Frankie the Fink

Got my restored master cylinder and booster back, installed them and bled the brakes twice. Worst part was getting the pedal height correct as factory (which I finally got done). Ran the booster check out procedures in the shop manual and it's all good.

My question is how far should you have to push the pedal down for the brakes to start working? My pedal, at rest, is 4-1/2" off the floor and it seems like I have to push it down a good 2-1/2" (more maybe) before things start to happen....seems awfully close to the floorboard.

I don't have a benchmark to know if that's normal or not. I dimly remember my Dad's Ford LTD '68 demonstrator acting kinda the same. A long push to get the power brakes going. If anybody has a measurement from the bottom of the pedal to the floorboard on a power brake car when the pedal is fully down (with engine running!) it would help.

Thoughts ?

Morley63 - how are your brakes working ?

morly1963

Now is the busy time for my company-just got 2-large shipments in and havent gotten to the brakes yet. morly1963

1KULC7

Remember, they are NOT power brakes, they are POWER ASSIST, so they will never be fully like power brakes, and they are on drums, so they will not be like disk brakes, entirely different world, even with power assist they are sloppy.

morly1963

The brakes are junk, if the car wasn't so nice to look at I'd trade for a 67 with disk brakes.

JohnZ

Huh??

wmf62

the 'power' assists; the travel is still going to be dependent on the master cylinder stroke and the adjustment of the brake shoes.
Bill

kingwoodvette

vintagecorvette

So what exactly are real power brakes and how do they work?

vintagecorvette

If your brakes are junk you need to fix them. You need to have the shoes re-arc to fit the brake drums.

I suggest you find a good mechanic to repair your junk brakes before you have a problem.
When the shoes fit the drums the brakes work pretty good.

jim lockwood

I'm glad to learn this now before my half-century old drum brake vehicles have a chance to fail.

W Guy

Frankie,
For what it's worth, I have the same booster and the same "style" master cylinder on my car and the brakes are applied with less than 1" of pedal travel.
It sounds like you need to make sure the push rod on the front of the booster is within 1/16" of contact with the MC piston. If you set that distance mentioned in the shop manual from the front of the booster case, perhaps someone used the wrong piston when they rebuilt the MC. You might want to use a vernier caliper and check the depth of the MC piston hole to the mounting flange and compare that to the measured distance of the push rod from the MC mounting surface on the booster.

If the brakes applied very quickly before the conversion, you can rule out loose shoes.

Verne

Frankie the Fink

I'll rebleed them this week when I get some time and if that doesn't fix things up I'll look at the M/C-to-booster push rod. The rework was done by Karp's Power Brakes for both the booster and M/C. I talked to them at length on the phone and they seemed very knowledgeable about power brakes and even the idiosyncrasies of the '63 setup. The point being that they sent the whole unit back to me 'married up' so I would assume the push rod is set up properly

rtruman

Next time out I will check for you

waynec

If the M/C rod clearance checks OK, you might also try backing-up while pumping the brake pedal to try to get the auto adjusters to snug the shoes to the drums.

Frankie the Fink

I re-bled the brakes and got a little more pedal. I think I was "...hollering before I was hit"....as my brother tells me. The M/C to booster push rod was dead nuts on the money.

The floorboard is a little deceptive - the toeboard actually drops off about 1/2 way up....so as you look down from the driver's seat it looks like the pedal is close to the floor when depressed fully.

However, if you pull the floor mat back and kneel down and press the pedal with your hand there is close to 3" under the fully depressed pedal.

I think I was the problem.....a case of 'recto-cranial inversion'...

rene-paul

How do they work? Is it a worthwhile up-grade? I am considering...........
Brgds,
Rene

Frankie the Fink

I think part of the problem is that I jump out of a 2013 Toyota Tundra with modern power, all disc brakes and then into the '63 Corvette with its sort of primitive brake system and all drums and the difference is a LOT. The power brakes are much nicer than the non-power brakes on the '63. Manual brakes just didn't seem to want to stop with a lot of 'conviction' if you will. The power brakes have a longer pedal travel than I'd like but when you nail 'em you better be careful cuz you're gonna stop quick. I'm thinking of adjusting the pedal travel for a better feel but its not super critical. There is also the underhood aesthetic appeal of the silver power booster and master cylinder. It just sorta fills up some big empty space in the engine compartment that looks odd compared to the rest of the engine bay...

If you're talking a '63 the boosters are not reproduced and prices for originals will hurt your feelings badly. Forum member "W Guy" has some passenger car boosters for sale on here and you can put the '63 bracket (from Dr. Rebuild) on the back and 99% of folks won't have a clue you did it. Zip now has the '63 power brake master cylinder available in a nice reproduction but without the GM casting number on the bottom (which nobody can see anyway).

This approach will get you power brakes (albeit with a little more work involved) for a fraction of the cost of original stuff.

Frankie the Fink

It turns out there is a spec for '63 power brake pedal height buried in the shop manual. It's 4-5/8" measured from the floor covering to the top of the pedal pad. I readjusted mine which dropped the 'at rest' position down 3/4" and I think that might be the ticket to take up the 'slop' that bothered me with the setup. I'll do a test drive tomorrow to see for sure....

rtruman

Show us a picture want to see how it turned out.