break peddles peddle question

[forestb]

I know that the brake peddles on this trucks are vary high but mine does not seem to even enguage the brakes until the peddle is about half way down.
I have front cpp discs and rear drums with a captonfab booster bracket. they stop the truck fine but it is a little bit of a pain. I have the correct proportioning valve for a disk drum setup. Will shortening the rod and lowering the peddle help? Or will I just be stepping around the problem?

[TheBrewery]

I'm chasing down brake problems too

If you shorten the pedal won't that just put the effective area out of reach? Have you checked the clearance between the booster and the master? It should be 0.25 - 0.75 mm of clearance, but if there is more it will cause what you are talking about. There also could be air in the setup that is compressing before the fluid moves. Have you tried rebleeding?

[forestb]

Do you mean clearance from the push rod or between the surfaces that come together when it is bolted together. No I have not tried rebleeding but when I took it to the mechanic to check them out he said they were fine. Maybe it is low on fluid.

I wonder if there is a way test to see when I start to get brake pressure maybe the rod is to short.

Originally Posted by TheBrewery

I'm chasing down brake problems too

If you shorten the pedal won't that just put the effective area out of reach? Have you checked the clearance between the booster and the master? It should be 0.25 - 0.75 mm of clearance, but if there is more it will cause what you are talking about. There also could be air in the setup that is compressing before the fluid moves. Have you tried rebleeding?

[TheBrewery]

Originally Posted by forestb

Do you mean clearance from the push rod or between the surfaces that come together when it is bolted together. No I have not tried rebleeding but when I took it to the mechanic to check them out he said they were fine. Maybe it is low on fluid.

I wonder if there is a way test to see when I start to get brake pressure maybe the rod is to short.

So check out this video, https://youtu.be/rYYzPIGoxfY?t=1915, It shows you how to measure the booster pin and MC piston to ensure they are "set" correctly.

[jayoldschool]

Originally Posted by forestb

I know that the brake peddles on this trucks are vary high but mine does not seem to even enguage the brakes until the peddle is about half way down.
I have front cpp discs and rear drums with a captonfab booster bracket. they stop the truck fine but it is a little bit of a pain. I have the correct proportioning valve for a disk drum setup. Will shortening the rod and lowering the peddle help? Or will I just be stepping around the problem?

Do you have the correct DISC drum master as well?

[forestb]

I believe so. It is a dual cylinder.

[forestb]

here is the best photo I have of it.

[TheBrewery]

That looks like the corvette style dual pot, it is equal but you have a proportioning valve so you should be fine there.

[Captainfab]

Is your booster pushrod in the original hole in the pedal or did you drill a new hole 1" lower?

[chevy_mike]

Originally Posted by Captainfab

Is your booster pushrod in the original hole in the pedal or did you drill a new hole 1" lower?

Yes, what he said. This is one of the most common mistakes people make. The pedal ratio is different between manual and power brakes. Power needs to be 1" lower than where a manual pedal would hook too. If not, your pedal will engage way too low and the brakes tend to be touchy.

Buddy did his truck conversion and didn't believe me. Had the same problem of low pedal engagement and being touchy. Finally drilled a hole 1" lower and the brakes were perfect.

[TheBrewery]

Originally Posted by chevy_mike

Yes, what he said. This is one of the most common mistakes people make. The pedal ratio is different between manual and power brakes. Power needs to be 1" lower than where a manual pedal would hook too. If not, your pedal will engage way too low and the brakes tend to be touchy.

Buddy did his truck conversion and didn't believe me. Had the same problem of low pedal engagement and being touchy. Finally drilled a hole 1" lower and the brakes were perfect.

Does this apply to the 1960?

[forestb]

I have heard of that but never done it. I should give it a try.

[The Rocknrod]

Brake pedal ratio - https://techtalk.mpbrakes.com/how-to...ng-pedal-ratio

[forestb]

Thanks. This is always something I have thought about doing but never got around to.

[verdell]

Originally Posted by TheBrewery

Does this apply to the 1960?

Yes, it does apply to the '60. Helped my brakes quite a bit.

[TheBrewery]

Originally Posted by verdell

Yes, it does apply to the '60. Helped my brakes quite a bit.

Sorry to Hijack the thread, I am using Captinfab's bracket, I did drill a hole for the clutch master but not the booster. I don't think the bracket would fit any lower...

[forestb]

So i lowered the hole but have not gotten a chance to drive it yet. But what I was wondering while I was laying on my seat pushing the break peddle down with my hand I heard what sounded like air coming out of where the rod comes out of the booster. But it might just be air being pushed out of the rubber cup that covers where the rod goes into the booster. Is this normal?

[The Rocknrod]

While the truck is running? or off?

[forestb]

while running