12-bolt question

[jpitcher22]

Have a 1998 formula M6 with the factory 10 bolt and 3.42 gears i believe. Was looking to do 4.10's but have heard nothing but horror stories linking back to the lousy factory 10 bolt and how gear swaps like i was planning on doing can be nothing but bad news..

since then, ive been curious about the 12 bolt and the possibility of compatibility from other models that used the 12 bolt. I know some of the 70's and 80's moderately sized cars like the cutlass and caprice sometimes used them.

Basically, does anyone know if its possible to use one of these; does extensive fabrication need to be made to make it work; any other info that might help.

Im just weighing the cost; since its about $2500 for a new 12 bolt/9 inch from Moser and Ive found factory 12 bolts in other models on craigslist for between 4-700..Let me know what you think guys!

Thanks for the help!

[c0ncEpT]

It would be a lot of work to get an older 12 bolt for work under a 4th gen. You would need to fab up a TQ arm mount, shorten the axle tubes, ect..

That being said 12 bolts don't work well in stick cars anyways. The torque arm stresses/distorts the housing to much.

[kammi10]

exactly what he just said

[Phantom409]

Ya, you are going to want a 9".
You can always go 3.73 in the factory rear and be safe.

[1BADAIR]

wanna buy a broken 12 bolt?

[MunsterZ28]

wanna buy a broken 12 bolt?

whats broken how much? sorry to thread jack



but ya mostly stick cars producing power go with a 9".

[1BADAIR]

the ring gear is broke.
I'm not gonna get rid of it til spriing probably. have to decided if i am gonna put an auto in it or not first

[sman]

Larry, I may be interested, if all it needs is gears. My 10 bolt scares me, I hate taking it to the track or beating on it, wondering, waiting for it to go.

[1BADAIR]

well its a spool right now. so probably a carrier and gears

[LS1Formulation]

I have an S60 and I love it. $2300 with a posi, 4.10's and ABS/TCS installed. I swapped the posi out for a spool though and put a set of 4.30's in it. Have yet to see what good it does me since my engine decided to kick the bucket, lol.

[mtuggle86]

you still dont have your engine up and running pat?

BTW the cam worked great I paired it with a set of LS6 heads and its making nice power

[9T8W66]

9" or S60 is the way to go for an M6 Car.

[LS1Formulation]

you still dont have your engine up and running pat?

BTW the cam worked great I paired it with a set of LS6 heads and its making nice power

Nope, don't have a place to work on it and don't have any more money to fix it. After my dog got hit, it'll be even harder to get the money together, so I don't know what I'm going to do. It'll prob. be the middle of next year until I can get it running again.

When it was running, I was launching at 6200 RPM and my S60 didn't even whimper. Never changed in sound either. They're a good choice if you want to save money over a 9". To build a 9" to handle the same power, it'd cost about $3000 or more.

[kammi10]

It would be a lot of work to get an older 12 bolt for work under a 4th gen. You would need to fab up a TQ arm mount, shorten the axle tubes, ect..

That being said 12 bolts don't work well in stick cars anyways. The torque arm stresses/distorts the housing to much.

Nope, don't have a place to work on it and don't have any more money to fix it. After my dog got hit, it'll be even harder to get the money together, so I don't know what I'm going to do. It'll prob. be the middle of next year until I can get it running again.

When it was running, I was launching at 6200 RPM and my S60 didn't even whimper. Never changed in sound either. They're a good choice if you want to save money over a 9". To build a 9" to handle the same power, it'd cost about $3000 or more.

that all depends on who you have build it pat. i have 2250 into my 9 inch and i am psitive it will hold just as much power as yours would

[LS1Formulation]

Does yours have 35 spline axles? Just curious.