CHANGED PROP VALVE NOW WHEELS LOCKED

[SkidmarkSS]

I have stock brakes up front and LS1 FBody discs in the rear,i had crappy pedal response with the disc/drum proportioning valve so i replaced it with a disc/disc valve from performanceonline,now the pedal is stiff with no action and the brakes locked the first time i pumped them,car is the 87 in the sig and has stock master cylinder and stock power booster.i will try to bleed the brakes and bench bleed the master,will this help?

 

[Anonymous]

You could drop the disc/disc proportioning valve and go to an adjustable. You need a 2lb residual valve for the rear discs to go with that adjustable.

All this may not help if there is a problem witht the rear calipers. I wouldn't imagin air in the lines making them lock. Perhaps to much residual pressure in the rear lines.

 

[butta]

I just did the same swap except I have the ls1s all around and they work great! I went with a disc/disc combo valve and a disc/disc master cylinder with a 1 1/8th bore size. The pedal feel is high and not too stiff but not soft at all. I bought the master cylinder and combo valve from master power brakes. They have good customer service and tech people who might be able to help too.

 

[LS6 Tommy]

First of all, you need a disc/disc master, too. A drum master has a residual valve that can cause a disc brake caliper to stick or drag. A secondary issue is that a disc/drum master isn't capable of moving the correct pressure and volume of fluid needed to properly operate the rear discs. Also, adjustable prop valves are not intended to replace combo valves. They're used in addition to them on a brake system as a tuning tool only, except when used on race setups with separate front/rear master cylinders.

Tommy

 

[SkidmarkSS]

I am getting plenty of bleed pressure from the front(which is locked up)and none from the rear(not locked up)since the prop valve is disc/disc then it would make sense if my stock 15/16 bore disc/drum master is not working properly, i am looking at putting a 1' bore disc/disc master in here.and i will also try putting the old prop valve back on to see if i an getting pressure back there again.ant other ideas?