infiniteuser

So I'm getting a clunk/pop when shifting from reverse to drive and sometimes when accelerating from a stop light. I thought it was the rear driveshaft u-joints, but when I got under there I found that there seems to be quite a bit of play in the differential.

I did open the differential recently to drain the oil and everything seemed okay (no metal shavings or obvious damage) but then again, I don't really know what I'm doing. I was getting the clunk then too, though.

What can I do to fix this? Also, is this something that needs to be fixed right away or is it mainly just irritating?

Thanks

EDIT: Just to be clear, when I say play in the differential it seems obvious (to me, and again, I'm a beginner at this) that the gear lash is off and there is too much space between the pinion/ring gears.

xjmarc

If your yoke has play in it then it is probably your pinion bearing. If you let it go it will kill the ring and pinion.

infiniteuser

I tested with the rear wheels jacked up and the transfer case in neutral. When I spin the driveshaft by hand, there's a slight lag before I can feel any resistance and the wheels will start to spin. Then if I stop spinning the shaft, there'll be a sight lag before they I feel anything/the wheels stop. It seems like this is what incorrect gear lash would feel like. Does this sound symptomatic of a bad pinion bearing?

storm101

I wouldnt rule out ujoints just yet. Reverse to drive clunking (and vibrations in the rear)....I recently had this, took me FOREVER to finally get the joint to prevail with good noise on accel.

Do you have any rear vibration (you can feel it/somewhat hear it) usually more on accel and between the speeds of 25-35? If so, look into them joints a bit more close....mine didnt have play or anything really off about them until after a few months of playing with them and the ds and everything else under it....then the noise FINALLY came in the standard bad ujoint sound.

I also have a 99 with the 8.25 rear, when i was trying to diagnose my issue that was stated above i noticed a bit of play, and also recently changed the axle fluid, with nothing bad found....there is a bit of play though before the shaft "engages" the wheels (seems pretty normal), if its not a WHOLE lot, I again, would look at the rear DS ujoints a little bit better. Drop the shaft if you need to, its a lot easier than tearing into the gears.

infiniteuser

Hmm... thanks for the insight storm101. I'll try to get under there and quantify exactly how much play there is tomorrow. I'm not sure I really notice any vibrations coming from the rear end, but it would probably be hard to tell for sure. The main symptoms are the pop when going from reverse to drive, and a clunk when accelerating (sometimes) and a clunk when coming to a stop (sometimes). I couldn't get the u-joints to move at all, but I didn't try that hard. They certainly didn't look very new.

infiniteuser

Also I've been noticing some squeaking lately especially when going over a bump, but I didn't think it was related. Hard to tell where these noises come from sometimes, the whole thing is squeaky inside and out.

storm101

Some of that sounds like an slip yoke in need of grease. (the stop then clunk and a clunk from a stop to a go, feels like a jump in the rear end most times too)

Yeah im not sure about them u joints sometimes.....i seriously played with my ds that day (when they finally started clicking) for about an hour, shaking everything with some force....STILL didnt get any real play out of them.......im not sure how the heck that worked out....I just heard it when I left the shop.....must have done just enough to make at least one make some noise....<shrugs> the play I found was after I had the shaft off, thats when I could REALLY tell there was some play in it (after i knew from the noise and had new joints in hand)

U joints can squeak if bad and im sure if the SY is in need of grease that it could make noise also....

Either way, they are two pretty simple things, good to at least rule out if theres a bigger issue at hand, or even better if they are the problem as its an easy fix.

infiniteuser

Well I got under there this morning and tried out the rear diff again. My best estimate is there seems to be about 1/16 turn before the driveshaft engages the wheels. So I'm guessing that's normal. So I guess that's really not much, my initial impression was that the gear backlash should be close to zero.

Also, there is a little clunk from inside the transfer case when I rotate the driveshaft back and forth, but I'm guessing that's normal as well.

BuckB91XJ

If you're seeing that much of a turn in the DS before seeing movement from the wheels. The play causing your clunk and pop from D to R is definitely in your rear diff. I believe I read that you said you can grab the DS at the pinion yoke and physically move it side to side. If you can move the pinion yoke in and out and especially if you can move it side to side with just your hands you have got some serious bearing wear in you diff. It's not something that will grenade on you in the next couple of weeks as I'm sure you've had that clunk for quite some time. You do need to start saving now and and the parts together to get it fixed as soon as you can.

infiniteuser

The pinion yoke is not moving side to side, it didn't seem to move in and out either but I didn't try that hard that way.

infiniteuser

Also, 1/16 turn may be a little excessive... it could be more like half that. It's difficult to eyeball it, but it's not very much, but it is very noticeable.

infiniteuser

This is basically the amount of play I get:

(This is from another user.)

http://www.youtube.com/watch?v=http:...?v=j_kZn-_Bx8w

BuckB91XJ

Awesome use of the You Tube video. Getting that look really allows me to be able to tell you that your rear differential (ring and pinion) is FINE! That being said, I would have to say that your issue most likely is rear driveshaft U-joints....which is a much easier and cheaper fix.

infiniteuser

Thanks, I guess I'll go ahead and replace them then and see what happens.

In the meantime, I shot a video of changing gears and uploaded it, so I'll post it for good measure. Hopefully it confirms u-joints.

http://www.youtube.com/watch?v=http:...?v=LemXSnUnYzM

OAS

Looks same as mine.