12 bolt question

[99Ls1fever]

I have a 99 camaro ls1, I want to see if a 1980's gm 12 bolt will be a direct fit with springs, lower control arms, and shock mounts, or will i be in for modifications. It is a 80's rear end with disc brakes and posi rear end. will this fit direct into my 99 camaro? thanks for the help.

[xirxious]

What did the 12 bolt originally come in? I thought they only put them in trucks and they were leaf springs. If you're having the mounts re welded, take it to someone who knows what they're doing setting it up. If the pinion angles off you'll blow u-joints.

[99Ls1fever]

i definatley a agree with you on the welds. for gm rear ends they can either be springs or leafs. But i asked a buddy and he told me that the abs wouldnt hook up right and a whole bunch of sh*t would have to be modified so i said screw it for now.

[INMY01TA]

That old 12 bolt wont work. I'm certain it won't have a torque arm mount.

[Firebirdjones]

Hmmmm,,,they didn't have 12 bolts anymore in anything in the 80's,,,,even the chevrolet full size trucks went to the 8.5 inch 10 bolt rear in the half ton applications in 1980. 1979 was the last year for the truck 12 bolt in the half tons. 3/4 ton and up got the 14 bolt with 10 1/2 inch ring gear. In any count,,,the 12 bolt trucks are not much count....they are weaker than the car version with a smaller diameter pinion gear that will likely snap in half under decent HP applications. A factory 12 bolt from a car is the strongest one to use.

Even if you have a 12 bolt out of something that was a factory application,,,none of them will drop in a 4th gen F-body,,,,they will not be the right width for one,,,,but even more important,,,,none of them have torque arm provisions.

If you want a 12 bolt for a 4th gen your only option really is to get a new cast housing from Strange, Moser, Currie,,,,as they come cast with torque arm provisions.

On a side note,,,I have seen some really crude and nasty applications where people have taken the aftermarket torque arm bracket made by Currie,,,which is actually designed to be welded to the 9 inch sheet metal housing,,,,,and they have actually welded it to a cast iron 12 bolt housing,,,,it was brazed with nickle,,,,and looked like shit if I may say so but it was in the car and working last time I saw it.
I personally wouldn't do this but it was cheaper than buying the real thing and people seemed to be attracted to cheap, even if it is dangerous. You see some really crazy stuff with some of these cars.
That is what happens when you mix drinking beer and welding together

[Hot Black Trans-Am]

I blew all the bolts off the ring gear in my 73 truck with about 500Hp and 42" tires. Yeah, they're not to strong.