I just got a 3.23 posi rear with disc brakes from a 91 Z28. This car didn't have the dual piston calipers in the front so do I still have to change my proportioning valve? The guy i got it from said no but I'm still not sure and everything seems to be working fine with the old one.

 

If you are changing out a drum rear to disc yes you have to change the proportioning valve. If the car already has 4 wheel disc brakes and you are just upgrading to the newer style rear PBR brakes then you already have the correct proportioning valve.

 

Thanks, I wasn't sure how that worked. This was my first rear disc conversion.

 

Slowmaro91RS: I see you are from around the Pgh area. Do you autocross your RS? If so who which club do you usually run with?

Have you ever taken it to the 'Flashlight Drags' (www.alteredgas.com)'?

 

Actually I'm still in the process of finishing my car. I really haven't had a chance to race it anywhere other than the street. Where are you from? I'm usually out in Irwin. If you're close by rmail me. There are a few good car shows out my way every week.

 

Where is the proportioning valve located and what does it look like?

 

Under the master, looks like a machined piece of aluminum with lines coming out of it.

Ed

 

On older cars they're cast instead of machined.

 

What happens if you don't change it when going to rear discs from drums?