1958 hydro-vac

Anyone has information about the hydrovac? Got one in mine and want to know more
The Hydrovac appears in the Buick master parts books of the time for application on 1956-59 models. It was one of three power brake systems used on '58 models. There doesn't seem to be any info on it in the shop manuals. Attached is an exploded parts view from the '63 parts book.

A few other cars used it in the '50s as seen in the 3-attached pages from the 1960 MOTOR's Auto Repair Manual. Plenty of usage too on large Chevy trucks as seen in the attached 7-pages from the '58 Truck Shop Manual .

The unit required only 4 lines to connect in to the brake system: hydraulic input, hydraulic output (boosted), air intake, and vacuum source. There was no connection to a brake linkage, so the Hydrovac could be mounted anywhere.

There were some Hydrovac accessory kits available at the dealerships to add power brakes to cars built with standard brakes. The Hydrovac was probably easier to add on than the integral cowl-mounted power units. It may have provided a workaround to add power brakes to a synchromesh car. At the time, power brakes were only available from the factory on Dynaflow-equipped cars.



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