12 bolt or 9"

[transamprincess98]

I'm sure this has been asked before, but I'm being too lazy to search. I know there are pros and cons to both rears. I'm looking for opinions from people who have used either set up, what gears and how they liked the results.

[Mr. Luos]

M6 = 9"
A4 = 12 bolt

[FuhBreezeE]

My moser 12 bolt will arrive today, I have an A4 and ordered 3.73 gears. I hardly doubt anyone on here complains about their aftermarket rear end. Much better than the original.

[transamprincess98]

I have the A4, but keep hearing alot of negative feedback about the 12 bolts and whine. What are the cons of a 9" with an A4?

[Mr. Luos]

Heavy. An A4 already 'eats' up power...no reason to eat more up with the 9".
Rock solid though. Won't have to worry about it.

I have a touch of whine in 4th gear with my 9". Not at WOT throttle though. Most of the time, if they are broken in correctly there isn't much of a problem.

[FuhBreezeE]

Heavy. An A4 already 'eats' up power...no reason to eat more up with the 9".
Rock solid though. Won't have to worry about it.

I have a touch of whine in 4th gear with my 9". Not at WOT throttle though. Most of the time, if they are broken in correctly there isn't much of a problem.

How does one break it in correctly?

[Mr. Luos]

Follow the instructions. :lol:
Each one is different.

My 9" called for light driving for about 30 minutes. No synthetics. Let cool. Repeat light driving once. Let cool.
Beat the piss outta it.