I'm working on my 39 chevy truck. It has a comero clip with disc" up front and a 8.8 mustang rear with drum's. I used all new factory correct conponets on each end, and a under the floor power brake setup from sothern rods a ccp proporting valve and willwood residual valves 2# to the front and 10# to the rear. My problem is I only seam to get half pedal, and only my front brakes work. I tried switching the ports at the mc and still no luck. Also I just got a power bleeder form Phoenix Systems and power bleed , vac***e bleed and revrse bleed them with no change! If anyone could help I would be greatfull !!!!! I'm out of idea's --- the next step is 40# 's of dynomite . Thank's Spike
Spike, if they are new calipers; they take a hell of a long time to bleed- a hell of a long time. I would bleed them ****ers more. Are you getting a pedal if you pump it up? pork
I am no pro but is your proportioning vlve adjustable and plumbed in the rear lines after the 10# residual valve? If it is adjustable make sure it is wide open to rear Bench bled master cylinder, air in trapped in lines.power brake pedal will feel a little lower than manuel not much tho. will feel different when running with va***n.
i may be totaly wrong here, but i dont think you can use both . a prop valve and residual valves as there basicly doing the same thing.
If the brakes are pumped up there is no change, also I haved jacked up both ends and bled them.. It is only my rear wheel cylinders that dont work, My wife can hold the pedal down and I can still turn the rear wheels, also I adjusted the shoes so they always drag kinda hard, I'll back them off once it works right. Could it be something as simple as the wrong master cylinder?
Sounds like the valve in your proportioning valve has kicked, shutting off the fluid to the rear brakes.
So I take it you are getting fluid to the rear cylinders. Recheck the shoe installation, springs all in the right spot, emergency brake cross bar in the right place, take drum off and check that rear cylinders are operating, don't press hard lightly to see movement from rods to shoes.
bleed till you get a stong piss stream .. and i had to take my ladie out to dinner when she pumps the pedal ..... check binding rubber hoses. good luck
When I switched the ports there was no change the front would work fine but the rear will not . Also I have rechecked the brake ***embly before but could have missed something, would not hurt to do it again. If the valve in the proporting valve stuck can it be fixed or is it a replace it kinda thing. Also the fluid seams to flow fine if you bleed it by hand.
By chance, are you using any thru-the-frame line fittings? Some have a large bore that can trap an air bubble. Morrison has a new one out that is small-bore all the way thru. Just a thought. Good luck with it, I know I've chased way too many brake bleeding gremlins around the car and back. My last one was just last month, a rebuilt caliper that had a bad seat under the new bleeder screw. East to type, about 3 hours to find.
If the fluid flows fine to rear I doubt (could be wrong) that the proportioning valve is bad. How are the rear wheel cylinders? With what I know from this post it sounds like the problem lies in the rear drums somewhere, brake cylinders, brake shoe misalignment, or emergency brake hardware not correct.
The pedal feals firm only at half pedal, but at that I only have front brakes, and the front will slide the tires, also no thru the frame fittings. It's gonna take more than dinner, she is tired of me being pissed about my truck. Maybee a pearl necklace.
I just had a similar experience with a 55 chevy step side with chevelle front clip and 12 bolt rear w/drums. power booster under cab. I made sure I bled the hell out of the master Then bled the hell out of the whole system just like you have already done. Seemed like i could only get half of a pedal. Took the truck for test drive and the brakes felt great. I ran a proportioning valve only. I think you may want to 86 the residuals.
After I put the kids to bed , I'll sneak to out to the shop and do a investagation, and I'll post my findings, I'd be happy even if I made a dumb mistake. Could have over looked some thing little.
I'll try ditch the the residuals, and make up some small jumpers.Then I counld always replace em. The reservoir is under the floor about 1 1/2 ' from the firewall. about 4" down from the floor.
I think someone else mentioned the pushrod length. but also check that M/C piston is coming back all the way..Bench bleed the M/C. Made me remember this: Not saying you did this,but; One time someone brought thier car in the shop after they did thier brakes w/ the same problem and the calipers were on the wrong side and that put the bleeders at the bottom and that won't get the air out at all.
maybe the flex hose between ch***is and rear axle housing is perished inside and blocked. I have had this before with a car that had been standing a few years.
I had a friends truck do this to me one time, he had bench bled the master cylinder put not good enough, i bled the hell out of the brakes and never could get decent pedal, until i rebled master cylinder
I only have front brakes, and the front will slide the tires, Spike Excuse me for being stupid but what does slide the tires mean. If it means your wheeel still can spin than I say check mc. You need to keep the residual valves in, Your mc and reservoir is below the wheel cylinders. The residual valves stop the fluid from flowing back to the mc. The front take the 2 psi and the rear drums take the 10 psi, disc have different psi requirements than drum. The proportioning valve regulates the pressure difference from disc to drum, some are preset and others are adjustable, when you mix applictions sometimes the preset ones are not set to the application, whereas an adjustable one in the rear comes to play. I would leave the residual valves in, verify they are installed in to in and out to out. Wildwood residual valves note which way fluid goes, I believe one side says out other mc. Double check that the proportioning valve is plumbed correctly. Front ports in to out correct and rear in to out correct It may be possible that the rubber seal on the piston rod in mc that is in between the front and rear outlet ports is defective and letting some fluid to byp***
You said when you manualy bleed you have fluid.Did you have pressure at the rear bleeders? If you have good pressure at the rear wheel cylinder bleeders something is wrong with the brake shoe setup,shoes being put on backwards or hardware missing .Never seen a set of drum brakes that had pressure at bleeder not work unless bad installation or bad wheel cylinders or adjustment.
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