Which master cylinder? Pushrod length?

[Rileys68Camaro]

I'm having an impossible time getting a master cylinder that works correctly.

So I'm begging for some help.

Is anyone familiar with SSBC disc brake coversion? I have their front disc kit.

But I need a new master, the old one leaked. I was told I could use one from a 70 and up year Camaro.

But I tried that, and they pedel stops halfway to the floor. I mean stops solid and not from hydraulic pressure, master is dry.

So, what do I need to do? Get a different pushrod? Try another master? Which one?

Will a 68-70 Corvette master work? I have rear drums still, but I have the factory proportioning valve.

Is it possible to have the pushrod connected to the pedal wrong? I read, but can't find, that there are two holes in the pedal one for power and one for non.

I don't know what the car orginally came with, power or manual, but it was a 4 drum car.

Please help, I've bought 3 or 4 different masters and can't return them because I added brake fluid before I started testing for pedal movement.

[fuzzyonion]

From your last picture, you do not have a stock valve. You have an aftermarket one. That's fine. You can use that.

A disc/disc master has no residual valve for the drum brakes. You can use a disc/disc master cyl if
1)the aftermarket combovalve has a residual valve, or
2) You add a residual valve

Have these brakes ever worked well?

The pushrod should be in the lower hole. There should be a brakelight striker in the upper hole. If the pedal is adjusted up enough to meet the stoplight switch without a striker, the pushrod angle will be wrong, and could possibly cause what you are describing.

68-70 Corvette has a deep hole for the booster pushrod where the master bolts on.
2nd Gen Camaro has a shallow hole.

Which one do you need? I suspect it is one with a shallow hole, so the 2ndgen Camaro master should work.

Maybe you should just give in and buy a stockstyle booster/master in a box, from your local parts store for about $100. Make sure you have the stoplight switch striker. They are available if you dont have one.

[Rileys68Camaro]

I've bought 2nd gen masters, maybe the pushrod is the problem.

The brakes have never been used, installed them, and the cars been in storage or having other stuff done too it. Stock rear drums, and the adjustable proportioning valve came in the kit, and I THINK the brass valve did too.

Thanks!

[Rileys68Camaro]

It appears the pedal is in the upper hole, what about the stoplight swtich striker? Never heard of such a thing.


Thanks again!

[ProdigyCustoms]

There are basically 2 power booster push rods going into the master. One is for a shallow hole only a 1/4" deep or so, the other goes in a good 1" to 1 1/2". I don't have one to measure right now. Once you determine you have a deep rod and a deep master, or shallow / shallow, you will need to be sure the pin is the exact length for the master. You can measure the pin in the booster, then slide it into the master to see where it will sit.
If you get any spring back from the master when you put it on, like the pin is pushing the plunger just mounting it, this will cause a big problem. Solution, grind it to fit. If it is too short by just a bit, weld the tip and grind to fit.
I like the 69 Z28 style fat body masters for disc / drum. It will be the short bulging one, not the tall 70 up version.
I just got one at Pep boys for $20 some odd dollars.
I was able to find a copy of an old article I did on power brake conversion. It has a nice cleaned up copy of the assembly manual page and pin location referred above. I added some arrows pointing the various locations for the article. Here is a scan.

[Rileys68Camaro]

To be sure, I want put a manual master on.

No welding or grinding as I do not have access to the equiptment.

[fuzzyonion]

https://static1.pt-content.com/images/noimg.gif
Power brakes.
Clevis in lower hole.
#11, striker for stoplight switch in upper hole


If your pushrod clevis is in the upper hole, that could explain why the pedal stops early. The rod is probably binding.

If you change to manual brakes, I might be interested in the booster.

[Rileys68Camaro]

I don't have a booster, or currently even a master cylinder.

I'm putting a manual booster on to save some money for now 'till I decide if I want to upgrade to the C5 kit.

I bought the car as a rolling chassis so have no way of knowing if it had power or manual brakes, just 4 wheel drums.