don't listen to the guys that are saying a 9" is a waste! They obviously have no clue... Look at the price of a 12bolt, then look at the price of a 9"... they are very close in price so why risk it? Not to mention I would never buy a used 12bolt off of anybody(unless it was DIRT cheap), but a 9" I wouldnt think twice. A M6 car needs a 9" period. The AUTO's are much more forgiving... some people need to quit giving out bad advice in this thread!!

 

I agree, both the 12 bolt and the nine inch are the same price. And for someone to even suggest that the OP could keep the 10 bolt with his M6... Bob

 

If I hadn’t just bought my car, and wanted to drive it so bad, I would leave it down over the winter until I could afford to buy a 9" moser. I guess I could use the 7.5 as a guinea pig to see how I like the 3.90's.

 

9"

take it from those of us who broke MULTIPLE 12 bolts....... For me, it was with 371 rwhp, and 430 rwhp....that was the last time.

Do it once......

 

Just drove up to Midwest chassis today and had them install their fab 9 for me took them only a few hours to do everything. First off Eric and his guys were great to deal with real good group of guys they really know what they are doing. Also my rear end is high quality and is working out great soo far hopefully going to get to pound on it next week, would definitely recommend Midwest chassis 100%

 

It was a pleasure meeting you today. If you have any questions just ask, and that is a nice ride you have for sure.

 

Go 9" or even S60!!! Just because you dont abuse it now, doesnt mean that wont change later. Going with a 9 (i really want a MWC Fab9, but i just bought an engine) will set you up for just about any future mods you may consider, and hey the pricing between the 12 bolt and 9 is very similar, so why not go with the stronger of the two?

 

I went through your exact same decision process and even nursed the 10-bolt for a very long time avoiding DRs and only occasionally racing it on the road course/autoX. Ultimately though I broke it a second time...on the street. It took me a while to decide but ultimately I went MWC fabricated 9" and here's why:

First, I called a vendor I really, really trust for unbiased advice...not a rear end guy really, but a racer for sure...Sam Strano. He said a few things...1) a 12 bolt will absolutely be fine for my car and is certainly strong enough for my needs, 2) he still recommended a 9" because of center section, gear, and posi selection, and 3) he said he wouldn't buy any components made by a certain company. I won't name that company here because I'm not sure if it's a sponsor and I'm not sure Sam would want me to do that.

I went with the MWC fab 9", Strange Aluminum center, Yukon Posi, Strange Axles, fab torque arm, fab LCAs, and aluminum drive shaft. The overall weight difference from the 10-bolt is negligible (10lbs I guess) and the 12 bolt is significantly heavier.

If I had it to do over again, I would have bought new backing plates and had it assembled at MWC, I ran in to several snags (my own fault not MWCs). But the workanship is amazing and the customer support is as good as any I've seen...Although Eric and Jason sound way too much a like on the phone.

Good luck on your selection, it's a huge investment and pricewise it all works out pretty close once you factor in the options you want.

Oh and some personal advice...if you buy a 12 bolt, get one that accepts through bolts on the rear for the torque arm. Several people have had problems with the torque arm breaking on rears that don't use through bolts. In fact BMR voids the warranty on their torque arms if used without through bolts.

 

to me it should be a question of fab 9" or s60 ... those two are the only real choices for stalled or m6 f-body cars..

 

"Needs" should be defined by the intended use / application specific...you don't "need" a 9" per your described use. In my opinion you don't need a rear end at all. 400rwhp? Street driven? The 10 is not going to grenade unless you're not being honest about your intentions . Don't get hung up on the hype that floats around here that the 10bolt is made of glass and is completely disfunctional . Don't get me wrong, I believe in a little "insurance"....but a 9" for your situation is overkill.

 

Unless the car is an automatic, I strongly disagree. Bob

 

Coming from someone who sells rear ends, I would expect nothing less Bob !

Seriously though, in my own personal experience prior to my current project I, without failure successfully drove my 450rwhp M6 STREET CAR sporting a 10 bolt just fine. Drove with spirit too !! Are there failures...sure. Not to split hairs, but for every failure we read in this type of venue, how many successes are there? Never here about those, do we? GM did not design these things to "grenade" with the mildest of upgrades.

