Brake issue

[63larkcustom]

I'm having a problem with the brakes on Lola. The pedal is firm and she doesnt feel like she wants to stop. Earlier was coming to a stop and it was slowing down, the brake pedal got hard and brake force seemed to drop and she just kept rolling. If I pump it, it seems to do better. The car has power brakes, kinda thinking the issue might be there as all the hoses lines and wheel cylinders are new. Any ideas?

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[bige]

Agreed, sounds to me like a booster issue. Hydraulic problems would give you a low, mushy pedal.


R2 R5388 @ Macungie 2006________________ 1988 "Beater" Avanti

[BobGlasscock]

Easy diagnosis to eliminate, brake fluid on the shoes.

'50 Champion, 1 family owner

[63larkcustom]

The next question becomes, one of the previous owners put a later avanti brake booster/m/c on the car. What is the part number or where can I find a booster. Thanks, Bob

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[bige]

A couple of the Stude vendors rebuild or have them rebuilt. There are lots of specialists that service the hobby that can rebuild your unit. But first, did you do a vacuum check on it?

The other alternative is a source like Master Power Brakes. You might be able to get a dual MC and booster that can be used in place of the Avanti unit.

ErnieR


R2 R5388 @ Macungie 2006________________ 1988 "Beater" Avanti

[StudeRich]

Wait a minute, hold the phone! Isn't this '63 Lark Standard a DRUM brake car?

If so a Disc. brake Avanti II dual master Cyl. and high power Booster is NOT going to work!

Also check the one way valve in the vacuum inlet of the booster, for one way only flow.

StudeRich

[63larkcustom]

Its a 62 regal hardtop. My 62 cruiser had power drum brakes from the factory. This is a different setup. It has a dual master cylinder on it. I haven't checked the check valve yet. I'll check that in the morning. There is a 64 cruiser in a salvage yard nearby. I may go take that setup off and have it rebuilt. as its the right one. I'm pretty sure this one is not the right one at all. Here is a picture of whats in it.



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[StudeRich]

OK that's right I got you confused with someone else. But it IS a drum brake car, then a Power Disc. master & booster for an Avanti II like you have (and that IS what you have), OR the same (similar) from a '64 Lark type will BOTH be the wrong unit to use on a drum brake car, too much power and no residual valve in front or rear.

After '62 (and even before,) a Lark with POWER drum brakes was VERY rare! Available, but rarely ever ordered without Discs.

StudeRich

[63larkcustom]

I guess the next question is what do I need to correct it. Would like to stay with the dual master cylinder.

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[StudeRich]

I would check the pedal push rod that pushes the booster for length to see if it is the possibly original one for Manual brakes or the (I think shorter) one for Power brakes. Then buy the one everyone here recommends for a '64 dual master for drum brakes (also on the Bob Johnstone site) it's the AMC Matador for manual drum brakes with the lines to the ENGINE side. Then you can sell the Avanti II unit and plug the vacuum port in the intake manifold and forget the unnecessary Power stuff ! [^]

StudeRich

[63larkcustom]

Will it have the residual check valves you referred to? The way the lines were modified for the dual. one port on the union was pluged and the line to the rear was extended up to the cylinder. Is there anything else that would need to be corrected?
Thanks,
Bob

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[StudeRich]

If it is for a [u]DRUM</u> brake AMC it would HAVE to have the valves!
Nothing except getting a correct '64 non-power, DUAL master cyl. push rod, someone here MUST have one, or know the length so you can see what you have. [^]

StudeRich

[bige]

I don't know if an Avanti ll set up would actually cause a problem on a drum brake car. The Bendix calipers may not need the extra volume and pressure like a more modern sliding single piston caliper. Also, there may be a check valve in the master because I believe the rear brakes on the Avanti ll's were a more modern self adjusting style. I also think they used a Ford master cylinder.

[u]If you did have a missing check valve it would cause a low pedal on initial application or after a long period between stops but not a hard pedal and reduced stopping power.</u>

The booster needs a constant vacuum supply off the manifold or a large carb port that has full vacuum at idle. With the car running pull the check valve out of the booster and check for a strong vacuum. Strong enough to stall the car sometimes. That's your initial check. If you have a good vacuum signal pull the hose from the valve and use a vacuum tester to see if the booster will hold vacuum when pumped to 15 lbs+. If it won't hold you have a bad booster.

An on the car check of the booster can be done by pumping the brakes a few times with the car off. Then with your foot on the pedal start the car. If the pedal drops your booster is probably OK.

A good booster rebuild could be a couple hundred bucks and take some time. I wouldn't automatically send either booster out without checking it out first. And, the Avanti booster may work just fine with the right master cylinder so don't assume you need to replace it.

There's a Ford Fairlane master Cylinder for a drum/drum power set up looks just like what you have. BTW, it looks like the stop switch is installed in the bleeder port and I don't kmow if that is a good idea.

Heres a part number and dimensions for a master cylinder that looks like the one you have. You might want to compare dimensions and look in the ports for the check valves to be sure.

RAYBESTOS Part # MC36248 {Professional Grade; Bore Size=15/16" Number of Ports=2 Primary Outlet Size=9/16x18 Secondary Outlet Size=3/8x24}
Front Disc Brakes; Rear Drum Brakes
Front Drum Brakes; Rear Drum Brakes; Power Brakes



[u]Notice the application covers both drum and disc brake cars and manual and power boosted </u>

You want to measure the bore size to see if the master that's on there to see if it's a different application from the Ford spec. Easy enough to do and you don't even have to crack the hard lines. Most disc M/C's are at least a 1" bore and some are 1.125 (1 1/8). Start there to see what m/c you might have. Too large a bore would give you a harder pedal. Smaller give you more stopping power less fluid volume, proper for drum/drum


R2 R5388 @ Macungie 2006________________ 1988 "Beater" Avanti

[StudeRich]

Fords are NOT correct for a Stude. or an Stude. Avanti, they used AMC with a 1 in. bore and lines TO THE ENGINE! [:0] Some Jeeps also fit.
No Ford brake parts work correctly on ANY Stude.

StudeRich

[63larkcustom]

I got lucky.. there was a leak in the hose from the manifold to the booster. The check valve is fine. Replaced the hose and nice brakes not the least bit touchy

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