dankl

iTrader: (1)

2001 Z28 M6 (mods in sig w/ more to come): Going to 4.10/4.11 gears and don't want to put $$$ into the 10 bolt. I have read a lot about the 12 bolt and the 9" rears, obviously the 9" being the stronger of the two. I've been offered a good price on a 12 bolt, besides that I was leaning towards the 9". I don't do much racing, but I do drive hard on the street. My mechanic thinks the 9" would almost be overkill for my set-up and also says the 12 bolt will be much easier to install and will fit better. So do I go with the "decently" priced 12 bolt, or go big and get the 9" ??? Thanks for the responses.

MikeSomething

iTrader: (11)

They say 12bolt = A4's
9inch = M6's

I would say since yer still under 400hp anyways, you'd be fine w/ either.

Blackhawk777

As long as there are no real high rpm launches from a dead stop, and you don't really go over 450 whp, you should be fine with a 12 bolt. That's what's going into mine when the 10 goes.

EPP

iTrader: (22)

Put a 12 bolt into a early Chevelle, Nova, Camaro, etc and you can beat the crap out of it, and not hurt anything. Put one into one of our cars with a torque arm, make a couple 4000 to 5000 dragstrip launches, and I can just about guarantee you'll pick up gear noise. If it is a drag only car, you'll never know or care about the gear noise. Drive your car home from the track, and the noise will drive you nuts. I feel the torque arm stresses the 12 bolt housing, causing distortion. We have never seen this happen with the 9 inch housing.

Exotic Performance Plus strongly recommends the Moser nine inch. This rear is even tougher than the Moser 12 bolt, and the horsepower of the late model F Body cars keeps escalating every year, which requires a very strong rear. With the recent introduction of the 6.2L GM aluminum block and the excellent flowing 6.2 litre heads, the horsepower of these cars is going to just keep climbing at a very fast pace.The nine inch will handle the power, plus we prefer the way the torque arm is bolted to the nine inch in the same way the oem rear-end is attached. (This is the only good thing about the stock 10 bolt...) The Moser 12 bolt uses four short bolts to attach the torque arm, and they have a habit of loosening up, even when loc-tite is used. Why the nine inch is stronger than the 12 bolt. The 9-inch has an internal rear-pinion support that also supports the gear end of the pinion to limit gear deflection under high torque loads. This seems to be the major reason why the 9 inch doesn't start whining after high rpm clutch dumps, when the 12 bolt will pick up noise.The 9-inch locates its pinion gear lower on the ring gear to improve tooth contact, than the 12 bolt does.The 9-inch has a 0.125-inch larger ring-gear diameter and internal pinion support than the 12 bolt does. This is not much of a difference, but it is worth noting.

http://www.exoticperformanceplus.com....html?item=145 Bob

ponyeater01LS1

so what are we recommending here? i have an auto and Im looking for a rear, is it safe to just go 9 in?

LS1BLKSS

iTrader: (36)

i say go for the 9" if you don't know if your going to add some "good fast goodies" if your not going to add anything else... then get the 12 bolt

ponyeater01LS1

oh im deff adding more maybe the juice. what gears do u all recommend, keep in mind its an auto

LM97Z

iTrader: (4)

Go with the 9" & a 3.89 gear max.

ponyeater01LS1

roger, thanx

EPP

iTrader: (22)

The Moser nine inch rear is designed to bolt right into these cars. The torque arm bolts up to it, as does the lower control arms, etc, just like the 12 bolt. The driveshaft length should be increased by one inch, while it is not totally necessary to do so, you may experience a vibration problem if you don't get the slightly longer driveshaft. The stock driveshaft is a weak link anyway, they have been known to turn into a pretzel for quite a few people.

Here is a link to the Moser 9 inch on my website.
http://www.exoticperformanceplus.com....html?item=145

Thanks. Bob

SuperSlow02

iTrader: (16)

Moser 9in fits like stock, had mine in and bolted up in an hour...so not sure if your mechanic ever seen one. And as to overkill. Nothing is Overkill

ssvert99

iTrader: (26)

nothing wrong with a "good" 12 bolt. there are some 12 bolts out there that arent so good, also. but with a M6 car and the possibility of future power increases, the 9 inch is usually the way to go.
the Strange S60 is also a good choice. it is by far the best bang for the buck in a true "bolt-in" rearend. uses original AAM stamping tools for the bracketry and includes the sway bar brackets. its a bit heavier, but you will never hurt it.

1sick'98WS6

iTrader: (19)

Honestly in an M6 car Id go nothing less than a 9 inch.. And I know you werent asking about the S60 but as stated By Ssvert99 it is a true bang for the buck and has a 9.75 ring gear i believe. The thing is nuts, Im going s60 good luck either way

SuperSlow02

iTrader: (16)

It came down to price for me between the S60 and 9in. 9in was cheaper by a bit. You WILL have to get a different driveshaft though with the S60

EPP

iTrader: (22)

I agree, Moser 9 inch fits really well and certainly is not overkill in todays performance market. Bob

383lt1impala

iTrader: (33)

9 inch not too much more and whole lot more surence!

ponyeater01LS1

i think when i get the cash ( us military men have to save ya know) ill get a 9 in, it sounds like its the best way ta go

DannoWS6

iTrader: (5)

Agree, I got a Stange 12 bolt ordered though "ssvert99" and it has 3.90 gears. I think a 12 bolt is plenty strong for an auto car, even if the car will see the occasional 9-10 second pass. In a manual I'd just get a 9", the clutch is like an on/off switch and over time the shock will start to put a hurting on it, its' the housing that takes the beating better, the auto doesn't shock the drivetrain.

BriancWS6

iTrader: (18)

Do it once, do it right, 9in all the way!

AFASTYZFR1

iTrader: (55)

9in from EPP