Rear End Swap
Thread Starter
Joined: Jul 2013
Posts: 303
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From: Indianapolis, IN
Rear End Swap My rear end is pretty noisy. I am trying to find out what my options are in fixing it. Should I rebuild the diff, find a used 10 bolt, or what? From what information I have been able to find, I believe that my cheapest route will be to find a used 10 bolt, and cheap is waht i need right now lol That being said, what specific fourth gen 10 bolts will be a direct swap for my 1994 A4 z28? Also, would I need any special tools or anything like that to swap the rear end out? Could someone possibly direct me towards a write up on a rear end swap? I couldn't find one. Thanks!
What rearend you pick will be determined by what abs system you have, and what gear ratio you want. Any rearend from 93 through 02 years will fit, but gears and brake systems are the biggest differences.
Thread Starter
Joined: Jul 2013
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From: Indianapolis, IN
Just to clarify, any 94-97 rear end with 3 channel abs will be a direct replacement? Also, how can i tell if a rear end is three channel or four channel? did the four channel ones come out of cars that had traction control? And that link is very helpful!
94-97 3 channel ABS(only) has a sensor on top of rear end housing. 95-97 4 channel ABS & TC(traction control) has a sensor at each axles backing plate. No,you cannot convert a 4 channel rear end to work in your 3 channel vehicle. (answering before you ask)
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Thread Starter
Joined: Jul 2013
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From: Indianapolis, IN
Alright, thanks!
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Verdad Gallardo Thread Starter
Joined: Jul 2013
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From: Indianapolis, IN
And this one would be four channel? http://muncie.craigslist.org/for/4712691082.html
Last edited by 1995_maro_z; Dec 11, 2014 at 04:26 PM.
Thread Starter
Joined: Jul 2013
Posts: 303
Likes: 1
From: Indianapolis, IN
Alright, thanks a ton! You have been very helpful and informative! Just a few more questions haha What are some problems or things I should check for when buying a used 10 bolt that is out of the car (or even on that is in a car at a junk yard or something)? And what would you say is a decent price for a used one in decent shape?
oily housing ends and brake area indicating potentially to be replaced axle seals. oily pinion housing area indicating potentially to be replaced pinion seal. a loose pinion,up & down and/or in & out. remove cover and look for broken pieces or if cover already removed,broken parts. gear wear. if Auburn,cone wear. even if everything looks good,noise won't be evident until running in car. 6 speeds/M6/3.42 more abused than auto/A4/2.73/3.23
the last 3 I sold were 3.42 4 channels for 125,125,100. they typically go for much more than that.
the last 3 I sold were 3.42 4 channels for 125,125,100. they typically go for much more than that.
Thread Starter
Joined: Jul 2013
Posts: 303
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From: Indianapolis, IN
oily housing ends and brake area indicating potentially to be replaced axle seals. oily pinion housing area indicating potentially to be replaced pinion seal. a loose pinion,up & down and/or in & out. remove cover and look for broken pieces or if cover already removed,broken parts. gear wear. if Auburn,cone wear. even if everything looks good,noise won't be evident until running in car. 6 speeds/M6/3.42 more abused than auto/A4/2.73/3.23
the last 3 I sold were 3.42 4 channels for 125,125,100. they typically go for much more than that.
the last 3 I sold were 3.42 4 channels for 125,125,100. they typically go for much more than that.
Thread Starter
Joined: Jul 2013
Posts: 303
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From: Indianapolis, IN
UPDATE!!! I was looking throught the service records that came in te glove box of my car and I saw that at 80,000 miles, (the car has 94,000 now) the rear end was serviced and the shop put 70w140 (might have been 75w140) fluid in the rear end and replaced the pinion seal. Isn't the rear end supposed to have 75w90...? Could that cause mine to be noisy? The service thing didn't mention any kind of additive either. If mine is a limited slip (I have clue if it is I just know that my car is a gu2 car) shouldn't it have some kind of gm limited slip additive?
Replacing the pinion seal,(IF,IF,IF the pinion nut was not torqued to specs/returned to it's exact original position) can cause gear noise as the pinion depth and lash have very slightly changed.
The most common gear oils are 75W-90,80W-90,75W-140,85W-140 and I don't hesitate to use any of them.
94 Z28 would have an Auburn 'posi' 2 series because of the GU2(2.73) you mentioned.
The most common gear oils are 75W-90,80W-90,75W-140,85W-140 and I don't hesitate to use any of them.
94 Z28 would have an Auburn 'posi' 2 series because of the GU2(2.73) you mentioned.
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Yes, if anything, the 75W-140 would have made a noisy ring and pinion a little quieter over 75W-90. 
But IF they did not put in 4 ounces of a limited slip friction modifier (even if the gear oil they put in claimed to already have the FM in it), with the Auburn diff which is likely in your axle (given that the previous owner did not swap it out for a Torsen T2/Eaton Truetrac/etc.), that could cause some noises.
But IF they did not put in 4 ounces of a limited slip friction modifier (even if the gear oil they put in claimed to already have the FM in it), with the Auburn diff which is likely in your axle (given that the previous owner did not swap it out for a Torsen T2/Eaton Truetrac/etc.), that could cause some noises.
Thread Starter
Joined: Jul 2013
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From: Indianapolis, IN
Alright haha I just wanted to make sure (and I was secretly hoping there would be a simple reason why my rear end is noisy) lol So since I have an auburn posi, does that mean that I don't need any kind of additive?
12 Second Club
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From: Bucks County, Pa.
If it is not added, it will lock up quicker out of turns, BUT, it will also make horrific noises, especially when turning at slow speeds in parking lots/etc., and it WILL wear VERY quickly, unless it is ONLY driven in a straight line.