66 Brake Issues

[C1066]

I have a 1966 Chevy C10 short straight bed with a 4.6 4 speed on the floor.

Purchased
front disc brake kit with drop spindles (installed)
new power booster with new dual master cylinder and prop valve with new brake lines (brotherstrucks)

I removed the old master cylinder with manual drum and drum brakes, and installed the power brake booster. I bench bled the dual master cylinder with the kit provided, attached the new lines to the prop valve to the front and new lines to the rear all the way to the T. Attached the brake pedal rod with no problem. Connected the vacuum line from booster to intake behind carburetor. Filled reservoirs with brake fluid and bled brakes to all air is gone, started from right rear to left front..felt normal when bleeding while the truck is off. (did this several times to make sure) Turn on the truck, press the brake pedal, but the pedal doesn't return unless I place my foot underneath and bring it back to normal. Even if I just tap the brake, it will go down however much I press, but not return at all nor keep sinking. Just stays there exactly when I let my foot off.

When the pedal is down, the truck will not move. When the pedal is returned to normal (with my foot), truck moves freely. I'm not sure why the pedal is not responding or what can be the root cause. I've bled the system several times, and the only thing I notice strange is when I do press the brake pedal, you can hear a swoosh, as it sounds like air is escaping near the pedal linkage.

Any help is appreciated. Thanks.

[65 C20]

I'm not an expert but is there not a spring up under the dash that connects to the brake pedal to return it to original position.

[pimpston65]

Originally Posted by 65 C20

I'm not an expert but is there not a spring up under the dash that connects to the brake pedal to return it to original position.

yes there is a return spring for the brake pedal

[C1066]

Please tell me there is a spring under there! I don't recall seeing one, but I will quadruple check. Thanks for the help!!

[pimpston65]

Originally Posted by C1066

Please tell me there is a spring under there! I don't recall seeing one, but I will quadruple check. Thanks for the help!!

here's where it goes

[C1066]

Thanks for the pic! As soon as I get home, I will check if there is a spring there or not. I'm just not sure how it would have came undone since all I did was remove the old rod and replaced it with the new one with the brake pedal still attached. Then again, anything is possible.

[C1066]

I went under there and saw the spring still attached. I even pressed the brake pedal with my hand and saw the spring open and close. Is it possible that maybe the spring isn't pulling enough and should get one with more tension?

[pimpston65]

Originally Posted by C1066

I went under there and saw the spring still attached. I even pressed the brake pedal with my hand and saw the spring open and close. Is it possible that maybe the spring isn't pulling enough and should get one with more tension?

anything is possible, but my spring has alot of tension and doesnt strecth easy. thats by hand anyway

[C1066]

Ok. I'll head to a hardware store and see about getting a better replacement. I guess springs weren't tested to last 48 years, ha!

[firemanjimtfd]

When I put my new booster and duel master cylinder on . My pedal would stick. I had the bolt and lock nut a little too tight that held the rod to pedal arm.

[C1066]

I know the booster came with a rod that has a swivel end linkage. It attached to the pedal arm with a bolt and lock nut which I tightened up well. I just figured it had to be attached solid to prevent any catastrophes while driving.

[65 C20]

Originally Posted by C1066

I know the booster came with a rod that has a swivel end linkage. It attached to the pedal arm with a bolt and lock nut which I tightened up well. I just figured it had to be attached solid to prevent any catastrophes while driving.

Was that the problem ?
Just so we all know.

[thelawdoc]

C1066, How did that spring replacement go? I do not know what kind of hardware store you have, but I would be nervous about getting the spring from one. Did you not find this spring at any parts vendor?