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Discussion Starter · #1 ·
I just recently installed power brakes but they dont have much power in the rear are disc up front drums I purchased a 7 inch booster and dual reservoir master cylinder is this booster big enough for a half ton truck plus should I install some type of regulator this truck stops very hard and all the brake system is new please help thanks.
 

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Hio Bob, welcome to the board :welcome:

It would be helpful to know what type/size brakes you have in the rear and what your front brakes are.
If you need to know if your booster/mc combo is sized correctly then we need to know if it is a dual booster and what the bore size is and what your pedal ratio is also.

For now, I'll assume that you have drum brakes in the rear and they are of a size that is proportional to the fronts.

Here is a partial list of possibilities,
Rear brakes not adjusted properly, not bled correctly, primary shoe not mounted in forward position. Mechanical differences,(big/little tire size),improper assembly.

If you have a disc/drum setup without a combination valve or metering valve you may experience the fronts doing the majority of the work at low speeds. This would make it seem that the rears are doing very little work.
If this is the case you need to install a metering or "stay off " valve in the front section of your system. This valve blocks pressure from reaching the front disc until sufficient pressure to activate the rears has been reached. 100 psi or so.

Most all OEM combination valves for disc/drum have this valve installed already. ECI sells them as a stand alone unit.

If you give a little more information we can help you better.
You wrote that "the truck stops hard". Does this mean you have alot of pedal effort?


Later, mikey
 

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Discussion Starter · #3 ·
brake upgrade

I have a nine inch ford axle with disc in the rear and drums in the front with all new hardware a 7 inch booster I am not sure what size the master cylinder is I was told to use a GM type porportioning valve and a residual vavle for the rear thanks much I would like to be cruising by spring I will post pics of this project as soon as I can figure out how. Oh the rear axle is out of a lincon town car early 80
 

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I think you need to go with disks on the front also.........Automotive braking systems are designed that most of the braking is done by the front brakes....and drums on the front just are not going to do that.
 

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Discussion Starter · #5 ·
studebaker brakes

I forgot to tell you that the pedal is very hard to push I think I have the right hole for adjustment and the front brakes lock up easly.when you rev the motor the pedal is a little easier but not much difference thanks for all the help Bigblockbob
 

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I'm sorry I read your initial post wrong. Punctuation would have been helpful. We got the thread moving though. :D

Poncho is right, disc on the rear and drums on the front is a MAJOR part the problem, as the braking bias is backwards. It will be a contributing factor for disaster if you ever need to do a panic stop, as unloaded pickup trucks really need more braking power in the front.



What type of GM proportioning valve are you using? If it is a OEM type combination valve with the metering valve and proportioning valve and a brake system warning switch, it is making the problem worse.

A 7" booster really doesn't give alot of boost, unless it is a dual diaphragm. Low vacuum could also be an issue, as you have said that revving it up helps. Your pedal ratio could still have something to do with it though. What pedal are you using?

Later, mikey
 

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Discussion Starter · #7 ·
studebaker brake

Thanks for the help I just talked to Rene Harger who owns slick street stuff in Knoxville and he builds complete IFS front ends for studebaker cars he is currently working on a setup for trucks he only works on studebakers. He allso makes a front disc setup for all studebakers so my truck is going to his shop for a front disc setup and power steering upgrade he uses 74 camaro steering box. The box bolts right to the frame just like the original did and looks really clean. I will send some before and after pics thank much Bob.
 
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