Rear Diff Problems

Well guys, I posted a little while ago about about some vibrations I narrowed down to the rear driveshaft.

I took it to a tranny shop today and they had it up on the lift, ran it, and their conclusion was there was too much slop in the diff to the driveshaft. They said that was the reason my rear ujoint was worn down, and the reason I'm having vibrations and a clunking/hiccup/hard gear changes.

They quoted me about $850-$900 to replace the carrier bearing and races? Axles and gears have always been a mystery to me- as I haven't had many problems with them. They said there should be about 1/100th of play in the driveshaft, and now there is a lot more.

Does that seem plausible?

Yes & no.

The backlash in your gears may have been at the high end of acceptable when new & it's worn to the point of allowing too much rotation of the shaft with no movement of the gears now.

I wouldn't think that too much backlash in the gears would cause the U-Joint to wear though.

I also wouldn't think that too much backlash would be causing the noises you describe. It should just be a whining sound.

This is why it takes a trained mechanic & a certain amount of black magic to properly set up a set of gears.

Without hearing the the noise...

...or seeing the wear on the u/joint its hard to know.

BUT....$850-$900 seems expensive.

You should be able to source a good used rear 3rd member for $250 ish..
....and fitting it shouldnt take a good mechanic more than 1.5/2 hrs.

Jo

Quote:

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Originally Posted by tom4bren

Yes & no.

The backlash in your gears may have been at the high end of acceptable when new & it's worn to the point of allowing too much rotation of the shaft with no movement of the gears now.

I wouldn't think that too much backlash in the gears would cause the U-Joint to wear though.

I also wouldn't think that too much backlash would be causing the noises you describe. It should just be a whining sound.

This is why it takes a trained mechanic & a certain amount of black magic to properly set up a set of gears.

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I didn't think it would cause U-joint wear that much either. With the research I did on here amongst other forums, it seems like if that was the problem I'd be having a whine as you described.

Well I guess I'll take it to a few other places and see if they have black magic in their toolboxes.. haha

Are there any recommendations as far as the next step?

Quote:

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Originally Posted by JoFotoz

Without hearing the the noise...

...or seeing the wear on the u/joint its hard to know.

BUT....$850-$900 seems expensive.

You should be able to source a good used rear 3rd member for $250 ish..
....and fitting it shouldnt take a good mechanic more than 1.5/2 hrs.

Jo

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I thought it seemed pretty spendy too. There is no "noise" other than a pretty bad vibration starting around 20mph. No whine. I rolled around without the rear driveshaft around the block and the vibes went away.

I replaced the "front" ujoint but not the rear because it "seemed" fine. After taking it back out I noticed it seizes up a little bit, not as smooth as it should be. The shop told me that replacing that ujoint would be a band aid fix as it would wear down quick due to the bearings.

I've assisted with a lower gear swap in an old toyota, and feel pretty comfortable with doing the work except for the fine tuning of the gears.

Gotta love a DD project... ha..

Just FYI, $800-1000 is pretty standard on NEW axle parts, done correctly with fresh seals and bearings.

Ive done a lot of research when mine went, and thats going rate. $150 for the ring and pinion, $150 for the master seal and bearing kit, the rest is labor.
And yes, it sucks to do the front, the rear isnt as bad, but the front is a *^&#...

I ordered mine from 2 different companies, Had the rear done by a shop because i needed it on the road, they charged me $850 out the door, the second time, when i got to the front, i picked up a new third with new gears, seals and bearings for $800, and did the install myself and saved about $400.

I have found that the 12 bolt pinion can loosen up over time. It uses a crush sleeve to set pinion preload, and I think it just crushes a little bit over time. Some times you can tighten the pinion nut back down a little which keeps the pinion from moving around so much. It won't fix the increased backlash, but it does help with the vibration. The 12 bolt is so strong that if you really wanted to fix it I have no doubt that is you installed a new crush sleeve and reset the backlash and pattern it would be like new. The bearings and R/P are big and durable, unless completely abused you can probably reuse them.

Are you lifted?

im having diff/axle/transfer case problems too - i get from time to time a weird noise coming from what sems like the front end but when you get underneath and someone else drives it you can hear something from the back grinding like a pencil sharpener - in 2wd it only happens when i turn but i know its not the power steeting because if i sit still i can turn the swheels with no problem or noise - while this noise is happening i dont get the drop that happens after i let off the brake on a hard stop, but the noise is more frustrating than the drop - my 4wd works but sounds like something is eating metal underneath the car -i have no warning lights and tod is working but i think the tod system could be the problem - i wouldnt say i have a vibration like you say, but im curious if both our problems are related

Evil-e, either your cv axles are worn out, something in the driveline needs grease or your rear ring and pinion are about to go out.

Check diff fluid levels, only remove top fill plug (bolt) and fill if necessary. Maybe your axle seals went bad and you didn't notice the axle grease leaking out?

drained and replaced fliud in both diffs, and topped off the transfer case - has never leaked a drop of anything but when i drained the read diff fliud i noticed a small piece of blue plastic in with the oil - any idea of wtf that was? ive greased all the nipples too didnt help - the driveline shops i brought it to said they didnt think they could find parts and were very reluctant to even attempt opening the transfer case but said it was probably something with the "lobes" inside? its def not my cv on the axles (ive had these go out before on different vehicles and know what they sound like this is nothing like that) but maybe the cv's on the prop shaft? when you guys say axles are you talking about the ones going to my wheels or the prop shaft goint to the diff? im confused -this is the first drive shaft ive seen without u joints... and where is the ring and pinion? also surprised at how tiny the driveshafts are on this vehicle

The ring and pinion is inside your axles. Its the gearing that causes your driveshafts rotations to translate into your wheels turning. If they are loose they sound like a grinding, but can take a very long time to finally 'go'. Axles generally refer to the part of your car that the wheels are connected to. Driveshafts are driveshafts.

As to the blue plastic in your diff fluid...most likely from the bottle of diff oil from a previous service job, I wouldn't be too concerned.