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Need some help Plumbing my brake system. I have dske on the front of my 41 1/2t with an sb engine. I have an after market mc/booster to mount under the floor, need info on mc to proporsioning valve tofront/rear I think I have all the parts but I need some guidance thanks

You don't "need" a proporsioning valve. Use a 2lb resideul valve for the front and a 10lb for the rear. Placed inline near the M/C.

Hey,41 which mc/booster are you using?i just mounted my after market booster on the fire wall which i really didn't want to.did you use your old brake pedal hole?

Here is a great link. Note the proportion valve is listed as optional...

http://www.ecihotrodbrakes.com/images/pic02_brakefacts.gif

WRONG! VERY WRONG! Even the spelling.

Disc brake calipers require more pressure than drum brakes. That means the rear brakes will lock up before you get any braking action and the truck will swap ends.

In that ecihotrodbrakes, drawing, I think what they meant was that an "adjustable" valve was optional.
They also drew the metering valve as though it were a "T" fitting. On most disc brake setups the pads are already against the rotor. The rear shoes are not against the drums. The metering valve holds off the discs until the drums can contact at the same time. The proportioning valve reduces the pressure to the rear so that front can do most of the vehicle braking.

Brake Valve Definitions

Even this company says you don't need an "adjustable" valve. What they are saying is that a "combination" valve will give you metering and proportioning.

A couple things I've noted on my brake system installs. Trying to use a salvage yard proportioning valve and getting your system properly bled and dialed in so you control rear drum lockup, especially with a boosted system, is a problem.

I've found that using an adjustable proportioning valve, in combination with the 2 & 10 pound residual valves will save you from a lot of rear brake lock-up headaches.

ECI, Master Power brakes and CPP offer some good insights but have a tendency to push their own pricey combo and proportioning valves. These same valves (Wilwood) are available from Summit/Jeg's for a much better price and let YOU dial in the brake bias based on your own driving conditions and preferences. I have pics of my valve setup in my album. Hope this helps.

Dave

I agree with Richard...you absolutely need a proportioning valve with mixed disc/drum setup. Residiual valves are needed for your rear discs if you are running a 4 wheel disc setup.

do you still need residual valves if you have a firewall mounted master cyl.? I understood them to be a sorta check valve pressure wise.

A 10# residual valve should be run on the rear drum setup to restrict the brake springs from pulling the shoes too far back away from the drum. The residual valve maintains enough pressure in the rear circuit to accomplish this.

Without them, you would have a difficult time getting and maintaining a good firm pedal without a lot of pedal travel.

Once again, there are some really great sites that take the mystery out of brake conversions:

http://www.ecihotrodbrakes.com
http://www.mpbrakes.com
http://classicperform.com

Hope this helps.