The Stovebolt Site Forums The Shop Area Engine Shop dual master cyl

has anyone done the switch from the single master cyl to the dual master cyl using the type of brackets sold by chevy duty/jim carter? im asking about the ones that leave the master cyl in the original position and use the original brake pedal. how difficult was it? does the bracket really line everything up or is there further fabrication involved? the truck is a 1951 chevy 1/2 ton.

thanks jerry

I did a conversion on my 1 ton with ECI's components and today I can say it works very well as its the first time I drove the truck.

As mine's a 1 ton, the frame was different, so had to do some spacers to get the clamp to fit on bottom of frame.

You'll also have to do a bit of plumbing with brake lines, so you'll need a flare tool, and you might want to try to rent a hydraulic high dollar one as I had a bit of trouble with mine getting them not to leak. I replaced all my brake lines as they were questionable at best.

I just ordered the kit from BROTHERS they are on the LINKS page here.
In the tech section of their site there is a good HOW TO on the installation. I'll post my progress wher the parts get here and I get the time to put it in.

Duddygoober,
The adaptor you see will bolt up to the orig location on your 51 for your dual-m.c. however what they don't make clear is the rod provided in the kit won't fit up cleanly to the orig location and the bolt they provide is not long enough. What is needed is an off set rod or a longer bolt drilled out so it can be safety wired. Strongly recommend you use a 69 Mustang Master Cyl that has the residual valves already installed. The ones you buy are expensive and more plumbing required to make fit in a tight location. You will need a mustang master for drum brakes. If you have already bought your general motors m.c. you will need a 10 lb residual for the front and back plumbed as close to the m.c. as possible for drum barkes front and rear. If you have disks up front you will need a 2 lb residual valve. Not a straight forward install. You also could try to install the adaptor behind the current mounting location. That would allow you more room, and a straight shot to the brake pedal atch location with a longer rod.

Do you happen to have a part number for the 69 mustang master w/the residual valves?

Don't know the part number sorry too long ago. Just ask your friendly NAPA counter man for the Mustang master cyl for drum or the one for disks. Before you leave the store take a small toothpick remove the plastic plugs and gently probe around down in the holes. If you feel some resistance there you have the m.c. with the built-in residuals. Thats the one you want.

I'm in the middle of a dual MC conversion on my '55 2nd. I have already purchased the MC and bracket from American Classic Truck Parts. Old parts are out and new not in yet.

Mr. 52pu,
Here's my question. Do I need those residual valves you're talking about? What do they do? Do I need 2 valves, one for the front and one for the back? The tech article on brotherstrucks.com doesn't mention anything about them.
Thanks,
LT

I'm in the middle of a dual MC conversion on my '55 2nd. I have already purchased the MC and bracket from American Classic Truck Parts. Old parts are out and new not in yet.

Mr. 52pu,
Here's my question. Do I need those residual valves you're talking about? What do they do? Do I need 2 valves, one for the front and one for the back? The tech article on brotherstrucks.com doesn't mention anything about them.
Thanks,
LT

thanks for all the replys. keep them coming. I guess that this is not an easy straight forward swap. this is my daughters truck and I already figgured that i would have to do some plumbing which i might as well get used to since i have another daughter that is in love with the early vw bugs and my youngest likes bulletnose studes, (sounds like more plumbing in the future). I didn't figure on the plunger (or whatever its called) not to fit properly. so now i have another question. does anyone make a striaght forward replacement that everything fits properly with only line fabrication? Are the systems that go on the firewall easier? will they interfere with shifters steering and such?

thanks jerry

LT, The rule is if your m.c. is under the floor and the fluid level in the m.c. is equal or close to the level of the individual wheel cyls then yes you require residual valves either built in's like the mustang reference or in line as close to the m.c. as possible. If you are running drum/drum brakes you will need one 10lb rated residual valve for the front and one for the back for a total of (2). If you are running disk/drum put a 2 lb residual valve for the front and use a 10 lb for the rear.

duddygoober, No, not that I've seen for the 47-53 cheby 1/2 ton pu. Its almost a bolt in with some plumbing and alignment of the rod issues.

