alright so i have had this problem since last fall and am just getting around to fixing it since summer is just around the corner. the rear brakes just barely seem to engage at all.

brake system consists of stock master, ssbc adjustable prop valve, aero space street brakes up front with wilwood drag rear discs. has 3/16's lines to both fronts with 1/4 inch out back and split into two 3/16ths to each side.

i have pumped and bled both sides and am not getting any major pressure like it should. you can feel the rear calipers clamp down a little but not enough that you can not still move the rotor by hand.

fronts clamp down great but the rears do not.

any idea's?

 

The first thing I would do if it was my car would be to pull the drums and see if the adjusters are gummed up. You can take this off clean them up use a little grease on the threads and adjust brake and put it back together and see if that works.

 

Don't think that's going to help much, but what do I know...

Sounds like time for an adj prop valve. Check your rubber brake hose from the body to the rear end first though, might just be rusted shut inside like they always fail.

 

have you tried adjusting the prop valve you have? you never mentioned doing it.

 

yes it has discs not drums.. there is no rubber brake lines on the car at all.. ive adjusted the prop valve a few times..

i talked to a buddy who is real familiar with drag brakes and he said i needed to get the car running and then let the vacuum build up in the booster... that should help out.. i did got it running and its way better then it was before.. i feel they should be a little bit stronger of a hold but he said thats normal

 

Are you sure the rear disc calipers are bled all the way? The stock quick take-up master cylinders can be a pain to bleed without a pressure bleeder. When I was doing the brakes on my car, the fronts were pretty easy to bleed using the 2 man bleed method, but the rears wouldn't bleed all the way, so I had to bring it to my school's autoshop to use a pressure bleeder. When my rear brakes were partially bled, they only slightly worked.

 

i think so.. they took a while to bleed but im getting no air at all out of them.. maybe i will get it going and bring it to a buddies shop and have him do that

 

gravity bleed, slow-ish but effective.

 

No rubber lines at all? So you're running solid line from the body to the rear? If so, you should probably look for a kinked line, but I'd be be willing to bet there is one on there, solid lines and moving parts don't get along well.

 

 

The axle I pulled from an 83 Trans Am and put on my 89 RS was that way. It had hard lines all the way to the calipers. Some models with the cast iron calipers only had one flex line with the other being a hard line to the caliper.

The only thing left from that 83 axle now is the housing - new gears, carrier, axle shafts and LS1 brakes

 

I think that the hardline to both calipers was a part of the 82-83 model years and that afterward the hardline went to the driver's side and a flex line to the pass side--this for the old style Declo-Moraine set-up.

JamesC