The Stovebolt Site Forums The Shop Area Driveline Drum-Drum Non-Power Dual Master Replacement Recommendations?

57 bone stock 3100.

My master cylinder has had it. Rebuilt it a couple of times, but it's tired, rusty, and leaks all the time.

I am happy with my drum brakes right now, but may switch to front discs at some point in the future. I would like the peace of mind of a dual reservoir system.

I know folks have found great deals on masters that swap out without modification at places like Rock Auto and the like. Is there a bolt-in, stock vehicle master cylinder that I can look for that will replace my original one?

I understand I will need to re-plumb, but that's not an issue.

Thanks,

Jim

You will have to not only do some plumbing but you will also need to make or get a adaptor plate they run about 100.00.When I did my 52 I bought an plate and used a master from a 67 C-10 Chevy truck.I bought the master from a local auto parts.There is really nothing wrong with keeping a original type master you can get one at any FLAPS near you.

Pete

I did the same conversion on my '56. Here's the story.

No one mentioned the front to rear bias control that is found on every dual brake Chevy truck I have looked at. On 67-72s it is on a bracket right under the master which is on the firewall. On 73 and later it is mounted on the front cross member, but it is the same for whatever year and power or manual brakes. I believe you'll need to use it. Because of the splitting up of your brake system you MAY need 3 pound residual valves front and rear because the master is as low as the drums.

Put a booster on this system and drum brakes will stop so fast they'll make your head swim!

As cletis says, it's a bad job and well worth the effort.

best wishes,

Les

Thanks all,

Looks like this is not going to be as easy as I thought. I will probably have to buy one of the kits. Have read a great deal here on the kits and some of the required "refinements" needed to make them work. Doesn't inspire a lot of confidence, particularly with us of lesser mechanical aptitude.

Cletis, appreciate the step-by-step.

Jim

For the rear brakes you may want to opt for an "adjustable proportioning valve". A 10 psi residual valve is needed in both the front and rear lines if the master cylinder is lower than the drum slave cylinders (2 psi residual valves are for use on disc brakes).... as shown in the diagrams at this link: http://www.hot-rod.com.au/builder/brakes.html

I did this on my two hot rods and it allows you to adjust the back brake pressure, basically adjusting the brakes so the front brakes don't lock up before the rear brakes. Hard to steer with the front brakes locked up.

Hope that helps!

It's not as difficult as it sounds. Do your research, shop around and it can be done fairly inexpensively. The most expensive part is the bracket and adapter parts. I ain't gonna lie and say it isn't a bit of work, though. You'll spend some quality time on your back. That's going to be the case whether you buy a kit or source it yourself. Good luck and never give up!

Mitch

Good advice, Mitch!

Thanks guys,

Anyone out there that sells just the bracket and not a full kit? Don't know that that's the way I'll go, but it provides an option at least.

rfs56trk gave me a lead on a company out of Orange CA that does power drum kits that look pretty complete. ABS Power Brakes. They seem to be having some technical issues with their site catalog, but I'll probably contact them and see what they have to offer.

Thanks again for the inputs.

Jim

Stovebolt member GHOSTRIDER
Use to sell a bracket, don't know if he still offers them

I love CPP and they have your bracket, sold by itself, check the link;

http://www.classicperform.com/Store2/Brakes/5559MCA.htm

Thanks Phil! Appreciate the help.

Jim

I think I bought mine from Classic Parts. It was just the adapter and hardware.

I've done two dual master cylinder upgrades, both with stock drum/drum brake set ups. It's not as hard as it may seem. You could do the upgrade now with drum/drum set up, then upgrade to discs and then add your residual valve then. Just a thought.....

That's exactly what I want to do; Make it safer to drive right now (considering the number of morons who pull out in front of me on the road), and have the effort not wasted when I want to go with the discs later.

So what I need to do is make sure whatever I add can work with the discs later. There's so much information here and elsewhere concerning this upgrade that I must admit I am getting a bit lost in the details. Seems they all require modifications of something, or a bracket from somewhere that doesn't work with the stock mounting holes, or residual valves because the cylinders are above the master. And then, how do you decide which port goes fore and which aft?

I think what I need is a kit where someone has already worked this stuff out. Have you done a TF series?

Jim

So, if you want to do the "bare minimum" to upgrade and keep your NON-POWER drum/drum system,this is what you need. I tried to keep it as simple and sourced only internet pricing.
1. MC adapter, Classic Parts #71-985 $89.95
2. Master Cylinder Rock auto #RMC36239 $18.45 ('69 C10, 1" bore)
3. Proportion valve and 2-10# RPV's on Ebay around $50.00
4. 25' of 3/16 brake line, about $40-50 source locally
5. NEW Rubber Lines rock auto about $8.00 each
6. All the fittings and Tees, Source local about $30-50

I come up with a little less than $300 for the upgrade. When it comes to brakes, price is irrelevant. What matters is that they WORK!

As far as installing them, It will all bolt right on, and look stock. As a general rule, I plumb the front brakes from the forward port and the rear from the other. Don't forget to bench bleed the MC, it will make your life much easier (learned that the hard way).

IMPORTANT!!!! This setup will NOT work if you decide to upgrade to POWER DISC later on. If you are think about that, my suggestion is to simply buy a new, stock master cylinder and replace your current worn out one. You will have to change everything to upgrade to POWER discs. You can change to NON-power discs later by changing out the Master Cylinder and the RPV's.

Hope this helps. It's confusing, but it is not that difficult. Write down what you want/need and then buy the parts to make it happen.


Mitch

The usual disc conversion uses a 8" dual diaphragm booster, a Corvette MC, proportioning valve, and the mounting bracket kit.
You could get this set up and use a non disc MC and convert to the disc MC later when you do the disc conversion. The basic plumbing will remain the same.
Fred

The brackets are different if you aren't using a booster.