VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc 1963 impala - brake pedal height

after having the power brake booster rebuilt and reinstalled with a new master cylinder, my brake lights aren't working...I tracked it to the brake light switch and pedal position...I cannot back the switch away enough from the pedal arm to make the brake lights come on unless the pedal is to the floor...obviously, the pedal / booster rod was set too long and moved my pedal too high (close to the switch)...does anyone know if I need to undo the hydraulic line, master cylinder, & booster to adjust this length?..after just getting the brakes operational again, I'd hate to have to go through that again...

Been too long since I worked on '63 brakes but think there is adjustment to the rod length at the clevis that attaches to the brake pedal arm.

that's what I'm hoping for, chipper...thanks...

I agree with Chipper that there is an adjustment for the push rod between the booster and the pedal arm. If I remember correctly there is also an adjustment between the brake booster and the master cylinder.

In your original post you stated the the master cylinder had been rebuilt. If the re-builder replaced the piston it could be that the new piston has a deeper or shallower recess in it than the one that was removed. If that is the case the rod between the booster and the master cylinder might need to be adjusted or in some cases replaced with a different length rod.

I suggest these 2 tips as part of your process to make the adjustment.

First, adjust the brake shoes at each wheel to get the desired clearance. If there is too much clearance it can mislead you with respect to setting pedal height and when the brakes start to apply.

The second is to make sure that the adjustments leave enough clearance so the master cylinder piston can return to the home position properly. If it does not the ports in the master cylinder will not open and let the fluid return from the wheel cylinders and the brake shoes will drag (at least until they wear enough!).

There is one adjustment and it is under the dash. The correct measurements should be in the shop manual.

the booster and master cylinder were rebuilt and the shop owner said he adjusted them correctly to spec, so I'll assume that to be the case for the moment...

the brakes were all adjusted only twenty miles ago when the brake system was reinstalled...

thanks for your tips, rusty...when I adjust the rod clevis at the pedal arm, I'll check to be sure the master cylinder can release all pressure...

as always, gene, thanks for your help...

I agree that you should take the easy step first. Unfortunately my experiences tell me to be skeptical unless I know a shop's work very well.

The pedal travel adjustment is done after power brake unit and master cylinder are installed in the car. The manual gives the adjusting instructions and is measured from the pedal to the floor mat. After that is done it says to adjust the switch as necessary.

I checked just now and the rod seems a bit too long...i was able to back the jam nut all the way down onto the rod until there were no more threads, then turned the clevis as far as it would go...this allowed me with enough room to adjust the brake light switch such that it will now light when the brakes are applied...so it's working now...

I didn't try, but I assume that I cannot or should not try to turn the rod further into the booster at this time, as there is probably a jam nut at that end as well?..

rusty & gene, thanks for your help with this...