specify, you can order shims w/o center holes
  • You can also specify off-center (e.g. 3/8" hole offset 1" toward the thick edge of the shim) or multiple holes.
• "Buy Now" buttons above:
  • 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:
    • Only need to enter your information once
    • You'll be able to check the status of your oder on-line, including a direct link to package tracking information
    • And with verified address and account information, your orders and shipments will be more secure
• For oversize shim orders shipped outside the US, additional shipping charges may apply:
  • Regular shipping ($12.00) covers shimpents up to 4 lbs., this is sufficient to cover most shim/block orders
  • However, for extra thick/large shims, weighing over 4 lbs., additional shipping charges may apply:
    • You will be notified once the items are ready to ship if this applies to your order.
    • 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;
    • e.g. a 2.5" wide, 5" long, 8 degree shim would probably exceed 4 lbs. and incur an additional $10.00 shipping charge.
• For shipments to California, add applicable state sales tax (automatically added by PayPal).
• Local pickup (for orders from the SF Bay Area) is possible, shipping charge will be refunded upon pick up.

Frequently Asked Questions:

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...

1. How do I know what angle to make my shims or if I even need shims?
2. How do I figure out how long to make my shims?
3. How do I figure out what width to make my shims?
4. What's the difference between bolt-on and weld-on shims?
5. How accurate are the shims?
6. Which way do the shims go?
7. How long will it take to get my shims after I order?
8. What if I measure wrong, am I stuck with the shims?
9. Is there any "volume" discount on shims?
10. How do I order the shims and specify options?
11. I only need a single shim, can I order just one?
12. Are there any drawbacks to lift blocks?
13. Do you make shims for other applications?

1. How do I know what angle to make my shims or if I even need shims?

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.

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.

How to measure the driveshaft angles:

Depending on the type of driveshaft you are running, the information on how to measure may be found here.

Front axle pinion and caster angle considerations:

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.

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.

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.

CV or double cardan driveshafts:

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.

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.

2-piece driveshafts (i.e. center support bearing):

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.

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.

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.

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.

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.

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.

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.

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: