I have a 89 with rear drums. i replaced the rear with a 89 pbr 9 bolt was wondering if it absolutely nessisary to replace the porpotioning valve?

 

I used the Proportioning vavle that came with the9-bolt PBR brakes and the parking brake cables also. But someone will tell you it makes no difference.

 

You can just do the upgrade which is basically removing the valve and whatnot and put a screw in its place. I'd double check to make sure since I'm not very knowledgable on brakes.

 

drum brakes don't take as much pressure to lock up as disk brakes do. So you could do the "bolt mod" as suggested. I did and added a wilwood proportioning valve in line so that i can adjust pressure.

 

could someone explain how exactly i would do that with the bolt?

 

I just swapped from drum to disc and haven't gotten around to changing my valve yet, and honestly don't know if i ever will.. the car stops wonderfully without changing it. Maybe if I get real bored I'll swap it Anyone considering this upgrade, I highly recommend it, makes your car look tuff!!!

 

did you have any issues with the parking brake cable? Did it fit the disc setup or was any modification necessary? Also, did the brake lines attach OK.

Doing an '88 rear drum swap to 91 rear disc.

 

i broke the the metal clips that connect to the brakets under the trans tunnel so i just left them off for right now.

 

But everything else fit up OK....

 

what do u mean the? the brake lines fits and so do the rotors and calipers in the stock 15x7 rim

 

what i meant (and I guess I should have said to begin with)

The brake lines were all the correct length, pointing the right direction, the emergency brake cable just attached without problems, etc.....

 

yes everything hooked up right. I dont know bout the ebrake cables i believe that they woulda worked i just never hooked them up cuz i broke those clips

 

I did a drum-disk rear end swap, and I chose to swap the proportioning valve since it all came from a parts car. to answer your question, I dont think it would be a problem if you used your drum prop valve... your brakes will still function fine, but I'd assume that you won't be getting the full benefit from the upgrade.

 

I did have issues with the e-brake cable, my stock cable was too long. You'll probably have the same problem, but since you asked that question it leads me to believe that u already knew that. I had to swap the whole e-brake setup for one that came stock on a disc car. I got lucky on the brake lines, they fit perfectly. However, Chevy did have some variations on the fittings, not all of them have the same thread pitch. Be sure to check that before you start wrenching down on it.

 

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