Chevy Nova Forum banner

CPP Brake Booster issue

2897 Views 8 Replies 5 Participants Last post by  nova656567
I took a 3 year hiatus on the project, but I started working on it again last spring.

Finally got it running.

I bought a CPP Booster/Master/Proportioning valve combo from a member here. It was new but not in the original box. Now that I have it running the booster won't hold vacuum.

I can actuate the master with the plastic cylindrical tube the extends out when the pedal is pressed, however it would appear that there's supposed to be a rod between the master and the booster. If you look down the hole in the booster there is a recessed hole that apparently a rod fits into. Could that be the culprit?

I called CPP and the "tech" guy I talked to there was absolutely worthless. All he wanted to do was sell me another booster. I did email them with some pictures, but haven't heard back.

I found a picture on another site of the same booster and it definitely has a rod, but the guy at CPP didn't know if there was a rod or not. He would have gladly sold me another booster for $189 though. :mad:

I can't believe a brand new booster would leak. If that's the problem, I'll have to buy a new one, but I'd rather not obviously.

Any ideas?

My booster

Picture I found online.

See less See more
1 - 9 of 9 Posts
You're right, there's supposed to be a pushrod in that hole. And that's definitely the source of your vacuum leak.

It might be worth calling CPP again ... with any luck you'll get to talk to a different person that can actually help.

If that doesn't work, it appears as though the rod is the same as what's used in the stock GM brake boosters. So you might be able to get one from a junkyard.
I was just looking through CPP catalog tonight and they sell that rod you need, I think it is $5. There are two different sizes though, short or long. Post a pic of your MC where it attaches to the booster and I can tell you which size to get.
Thanks for the replies.

Here's a picture of the piston end.

See less See more
You also need that clear plastic piece that holds the rod in place. That piece is the seal between the m/c and the booster. RICK
Chevy2Only lists a booster and it has two rods that come with it. From the picture it looks like a CPP? Kinda answers my question. If I can get the part number hopefully I can get what I need from CPP.

See less See more
I downloaded the catalog today and sure enough they show the parts. I do think I need the long one. Part # 6474SRB-DP for $2.00. Their website leaves a little to be desired and I wasn't even aware there was a downloadable catalog. I wonder why the guy at CPP couldn't have done that? I've spent two hours on something that would have taken the guy 60 seconds. Oh well, I've wasted time on more trivial things I guess.

Thanks for the help!
Normally that booster would come with a short rod, and there would be a bullet in the back of the master cylinder to make it work with a short rod. You should be able to get the long rod to work, but be sure to double check the length of the rod and the recess in the master cylinder. Needs to be close, but not keep the spool valve of the master from returning completely.
1 - 9 of 9 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.