Brakes

[steve from staten island]

Im putting this in the general tech forum only because i need as many opinions as possible. I have a 69 satellite 383 with factory power drum brakes. The booster is from dewy boosters. I just installed a front disc conversion from SSB. The car stops straight as far as i can tell but requires to much pedal pressure and i cannot get the brakes to lock up. Ive only had it up to maybe 30 MPH but the brakes will not lock up and again I'm standing on the pedal to stop abruptly. Something is wrong. The check valve in booster was replaced and the booster is working as far as i can tell. I talked to Dewy and i have to call them back. There is a adjusting valve supplied in the conversion kit that regulates pressure to rear brakes and I've not touched it yet but none of the brakes lock up. This car is wearing me down. Any ideas are apprenticed and thanks

 

[Mike67]

How old are your hoses going to each corner? You may be loosing some pressure due to the hoses expanding when you hit it hard....

 

[rumcustom]

Is your booster holding vacuum now? I was trying to help you a while back and we narrowed things down to your new booster assembly was not holding vacuum. You pulled the check valve out of the booster after running the engine and there was no "suck" sound of the stored vacuum. That is a major problem. You said you would talk to the seller about it and never posted a followup. I even asked you a couple times what you found out and my helpful concern was ignored. So here I am again because I am a car guy trying to help another. From what you said a while back your booster would not hold vacuum. Did you fix that yet?

 

[Yatzee]

Im putting this in the general tech forum only because i need as many opinions as possible. I have a 69 satellite 383 with factory power drum brakes. The booster is from dewy boosters. I just installed a front disc conversion from SSB. The car stops straight as far as i can tell but requires to much pedal pressure and i cannot get the brakes to lock up. Ive only had it up to maybe 30 MPH but the brakes will not lock up and again I'm standing on the pedal to stop abruptly. Something is wrong. The check valve in booster was replaced and the booster is working as far as i can tell. I talked to Dewy and i have to call them back. There is a adjusting valve supplied in the conversion kit that regulates pressure to rear brakes and I've not touched it yet but none of the brakes lock up. This car is wearing me down. Any ideas are apprenticed and thanks

You mention that you have an adjustable proportioning valve (I think that's what you are refering to in your post) so you can try a little experiment to isolate the problem. With the valve almost completely closed, it isolates the rear brakes from the front and you will have the bulk of the fluid pressure going to the fronts only. If the front brakes are still poor after making this adjustment then the issue is definitely in the front circuit. You are possibly not developing enough fluid pressure because the bore of the master is too large, or, you have not enough fluid displacement because the bore of the master is too small. If it's too small the pedal will go damn near go to the floor before any braking is felt. If too large, the pedal doesn't drop much but is terribly hard too push. Another factor is the pedal ratio which may have to be changed to match the bore of the master. Search "braking pedal ratio" for insight into this phenomena and how to correct it. I had an SSBC system once and was very disappointed with the results and I came to the conclusion that obtaining the necessary clamping force on their calipers was too tricky so I went with a four piston setup. For some reason their product is hard to match with other components and you're not the first to notice this. There could be numerous reasons for your issue but you shouldn't have to beat a "dead dog to death" in order to achieve good braking. It's really not rocket science. Call them and have a little chat as to what they recommend for a master bore size and pedal ratio.

 

[Sixpactogo]

Im putting this in the general tech forum only because i need as many opinions as possible. I have a 69 satellite 383 with factory power drum brakes. The booster is from dewy boosters. I just installed a front disc conversion from SSB. The car stops straight as far as i can tell but requires to much pedal pressure and i cannot get the brakes to lock up. Ive only had it up to maybe 30 MPH but the brakes will not lock up and again I'm standing on the pedal to stop abruptly. Something is wrong. The check valve in booster was replaced and the booster is working as far as i can tell. I talked to Dewy and i have to call them back. There is a adjusting valve supplied in the conversion kit that regulates pressure to rear brakes and I've not touched it yet but none of the brakes lock up. This car is wearing me down. Any ideas are apprenticed and thanks

Do you have the dual ballast booster or the single?

