I've got a lead on a `79 trans am disk rear end out of a 4 speed car...I have not seen it in person yet so anyone know what options there were? What should I look for? Any way to ID the ratio? Thanks in advance!
As far as I know all T/A's were posi. Pontiac motors for the most part not being high rpm motors the gears generally were 3:23 or 3:42 at best to let the torque of the motor work.
Sorry to go all non traditional here 79 was a weird year for TAs as the pontiac 400 was phasing out. Automatic 6.6 cars got the olds 403s and 2.41 rear gears. 4 speed cars got the "T/A 6.6" pontiac 400 that were supposed leftovers from 78. When those motors ran out, no more 4 speed 6.6 birds. The "T/A 6.6" was always the higher output of the engines available, and when coupled with a 4 speed meant 3.42 gears.
Well..to bring it back to semi-traditional, its for a 58 Chevy Panel truck.. So...what I'm gettin is, no matter which gearing, its still a posi, correct?
the ratio code should be on an aluminum tag held on by one of the cover bolts. lacking that, rotate an axle and count the number of times the pinion turns. also if it is a posi, both axles will turn the same direction, if it is an open diff, the axles will rotate in opposite directions. Is ther anything else left of the parts car/ thanks
Hey Firedome, Challenger/Cuda 8 3/4s are what fits best in '50s Mopars... that's what you should be looking for.
Hey Cliff, thats' the same rear end I will be running in the coupe. Mine is posi, but the gears are 2.73, and mine has aluminum finned drums.
The rear end in my '39 is from a '81 Trans Am that has disks but NO posi. I think it was an '81 thing for Pontiac. I would check it first if you really want a posi.
I am definitely going to see it personally before handing over $. Looking for the gearing tag, spin the axles see if it looks like what everyone has described...and also see if he still has the proportioning valve for the brakes...going out this afternoon since its in Bastrop.
I put the same rear end in my 56 Task Force Chevy Pickup (half ton). I thought mine was a 3:08, but could be wrong. The thing fit well. I went with the Lokar emergency brake kit. easy Install, I think I got the spring perches from Brothers (chevy truck parts company)
I have had several of those rear ends. 81' was the only year you could get disk brakes and no posi. Otherwise the WS6 option automatically came with the limited slip. Most of these rears are 2.73 and 3.08 gear ratios, so a 3.42 one would be a real find. Or you could just grab the brakes off of it and swap them over to a standard drum brake rear. They are a bolt on to any 10 bolt, and I understand they will fit a 12 bolt also. The axles and everything are exactly the same as the drum brake rears. I have a 3.42 geared one in my Z28.
Take a 1/2 inch socket and remove the cover; then you'll KNOW what gear ratio it is, and also if the gear oil looks like black metallic paint.
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