• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

added shims now VERY BAD vibrations

C

CHUGLYxj

NAXJA Forum User
Location
Ephrata, PA
After my SYE I had some noticable vibrations at highway speeds which I have blamed on the rear pinon angle being off. I researched and found the recomended difference to be 3* lower at the pinon vs the driveshaft. Mine required a 4* decrease in angle. I added the shims today, RE 4*, and now have a very bad growling full vehicle vibration at low to moderate speeds. It gets worse when slowing or going down hill. It was so bad driving home from work it hurt my ears. It seams to get worse the more its driven, could it be a bad U-joint? Please help me fix my DD, at this point I am just going to remove the shims and deal with the high speed vibes.

01, auto, lifted 4" w/ RE H&T using a front DS in the rear, D35 rear.
 
I assume you actually measured your drive shaft and rear pinion angles, and they show the pinion angle 3* below the the drive shaft angle? Personally, I'd set the angle at 2*; however, it appears your angles are still off.
 
Make sure that high end of the shim is at the rear of the vehicle, if you have the higher end to the front, the angle is much worse. Maybe have the the rear DS looked at to see if it's balanced.
 
I have the thicker end of the shim to the front as I needed to raise the pinon angle to be w/in the 3*. I used a magnetic angle finder and compaired measurements from several locations which all showed a 6-7* difference. I went with a 4* shim to be w/in the 3* range. I don't think it is the DS as it has been a few months since I did the SYE, I only see short highway trips every now and again so I wasn't worried about the vibrations. I did the shims in anticipation of a few long trips this summer for vacations. The vibrations are bad enough to rattle the teeth from you head at this point and it has only been getting worse, so now I am not driving it. I have put about 20 miles on it since the shims. 15 back from the shop that has a lift to my house, all highway, and 5 to and from work lastnight. The strange thing is that I have lost the high speed vibes now its all low speed like before the SYE but MUCH worse.
 
What Toyman said was correct. If what you are saying is that you had to rotate your pinion up, your shims are backwards. The axle is below the spring, look at it again. If you lifted your XJ, you found that your pinion was pointed down too much (which would be true), you would put the required shim in fat end to the rear to rotate your pinion up.

I am a little skeptical that you need a full 4*, but if you measured your angles, I would go with that instead of my guess. Also, with the setup you have, make sure you flex out your drive shaft well to be sure it is long enough. The setup you have is pushing it. I ran the same until I put in my D44 and it was long enough no problems. However, no 2 XJs are the same and others have been too short with the same. Just make sure you have enough spline engagement in the slip.
 
Last edited:
3* sounds a little drastic. With an SYE, you really want the pinion to be 0* to the driveshaft although with our suspensions, real-world numbers are more like 1-2* below the driveshaft. 4* is quite a bit, and I hope it was measured with an angle-finder and not a calibrated eyeball.

Did you re-measure after installing the shims? The only time the "fat part in front" will raise the pinion is if you have a Spring-Under-Axle (SUA) arrangement, like a YJ or MJ. To raise the pinion in an XJ, the fat part of the shim faces the rear.
 
It sounds like the shims are backwards. Think about it. With the "fat" end of the shim forward, the axle housing moved down. You want it to move up.

With the S.Y.E, the lower U-joint needs to be almost straight (edit: with a CV joint on top, sorry). Since you said the problem is getting progressively worse, drop $15.00 at your local parts store and get a new U-joint for the rear of the DS. Chances are it has taken some damage.
 
ok so I am betting that I have them in backwards being that I put the fat forward, simple fix. I was also planing on getting a new u-joint as I was thinking the same thing... for a few bucks eliminate a potential issue as it was most likely getting damaged.

As for the sims, after I found the measurements and decided I needed 4*, I had my brother check for me and he found the same.

If the RE kit had ANY instructions this would have been simple, they also sent really off sized leaf pins.

Thanks for all the help guys, I need to pony up the $$ for the membership, I know I'll get to it.

Also as for the drive shaft I have at least an inch more travel them my axle will alow when connected to the leaves, another reason why I wanted to do the shims on the lift, I wanted to droop the suspension as much as I could to see if things work, I also found out I need a longer break line if I go bigger, the shocks keep me safe but the line is close.
 
CHUGLYxj said:
Also as for the drive shaft I have at least an inch more travel them my axle will alow when connected to the leaves, another reason why I wanted to do the shims on the lift, I wanted to droop the suspension as much as I could to see if things work, I also found out I need a longer break line if I go bigger, the shocks keep me safe but the line is close.
Click to expand...

Good deal. Glad you checked. Moving the pinion up will help a tiny bit more too.
 
Thanks for the idea of the 95 YJ brake lines, I'll have to do that.

As far as checking everything, I am doing this build as right as I can, double and triple check everything.
 
Rules of thumb..for rear shaft in 2 wheel...vibes under accelleration, vibes stop under decelleration, pinion too high.....vibes under decelleration, vibes stop under accelleration pinion too low.
 
You must log in or register to reply here.

Similar threads

N
Leaf Spring Options
Replies
2
Views
123
nrparrott
N
S
Work in what order to fix driveline vibes?
Replies
15
Views
5K
denverd1
denverd1
M
Rear Bumper
Replies
5
Views
2K
SlowXj
S
Anak
Hitch Stinger Storage
Replies
0
Views
550
Anak
Anak
T
Death Wobble Questions (I searched first)
Replies
11
Views
3K
Anak
Anak
Back
Top