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I posted this question in another spot, but it probably should have been posted here.

When hooking up the front and rear brake lines on a four wheel brake drum vehicle, all drums, no disc brakes, with equal sized master cylinder chambers, where does the front brake line go and where does the back brake line go? In other words, front brake line to front port and back brake line to back port, or the opposite, or does it really matter? :confused:

Thanks,
Joe

As an indirect answer...
I went to an auto parts store to find a suitable master for my 1940. I looked at master cylinders for corvettes, camaros, and mustangs. The camaro had the smaller reservoir in front...that means the back brakes were in the front, and the front brakes were in the rear. Hope that helps. I call the front, where the master cylinder push rod is.

John

Joe,

What master cylinder are you running. May save me some time. I think I read somewhere that you are using a "basically gm master" that exits on the Left side to avoid the transmission. Do you have a part number?

too many2 ??
why front to rear and vise versa??
what is the reason? if the system is split and equal....., why not simply do front and rear respectively??
what about right and left exit ports on a master (if there is one) and how would that work??
i'm just asking....
i understand if the larger vs smaller resovoirs are used the rear would get the larger, also these are drums only and no disc, does that make a difference??

There are some parts I'll buy at swap meets or from wrecking yards, but anything to do with safety, such as brakes, I try to get the best I can.

I bought my dual master cylinder from Master Power Brakes (www.mpbrakes.com). The part number is MC390387M. It is a master cylinder with the ports on the engine side, which means they exit the master cylinder on the side opposite the transmission when mounted in the master cylinder position on 36-46 Chevrolet 1/2 ton pickups. It has same size chambers. If you call to order one, just be sure to explain what you want. Their number is: 704.664.8866.

I'm very happy with the master cylinder and I can't imagine how tough trying to plumb one on the side next to the transmission could be. With a T-5 like I've got now, it would be almost impossible.

Joe

The difference is in how they front brakes work. Most master cylinders will apply the rear brakes just a touch before the fronts. If you hook them up backwards, it will still stop, it just won't feel right during a quick stop. I have done it! The power brake master cylinders are different from the manual brake ones. The difference is in the bore size and where the resivoirs are. There is a lot going on in the master cylinder other then just pushing fluid! Joe

I would recommend that you visit a junk yard and find a truck that has brakes similiar to what you are running, that way you are not miss matching components... in my case, I'm using a manual system off a 76 chevy pickup (front disc, rear drums)... I pulled the differential valve off the 76 truck, and bought the master cylinder and rear cylinders new.. the front stuff came with my hiedts IFS kit...which are the 11 inch camaro parts.

There seems to be a bunch of confusion here.

For me, the master cylinder 'front' is closest to where the plunger enters it.

There are some differences between master cylinder resevoirs, mainly for drum/disc masters. That is because disc calipers are larger and need more fluid, so the disc resevoir is larger than the drum resevoir, even though the drums will often will have larger diameter brake lines.

Disc brakes need more pressure than drum brakes. There is more pressure from smaller diameter bore master cylinders- ie 1" is more pressure and 1 1/2" is more volume. The bore is the principal difference between drum/drum, drum/disc and disc/disc master cylinders.

Someone mentioned the front brakes being applied a little after the back brakes by the master cylinder. That isn't true. The combination valve or metering valve/stand-off valve does that and it is external to the master cylinder.

If you are putting a drum/drum master in your truck I don't think it matters which half of it goes to the front or back brakes.

You will need a proportioning vavle, metering valve and 2 residual valves in addition to the dual master. Your best bet would be a combination valve and residual valves that are designed for a drum/drum set up. It does matter how you hook up the combination valve, since one outlet is for the rear and one is for the front. If you use individual valves rather than a combination valve you would put the metering valve in the front brake circuit, the proportioning valve in the rear brake circuit and residual valves in both circuits. The residual valves are only necesarry if the master cylinder is lower than the brakes cylinders, or may be lower than the brake cylinders if you are going up or down a hill, which is the case with these trucks when you put the master in the stock location...

MP Brakes is a great company and will have exactly what you need. They also have a good tech line and you can call them with your questions and report back if you want.

OK - TooMany2count -

I read you latest post and I need clarification. When you say front to rear, rear to front, you say the rear is closest to the fire wall - right? That means it is closest to the mount of the cylinder. That means when installing a master cylinder on a 36-46 Chevrolet 1/2 ton pick up, the front goes to the front and the rear to the rear because the master cylinder is turned around, if you are mounting it in the "original" position down next to the transmission. In other words, the front goes to the port closest to the master cylinder mount. So it actually is, front to front and rear to rear. Not trying to argue here, just getting everything laid out so it can be understood. Does this sound right to you?

Joe

now i'm confused. i thought the larger reservoir was for the discs, on a disc/drum system. what would you use for a disc/ disc system. I want to use the big 12 inch rotors all around.

I just went to Master Power Brakes web site and there is the information I'm looking for.

The rear brake line goes to the port closest to the mount of the master cylinder. The front brake line goes to the port furtherest from the mount of the master cylinder.

bigbadswingdaddy - I don't know the answer to your question. Maybe someone can explain.

Thanks for the lesson in brakes!
Joe

On a disk brake system the larger reservoir is used for the front brakes. Usually on master cylinders that have different sized resevoirs, the piston sizes are stepped. I would think that if the piston sizes are the same, it shouldn't make a difference.

One way to remember what reservoir is for what, look at the system. Calipers take a larger volume of fluid than wheel cylinders. Therefore, you need a larger reservoir to supply them.

In that diagram the master cylinder is hooked to a combination valve and from there the lines go to the front and back.

That diagram doesn't show where the metering valve and proporitioning valves would go if you don't use a combination vavle. It also doesn't show residual valves, which are important whenever the master cylinder is going to be lower than the brake cylinders, such as when it is mounted below the cab on the frame.

I was wrong in my earlier post that it wouldn't make a difference whether the front or back resevoir is hook up to the front or rear brakes. That should teach me to guess! According to the folks at ECI it does make a difference.

Here's another diagram, with labels, from the ECI site and it shows the front circuit hooked up to the resevoir furthest from the plunger.

[img]http://www.ecihotrodbrakes.com/images/pic02_brakefacts.gif[/img]

[img]http://www.ecihotrodbrakes.com/images/pic04_brakefacts.gif[/img]

A good site to use as an information source is Master Power Brakes. In the past I've gotten some good suggestions on the proper way to plumb in all kinds of brake hardware from their tech section.

http://mpbrakes.com

I need to check The coupe, and see if it needs residual valves, since the master cylinder is under the floor... thanks for the info

I am getting ready to do the suspension and upgrade the brakes on my 39. can anyone tell me if i need power brakes? if so why and can you point me in the best direction to keep stock pedals and below the floor mounting of such. I will also like to hear the reasons i dont need them lol

thanks

I forgot to add that I want to put a dual master cylinder in also. is there a bolt in set up that will retain stock pedals?

Hey Fatboy (I like the name - I have one too - Harley??)

You should probably start another post with your topic. It'll get more responses being a fresh post and not tagged onto this one.

Just my $.02

HC

PS: Welcome to the bolt

Starting another post might help, but I'm willing to talk on this one.

I can tell you that there is not a bracket made for a direct bolt in. I maintained my stock pedals on the bell housing mount with a partial stock bracket and built a supplemental bracket to set the new master cylinder in the stock position. Several Stovebolters have converted the stock master cylinder bracket to hold the dual master cylinder. One of them is Bill Schickling: http://home.twcny.rr.com/schickling/1940Chevy/index.html
Hope this helps!

Joe