JTtransAM

I'm going to be having my stock 10 bolt rebuilt with new AAM 3.42 gears and a Richmond mega rebuild kit will Timken bearings. I'm also going to be using a solid pinion spacer in place of the crush sleeve. The car has over 130k miles on it right now and it is my DD and will probably never see a drag strip. Being that it's a 98 (A4) with an unrebuildable Auburn posi, should I go ahead and replace that too while I'm at it and with what? I was thinking the Auburn Pro series. What are your guys' thoughts?

FirstYrLS1Z

iTrader: (4)

I had an Auburn with 205,000 miles on it and still performing as an Auburn should. My current cars' Auburn has about 150,000 miles on it and is at the end of its' service life,the cone clutches spirals are virtually non-existent. Yours at 130,000 miles is still probably fine but since you're rebuilding,I would replace it. Being it's a DD and not 'abused',I would suspect the standard Auburn would be fine.

JTtransAM

Standard as in keep the stock or just replace with a basic unit?

HCI2000SS

iTrader: (2)

I can't speak for the Auburn but I'm running a Detroit Truetrack and with sticky tires with a M6 and 4.10 gears (and about 600 rwhp on top of it) and my 10 bolt seems to be holding up just fine right now

JTtransAM

Would this be the correct one for me that you are talking about? The price is similar to the auburn so I might go with this one.

https://m.summitracing.com/parts/dtl-912a317?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-detroit-locker&gclid=CPvXqMfhw80CFQ6LaQodB3kOeg

dailydriver

I believe he meant the standard Auburn Pro, and NOT the 'Racer's diff' from them, although the latter does have their D-REX warranty program going for it.

JTtransAM

There's a high performance, a pro series, and a race diff. I heard that the HP came standard in the 98s bit I'm not sure. I'm pretty sure that they both have the D-REX option though.

JTtransAM

I think I'll be going with the Auburn Pro series. Thanks for the input guys.

dailydriver

Yes, I forgot they had THREE levels, and yes, the '98s came from the factory with the HP level diff.

IF you are not going to road course, or seriously autocross the car, then the Racer's Diff is not necessary (and most who have used them in that capacity with very sticky tires, wear them out VERY quickly, and even though they have that D-REX program, it becomes a major pain to replace them so often ).

FirstYrLS1Z

iTrader: (4)

to OP,are you going to be doing it yourself or have it done by a shop ?

Since you're purchasing a new Auburn,you'll then have the removed Auburn as a backup spare in case of need.

JTtransAM

My thoughts exactly, and yes I am having it done by a reputable shop in my area. I have spoken to them to see what they recommend as well and they pretty much agree with the parts I have listed.

JTtransAM

One more question. If my car came stock with 2.73's(GU2) and is therefore a 2 series carrier, do I need the posi that is meant for 3.08 and down ratios even though I will be putting in 3.42's?

FirstYrLS1Z

iTrader: (4)

2.73s' came on a series 2 carrier,3.23s' and 3.42s' came on 3 series carriers. As far as I know OEM AAM 3.42 gears are only available for a 3 series carrier(I could be wrong as I've never checked into AAM gears). Some aftermarket manufacturers have 3.42s' for 2 series carriers(they're referred to as 'thick' gears). They're made specifically for those that are changing from 2.73s' and 3.08s' and still be able to use the original 2 series carrier.
If you put in a 2 series carrier,you will need the 'thick' set. If you put in a 3 series carrier,you will need a regular set.

JTtransAM

So would I be able to just put a posi meant for a 3 series carrier in with the set of 3.42's?

FirstYrLS1Z

iTrader: (4)

Yes,if they are 3 series 3.42s'.

JTtransAM

Nevermind, I have GU5 on my door. I don't know why I was thinking I had a 2 series carrier lol. Thanks for the clarification though.

FirstYrLS1Z

iTrader: (4)

I guess THAT leads to a few more questions & comments.
Why change the 3.23s' to only 3.42s',the more popular consensus is to go to 3.73s' for A4s'. 3.23s' to 3.42 will increase torque to rear wheels by 6%,3.23s' to 3.73 will increase torque to rear wheels by 15%. If MPG is the concern,3.23s' have about 24.5 MPG,3.42 have about 24.0 MPG,3.73 have about 23.0 MPG.
3.73s' and a 3500-3600 convertor is the most popular combo.

JTtransAM

Trust me I was torn between 3.42 and 3.73. At the end of the day my concerns weren't necessarily for performance but reliability and longevity being that it's my DD and I plan on having it for a while.

capelajc

Change out the flimsy stock Torque arm while you are at it if you still have the stock one. That IMO made a noticeable difference on my car when I had my rear freshened.. about a month ago. I went with a BMR adjustable

DANOZ28

iTrader: (1)

if your car has 2:73's maybe also checkout motive 3:42 gears for series 2 carrier part# G875342X. I called motive & thats the part# they gave me.