The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Help, no power brakes, need some suggestions.

shawley · 07-28-2015, 01:49 PM

I've got a 1969 C10 I just finished up, it has a 350/700R4 in it, the motor has a very very mild cam. It originally had power drum brakes, but I did a conversion on the fronts to discs from CPP, and did the CPP brake booster. The motor is not the original motor but the truck it came out of the brakes were working just fine.

So right now after finally getting the truck onto the road I have no power brakes. The booster is getting 16-17" of vac according to a test we did last night. CPP says it needs 18 to work properly, but I figured with 16-17" it should at least do something. But it doesn't do anything, the pedal is just as hard if it is running or if the truck is off.

The pedal is just extremely stiff, very hard, and feels like full manual brakes.

Any suggestions of what I can do or test? I read a thread somewhere that you can take apart the booster/master and there's a rod to adjust, but CPP has said nothing about this. We have checked the check valve and it seems to be working just fine.

I'm in Canada so its not too easy to just take it out and send away for warranty, and I highly doubt that its a bad booster, being that its brand new.

Would a vacuum canister help at all?

Thanks in advance for all your help!

This is the booster I have

07-28-2015, 01:49 PM	#1
shawley Registered User Join Date: Oct 2014 Location: Edmonton, AB Posts: 48	Help, no power brakes, need some suggestions. I've got a 1969 C10 I just finished up, it has a 350/700R4 in it, the motor has a very very mild cam. It originally had power drum brakes, but I did a conversion on the fronts to discs from CPP, and did the CPP brake booster. The motor is not the original motor but the truck it came out of the brakes were working just fine. So right now after finally getting the truck onto the road I have no power brakes. The booster is getting 16-17" of vac according to a test we did last night. CPP says it needs 18 to work properly, but I figured with 16-17" it should at least do something. But it doesn't do anything, the pedal is just as hard if it is running or if the truck is off. The pedal is just extremely stiff, very hard, and feels like full manual brakes. Any suggestions of what I can do or test? I read a thread somewhere that you can take apart the booster/master and there's a rod to adjust, but CPP has said nothing about this. We have checked the check valve and it seems to be working just fine. I'm in Canada so its not too easy to just take it out and send away for warranty, and I highly doubt that its a bad booster, being that its brand new. Would a vacuum canister help at all? Thanks in advance for all your help! This is the booster I have Last edited by shawley; 07-28-2015 at 01:57 PM.