The Stovebolt Site Forums The Parking Lot Big Bolts 2 circuit MC with 2 Hydrovac's

I just had my tow truck Master Cylinder fail while pulling into the garage and I want to replace it with a Dual-Circuit type.

So the question is, have any of you upgraded your single pot MC to a Dual-Circuit MC and then connected a Hydrovac to each circuit? I'm told this should work and that some British cars were made that way.

My truck has the 1-1/2" bore MC and the largest Dual-Circuit MC I have found is 1-5/16" bore (1970's Chevy 1-ton). Any reason why this won't work?

Thanks,

Mike B

It will work.

I'd go look at some 70's Ford medium duty trucks as well as many import cab over trucks, I've seen modern versions of what you describe on each, and others too I'm sure. The remote mount boosters could be a new off the shelf item if you like, I've seen them in the brake parts catalog at NAPA.

Grigg

Grigg,

The reason I was thinking of the remote boosters is due to fitment/lack of space to put a modern booster at the MC. I could add a Power Steering pump to the 350sbc and go Hydroboost if you think that would be better. I need to see if they have them in 1-1/2" bore. I'm thinking if I keep the same bore I'll have the same peddal travel...thoughts?

Mike B

I asked this same question quite some time back. There are dual hydrovac models available that look like two smaller canisters attached back to back with the brake line fittings on either end.

I can't find it via the search feature. Maybe you'll have better luck.

Jeff

That would be better for sure. May or may not be any cheaper, and yes you can get a large enough MC, I'm running 1-5/8" on my truck. Your most economical method of gathering parts is the salvage yard, and new at NAPa is not so bad either. I'd skip the aftermarket vendors if you don't need their tech assistance.

If you also want power steering or already have it then it's a no-brainer, use the hydroboost.
Without a PS gear you can still run bydroboost but you'll need to braze a high pressure return fitting to the pump reservoir (-6 AN/JIC or 3/8" inverted flare).

Excellent info on hydroboosters and a good resource.
http://www.hydratechbraking.com/FAQ.html
Note this one though...

Last time I researched this it wasn't a problem to use a PS pump solely for a hydrobooster. In fact that's the plan for my 1 ton, use a small (model TC I think it's called) PS pump so it'll fit nice and clean on the little Detroit.

Grigg

hey grigg, my neighbor has an 82 ford b600 school bus with a gas v8. it has a dedicated ps pump for the hydroboost, and another larger one for the steering... just an fyi

I would think that the 1 5/16 bore would be ok.

Thanks, I'll keep an eye out just to see one. Have no doubts about using a new TC pump though.

Grigg