Chevy Tri Five Forum banner
1 - 15 of 15 Posts

·
Registered
Joined
·
1,299 Posts
Haven't seen that one before....Not stock and not the run of the mill aftermarket setup like myself and everyone else seems to be using.Let us know if you discover more info.
 

·
Registered
Joined
·
71 Posts
Sorry, no help here either. Although it's not very big it sure looks like a strange setup?????
 

·
Registered
Joined
·
26 Posts
Can someone educate me on this power assist brake booster?
I see that booster in a 56 chevy here in my country. If my memory don't fail, the version in Spanish of the body shop manual, as a section dedicated to this booster, in addition to another one for the traditional power brake.

I believe that it's a factory unit but I am not shure

This booster works jointly with the master cylinder, does not replace it like the traditional power brake unit.
 

·
Registered
Joined
·
66 Posts
Hydra-Vac

According to my info, in '57 there were two styles of power brake boosters. One was used on manual transmission cars and the other on automatics. The one shown was called the "Hydra-Vac" and was used on manual transmissions, and the "Treadle Vac" was used with the automatics. The Treadle Vac was used in previous years, but when applied to the '57 with different fender & hood lines it was shifted 1-1/8" towards the center of the car and there was interference with the clutch linkage controls. So, to offer power brakes on all models, the Hydra-Vac was offered. This is the only one I have ever seen other than in literature.
 

·
Senior Member 4 Gold Stars
Joined
·
4,460 Posts
Discussion Starter · #8 ·
Thanks guys. It was familar to me, but I couldn't remember exactly where I had seen one. Having done a bit of medium and heavy duty truck repair, I suspected I was remembering it from there. They are simular in appearance to truck boosters.
 

·
Registered
Joined
·
4 Posts
Hydra-Vac power brake

Your right 55NOMAD57 , It is a stock power brake unit for standard shift cars . Just listed a rebuilt one on E-Bay .
 

·
Registered
1957 Chevy BelAir 4 door sedan
Joined
·
78 Posts
Resurrecting an old post

Came across this thread and wanted to put my 2 cents in. I have a 57 4 dr sedan, all original, 283 power pak, powerglide with the Hydra-vac brake booster.
 

·
Registered
Joined
·
170 Posts
That's unusual and interesting that you have an automatic (powerglide or turboglide?) with a stock Bendix Hydro-vac power brake unit which was made for the manual transmission cars.

Bendix made numerous Hydro-vac units for many applications, including heavy duty military equipment, so be sure of the unit and that it fits before you purchase one.

If anyone has a complete working unit out of a 1957 chevy, please advise as I'm looking for one. Thanks!
 

·
Registered
Joined
·
2,780 Posts
Came across this thread and wanted to put my 2 cents in. I have a 57 4 dr sedan, all original, 283 power pak, powerglide with the Hydra-vac brake booster.
Prior to 57, ALL hydro vacs were dealer installed. In 57 they were also installed on the assembly line if so ordered. Dealers still installed them, so that's likely where yours was installed.

The hydro vac did not provide quite as much braking assist as the TreadleVac, in my opinion. But the hydro vac is certainly easier to install, has a lot fewer parts and isn't too difficult to find. The 55-56 units are slightly different than the 57 units, mainly in the routing of the vacuum piping on the unit. The 55-56 mounting bracket is completely different than the 57 version too.

The mounting brackets and the check valve and tee on the carb, as well as the correct vacuum hoses and clamps, are all reproduced. Rebuilders still work on them, though some do a better job than others.
 
1 - 15 of 15 Posts
Top