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Best Power disc brake conversion kit for 1968 Coronet Sedan

Kip Page

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Location
San Diego, CA
I have power front drums brakes and I want to convert to disc.... do I need the booster etc too?? what kits are the best...thx
 
I will say, wheels are a factor in planning a brake swap. I don't run a booster
 
Your drum brake booster won't provide enough boost for front discs. You will need to replace it with a dual ballast unit.
 
email Dr Diff
he will get you a plug and play kit
 
Even with an adjustable proportioning valve?
Yes. You will end up with a hard pedal and not enough boost to lock the wheels. Front or back. If you don't upgrade to the dual ballast booster, you would be way better off with no booster at all. Ask me how I know.
 
Yes. You will end up with a hard pedal and not enough boost to lock the wheels. Front or back. If you don't upgrade to the dual ballast booster, you would be way better off with no booster at all. Ask me how I know.
So I guess I pissed my money away on an adjustable proportioning valve then, haven't installed it yet
 
So I guess I pissed my money away on an adjustable proportioning valve then, haven't installed it yet
Not necessarily. You will need a proportioning valve with front disc and rear drums no matter what. For the most part, they're job to delay the pressure to the rear brakes so they don't lock up first sending you into an end for end spin when you want to stop. The adjustable one just gives you more input.
 
I run an adjustable PP valve. You can dial things in very nicely
 
Yes. You will end up with a hard pedal and not enough boost to lock the wheels. Front or back. If you don't upgrade to the dual ballast booster, you would be way better off with no booster at all. Ask me how I know.
I'll bite...how do you know?
 
I'll bite...how do you know?
Some lessons are costly......My 68 Charger had power drum brakes originally that worked fine. When I converted to front discs, I couldn't stop the car and the pedal was hard. I thought my booster was bad so I sent it to Booster Dewey for rebuild. Reinstalled it and had the same issues. Then I replaced the master cylinder thinking that was the problem. It wasn't. I finally called Cass at Dr Diff and was told the same message I gave in post 7. I needed the dual ballast booster to provide enough boost for the front discs. If I had asked the question like Kip Page did before spending a few hundred dollars and a couple weeks of trial and error wondering what the hell was wrong, I would have saved myself a bunch of grief and money.
 
Never heard of a dual ballast brake booster....

I’ve heard of a dual ballast used in the ignition

And I’ve heard of a dual diaphragm brake booster

But no dual ballast brake boosters...
 
I guess the technical term is diaphragm. Either way, a single (diaphragm or ballast) will not provide enough Boost or ballast for front disc brakes. Clear as mud?
 
Well great, I guess I have to replace the original single diaphragm brake booster on my Challenger... Oh, wait, the brakes have worked great ever since 1970...
Maybe the fact that 80+ % of the disc brake cars having single diaphragm boosters should be considered here...

The fact allot of guys run discs with no booster at all means something...

Perhaps pedal pressure, mechanical advantage, M/C bore sizing and the booster all are a balanced package... And if you get it wrong then either you get a hard pedal or a very touchy pedal..
 
Well great, I guess I have to replace the original single diaphragm brake booster on my Challenger... Oh, wait, the brakes have worked great ever since 1970...
Maybe the fact that 80+ % of the disc brake cars having single diaphragm boosters should be considered here....

The fact allot of guys run discs with no booster at all means something...

Perhaps pedal pressure, mechanical advantage, M/C bore sizing and the booster all are a balanced package... And if you get it wrong then either you get a hard pedal or a very touchy pedal..
I'm not here to argue the point one way or another. Just trying to save some people some grief. All I have to go on is my own experiences and word of mouth from others that have been down the same road. I had a 70 Challenger with disc brakes too but it was manual not power so I have no input as to whether a single diaphragm booster is enough. If it works good for you, that's all that counts. This is a B body site and from what I've seen and been exposed to on the 68-70 B body cars with power disc brakes, (which this particular thread pertains to) The factory provided the dual diaphragm booster. They would not have done that if they felt it was not needed.
Probably closer to 100% of the newer cars have single diaphragm booster because they are manufactured to work with newer systems. You are correct in saying Master cylinder bore comes into play and you need a balanced package.
 
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