 

I have to agree with Bob on this one and not only because we are both vendors either.

We spend every day talking to rear end customers either through phone calls, PM's, or emails talking to yes potential customers about how their daily driven car broke the rear end and some mention how they are on their second to third fix.

Me personally I am not sure how you can say one is over kill to another? What makes a housing package like ours being a fabricated nine inch overkill to a 12-bolt,S60, or a stamped 9 inch? Pricing is similar by the time you add in the torque arm and cross member with our package deal. PLUS what makes it not over kill is the fact a fabricated nine inch like ours gives you room to grow simply based off the fact their is so many choices with a nine inch.

We are budget builders like everyone else and the reason we even started making our fabricated nine inch was because Eric needed something better for his own personal F-Body and this made the most sense by the time he looked at all the options out there. He didn't produce them looking to sell them people found out he was making them and asked if he would make them one as well and that's how we got started.

 

The ring gear and pinion are small and weak, and the case flex's, diffs break... thats just what I want.... I blew my 10 bolt at 25 mph, driving normally, cut the case in half as the ring gear pushed out then back in.. Granted I had drag radials on the week before and was toying with it, but it broke on street tires, at 25 mph, with 330 rwhp. This story is very common. Hence why everyone seems to be buying rears for these cars, hell 80% of the cars on our local forum have 12 bolts or 9", and only because their 10 bolts broke again and again. To say they arent weak is ignorant.

 

Hey, I get it. Honest....but I am still taking the position in that we only hear about the broken cars, not the ones that have survived. Hard to define the threshold of the 10 because each car is different...hp, driving habits, driver, etc.

Not to make a mountain out of a mole hill but I was responding to the input of OP's info:

Based on this info, nothing is "necessary" until its broke, agreed? My position is if aint broke don't fix it. Simple. Understood at this time its a "what if" scenario, but IMO going from a stock 10 bolt to a 9" sounds a little agressive given the use of his vehicle versus the punishment a 9" can take hence, overkill. At the end of the day its OP cash and only he can justify what he feels is needed...

 

Need more data before we start adding non-valued statements. To assume rear ends break going 25mph and therefore all 10 bolts are weak is ignorant. How many trips down the 1320 before it broke . Beat something enough, its bound to break.

 

there is plenty of info on this board about this topic!! The Autos have been 10's w/ the 10bolt... M6 cars have broke the 10bolt with stock power. Again if your lookin to upgrade from a 10bolt in a m6 car, then a midwest fab 9", moser 9'', or s60 is a must! I broke the 10 bolt in my old 96 z28/ m6/383 setup... Launched it @ 4k on the street with 275 nittos and it went boom...only had 30k mi on it! That was with stock 3.42 gears too. Not to mention it had only been to the track once prior and that was back when the car was bone stock... The 10bolt is weak end of story.

 

Apologies to your muddied thread....as you can see, there are some rather passionate and sensitive opinions on the subject. Mostly one dimensional, lost in the translation responses but...hey, these are the joys of internet experts and keeping up with the Jones'.

Is the 10 weak when punished, yep. No argument here. Will it work based on what you claim above, yep. Want some insurance because we all know you're gonna drive it like you should OR if you have some cash burin' a hole in your pocket and a 12 bolt is an option, then I would pony up for an S60 at least.

Either way, good luck and if you still on the fence, give a sponsor a call....

 

The 10 bolt in my car broke while I was teaching my G/F how to drive a stick. The car was pretty much stock and right then bought an 9". Heads, cam, intake, nitrous and tons of 6200rpm clutch dumps later its still holding up like a champ. No whine or anything stupid. Get a 9", do it once, and then dont worry about it again. Its worth the money to me to KNOW that my car isnt gonna break when I dump the clutch.

 

the only non valued statments are yours. Do you read well, because you only qutoted my own issue, not the fact that 10 bolts are rarer in these cars than an aftermarket rear. Funny how I remember back in the day, in 2000 when I was on slpeng's forum how many people busted 10 bolts, almost everyone was stock then..... If you really think a 10 bolt is worth anything in a 6 speed car, good luck to you. You remind me of the idiots who say they can build a 10 bolt to hold anything you throw at it..... and when you grenade one they are no where to be found.