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I have a 1954 Chevy 4500 short bus. The hydrovac underneath was disconnected when I bought it. Without power assist, one really has to stand on it to stop. I really don't know much about hydrovac's. It appears to have a steel tank underneath that is part of it.

I have seen dual master cylinder, power brake units for the smaller chevy trucks on EBay. Could I ditch the original hydrovac and use something like this?

I am sure that the hydrovac needs rebuilding. I like keeping things as original as possibly with the exception of 1 things, the brakes.

Has anyone upgraded the front brakes (discs, dual master with power assist on a big bolt?

Or, might it be better to use a more modern hydrovac off a newer bus? (I would have fabricate brackets, etc. of course)

Thanks

Well first it is possible to rebuild your hydrovac and its not real expensive.

Upgrading to a dual master and vacuum or hydralic power can be done and I believe the same brackets as the smaller trucks will do it, though sizing the master cylinder might be different.

I don't know if newer buses use hydrovacs or not.

As for disks on a big bolt, I'm not aware of anyone who has done it without also changing the axle also.

Search for posts by Grigg and his axle replacement story. His approach is probably the high end way to get it done, but proves it can be done effectively.

I have a dual res master and booster under my trucks floor. I fabbed my own bracket to mount them to. I can't remember exactly which booster I used but it was from a mid 70's GM product. The master is a 1970 C10 from a drum/drum system. I use this truck to plow with and usually have about 4 tons of gravel loaded on for traction. This brake set up has more stopping power than any other big bolt I've driven and they're easy to apply, maybe a little too easy, but I like them.
Scott

Great. Thanks a lot for the help, Scott.

Thanks a lot for the help

My 47 had the same thing, hydrovac was not connected. Brakes worked but like you said it took real effort and they were scary,Had the hydrovac rebuilt + rebuilt all the brakes. The brakes work quite well, I only have the one reservor, I know it would be better to have two. But the brakes are the best working brakes I have ever had on any antique vehicle I have ever owned. This is my first truck larger than a half ton though.

My 53 had a hydrovac setup similar to the one you're describing. Instead of re-building it, we decided to upgrade to a dual master cylinder power brake system. The donor cylinder and booster came off of an 81 1-ton Chevy Suburban. We wound up fabricating a bracket and mounting it on the frame in the same general location the old master cylinder was. The only real issue was that we had to make an access panel in the floor to get to the cylinder to fill it with fluid and the inlet sizes for the brake lines on one side of the cylinder were different than the other. However, after we got those few minor kinks out, it brakes extremely well and we're happy with it. If you'd like any pictures of the set up on my truck, let me know through private message or e-mail and I'll be happy to send them to you. Good luck!