I am going to change the gears in my rear. I was looking at SLP 4.10 gear package for like $800. But also wondering about getting a whole new rear assembly for a little over 2 grand. Any advice on brands or which route to go? I will also buy an LS1 drive shaft.

 

Well i would wait till your rear is toast before spending the money for a 12 bolt. When mine goes out i will be getting a strange 12 bolt. But when my posi goes out, (which i believe is gonna be soon) i'm gonna buy the zexel torsen carrier from slp for $99, i will probably only go with 3.73 with that. Then when that goes i'll get the 12 bolt with the 4.10's.

 

ouch on the price..... go to www.drivetrainspecialists.com

they list all of there parts and prices

 

3.73s are alot of gear for an A4. An M6 can go with 4.10s with its overdrive ratio. Not sure which you have.

In my A4 I went from 1850rpm at 70mph in 4th to 2650rpm at the same speed going from 2.73 to 3.73 gears. I love the gears and acceleration but don't like driving for long distances down the highway. I also need a new driveshaft because mine vibrates bad over 80mph now. I could get the stocker rebalanced but I want a stronger, prettier one. Something to think about before you do the gears.

 

Don't make the mistake that I made. Save the $$$ for a 12bolt or a 9". If you have power or run the car hard, rebuilding it will only cost you in the long run when you have to upgrade. It is a quick fix only unless you drive gently, and why would you be driving a F-body if you don't run it hard?

 

i would really suggest the 12 bolt if you can possibly afford it.

if you have to keep the stocker, stick with a 3:73, the rear is weak enough, 4:10's just weaken it more. besides if you have an auto the 4:10's would be silly, stick to 3:73's.

the 12bolts are worth the money, i belive currie and strange make them, usually around $2300 or so.

 

You don't need a 12-bolt if you have an A4, unless you are making big power on slicks (like low 11s and faster). They just aren't that rough on the rear. An M6 is a different story, though it is only justified if you drive the car really hard on the street or drag race on drag radials. A 12-bolt is not just a stronger 10-bolt. They are noisier and when run hard have their share of breakage and problems too. They just don't break as easily. If you think you are going to get a 12-bolt or 9 inch, especially a Moser, then you will probably need a shorter than stock driveshaft, so you might want to hold off on replacing your driveshaft now.

If you do decide to stay 10-bolt, don't spend $800 on that package. That's insane. The cover will only marginally help the strength of the rear. You don't necessarily need a new diff unless yours is shot (ie, if you can't spin both rear tires). And the price of gears and an installation kit should be around $300. If you spend $800 on parts plus labor, you are well on your way to investing in a 12-bolt. And if you break the 10-bolt, your investment is lost.

 

I disagree that anyone should wait until their 10 bolt breaks before going 12 bolt. My friend Matt has been waiting 6 weeks for his Strange 12 bolt. Luckily, he hasn't broken his 10 bolt yet, but with 400+rwhp he will soon.

 

Yep, if you can't afford to have your car sit for a couple months or more then don't be racing it cause the stock rear will eventually go bye bye.
If you have the funds, then do it right and be done with it. Currie, Moser, Strange all make a good quality product. One other thing.... the cost doesn't end at the rear. It just becomes a matter of finding the weak link.

-Mindgame

 

I would have to disagree on the not needing the 12-bolt. My car, fairly stock, broke the pinion gear with 40k and on street tires. However, I totally agree with the losing your investment portion. I wish that I thought of that before I bought all of the stuff needed to strengthen/rebuild my 10 bolt.

 

I have yet to break my 10 bolt...now I am on my 3rd diff though....

A couple of schools of thought here....

keep running your 10 bolt until it breaks and then get a 12 bolt or 9". If it breaks, your out the coin you spent on the 10 bolt in addition to having to by something that cost a couple of grand.

keep running your 10 bolt and fix it every time.

keep running your 10 bolt until you buy a 12 bolt or 9" and if it is not broken, sell to someone to help with the cost.

sit put and just save for a 12 bolt or 9".

 

many valid points have been made, i suggest buy the 12 bolt and when it comes, sell your 10 bolt!