Thread: Power brakes

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I have vacuum power brakes with a booster and I added a canister to help with supply but it just didn’t cut it. I changed over to an electric vacuum pump but it wasn’t adequate either. Today I thought, why not ask you guys, which I can’t believe that I haven’t to this point. This problem has haunted me for years. The cam is too big so I was wondering if a brake pump such as in a diesel might work. I have a S-15 Jimmy with a sbc in it. I use the V- belt and I really don’t want to switch over to a serpentine belt, I tried it and they kept flipping off. Does anyone know if a belt driven pump would work and if so, which Chevy diesel do I look for in the bone yards? Thanks.

Hi Denny and thanks for answering.

Originally Posted by DennyW

How big of a canister.

I bought a Moroso canister whcih is approximately 2 quarts in size.

Originally Posted by DennyW

Cruise speed is when the vacuum is the highest, so you need a checkvalve also to lock in the higher vacuum level until needed. .

I do have a check valve and yes, when I come off of the hwy, my brakes are fine but as soon as I do stop and go driving in town, I'm in trouble.

Originally Posted by DennyW

A idle pulley will help keep the belts on. If the belt is stretched to far between pulleys, if will come off.

What I had was a newer Chevy aluminum bracket with the idler pulley etc and still no good. At this point I don't really want to try that switch over again. I have a small 4 inch drive pulley on my crank and I would like to keep that system.

I am wondering if I bought a diesel brake pump, Would it mount to my master brake cylinder and could I mount a v-groove pulley on that shaft? Are they interchangeable?
Thanks.

Also, how would I mount the lines? Are the fittings the same in an S-15 and a full size truck?

get the vac pump from a 1980's Mercedes 300 D, they have an electric pump that is under the rear shelf near the vac storage tank, 12 volt and it operates everything vac related including the power booster. it pulls 13- 20 HG

Originally Posted by Matt167

get the vac pump from a 1980's Mercedes 300 D, they have an electric pump that is under the rear shelf near the vac storage tank, 12 volt and it operates everything vac related including the power booster. it pulls 13- 20 HG

Hi Matt. That sounds like an easy solution. I was using a Cadi pump but it was meant to operate the accessories only, not the brakes. When you say rear shelf, is this behind the back seat or in the engine compartment? The mid 80's Cadi has theirs under the left front fender. Thanks

Why not just bite the bullet and go to a hydraulic booster off a newer diesel? Runs off the power steering pump.
just how much cam have you got in there? A 400 should pull lots of vacuum if it'll idle at all. Are you sure your booster isn't FUBAR?

Originally Posted by R Pope

Why not just bite the bullet and go to a hydraulic booster off a newer diesel? Runs off the power steering pump.
just how much cam have you got in there? A 400 should pull lots of vacuum if it'll idle at all. Are you sure your booster isn't FUBAR?

Hi Pope. I was thinking the same thing. I just didn't know where to start. As for my cam, it has 266@0.050 intake and 272@ 0.050 exhaust. I can't remember the lift exactly but it is somewhere around .650.

So do I have to replace my current power steering pump? Will the fittings work?

I took a look at the diesel setup and I think I will give that a try. It might be a little over kill but rather that than what I have now.

Originally Posted by TyphoonZR

Hi Matt. That sounds like an easy solution. I was using a Cadi pump but it was meant to operate the accessories only, not the brakes. When you say rear shelf, is this behind the back seat or in the engine compartment? The mid 80's Cadi has theirs under the left front fender. Thanks

yep behind rear seat. up and under.