Brake pedal return spring with PB?

[Patrick B.]

I am installing the power brake booster on my 67, and the pedal does not appear to have a return spring. The internal springs in the booster seem very strong and would set the pedal position regardless of a pedal return spring. Do the Power Brake cars have a pedal return spring? And what function would it serve?

[Gene M.]

Re: Brake pedal return spring with PB?

No return spring w/power brakes

[Patrick B.]

Re: Brake pedal return spring with PB?

Thanks Gene. I bought a return spring but I wasn't looking forward to disassembling the pedals under the dashboard.

[Frank D.]

Re: Brake pedal return spring with PB?

I left the spring in during the conversion to PB on my 63. It doesn't hurt anything but a savvy judge would spot it right off.
I'm certainly not taking everything apart to yank it out at this point..

[Richard M.]

Re: Brake pedal return spring with PB?

Agree with Gene.... Frank too.

Also, Ensure that your supplied rod is of proper length. If too long, it could cause hydraulic "lockup".

MC rebuild kits can also have piston rod depth variations which when combined with wrong rods, produce similar anomalies.

Rich

[Patrick B.]

Re: Brake pedal return spring with PB?

Rich -- I was thinking about that when putting the booster in. It is my original booster rebuilt by Booster Dewey, and I think the rod is still the original. I bought the master cylinder from Lone Star because mine was a little pitted and they had a correct date coded core. I tried to feel if the master cylinder was being depressed when pushed hard up against the booster. I did not use a gasket between the booster and the master cylinder (correct?). As I understand it, the cause of potential problems is that if the MC piston is forced a little forward during assembly, the rearward hole in the master cylinder reservoir would be blocked by the piston seal. Where I left the project last week was gravity bleeding the new empty system to get fluid into the lines and calipers. Since it gravity bled very freely, I took that to be a sign that there was no interference within the MC that would lead to hydraulic lockup. Next step is to get a helper to push the pedal to complete the bleeding.

By the way, I am using silicon fluid. I would not like to get regular brake fluid anywhere near my new and very expensive paint job. I first used Dow silicon brake fluid in 1975 when it was still experimental in my 1970 Corvette. I still have that car and the silicon fluid has protected the original MC and calipers from corrosion all these years. How many 1970 Corvettes still have their original calipers without sleeves?

[Timothy B.]

Re: Brake pedal return spring with PB?

Pat,

FWIW, in the archives these should be discussion about the 1967 corvette master cylinder deep piston. Also, there should be a identifying mark on the booster to master cylinder rod that identifies it as the correct 67 part. I can't remember if that was a driveline article or discussion here, maybe someone can add to that. I hear to many stories about brake pedal height, dragging brakes etc. So be sure the parts are correct before you pull your hair out.

[Patrick B.]

Re: Brake pedal return spring with PB?

Thanks Tim. I sent my original booster to "Booster Dewey" but I had an old spare 67 booster as well. The rod looked the same on both boosters and it appeared to stick out the same amount, so I figured Booster Dewey reused my original rod. Since the gravity bleeding flowed well, I figured that indicated that the MC piston had not been pushed out of place by the booster rod and that there were no flow obstructions between the calipers and the MC reservoir with the pedal up. Do you think that reasoning is sound? I can't spare much hair for pulling out.

Oddly none of the other C2 Corvettes I have over the years were power brake cars. I once installed a complete J-56 brake setup on my 69 autocross car, but that was back when all my parts came from the local Chevy dealer and compatibility problems were rare.

[Joe M.]

Re: Brake pedal return spring with PB?

Ugh! My 63 coupe is an original PB car. Tossed the booster back in the early 70s for a replacement. Just last week I replaced the replacement booster and noticed there was no brake pedal return spring. Grunted and did gird my loins. Got to make this right. Managed through ZEN, YOGA and Insight meditation to get the pedals out....and back in, without removing the dash. So I now have a return spring and bushing on an original PB car. I can always go back into a ZEN state, dremel in hand, remove the spring and bushing, but my loins and and other parts protest the thought. Maybe when I come across an original booster.

[Frank D.]

Re: Brake pedal return spring with PB?

Ugh! My 63 coupe is an original PB car. Tossed the booster back in the early 70s for a replacement. Just last week I replaced the replacement booster and noticed there was no brake pedal return spring. Grunted and did gird my loins. Got to make this right. Managed through ZEN, YOGA and Insight meditation to get the pedals out....and back in, without removing the dash. So I now have a return spring and bushing on an original PB car. I can always go back into a ZEN state, dremel in hand, remove the spring and bushing, but my loins and and other parts protest the thought. Maybe when I come across an original booster.

As I said, unless you're getting the car judged I'd save myself some backache.

I had my pedals and support bracket out as part of a dash pull for other issues; hats off to you for getting those parts out with the dash in the car...