I used the ChevyDuty kit to do this on my '55 1st GMC. I later decided that it was the same kit available from Clasic Performance Products for about $15 less.

I bought the appropriate residual valves for a drum/disk system, and spent one whole Saturday replacing all the brake lines.

I had one leak that proved to be a poorly done flair.

I have a continuing problem with the brake pedal not returning all the way to the top under some circumstances.

In my case it only occurs when I've made a hard right turn, and I've developed a habit of lifting the pedal with my foot after hard rights. There is only one corner like that on my usual path, so its not a big deal.

It doesn't hold the brakes applied, but it does leave the brake lights on.

I've concluded that I need to replace the body mount to better control movement of the body, but I've not done anything about it yet. The problem might not exist at all if the rod was aligned a little better. I'm not sure what it would take to fix that issue.

i looked at the brothers site tech section, it looks like a pretty easy swap to me. i still don"t quite understand the rod alignment problem several posters have mentioned. how does the rod not align properly ? is it too far toward the outside of the truck or to the inside? or is it not aligned up and down? or is it not aligned front to back? thanks for all the responses and keep them coming. after seeing the tech article on the brothers page i am especially interested in people who have used their system.

In my case the new master cylinder is a little further from the frame (toward the driveline) than the original location.

old sub. looks like you have a lot of experience with these oldies. I hoped that it was misaligned to the outside so the difference could be made up with a piece of flat stock. since it is misaligned to the inside my next question would be, is there clearance for the master cyl to be moved toward the frame by elongating the mounting holes on the bracket? or is the master cyl already resting close to the frame.
thanks jerry

Good question. I don't know....

It looked to me like the bracket was made to fit a number of different trucks. _IF_ I was planning to use the existing frame long term I think I'd approach it a little different.

The bracket I bought is bolted to a bracket that in turn bolted to the frame. I think the best plan would be to remove the original bracket and build my own. Starting from scratch would allow aligning everything correctly.

But my operational problem with the bracket I'm using seems related more to the body shifting as I go around some corners. I don't know that getting things lined up exactly right would solve that problem.

My experience with these trucks is limited, there are a lot of things I have no direct experience with. But when someone asks a question where I have some experience I always try to share what I know to ensure that I'm contributing what I can to the store of knowledge adn the support this community represents.

don't like the sounds of that body shifting thing you got going, should probably get that fixed. but that leads me to another thought. is it possible that the alignment problems people are having is due to worn out body mounts on these 50 year old trucks and not due to a faulty design of the kit?

jerry

I had no problem with a kit from CCP (classic performance parts) The rod hooked right up. There are some pix on my "site".

I think: no porportion valve if you don't go with discs. No residuals if the truck is not lowered.
I put a power dual set-up in the stock position with drum brakes all around. Pedal feels great and it will drag all four wheels equally in a straight line with very little effort.

Has anyone here done this swap and installed the Saginaw transmission kit from Patrick's on an Advanced Design truck? I am running into clearance issues with the brake lines and the shifter and was wondering if anyone has any thoughts. Thanks.

Steve

I to am getting ready to do the change over to a dual MC. After checking out some of the pics of the bracket from different vendors I have a question. Are some "beefier" than others?

thomas,

I purchased my dual MC kit from American Classic Truck parts. I'm pleased with the "beefy-ness" of the bracket. It's made of heavy steel plate parts welded together and nicely finished. I havent seen others, so I can't compare. I've only seen pictures of the brackets on sites such as brotherstrucks.com, and they are not the same as mine. Can't say if they are better or worse because I can't tell from the picture. All I can say is that they're different.

LT

duddygoober: good thought to re align the m.c. however when I contemplated that on the 52 Chevy 1/2 ton I would not have been able to make the m.c. move over far enough to the frame direction for the rod to line up properly.

stevejumper: patricks saginaw set up and dual m.c. install was tight fit for lines and residuals, but with a little cussin and hand bending of lines it did work. The bracket was make of 3/8" steel and welded.

russntustin
that is a pretty neat looking setup! the dual mc is a lot different from others that i have seen, did it come with the conversion kit?

jerry

52pu,

Thanks for the reply. That is about what I am finding as well. Very tight coming out of the master cyl with a 90 degree bend in the lines.