I have an 89 Firebird Formula with four wheel disk brakes. Will a rearend out of an 87 trans am with four wheel disk brakes fit in my car? Are the rearends the same?

Ok thankyou, quick question though, can i take the callipers off my 89 rearend and use them on the 87. Will they fit?

 

It will fit, however, I beleive the brake calipers are different. I think in '89, they had Aluminum PBR Calipers, and I know for a fact that in '87 they had the notoriusly sh1tty cast iron calipers. Therefore you may run into problems with the e-brake cables and brake hoses but I don't know for sure.

 

Right, and you may also have the 28-spline axles in your 89 rear, if it's a 10-bolt.

All in all, it would be a major downgrade to your car. I would not do it if it were mine.

If you go from the aluminum calipers to the older crappy cast-iron system, you will need to change your master cylinder and proportioning valve, and modify the prop valve; otherwise they rear brakes will work basically not at all instead of merely very weakly and unreliably.

 

Why go backwards with that rear, unless your mind is set on the gears??
The 89 9-bolt with the PBR brakes is a better set up in my opinion.
Maybe because thats what I am using.