Ok, i have an 89 bird rear drums, i found a rear disc rearend today in a 84 firebird in a junkyard. i know i will have to swap the whole rearend, brake lines, master cylinder and proportioning vavle(can I get a spell check?)I also know that those calipers have a problem of backing off and not working, a friend of mine who is a mechanic said that I can buy replacement ones from GM and it will fix the problems. My main question is, is it really worth it putting rear discs in? will i notice a considerable differnce in braking? thanks for any help Jay

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Wide Open Till You See God.....Then Brake

 

I did, I went from aluminum drums to a 88 9 bolt disc rear and then I swapped on some 92 rear disc. I would do it. I have a complete set up with the new gm calipers they are the old stlye. Make a offer if you would like. I also have new rotors.

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86Z28, GM 350, Jet perf Q-jet & chip Dual snorkel air cleaner, Edelbrock performer intake, Edelbrock headers, Edelbrock cat-back, Off road pipe, MSD 6AL, Accel Super Coil, Taylor Spiro-pro wires, Rapid fire plugs, Jet fan switch, World class t-5, Hurst Short Throw Shifter, Ram Flywheel, Center force dual friction clutch,Aluminum drive shaft, BW disc rear 3.45's & a posi, PBR calipers, Earls braided brake lines, Polygrapite bushings all the way around, poly tranny mount & torque arm mount, Hotchkis lower control arms & panhard rod, Rancho limiter straps, KYB struts & shocks, Gm Wonderbar, Edelbrock strut tower brace, SSM sub frame connectors, Jamex lowering springs, Carbon metallic brake pads, Crossed drilled rotors, Mobil 1 Tranny fluid & motor oil, GM syntheic rear end oil, K&N, Grant stering wheel, 1,200 watt system, Jet Black Paint, 91 Z28 rims, 92 wing, Tinted windows.

 

I did the swap to discs, and though I like the idea of the rear discs, when I weigh time and cost with benefits, I'm not sure I'd recommend it. By the way, I've never had any trouble with the rear calipers, but I have a manual and I use the handbrake frequently.

JamesC

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What gears do you have right now and is your current axle a posi or peg leg?

If you've got low gears and a peg leg then yeah I would probably recommend it. TomP did the conversion and you can ask him about the hassle he went through with his master cylinder - he was without his car for a week or so!

My '91 has 2.73 gears, peg leg (open), and drums and converting to an axle with 3.73's, posi (closed), and discs is on my list of future mods. If you've got power tools this whole upgrade would go alot smoother too.

Found out the part number cast in the right side of the axle (both yours and the one you found) and get out a Haynes or Chiltons manual and look up the numbers to see their gears and whether or not they're posi.

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'91 Firebird
305/TBI/700R4/T-tops
Mods: Catco high flow cat - B&M Shift kit - Taylor 8mm Spiro-Pro's - ACDelco Rapidfire Plugs - K&N Air Filter - Trans Am tail light conversion
Stereo: Pioneer DEH-P8200R - Pioneer 6x9's - Kenwood 8" Tube
'91 Pics

'87 Firebird
2.8L/MPFI/700R4/220K Miles on its original, never been rebuilt engine!
Car being parted and sold, just ask what I have.
'87 Pics

 

Iron calipers - No.

Aluminium calipers - Maybe.

I have had both and would love to dump my early iron calipers. They have been redone several times and rarely work right. The e-brake has never worked.

 

I've got an '82 bird and just swapped an ausie 9 bolt w/ discs. Wow what a difference!! Only two problems:
1) The 9 bolt that I got had metric threaded brake lines and the car had standard. The soloution, I bought adapters and ran new lines.

2) The pedal feels a bit mushy. I haven't fixed that yet cause of back problems, but I'm thinking of changing the porpotioning vavle.

But I highly recomend the change over.