1963 Power Brakes locking up

[Richard M.]

Re: 1963 Power Brakes locking up

Since this just started to happen, I'm going to check the brake adjustments on the wheels first. The booster rod you refer to is the rod that comes out of the booster and onto the brake pedal? And not the one that goes into the master cylinder, correct?

Between Master & Booster.

[Gerald C.]

Re: 1963 Power Brakes locking up

Rich,

After my research and discussions with fellow members, I understand the fix that may be needed to be accomplished in order to get the brakes in line. Thanks again!

Jerry

[David M.]

Re: 1963 Power Brakes locking up

Gerald, do share your epiphany?

Add rod length and hydraulic piston over travel to my list above.
You should never "over travel" a master cylinder piston when bench bleeding for that very reason.

What is the story of your master? Original, rebuilt, new OEM or aftermarket replacement?

Is it possible the piston in the master is wrong?
Do they come in different sizes on the ID (rod hole depth) & OD for 63?

Some manufacturers use different bores and depths on the rod hole for different applications within and outside of the same model...power vs non-power brakes. Disc vs drum etc.

The Vette masters are typically application-specific as most are quite different in form & fit from other passenger car/truck lines within the GM lineup. I know my 68 442 has a similar-looking fat squatty master as the 68 Vette has. The Vette is non power the Olds is power. Have not compared the business end of these masters side by side.

I've seen and heard of situations where these parts were mismatched by the rebuilder.

Without sending you down the rabbit hole....If it was a rod length issue I think it would do it each time the brakes were applied not randomly.
Do the spin the wheel test to see if it's all 4 wheels locking or just one. That will eliminate the master.

[Gerald C.]

Re: 1963 Power Brakes locking up

Dave,

I followed Harry's advice and bought the tool that will allow me to measure the depth of the m/c bore and then measure how far out the push rod off of the booster should be. The 63 push rod off of the booster is adjustable so according to the tool's explanation and what I saw on youtube in using this tool should allow me to adjust the push rod accordingly. The car is going into the shop tomorrow to perform the spin wheel test after double checking the adjustments in the wheels.

I'll keep everyone posted as to my progress.

Thanks!

[Gerald C.]

Re: 1963 Power Brakes locking up

To answer your other question, the original m/c was rebuilt by Lonestar.

[Gerald C.]

Re: 1963 Power Brakes locking up

Okay. Problem solved! The shop adjusted the push rod coming out of the booster into the m/c. They said it was out a bit too far. I haven't taken the car out for any length of ride today, so we'll see what happens then!

Thanks for all the feedback.

[Richard M.]

Re: 1963 Power Brakes locking up

Okay. Problem solved! The shop adjusted the push rod coming out of the booster into the m/c. They said it was out a bit too far. I haven't taken the car out for any length of ride today, so we'll see what happens then!

Thanks for all the feedback.

Jerry thanks for the follow up. Glad you solved it.

Rich

[Gerald C.]

Re: 1963 Power Brakes locking up

Rich,

You're welcome. BTW, I took the car out for about 35 miles and it was good and hot. The brakes performed as hoped and so far, all is well with the world.....

[Gerald C.]

Re: 1963 Power Brakes locking up

Okay....slight update.....the brake pedal became a little sensitive and "grabby" after driving for about an hour. Otherwise, the brakes work fine. Would I eliminate this by shorting that PB pushrod "slightly" without affecting the overall brake operation. The gap is about 1/16" between the measuring tool and the PB pushrod end.

Thoughts

[Timothy B.]

Re: 1963 Power Brakes locking up

Gerald,

I can't answer your question but don't rule out that there could be two different problems.

[Richard M.]

Re: 1963 Power Brakes locking up

Okay....slight update.....the brake pedal became a little sensitive and "grabby" after driving for about an hour. Otherwise, the brakes work fine. Would I eliminate this by shorting that PB pushrod "slightly" without affecting the overall brake operation. The gap is about 1/16" between the measuring tool and the PB pushrod end.

Thoughts

Jerry, If you think the rod clearance may still be too close, you can use the test method I suggested in post#11.....

Remove the master cylinder from the booster. Add 1 or 2 flat washers at each stud between them, retighten the assembly, then test drive the car to see if it reacts differently.

If it appears your problem is solved, you could then shave the end of the rod the approximate thickness of your "test washer(s)".

Rich

[Gerald C.]

Re: 1963 Power Brakes locking up

Rich,

I'll try that and see what happens.

Thanks

[David M.]

Re: 1963 Power Brakes locking up

Grabby brakes can be as simple as bad/wrong friction material. Or the shoe arch doesnt match the drum arch.

Inspect the drum to shoe contact pattern. Is the wear pattern uniform and even on the entire shoe surface?

Where did you get the shoes?

Did you "surface" the drums?

[Gerald C.]

Re: 1963 Power Brakes locking up

David,

The brakes get a little grabby only after I've driven the car for about an hour. The drums are original for the car and all the surfaces were fine so I didn't have them turned. I will probably get them turned over the winter, just to be 100% sure there fine. I'm also doing to perform the task of backing the car up several times and hitting the brakes so that the self-adjusters are set.

Thanks