The Stovebolt Site Forums The Shop Area Driveline Corvette Style Master Cylinder Use for Non-Power Drum/Drum

I picked up a corvette style master cylinder (dual reservoir) a couple of years ago and wanted to use it to power my drum/drum setup (while leaving the option open for disc/drum in the future).

My truck is a 1957 3100 with the single reservoir MC currently leaking its way to oblivion (having been rebuilt twice). I bought a corvette style that a friend had who was planning on doing disc/drum and it came with a proportioning valve and the rod. I'm pretty happy with my drums, but may eventually do a front disc setup if I can find a way to do that with COTS parts. For now, though, I'd like to install this MC (which has the bolt-on bracket) in place of my original.

Any issues? Residual pressure valves needed?

Thanks,

Jim

Hy Fourbrads, yes residual pressure valves will be needed in both braking circuits 10 p.s.i for drum brake systems. A proportioning valve may not be required as a lot of their function involves the disc brakes however if you experience rear wheel lockup you can install an adjustable proportioning in the rear brake circuit and dial it in to eliminate the rear brake lockup, hope that helps.

Thanks 3B.

Since this thing is already plumbed with a proportioning valve, maybe I should just leave it in in case I experience the lockup. If I do end up using it, does that mean I can go without the RPVs?

Does it matter where in the lines the RPVs go? Does it have to be higher than the MC, for instance?

Jim

Hy Fourbrads, you should install the residual pressure valves as close as practical to the master cylinder. I do not believe there is any residual pressure function built into the proportioning valve. Do you know if your proportioning valve was used in a disc/drum or drum/drum application? The early drum/drum dual brake master cylinder systems didn't actually use a proportioning valve, what they used was more or less a manifold with a switch in the middle to warn the driver of a pressure differential between the two circuits, hope that helps.

The guy I got it from said it was for a disc/drum setup.

I'll plan, then, on doing the MC only, together with RPVs near the MC.

Appreciate the help, my friend.

Jim

Check the piston size 1" for non power assist.If its larger than 1" it may not give you enough pressure. That's according to all the brake suppliers I've been looking at.

Fourbrads, are you going to fabricate a bracket or do you know which one you are gong to buy? I am close to sorting out my brake system and will be using a Corvette MC in a non-power disc/disc setup on my '50 3600. I found a bracket for $85 online, but it seems like so much $$$ for a bracket that I may make my own...

Dave,

I will not be fabricating one. The only thing (well, other than cost) that has kept me from buying a set was the uncertainty that is created with wheels and tires and all the other steering 'stuff' that gets impacted. There are so many dependencies with this type of upgrade that I've ended up with paralysis by analysis.

Trying to get off the stick now that I have tightened up my steering a good bit. I'd still love to buy a pair of purpose-made brackets, then get a list of off-the-shelf brake parts (calipers, rotors, etc) that will bolt up. Then, of course, figure out which rebuild kit works for the corvette style MC (29969 casting number), etc, etc...Here I go again.

goneagain, thanks. I'll measure the bore and see what's out there.

Thanks guys,

Jim

Jim I know what you mean about paralysis.Check out different web sites like Willwood for specifics. Learn about pedal ratio. If your truck had manual brakes your pedal will be fine unless you ad a booster then you'll have to change the ratio to decrease the leverage.
You can buy brackets everywhere. Some use your old pedal.I built my own brake pedal bracket using the original pedal using a long push rod 14" I think and a second bracket holding the booster & master cylinder. I have a V8 with an automatic and wanted to move the booster away from the transmission.
Hope this helps.

Jim,
In my opinion what you don't want to do is do this twice.
It sounds like you want install the dual MC & bracket, split the lines, install the RPV's for the drum brakes and then later convert to disc brakes with a booster, etc. You would have to undo much of the previous work to accomplish this task. The disc brake MC/booster, brackets, prop valve kits generally come as a unit. While you have the MC you would have to get the bracket and the other components separately. I don't know who sells them that way.
I just did a 59 for a customer. We bought a kit (rotors calipers, bearings, booster/MC, etc) and everything bolted on. Had to purchase a couple of lines and some bolts separately but that was it.
Fred

Thanks Fred (and goneagain),

My plan did not include a booster, but the rest is pretty well on the money. The 'nice-to-have' part of that equation being the (later) ability to leave it all in place and just bolt on some type of front disc.

At this point, though, I'd be happy with my stock drums and finding a way to include the dual reservoir MC.

If there's no reasonable way to do that, I'll just buy a non-leaking reman standard single-bore and call it good. It seems to have done the trick for this long and I don't want to buy more trouble than I already have. Probably wasn't a good idea to buy the dual MC without a plan for how it would work with my stock components. Live and learn.

Best,

Jim

I'm with you Fred
All things considered a full drum/disc conversion kit is the way to go and cheep! Were talkin brakes here the most important part of the truck. My only other thought is avoid stainless brake lines unless you enjoy pain.
Ken