 

[R/T Boy 67]

Rumcustom is right. First and foremost, make sure the booster is working. A car with power disc brakes with a bad booster is almost unstoppable. With the bellcrank assembly the pedal ratio is horrible.

 

[steve from staten island]

The calipers are four piston and i will try that test you described. Thanks

 

[steve from staten island]

Is your booster holding vacuum now? I was trying to help you a while back and we narrowed things down to your new booster assembly was not holding vacuum. You pulled the check valve out of the booster after running the engine and there was no "suck" sound of the stored vacuum. That is a major problem. You said you would talk to the seller about it and never posted a followup. I even asked you a couple times what you found out and my helpful concern was ignored. So here I am again because I am a car guy trying to help another. From what you said a while back your booster would not hold vacuum. Did you fix that yet?

I do not ignore anyone and please if i did not thank you, my apologies. I apprentice all help. I did talk to Dewy booster and he sent me a new check valve.. Im still not sure if its a booster or master cylinder issue as of yet. Will get back asap and thanks

 

[steve from staten island]

Do you have the dual ballast booster or the single?

single

 

[Sixpactogo]

single

That is your problem. Ask me how I know?

 

[steve from staten island]

Ok how do you know LOL.....

 

[Sixpactogo]

Ok how do you know LOL.....

OK Steve, Here is my spin on it. I went down the same road as you with my 68 Charger. It had manual drum brakes from the factory. I bought a factory power brake booster and hardware from a swapper and had the booster rebuilt by Dewey. I upgraded to front disc brakes during my build. When I got everything all together and the car up and running, the brakes couldn't stop the car. Front or rear. I thought it was the Master cylinder and tried a different one to no avail. Then thought maybe it was the proportioning valve and bought another new one that didn't help. I finally spoke with Cass at Dr Differential about my problem. He immediately told me I needed the dual ballast booster that all disc brake B body cars used since the single ballast didn't provide enough boost. I bought a dual ballast set up from Pirate Jack and replaced the single ballast unit. The new dual ballast boosters are made in China and the boot and rod that go through the firewall are larger in diameter than the factory ones so if you go with one of them, you will need to enlarge the hole in the firewall too. Once you jump through all those hoops, you will be happy with your new power brakes. At least I was.

 

[steve from staten island]

PM is being sent and thanks

 

[steve from staten island]

Many thanks to all but especially Sixpactogo. I believe the problem is the brake booster. In the factory manual for the optional front disc brakes a dual diaphragm booster is used. Talking with Cass from Dr Differential he explained the problem and solution. Im confident this is the fix and i ordered a dual diaphragm today. Time will tell and i will report back when its done and tested....Thanks again

 

[rrTor-Red]

Power discs and a single bore master?....NEVER

 

[munger77]

I bought the Power booster/MC/prop valve complete kit from Pirate Jack that specifically states "no mods to the firewall are necessary." This is false. You have to modify the factory manual plate per Sixpactogo's thread above. The new booster assembly is too large in diameter to fit through the manual/factory plate on my car, AND the 4 bolts on the booster itself are WAY off and not aligned to the plate either. Pretty bummed about it. This is not a small oversight by the manufacturer and instructions for how to make it fit and look could should be very clear, specific, and stated up front. You also have to remove and modify your original brake pedal. So if this doesn't work, I'll have to buy new OEM parts that I had to modify to make it work. I could understand if it was a company that specialized in something other than automotive and this was a small side business. But these are "the brake guys" for OEM upgrades. Holy crap.

 

[68 bee]

What modifications do you have to make to the original brake pedal? I also bought the booster and master cylinder from Pirate Jacks but it did not have any instructions. I have a very low brake pedal after the installation and soft pedal. I bled the brakes 4 different times and still low and soft pedal.