new LCA's = Grinding & Vibrations

replaced my 3" coil spacers and stock LCA's with rough country springs and Rustys Fixed Lower control arms, suspension is alot smoother now, but i get bad grinding/metal "Clinking" sounds, at lower speeds, and at higher speeds (45+) bad front end vibrations...

im thinking these BOTH are driveshaft issues, im planning on doing Ujoints and a Transfercase drop. but the noise has me thinking this wont be a quick/cheap fix.

I also find my Transfercase Is acting funny now, i put it in 4lo for Sand driving, and it took Brute force and atleast 15 minutes of Tinkering to get it OUT of 4lo. the handle was "Stuck" in 4lo

any insight?

89 xj pioneer, 4l auto with 242 case 3" lift on 31"s

you can always remove your front ds to see if that is the cause of your vibes....

if you're having problems changing the TC selection, it's in the linkage. i know plenty of guys that have to crawl under their jeep to put it in 4L

What is the difference in length from your stock lowers to your new fixed lowers? I bet this is throwing off your caster which is changing your pinion angle.

If you only did front end work, droping the T-case will have no affect as the front shaft is a double cardan jointed affair. Your front pinion angle needs to be about zero. A bit down is acceptable, but up is right out.

Worry about pinion angle first, caster later (if at all).

Well, I checked the Pinion angle, and its definitely pointed up by a degree or two, not at all "right at 0"

How do i change this? New upper control arms help?

nw-xj-scott said:

Well, I checked the Pinion angle, and its definitely pointed up by a degree or two, not at all "right at 0"

How do i change this? New upper control arms help?

Click to expand...

Longer UCAs will worsen the problem.

The factory thought about this issue a bit. The frame side of the LCA mounts are adjustable. You loosen your Frame side LCA mounts, and add shims between the inner slider part, and the outer frame mounted part. You have about 1" of slide. Adjust both equally to adjust your pinion angles then retorque your LCA frame side bolts.

I know this thread is a little old, but I faced the same issue with T-case shifting after my lift. Solved with a simple T-case linkage adjust. Just see the Chilton's...it's easy and solved my shifting issues.

nw-xj-scott said:

Well, I checked the Pinion angle, and its definitely pointed up by a degree or two, not at all "right at 0"

How do i change this? New upper control arms help?

Click to expand...

Because the front is a dual cardan driveshaft your pinion angle should match your driveshaft angle.
When you say your driveshaft is "not at all "right at 0"" do you mean it's a little bit up from horizontal?

I'm guessing here but if you installed longer lower control arms... I'm betting your pinion angle dropped closer to horizontal meaning it's no longer aligned with the driveshaft and is the source of your vibes. Adjustable upper control arms (which can be set longer than stock) are the solution to realign your pinion with your driveshaft.

Note: there are other solutions but they are $$$. The first is the best solution performance wise and involves reconfiguring your front axle to rotate the diff casing. The second is not ideal (weaker shaft) and involves having a custom driveshaft with dual cardan joints at both ends of your front driveshaft.

I ran into the same problem and decided to go with the adjustable upper arms. My 0.02$

Zuki-Ron said:

Longer UCAs will worsen the problem.

The factory thought about this issue a bit. The frame side of the LCA mounts are adjustable. You loosen your Frame side LCA mounts, and add shims between the inner slider part, and the outer frame mounted part. You have about 1" of slide. Adjust both equally to adjust your pinion angles then retorque your LCA frame side bolts.

Click to expand...

Agreed.

I would just get an alignment and have them return your caster/pinion angles to an acceptable level.