47-59 Long shot picture request

[1project2many]

I'm planning to install reproduction OE power brakes in my '57 this summer. Anyone stumble across a picture of this in a Chevy pickup? Or maybe an actual OE PB truck? It's a very rare option for sure...

[mr48chev]

The only thing that I can find is that depending on how you read this the add on Hydrovac was listed as an option for 3000 series trucks.

I've never seen one on a truck and expect that primarily the ones you would find would be on a 3800.

First you would have to find a rebuildable unit then you would have to find someone who either has the parts to sell to rebuild it or offers a rebuilding service. That alone may be close to impossible unless the internal parts match those on the other Hydrovac boosters for the 4000 series trucks.

In truth I don't see it as a viable project that would primarily be in quest of Bubba points at car shows when one tells others that they have that unit on their "all original" truck.

[leegreen]

it shows on the outside of frame rail behind front cab mount on medium duty trucks, I bet light duty are the same:
https://www.lov2xlr8.no/brochures/ch.../bilder/15.jpg

this has many pictures of servicing the units for '56, if you go through them you will get some idea how it attached to frame
https://chevy.oldcarmanualproject.co...5614top01.html

reading that will also give some clues why most of these under cab & out of sight units have a bad reputation.....oil with bendix air cylinder oil ever 6 months.....install the 'leather' packing.

I'd consider figuring out how to mount a modern dual pot master with compact 7" diaphragm vacuum booster and preserve your clutch pedal....there was an example posted in another hydrovac thread showing an extended push rod to allow the booster/master to mount further back on the frame. people working on '40s cars face this issue as well, complicated by weirder masters....there are solutions out there

or switch both clutch and brake to firewall mounted hydraulics

The hydrovac adds hydraulic complexity without improving safety, it is still a non-reduntant system but now with more failure points.

[Second Series]

What are the OE power brakes for ’57? Do you have a source for the repro? I’m just curious. I have the hydrovac in my ’55 6700 bus, it works great. I did a quick search and read about the Treadle-vac, looks like it was in cars of the era and in Studebaker trucks. There are a few videos of the Treadle-vac on youtube, if that is what you are looking for.

[leegreen]

https://www.oldcarbrochures.com/stat...re/image5.html


ps: I like your bus!, more pictures somewhere?

[1project2many]

Thanks to everyone who provided pictures. I appreciate the link to the rebuild manual as well.

Bendix Hydrovac boosters were available on 1/2 and 3/4 ton Chevy trucks. They could be installed by OEM or by a dealer.

There are OEM installation instructions for 3000 series trucks in the FAM on pages 595 and 596:
https://www.trifive.com/d1/55-59Assy.pdf

There are dealer installation instructions for 3000 series trucks in the 1958 Dealer and Accessory installation manual. I have this manual and I have included scans of the instructions.

Even with this info, I would love to have a picture of an actual installation in a 3000 series Chevy. GMC trucks don't count, though. GMC used a Midland booster which was attached to the RH inner fender.

I have worked with Hydrovac units in larger trucks before. They work great but they definitely last longer when they are not ignored. We saw many trucks with Hydrovac while I worked at the dealership in MT. I dug out the old service leterature and taught myself how to be successful in reparing and maintaining these misunderstood brake boosters.

In 2007 I purchased a rebuildable Hydrovac core along with an OE vacuum can, hoses, and check valve from a '63 truck being stripped in Oregon. I disassembled that unit in December of '23. Hydrovac units were used on a number of vehicles in the 40s and '50s and there are several vendors that support rebuilding one. I checked pricing for rebuild parts and came up with a total around $350.00. I also checked prices for having the unit rebuilt and found prices range from just over $300 to near $1,000.

I searched Ebay and found a new Japanese built unit that appears to be a copy of the original Hydrovac. These units are sold by the manufacturer as replacements for Isuzu and other Japanese trucks and are used by a number of European companies. I have purchased one from a US importer that is similar to the OE Bendix unit to use in my truck.

The truck is not going to win many points as original considering it has a 302 ci V8 with electronic fuel injection. I don't really understand what "Bubba points" are but I don't think I'm trying to collect them. My plan for my truck has remained consistent for years. I am working to install OE or OE style brake, steering, and suspension upgrade parts to improve the truck. I really want to build an example of what can be done with careful planning and research. I'm ok with the "not worth it" and "I wouldn't bother" comments.

I have already installed an OE sway bar and upgraded steering arms. Believe me, they make a very noticeable difference. I have collected parts to install OE 11" X 2-1/2" heavy duty front brakes along with the Hydrovac. Since truck and Corvette "Heavy Duty" shoes are NLA (and NOS parts sell for $500+) I'm thinking I will use Kevlar shoes for the front and rear. Once the brakes are done I plan to rebuild the steering box and install OE style power steering.