so when I built my car a couple years ago, I bought a brake booster and master off of ebay, The master things were the lines thread in, both are 3/8" size fitting. My problem is that my brakes, are very lagging and only brake at the very end of the pedel throw, now they stick. So I thought it was my prop valve, so I bought one from cpp, I went to bolt it on and it is 1/2" and 9/16" threads, do you think that the booster and cylinder is my brake problem?

I'd have to make some mods to the new prop. valve in order to make it work (hits the inner fender)

Do you think i should just buy a new booster and cylinder from cpp that's supposed to fit? I need one with a 7" booster to clear my tall valve covers.

here's some pics
http://i88.photobucket.com/albums/k174/66chevlmalibu/IMG_0023.jpg
http://i88.photobucket.com/albums/k174/66chevlmalibu/IMG_0024.jpg

Paul,

I just completely rebuilt my brake system. From your pics, it looks as though you used a dual chamber booster from cpp. I used the same setup as yours. One of the problems with it is those boosters require a lot of vacuum. If your engine isn't producing at least 18" at idle, that booster will not work properly. I added a vacuum pump so it would work. I am now in the process of reinstalling my original booster and removing the vacuum pump because it was noisy and annoying at idle. I am going to install a piece of rubber on the side of my booster to guard against the tall valve cover myself. I know those small boosters look cool and take up less space, but, I just don't think they are worth the hassle or provide any additional performance. CPP has a good tech area for brake troubleshooting as well. You may have air in your brake system?

Eric
69 Chevelle SS
World Products 454/454
T-400

no I bought this from a guy named fatrodder? it is supposed to be a corvette style mast re cylinder.

Paul,

Maybe the push rod that goes between the mast cyl and booster is not adjusted properly or of proper length. Is that cpp combination valve properly plumbed as per the cpp diagram that comes with their kit? A lot to think about when making brake mods.

Eric

no the cpp prop valve isn't installed yet! I cant with the master cylinder, I've tried adjusting the rod a whole bunch of times.

Paul,

Hey, need more info about your brake system. Was your Elcam originally a power brake car? Do you have disc/drum setup? Most cars that came with manual brakes require a complete conversion system to work properly when switching to power brakes. For instance, I had to fabricate several of my own brake lines to install that combo valve from cpp. I installed it under my master cylinder. I had to make my own bracket. I will take pic and show you what mine looks like if interested.

Eric

Not to thread jack but will to little vacuum cause a hard pedal or a soft pedal?

Paul,

Hey, need more info about your brake system. Was your Elcam originally a power brake car? Do you have disc/drum setup? Most cars that came with manual brakes require a complete conversion system to work properly when switching to power brakes. For instance, I had to fabricate several of my own brake lines to install that combo valve from cpp. I installed it under my master cylinder. I had to make my own bracket. I will take pic and show you what mine looks like if interested.

Eric

yah when I posted this I was tired and ticked off, it was originally a manuel drum brake car and I took a disc setup from a 69 chevelle, complete. Had everything rebuilt and rotors turned. I suspected a little fab, because mine is prop is mounted to the frame.

Not to thread jack but will to little vacuum cause a hard pedal or a soft pedal?

Chris,

I found some pretty good brake booster info. Generally too little vacuum will cause a harder pedal with braking occuring after pedal is depressed farther in travel. I will try to post this link to a good article on brake boosters.

Eric
69SS
World Products 454/454
T-400
411 diff
Gearvendors overdrivehttp://www.autoshop101.com/forms/brake05.pdf

Paul,

In 69, that power brake sytem had a metering valve installed up by the master cylinder and a proportioning valve mounted on the frame, like your elcam. I noticed in your pic, all you have is the lines running down to the stock prop valve. That cpp valve is a combo valve which takes the place of the metering and prop valve functions. Perhaps that is part of the problem. Just trying to think it out.

Eric

Yah I went ahead and ordered a new booster and master from cpp, My motor pulls 12" of vacuum at idle (not in gear) and the pedel is SUPER soft

Paul,

Hey, need more info about your brake system. Was your Elcam originally a power brake car? Do you have disc/drum setup? Most cars that came with manual brakes require a complete conversion system to work properly when switching to power brakes. For instance, I had to fabricate several of my own brake lines to install that combo valve from cpp. I installed it under my master cylinder. I had to make my own bracket. I will take pic and show you what mine looks like if interested.

Eric


I am having the same issues right now...I would like to see a pic.

Please