i rebuilt my brakes last year, a few new lines etc, bled them all , all seems well, but,now that it's running it seems the proportioning valve hasent reset itself,how do you do it?i tried hard on the pedal but to no avail any advice??

 

It should reset itself if you follow the correct bleeding sequence: RR, LR, RF and LF. Of course on 79's, each rear wheel has a top and a bottom bleeder. Do the top then the bottom on each wheel before moving to the next wheel. Have a friend firmly pump the breaks for you and make sure he takes the petal all the way to the floor while you bleed off some fluid. Unless you've got other problems, one good pump per brake bleeder should do it.

 

i put 4 new calipers on, the rear brakes were not working and the line to one side was capped when i bought it 3 years ago. i replaced the rear lines and bled the whole system the pedal seems hard but when i move it in the driveway(gravel with problem carb that idles at 1500.) the rear wheels push the front wheels (they are locked up)the rear brakes are not stopping the wheels. also the brake light is still on.

 

Tell me more about the proportioning valve. I just put a set of semi metallic pads on my '79 and can really see the "clean-up" on the front rotors but no indication the rears are doing much. Brakes have always worked great and still do, but maybe they're not up to their potential. Am I just ??

 

The rear brakes, due to design with smaller pistons and the proprtional valve, don't work as hard as the fronts. This keeps the back end from coming around under hard braking....Rear rotors hardly ever wear out..lol

 

Thanks for clarifying!

 

The brake light still being on is what I'd concentrate on. Yes...it does appear that the proportioning valve has not reset itself. It is very possible that it's defenctive...after a long time of the check ball being driven to one side it may have decided to stay there for good.

If you have followed the procedure properly (driven at 25mph and stopped quickly...including in reverse) and the light is still on, then I'd recommend replacing the valve.

 

now there's a number i never heard.25 mph, i was jut moving (or stopped). you do it in reverse also? i'll try it once i fix the leak in the new oil pan gasket.

 

An easy way to check if the "switch" reset is to pull the wire off on the valve. If the light goes out then the valves piston is stuck and you'll need to take it apart and rebuild it or buy a new one. If the light still stays on, then it's the ebrake switch. (same light). This procedure assumes that the pedal travel is good (no air) and you varified that all brakes work.

 

I checked into this last nite but had puter problems.

Anyway I somehow read this many times without it ever sinking in.

To bleed your brakes your supposed to use special tool xx and hold the pin on the valve so its open. This special tool is just a bit of metal with the end bent to push the pin in and a slot for the bolt on top to hold it in place.
So the valve is spoda be open everytime you bleed your brakes.
Your spoda pump the pressure up on the pedal before opening the screw so there is a good pressurized squirt.
And the brake pedal is spoda be released slowly.

 

Where did you read that Techno? What pin is being pushed in? Can you supply a picture for the special tool?

Oh...wait...I see it. The GM repair manual is talking about the combination valve used on all GM cars EXCEPT corvette. Quote: "This can be accomplished by installing Tool J-23709 with the open slot under the mounting bolt and pushing in on the pin in the end of the valve." But, since fast idle is working on a corvette then I think we can ignore that.

I'd also like to point out that the GM repair manual has a manual bleeding procedure which does not comply with the California Bureau of Automotive Repair (BAR) procedures. Maybe it works fine in other States, but in California I really hope that do-it-yourself mechanics read the BAR manual. Heck...it's a good read for anyone...the more people that read that book then the more people that will laugh at the procedure outlined in the GM repair manual.

But, now at least I know where people have been getting the whacky procedure of opening the bleeder and then having someone depress the brake and then trying to time it so that the bleeder is closed before the brake pedal goes all the way down. If a shop mechanic tried that they would be fired immediately...not only because it would not result in a good stable solid pedal (unless they get real luck), but because it would take hours to bleed the system...and it would require a second person.

One thing on the GM procedure I'd like to point out...is that in step 4 it says to immerse the hose into a transparent container to ensure that the end of the bleeder hose will remain submerged during bleeding. But, the procedure in step 5 is like something that Bubba would come up with if he didn't have a hose to attach to the bleeder, or didn't have a container to catch the fluid. To make myself clear...if the hose is submerged in fluid then it doesn't matter if you release the brake pedal...or pump it a bunch of times and let go because the end of the hose is submerged and any vacuum created in the lines due to letting up on the pedal will just suck fluid back in. But, at the same time I have to say that I've had better results following the BAR requirement of holding the brake pedal down and not letting up until the bleeder is closed...I use a 2' 2x4 and wedge it between the brake pedal and the seat (with a heavy thick towel on the seat to protect it of course) when I do my brake jobs...it's a one man job if you do it right.

fast idle...I think 25mph is the requirement for the emergency brake to lock up the rear wheels to determine if they are adjusted and working properly. The GM repair manual says there needs to be 100 to 450 PSI of pressure in the system before the switch is fully reset. You don't actually have to drive the car to center the proportioning valve and reset the switch, but I've found it to help...the engine needs to be running if it's a power brake system.

Oh...I guess I should add that my info is based on the BAR manual I read...let's see...around 1985 I believe. And, the 20 or so brakes that I've bled with the same procedure without a single spongy brake.

 

Theres no "except corvette" on the instructions.
GENERAL DESCRIPTION
VALVES
Front Drum Brakes and Corvette
It mentions it for pressure bleeding, which I think a garage would do. If your doing the manual method tying up 2 people and more time I can see why you would get fired.

It also repeats it for manual method.
Thats twice.

I have no idea of why a surge is needed other than to flush bubbles towards the caliper. But this is listed in the instructions.

It mentions it under the heading of brake combination valve
Twice it mentions it.

THEN
It mentions So it mentions it 4 times apparently for no reason?

For California procedures I could care less, everyone knows everything is carcinogenic in cali
I don't see the step 4-5 issue unless its the note of rapping with a rawhide hammer, I use the handle of a screwdriver.
Hell half the time I don't bother with the hose or jar. Thats not for sucking air in, it can leak past the loosened bleeder, but so you don't spray carcinogens all over the floor, Paint remover

As for the trying to time it??? where do you get that. You don't open it before the pedal is pushed but while it is. Timing is really simple. We can talk.
Usually the pedal pusher is monotonsly droning "down", "up"
While the bleeder is droning "OK"
Some people go with more information like "the pedal is down"
"The screw is closed"
"The pedal is up"
"push the pedal down"
"the pedal is down"
"The screw is closed"
"The pedal is up"
........................................ ...........
It really is easier with 2 people than one.
I bet I and anyone else could manual bleed faster by at least 4x than you running around the car by yourself. The 2nd persons job is that of your board after all, but they do require beer for lubrication.


I never had a reason for wearing seat belts. And I've survived many accidents.