AllThrottleNoBottle

First off, is there any performance gain in switching to a 12 bolt rear end, or just peace of mind? Also, what usually causes the stock 10 bolt rear ends to break, is it most always launching hard? Thanks, Ryan

LS1SS4ever

What I can say is that bolt 12 can handle more hp and stronger than bolt 10

jeffws6

I Have done a buttload of searching and reading on that very subject....... It looks like going from the stock 3.42 to the moser/w 4.11 will defenitely net you a faster et as long as traction is there. I will let you know on my particular set up, because I am getting my car from the shop today with a new moser /w 4.11

Blue Hawk

With a 12 bolts, your drivetrain loss will increase by about 2% (say 6-10 rwhp depending on engine mods) over the stock 10 bolts due to increased friction. This is strictly a "peace of mind" mod.

Of course, if you go with a more aggressive gear in the 12 bolts (3.73's and higher) over the stock 3.42's, you will net better accelerations despite the loss of rwhp.

Yes, hard launches with an M6 + sticky tires will usually kill the 10 bolts. There is no real "weak part" as the entire rear end is "weak". The 10 bolts was designed for the Vega back in the late 70's, not for a 300+ rwhp car.

AllThrottleNoBottle

What I mean is...when the 10-bolts break, is it almost always from launching hard. Im asking because im going to have to keep the stock 10-bolt in for a year or two, and im wondering if i keep from dumping the clutch, or trying to launch too hard, and just get on it after first or something, if I will greatly reduce the chance of my rear-end breaking...?

Thanks, Ryan

Blue Hawk

Definitely! I made over 100 passes with SZ50's and 22 passes with drag radials with my ten bolts (4.10s), not launching higher than 2500 rpm, without breaking it. With the D/R, I got a lot of slippage from the stock clutch and that probably helped save my rear end at the time. It was dead silent, even with 4.10s, until I start to use D/R, then it began to howl more and more after that.

What kills a ten bolts at the track: wheel hops, dumping the clutch at high-rpm (shock), having an aftermarket clutch and sticky tires.

The A4 are less prone to break their 10 bolts because they can preload them, unlike the M6's.