i know this has probably been asked a million times over, but, here it goes again:

how can i change my rear drums to discs???(sigh) what do i need to buy???

I think since you have a later model, all you need is the proportioning valve and obliously the rear. There is some issue with the master cylinderm but i think thats for earlier years. Other than the prop. valve and the obvious you should be good to go.

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• 89 Formula 305 WS6
  SFC's, LCA's, Air Foil
  Spohn Panhard Bar
  Flowmaster Cat Back, Tranny Cooler
  A/F Ratio Meter (not a mod but it sure spurs interest)
  Trans Temp Gauge
  Most "Free" Mods
  3:73, Zexel Torsion Posi
• 90 Eagle Talon 2.0
  (Winter Beater)
  Mods? Um, no

Don't change your master cylinder or proportioning valve. If you have a 10 bolt you may be able to install the PBR aluminum calipers on your stock rear.
Check the Spohn Preformace board on this.

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82Z 305 w/comp 270 magnum cam,Edelbrock Performer RPM,Holly 1850-4,serpentine belt drive.TH700R4 w/B&M holeshot 2000 converter,& megashifter.1LE front brakes, 9bolt 3.27 w/1LE rear brakes.Aluminum driveshaft,boxed rear susp.poly everything,IROC swaybar+wonderbar. 70mph@2200rpm ASE Master Tech plus L2
also recently obtained a
'69 chevelle SS396 w/Turbo 400,3.31 posi,11.0 to 1, headers,etc. Latest project car,'86 IROC stock 305TPI hit on left side,but not too bad

You need to buy a whole disc rear end, preferably one from an 89-92 f-body. My dad got one from an 89 GTA, 9-bolt with 3.27's, and it was a direct bolt-in. He just had to change his speedo gears in his trans for the new ratio.

If you get a rear end from an 82-88 f-body, then you might have to change the master cylinder, proportioning valve, and the parking brake stuff.


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1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.23 @ 107.62 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

Check the 1LE board frequently (Spohn Performance). Info on this conversion will be coming soon.

Stainless Steel Brakes sells a bolt-on kit. It costs around $700....

You do not have to get a new rear end. The durm brake rearend has two bolt holes at the bottum of the flange. they line up with the two bottum holes on the disc backing plate,just need to be drill them to the size of the backing plate holes. The top of the flange will need to be cut off to the bottum of the big hole. then mount the backing plate on and mark the location of the top two holes and drill them to the size disc backing plate holes. That kit you can get from SS brakes will tell you to do this. This will work for PBR brakes or the cast iron brakes, because both have the same bolt pattern.

I switched from drums to disc in my IROC, I bought a 9-bolt borg warner disc rear from thirdgenresource.com for $350, it's a much stronger rear end than that crap a$$ 10 bolt, I also got the disc brake master cylinder and proportioning valve from them. THIS IS THE RIGHT WAY TO DO THE CONVERSION and its only $350- $400!!

IROCTOM, use your stock (J50) master cyl, and prop valve.

OK YOU DO NOT NEED TO REPLACE THE MASTER CYLINDER/PROP VALVE. REPEAT YOU DO NOT NEED TO REPLACE THEM. Everything is the same not matter the disk/drum set up. Thats why the 1LE systems use the same master clyinder as my 92 RS disk/drum. I looked it up in a parts book. And to let everyone know now most later year 3rd gen DON'T EVEN HAVE A PROP VALVE!. Its inside the master clyinder!.

There is no cutting or drilling with the Stainless Steel Brake kit. It is a straight bolt on, take a look at the article in the new issue of Camaro Performance...

The reason i switched to the other master cyl. and prop. valve is i called the chevy dealership, and they said they are different part numbers. thirdgenresource threw them in at no extra cost. some people say you have to switch them, some people say you don't, it's only a few minutes of work to swap them, so i figured better safe than sorry!

I went back to the stock disc/drum master cylinder on my 1LE conversion. I had used the J65 disc/disc master cylinder. The J50 disc/drum master cylinder was a BIG impovement.

I swapped in a 9-bolt rear about 6 months ago. That is it so far and I drive it every day.

With that said, I have an adjustable prop valve in the back seat (for about 6 months) and I need to buy a new master cylinder at Autozone and install these. This is because my rear brakes are not doing squat. They work a little, but not enough to feel good about! This is on a 1984 car though... you don't need to do all this.

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

I also have a 9 Bolt. I use the stock J50 disc/drum master cyl. with the GM#14089496 proportioning valve, and my rear brakes really work well.
Rubber on the road testing is really the only way.

[This message has been edited by ANDYZ28 (edited June 14, 2001).]

I would suggest keeping the drum brakes. Wish i had 4 wheel drum brakes. You can make them work great and they dont drag like disc. Also they dont dirty up your wheels.

The problem with drum brakes, is that they are not nearly as efficent at dissipating heat. And this makes them much more prone to brake fade. Thak a rear drum set up out on a quiet, straight road. And make 10 consecutive 50-0 aggressive brake stops. As you get progressivle closer to the 10th stop. you wil really notice the onset of brake fade. Something to be always avoided if possible. this is very true for our autocrossing friends.
Thanx,ANDYZ28