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Front end rotational chatter

91to99

91to99

NAXJA Forum User
Location
utah
First off... 99, 4.0, AW4, NP231, 8.25/30 4.10s, powertrax no-slip, 3.5-4 inches of lift, hd relocation brackets, and sadly a tcase drop for now...

If I drive more than 10 miles I get some sort of rotational chatter coming from under my feet. Only noticeable at 35-50mph coasting. The tcase has new bearings and chain. Front pinion is leaking (seal is awaiting installation). The U-joints are healthy and tight.

Any thoughts???
 
Check for play in the u joints in the front driveshaft, check for play in the slip joint, check for play in the pinion.
 
No play in u joints, no play in pinion, minimal movement in the slip joint. The shaft has been checked out by a local drive shaft shop also...
 
Check to see the front shaft centering ball is moving and rotates free, you can also remove the front shaft and see if it goes away. If you dont have a sye at that height Your slip yoke going into the tcase can make noise, the yoke ears can actually touch as well. I have two other xjs , one at 3.5" and one at 5" , both with stock rear driveline, and we had to clearance both slip yokes to the u joint ears dont come into contact. Mine made a lot of noise on decel at 4.5" before my sye
 
Update:
Now it is "chattering" down to like 20mph. Will pull driveshaft in next couple days. And the ears are not contacting.

SYE will be on its way soon.
 
I have this issue with my 99 too (3.5" lift, JKS adj control arms
OME springs/shocks front & rear, 31" MTR's).
I've tried:

1) removed the front shaft -> no chainge
2) Replaces unit bearings (290K on these) -> no chainge
3) adjust pinion angle downward (adj control arms) -> some improvement
note: pinion was adj up when lift was first installed

My tires were cupped prety bad in the front, rotated them to the back
and vibration went away.

Also I'm not too sure how the tie rod ends are doing. Could be that
in my case the joints are worn.

Anyway, please post up when you get this figured out :eyes:
 
SleeperXJ said:
I have this issue with my 99 too (3.5" lift, JKS adj control arms
OME springs/shocks front & rear, 31" MTR's).
I've tried:

1) removed the front shaft -> no chainge
2) Replaces unit bearings (290K on these) -> no chainge
3) adjust pinion angle downward (adj control arms) -> some improvement
note: pinion was adj up when lift was first installed

My tires were cupped prety bad in the front, rotated them to the back
and vibration went away.

Also I'm not too sure how the tie rod ends are doing. Could be that
in my case the joints are worn.

Anyway, please post up when you get this figured out :eyes:
Click to expand...

Are you running tcase drop or SYE?
Probably not going until be friday when I can get the front shaft out to see if makes a difference.
I also have fixed RE superflex lowers.. No adjustment for me:(..
 
AA SYE installed along with Tom Woods DS.
I read a thread a while back that discribed the arch in the front
spings after you lift your vehicle. I think it was the guys dad told him
that the springs wouldn't be seated flat on the front axle and any resonance
would set the springs vibrating on the partialy seated surface. He tried temporarily
installing a roll (ball) of duct-tape and noticed the noise stopped.
You might try cramming some tape between the lower spring coils to see if
it dampens the vibe. That MIGHT help diagnose your problem.
 
I didn't see if you tried driving without the front driveshaft. Remove it and drive and post up your results. The T-case drop will make front ds angles more extreme...

If noises/vibes go away, then I'd suspect the front DS.

Let us know
 
Mine did this, but at slower speeds. One day I realized that it went away while I was pressing on the brakes. Come to find out it was the passenger side brake pads clicking on the knuckle where they're held in place. The little ears on the bottom of the pads were wearing a small groove in the knuckle causing them to clank in place.
 
Finally had a nice enough day (and time) to take the front drive shaft off..
No more chatter.
I did forget to mention that the front axle is a HP from a 91. Could there be some issues with the length of the drive shaft because it is the original 99 and being low pinion??
I still have a slight oscillating hum in place of the chatter. Pinion bearing maybe? That part of the pumpkin did seem kind of warm compared to the rest of the housing.
I will give it one more day and have the drive shaft refurbished and go from there i guess...
 
91to99 said:
Finally had a nice enough day (and time) to take the front drive shaft off..
No more chatter.
I did forget to mention that the front axle is a HP from a 91. Could there be some issues with the length of the drive shaft because it is the original 99 and being low pinion??
I still have a slight oscillating hum in place of the chatter. Pinion bearing maybe? That part of the pumpkin did seem kind of warm compared to the rest of the housing.
I will give it one more day and have the drive shaft refurbished and go from there i guess...
Click to expand...

Driveshafts are the same for HP and LP.
 
Update:
No chatter with front drive shaft out.
While it was out i replaced the front u-joint (for S&G) and greased the slip joint up really well. Put the drive shaft back in and still have the chatter...
The slip joint is really tight when i twist it but if i "bend" it there is some play there. Is that normal??
Should I go ahead and have the other joints replaced and the centering ball? The centering ball is a little dry.
Is there a possibility that the pinion is making noise and resonating through the drive shaft? The differential bearings could easily have over 250k miles on them. The ring and pinion was set up about 5 years ago.
 
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