Steel shims to go between your leaf springs and your spring perch. These are used on leaf spring vehicles in order to adjust pinion angles and achieve proper drive line geometry. Our shims are 2.5" wide and 4" long, machined from steel, and include a new set of 3/8" diameter center bolts. Select size (in degrees). Measure the width of your springs to make sure they are 2.5" wide as this is not the stock width for some applications.
Use the calculator below to determine the right size shims. The shim calculator figures out the current joint angle, takes into account how much the drive shaft slope changes as a result of the shim, and aims to achieve a 2-3 degree net joint angle. The calculator is only for double cardan rear drive shafts. If you have something else or if you have questions, give us a call. 801-737-0757
Worried that too much pinion angle will prevent your pinion bearing from getting oil?
This is a common concern, and one that makes a lot of sense at its surface. However, once you take a closer look at how the oil circulates through the differential you can see that as long as you have the right amount of oil in there the oil will go where the oil needs to go. This is demonstrated in the video below. The video primarily focuses on the need for rounded shape in the diff cover but it also shows you how the oil cycles through the differential.
Typically these are used on the rear axle to better align the axle and t-case angles, but I needed them on the front to correct a very positive caster angle. Too much caster angle can cause an impact shimmy when hitting a bump. It's very annoying and can pull the wheel out of your hands for a split second before it self corrects. If you're truck is doing this, you likely have too much positive caster on the front axle. I went with 4deg shims and this nearly eliminated the impact shimmy. 5deg probably would have been just a little closer, but this also really helped the front driveshaft angle as well. On my truck, all of this was caused by longer than stock shackles (trailing shackles, not leading ones).
They worked perfectly! Brought the caster to right where it needs to be. Thank you
Using the calculator, it was decided that I needed 10 degree shims on the rear of my 1979 CJ5. The only 2 mods that I made were that, because I didn't like the fact that the pin through hole was not counter-bored to allow the head of the bolt to sit flat, I milled a flat spot on the shims.
The second mod...I painted them!
After installation, the pinion is about 2 degrees below driveshaft centerline, and the vibration is gone.
Shims worked good. The supplied pin head was to big for dana 35 axle. Had to grind it down some to fit
91YJ, in-line 6, 3.5 inch lift, SYE, 32 inch tires. The 5 degree shims on the rear leafs seem to line up everything as needed. Pinion about 3 degrees below the drive shaft angle. I have 6 degree shims as well but if I used those I think it would have put the pinion in direct line with the driveshaft which would be a problem with the possible axle wrap. Agree with other comments, I had the reuse my old pins as the new ones were too thick for my leafs and I would have needed to drill out the leafs and grind down the top of the pin because it was too tall. Overall good to go. Good purchase.