I reacently installed the rear disc convertion (all most). Using 80, cadi. calipers (used rebuilt), 79 Firebird rear rotors and brackets I purchased. Installed a manual booster ( 4 wheel drum). I am using manual due to the high lift and duration cam. Installed an adjustable proportioning valve. Then filled the res. Pumped for preasure. the fronts did good, but the rears seam to be soft. We tried for a few hours :confused: to no evail.Kept pumping fluid through and wuold not stiffen up? There is no e brake cables present at the time. Any help??

If you got all the air out but are still having a low pedal you can "adjust" the rear calipers by manually manipulating the parking brake lever on the caliper.Look at the pad to rotor clearence, if its excessive you'll be able to fit a large feeler gauge between the pad and rotor.This is the clearence you want to take up.As you stoke the lever you'll notice the clearence between the pads and the rotor will lessen.Just adjust till you get a very slight drag when you spin the rotor.When its right you should be able to hear it more than feel the drag.

Are you still going through the original Prop valve? If yes That is likely a problem area.

I installed a adjustable proportioning valve. Im going to hook up the ebrake cables and see what happens. Thanks Guys.

Yes, you need to adjust the rear calipers by hand before you start bleeding the brakes. You do that by pumping the ebrake lever several hundred times! Depending on how much the piston is out when you install it! Once it is close, you can then bleeding a do final adjustments, but it ain't easy!

One problem I had on my set up is that when activating the ebrake, the ebrake return spring on the outside would bind up before the lever would move all the way. I ended up trimming like 3 coils off the srpings and stretching it out so the lever would then swing all the way and the caliper would adjust.

Good luck,
Bill C.

Originally posted by Low Rag 67:
Installed a manual booster ( 4 wheel drum)Is it OK to use a 4-wheel drum Master Cyl.?

I used a non-power 4-wheel disc '68 corvette MC and bolted it right to a stock chevelle Power Booster and it worked fine. I'm not sure whether a drum/drum master will work properly on a disc/disc car. :confused:

Try bleeding your brakes with a pressure bleeder, worked for me.