another question about rear swapping

[JDub]

i feel like im beating a dead horse when i ask this question, because there are so many posts similar to this. but i cant seem to find an answer that im looking for.

ive got an 1978 MC that i will be starting on soon, and i really want to upgrade the rear. basically i want:

*a direct bolt in
*posi
*3.73 gears or similar (not terribly worried about gearing)
*disc brakes

is this even obtainable? i know the monte ss had discs in the rear, but my mom used to have one and it wasnt posi. so is something like this even possible to find?? id love to be able to pick one up in a junkyard. :lol:

 

[megaladon6]

unfortunately none of the 81-88 g-body's had rear disc. i don't think the older ones did either, but they may have the standard 4-bolt flange. if they do you can find a junked 92-96 camaro and pull the brakes and mounting flanges. otherwise you need to either cut and drill the axle flanges or but an expensive mounting plate and still modify the flanges. then you use mid 80's? eldorado calipers and s-10 rotors.

 

[85 Cutlass Brougham]

The only G body rear with the 3.73 and posi that has a standard GM 4 bolt flange is the 8.5. It was only used in the Turbo Regals and 442/ H/O Cutlass from 1984 or 5 to 1988. All 7.5/7.625 axles use the odd 3 bolt flange and discs require an aftermarket kit or fabrication. You will also need a disc brake proportioning valve (has no residual pressure valve in it) and an appropriately sized master cylinder to work with the rear discs. Just remember that if you go too big on the rear caliper piston size relative to the front you will lock the rear brakes up faster than the fronts and it will be nearly impossible to compensate. Also, the master sizing is critical because the disc calipers require more fluid volume than drum brake wheel cylinders do. Most of the vehicle's weight transfers to the front during braking, so the front wheels do most of the work of stopping the car. It is easy to make the car worse and not better when mixing and matching these parts, so just be careful and test the car only in unpopulated areas.

 

[andrewmp6]

Rebuild the rear you have how you want it its cheaper.

 

[JDub]

Rebuild the rear you have how you want it its cheaper.

How much would it cost to take my stock rear and make it a posi with a 3.42 or 3.73 setup? How difficult of a job is that? I've never done it.

 

[85 Cutlass Brougham]

The labor is usually around $150 to have a shop do it. As for the price of the parts, that all depends on your source. Used could be less than $100, new could be $600. You could find a 4x4 S10 with a 7.5 axle from the 80's and use it's axle for parts too.