Dougs91

Hey everybody I'm kinda stumped here. My car is a 91 RS that I changed the the stock 3.08 one wheel wonder for a 3.23 limited slip disc brake unit from a 91 Z28. The problem is the rear pads are not contacting the entire surface of the rotor just about 1/2 to 2/3 of the outer diameter on both left and right wheels. I rebuilt both calipers, turned rotors, installed new pads, and installed prop valve from donor car. Any ideas would be appreciated.

JamesC

iTrader: (5)

[QUOTE=Dougs91;3965092...I changed the the stock 3.08 one wheel wonder for a 3.23 limited slip disc brake unit from a 91 Z28. The problem is the rear pads are not contacting the entire surface of the rotor just about 1/2 to 2/3 of the outer diameter on both left and right wheels.[/QUOTE]

The pad won't contact the entire surface. Two-thirds or so sounds about right.

JamesC

subroc

iTrader: (2)

Im having the same problem with my PBRs. They made nice contact but were rubbing the rotors or so i thought. I then saw a post that showed i had the pads in the wrong way (inside pads on outside and visa versa), so i switched them to the correct way. Now only the outside half of rotor is getting cleaned. What gives. I would think it should clean the entire surface the pad is touching. Its touching more than just half the rotor.

jjlabinski

Disc brakes often require a different master cylinder. Also, what are you using to proportion the distribution of fluid? Factory rear disc cars are already set up for what you are trying to achieve.

subroc

iTrader: (2)

how come i never heard that before? I have the stock MC for drums. I have an adjustable prop valve.

JamesC

iTrader: (5)

You have the correct master.

JamesC

Dougs91

I checked with NAPA, O'REILLY, ADVANCE, And AUTO ZONE and all 4 places only listed one master cylinder. As for the prop valve, it's the one from the donor 1991 5.7 Z28. I talked to Chevrolet and the mechanic believes I have defective pads. I will be Getting new ones from NAPA Thursday. If that doesn't work I'll look into a new prop valve from GM parts direct for $70.00 .

subroc

iTrader: (2)

According to this page, there is a different M/C for disk brake cars as opposed to drum brake cars. It says so right above the pictures.

http://www.camarotech.com/differential.html

JamesC

iTrader: (5)

They are different, but....

https://www.thirdgen.org/forums/susp...fferences.html

That said, OE PBR's were equipped with the drum master.

JamesC

subroc

iTrader: (2)

hmm ok. Then i guess my brakes dragging is due to something else then...or me mistaking bad axle bearings for dragging brakes.

JamesC

iTrader: (5)

Did you rebuild the PBR's and/or clean and lube the slide pins? Is the e-brake adjusted correctly (to include "free travel"?

JamesC

subroc

iTrader: (2)

I did not rebuild the PBRs since the rubber gasket was uncracked. I did however regrease the slidepins because one on each side was siezed. How much free travel should the cables have? I can pull the handle up about two inches before i have resistance.

JamesC

iTrader: (5)

If a pin were seized, I'd think there'd be a good chance of the piston being frozen as well. At any rate, you'll find the info on free travel in the following link:

https://www.thirdgen.org/forums/faq-...iscs-89-a.html

JamesC

subroc

iTrader: (2)

I looked through that link twice, but i couldnt find anything about the parking brake.

ebmiller88

iTrader: (7)

Sounds good to me. If you have the ability to adjust it, put it where you want it. Need more lever travel? Back the nut off the long stud in the trans tunnel. Need less? Tighten it up.

Ed

JamesC

iTrader: (5)

Post #2 of the above link, "Free Travel"

JamesC

subroc

iTrader: (2)

Thanks James. Im blind apparently

Dougs91

Well the problem with mine was pretty simple. I regreased the caliper pins, cleaned the mount bracket where the pads ride and greased, and installed new NAPA pads. Now the entire surface of the pads make contact. The duralast (auto zone) pads didn't want to cooperate. Hope this helps.

subroc

iTrader: (2)

Found one problem with mine tonight as i was pulling the rear for the second time. It seems that i tentioned my ebrake cables too much so the ebrake was dragging on at least one if not both sides. I will adjust it when the rear goes back in. I will also spring for caliper rebuild kits. I just want to be done with that noise.