I recently put a 2 inch budget boost on my 96' Cherokee and I've developed a few new noises that I would like to solve. My front uses the RE spacers, while the rear uses their AAL.

I know I should ultimately get a SYE, but funds are a little short right now so I would like to see if I can't get by with pinion shims and maybe a TC drop, though I would rather avoid the TC drop.

I have a slight vibration which i'm pretty sure is due to the angles or alignment, but I also am getting a grinding sort of sound when I go from giving it gas, to coasting. It's hard to explain but it happens right during the transition from throttle to no throttle. It sounds like it's toward the rear of the vehicle but it's hard to tell.

I'm trying to figure out what the problem is. It could be a poor pinion angle but I didn't think my angles were too bad. I'm going to check my U-joints for play and I plan on replacing my diff fluid and inspecting the gears later today.

Does anyone have any more suggestions as to what this could be?

I measured the angles in my driveline, they're shown in the picture below. I am thinking about adding a 2* shim to help even out the angles a bit, but like I said, they don't seem to bad but I could be wrong.




Thanks in advance for any help you can offer!

hotrod

 

This might be a strange question but should I replace all (4 i think) u joints?

I didn't notice any play in them but they do look pretty old so I figure it can't hurt.

I checked the fluid level in the diff and it's at a fine level, but I'm thinking it has probably been forever since it was replaced so I might as well do it now.

I'm going to at least price out new u joints, and make sure I get greaseable ones.

 

I did some more searching and found a posting on another Cherokee forum stating that the pinion should be 1 to 2 degrees lower than the TC angle.

http://www.jeepforum.com/forum/f11/c...angle-1047489/

My only question still is which angle I should be concerned with. For example, my TC angles down at 5* from the ground while the pinion angles up at 7* from the ground.

However in relation to the driveshaft my TC is 12* while my pinion is 10*.

So... one set of angles make it seem like I'm perfect by the 1 to 2 degree less theory (that being looking at the angles wrt the driveshaft) While the angles wrt the ground says I'm opposite...

Can anyone please shed some light on this?

 

for a 2in lift should noy need an sye. when my angles were off i just got a poping or went through u joint's like they were free. hate to throw him out there but pm pingpong on this forum hes great with this stuf https://www.cherokeeforum.com/members/pingpong-3781/

 

Yeah, I didn't expect that I would need a SYE with this little lift. I'm debating just ordering 2* shims and seeing how that goes. I don't want to replace the u joints until I fix the angle but maybe I will just do them while I try and figure out the angles...

I figure a 2* shim can't hurt... but who knows.

 

I will admit first off that I have not lifted mine as of yet. However I have read several different posts on this subject and I have heard mentioned several times in various cases to always get all new U bolts for the rear leafs and make sure they are nice and tight. Also a good idea to re-check the tightness after driving a while.

 

hmmm... I did not get new u bolts, perhaps I should though. They're nice and tight but I'll get new ones to put on when I get the shim.

 

you shouldn't need them but yes the ships will be enough bc people only put 3-7* on like 4.5 lifts and up just seems odd that you have any vibs as i didn't even when i drove it lifted with stock tires, however i had extended shackles instead of aal so maybe that was the difference.

 

Yeah, I was a little surprised as well. I'm going to replace the u joints and drive it to see if that helps anything. As far as I can tell they're original, which means they have like 144K on them...

 

hotrod6657 did you add the 2* shims? Any more vibes? I put a 2" AAL on my 99 and had a low frequency vibe at around 20mph and the same noise you had when letting off the gas. I think that sound may be the slip yoke moving around. I added a 1" t-case drop and it got rid of that noise and most of the rumble. I measured my angles and the t-case was 4* lower than the pinion and after the drop it was 2* lower. I have some 2* shims on the way so hopefully that will smooth it out. I wish I would have measured the angles before the AAL because it's weird that the extra leaf would bump the pinion up so much. I also replaced the u-joints before putting in the AAL.

 

It sounds like you ended up doing the same thing I did. I added the shims, which only helped a little, then I replaced the u-joints, which didn't seem to do anything but didn't hurt. Then I even took off the front drive shaft to no avail.

Then I added a homebrewed 1 inch TC drop and voila! No more vibes and no more terrible sound.

I haven't measured the angles since this all happened but I just finished an 800 mile trip to my new home and all is well.