I need to put degree shims under the front axle in my jeep, I don't really understand the reason for the shims. I get why they are needed in the rear but cant get the front. I heard that they go in backwards in the front.

I have a 79 CJ 5 with a 258/ T18/ Dana 20 combo with a 2.5 inch rancho lift and a 1 3/8" shackle lift. I have 2.5 degree and 4 degree shims which will be the best for the front. What does this do and what will it help. I have heard it helps the wandering/handling? WHich direction do the shims go?

let me know.
Thanks
tony

Originally posted by cjhunter
I need to put degree shims under the front axle in my jeep, I don't really understand the reason for the shims. What does this do and what will it help. I have heard it helps the wandering/handling?


It's to bring caster back into spec IF NECESSARY after the lift. Have the castor angle checked on an alignment rack to determine what the caster is now. If you need to correct, the reading on the rack will tell you to what degree.

Do you have a wandering problem?

I do have some wandering at mid speeds. Isn't their just a standard for a lifted CJ?

thanks anyways
tony

Originally posted by cjhunter
I do have some wandering at mid speeds. Isn't their just a standard for a lifted CJ?

thanks anyways
tony

I think it around 5-6 degrees. The others on the board can confirm or correct this. But unless you know where your at now - you won't know how much to add. The alternative would be someone who'd done exactly the same thing as you have and determined what degree to add......

If you add to much or too little, I don't think you'll get the results your looking for.

Thats what I was looking for, someone who has added around 3.5 lift to their 79 CJ 5 and finding out what they added as far as shims go.

Since you guess is around 6 degrees, that meaans I am presently 6 degrees of, so if I add a set of 4 deg shims, that would put me in at 2 degree off. Would this not be better then nothing. The nessecary angle modification would heve to be at less then 2 deg, for me to make it worse if I just add 4 degree.
Does this sound correct?

Also if anyone has done this lift and had their angles measured, what shim did you need?

thanks
tony

those shackle lifts change your pinion angle way more so than just a normal lift of that amount. you should MEASURE the caster before you shim it.

Go to an alignment and have the caster checked.
Try to stay with about 3deg. positive caster.

I'm not sure about what state you're in...
But here in PA, front axle shims are illegal.

(not that any techs would take notice to that, but thought I'd mention it)

why??

are they unsafe? How do most people that lift their rigs correct the caster? I am in california, and rancho sent me front axle shims with the lift, that seems a little wierd?

Do you recomend I just leave it the same then
?

thanks
tony

CJHunter,

I really don't know the technical reasons why they're illegal in PA - PA is very anal about a lot of things.

They probably view them as 'unsafe' and I could guess its because of the steering geometry.

I've never done this and who knows, after my build up, I might have to....

You can cut off the knuckles from the ends of the axle tubes, set pinion angle, and reweld the knuckles. I couldn't tell you how to do this because it inovlves a lot of pre-measuring and measuring to get the stuff set-up properly. Do a search on the net ...I'm sure you'll find lots of info.

Just seems like a royal pain in the butt if you don't have the tools or any buddies to help you do it. A lot of extra work....

So do you all recomend I even mess with it?

I am not sure yet, the jeep is on blocks now(in the middle of new front brakes and wheel bearings) so after that is done I may just put the shims that came with the rancho lift in and call it good. All that rewelding and cutting measuring buisness is what normally runs me into trouble. And I am ready to drive the Jeep for a while, it seems like it spends 75% of its time on blocks. Unless it is all over the road, then I may see what I can do. Just have to wait a few more days to see. Spring break is next week so I should get some time to work on the CJ, its about time.

thanks for all the help.

Tony

Hey Tony,

You could put the shims in that came with the lift kit - obviously, they were designed to run with the kit.

After a while, if you feel energetic, you may want to take them out and see how things ride without them. It depends on the size of the shim whether you'll notice anything.

We had 2.5 degree shims in and took them out as soon as we found they were illegal. Didn't notice any changes in handling.

But you may want to be careful with larger size shims...

I have a YJ but it shouldn't be very different. You don't need to shim the front with a simple suspension lift but when you use longer shackles then that changes the caster and can cause the wandering. It did with me. I had put in shackles that lifted the Jeep one inch. that means that the shackles were two inches longer than stock. I put in 4 degree shims that pointed the pinion DOWN (fat side of the shims forward) and it helped alot. When I went to a taller spring I reduced the shackle length to 1/2 inch lifted which handled better but i used the same shim and it was fine. Pesonally I think that the best thing would be to reduce your shackle length to a maximum of one inch lifted and preferably one half inch. in my opinion your shackles are two long, but shimming is very easy. takes a half hour or less. Try the 4 degree shims first, for your height shackle I would think that would work. If it feels funny on the road, then try the 2 1/2 inch. Its no big deal to experiment, just drive carefully and not too fast at first,really a shorter shackle will give you better handling if you don't get tire rubbing. I think that a mild body lift would be a better choice than a shackle with over an inch length.

thanks for the input.

I think I will stick the 4 degree shims in for know. I agree with you on the shackles. I ordered 1inch lift and they sent me the 1 and 3/8 so I just put them on, not wanting to deal with 4 WHEEL PARTS customer service. I plan on doing a 1 inch body lift and the TJ fender flare conversion in the future so this should give me enough clearence that I could drop the shackles down to 1/2" lift. But thats in the future, for now i have way to many jeep related projects going at once, I just want to wheel the thing.

thanks agian
tony

First lets make sure we're clear on shackle length vs. lift. You only get 1/2 the lift as the amount your shackles are extended because you are only lifting 1 end of the spring. Thus, your shackles would be 2 3/4" longer than stock to give you 1 3/8" of lift. That is an extremely long shackle & will cause some instability & handling problems in themselves.
Second - I would not use the crappy cast aluminum shims that come with kits for 2 reasons. The head of the spring center pin has to go through the shim before it gets to the hole in the spring perch & you may not get enough engagement for a secure location of the spring. Also, they can break or wear causing looseness between the spring & axle. I would consider either of these conditions to be unsafe.

What I would do:
1) If the shackles are that long - get rid of them. If they are only 1 3/8" extended (11/16" lift), they are probably OK.
2) Drive it without shims. if it handles OK, leave it olone.
3) If it wanders and/or does not return to center - find out what your castor angle is at. Correct it to 4 - 6 degrees positive ( top ball joint tilted back), useing steel shims that bolt to the spring pack. A good alignment shop should be able to get steel shims. I have gotten them from Rubicon Express, but they are for a Wrangler so they will need some modifications. The hole has to be drilled out for the larger spring center bolt on a CJ. Tey are also 1/2" too wide so you will have to notch them for the u-bolts. Beieng bolted to the spring they are more secure & do not reduce the engagement of the head in the perch hole.
4) Go out 7 have fun with no worries.:)

I did a shackle reversal which gave me the caster I needed without using shims. Plus It gave me a smother ride.