The Stovebolt Site Forums The Shop Area Driveline 1957 Chevy 3100 Hydrovac

Hi,

Anyone ever seen or put a Hydrovac system on a 3100? I see it was an option but curios how many truck got them? Anyone have a 1/2 with one installed?

Thx

Cozsum Never really saw it but would be OK, however more of a 47 to 54 guy. Others will chime in on that .

It would really depend on if you are using the original master cylinder or an aftermarket type. Performance On Line (POL) supplies a kit for a Hydro Booster...

https://www.performanceonline.com/1...ost-power-brake-booster-kit-frame-mount/

The Factory Assembly Manual Sect 5 Sheet 3.00 shows the mounting location for the hydrovac on the inside of the right frame rail behind the transmission for models 4000-6000. Other references I have show it as an option for 3100 through 3800 series but don't show any location information.
I saw one on a 57 Cameo several years ago that was optioned with power steering as well. The unit was mounted under the hood on the lower left side behind the core support. I'm not sure it was correct however, it looked like a passenger car unit. It may have been dealer installed.
Fred

I'm assisting in the completion of a 57 3100 that has been apart for several years. The owner has a hydrovac unit that he wants installed but he is mostly busy chasing shinny objects. At some point he is going to get serious so we can finish it.

Hi,

I think thats where I got those pictures, I never really checked to see what model those pics belong to, I will double check. There is a truck on hemmings that sold that had factory power brakes and power steering. The location was on the pass side frame close to the front side of the engine.

Im working on my 57 3100 now, have it down to the frame and doing the brakes. Im getting the engine done and hydramatic rebuilt... thought it would be the time to one of these units (hydrovac's) in while everything is open. What are you doing on your friends truck?

My 1957 Accessory Installation Manual doesn't show a Hydrovac for the trucks, only the cars. But it is shown in the 1958 Accessory Installation Manual. It's shown hanging on the right side frame rail over the front axle, with (2) hydraulic lines running from it back to the crossmember that has the right front brake line already on it and then back up to the MC. The Vacuum hose comes from the intake manifold and crosses over the top of the engine between the front of the valve cover and the T-stat housing.

Mike B

The 57 belonged to my friend's father which was passed down. The body and paint were great but the everything else was tired. He tore it down and had the frame powder coated. The body is back on the chassis and the engine has been upgraded to a 327. I built an overdrive trans for it. I'm just waiting for him to get his act together so we can finish it.
Fred

Wow, sounds like a great truck. Hope it sees the road soon!

Thanks! If I find the correct brackets I will put one in, if not I will keep it as is. Im thinking its going to be tough to find!

In all my years of playing with the TF trucks I've only seen 2 or 3 and they were all on show quality Cameo's...never found one in any junk yard hunt and I've been doing that since the mid 70's...most of the good old yards are all gone now. If it's more than 10 years old it gets crushed, no one saves the old stuff anymore.

Mike B

Hi,

I found a Hydrovac unit from a 57 3800 and the brackets match what is in the assembly manual. Does anyone know if the MC for Hydrovac equipped units came with a larger bore. I know the larger truck may have but not sure about the smaller ones (3100-3800). I don’t see much info on this stuff!

Thx

Do you want the Hydrovac for correctness or do you want power brakes? For power brakes on a TF but to keep stock pedals we gut the factory MC then run a longer actuator rod straight through the gutted MC to a double diaphragm 7" booster and dual chamber MC mounted behind the stock unit. Only can be detected from underneath the truck and much more sanitary install. Picture of one that had the Hydrovac replaced with a conventional power brake set up:

[img]https://i.postimg.cc/gXctFKrD/Cameo002.jpg[/img]

Hi,

I was doing it for correctness. I decided to go back stock or period correct. The picture you provided is a beautiful truck!

I agree, it’s a beautiful truck but I was hoping to see pictures of the brake setup your talking about.

Cozum,
I sent you a PM.
Fred

Just a word of caution for anyone intending to do this conversion. Back in the early 1950's my father had a 49 Oldsmobile he used as a test bed for various modifications, including power brakes. He fitted a Hydrovac that was intended for a 3/4 ton pickup to it, and ended up with a brake system that required a feather-light touch on the brake pedal or it would lock up all the brakes. In those days before seat belts, I can remember getting bounced off the dash pretty often. Use a Hydrovac unit that's matched to the weight of the vehicle you're driving and/or the load you're planning to haul.
Jerry

Hi Mike,

Is it possible for you to send me pics of the pages of the hydrovac install sheets. Trying to figure out the routes the tubes run.

Thx

Here ya go...

Mike B

Here's an enlarged copy of the hydraulic line routing and Master Cylinder detail where I colored the lines so it's easier to understand/follow.

Hope this helps!

Mike B

Hi Mike B,

Thank you so much this is perfect. Im not to familiar with 58/59 trucks but isnt the rear brake lines on the 58/59 on the drivers side. I know the 58/59 has the brake bracket for the tee on the rearend on the drivers side?

Is that Tee on the MC anyway connect to the master cyl?

Thx!

Going by the manual it looks to me like the TEE is just sitting on top of the MC...not connected. It has the LF (orange), RF and Rear (Red) and the output line from the Hydrovac (Green) making up the three ports on the TEE. The new control line comes out of the MC where the original brake lines connected and goes to the Hydrovac (Blue).

I can't help with the actual line locations on the 58/59's as I've never owned one, but that shouldn't really matter...just run the lines to which ever side makes it look right for your truck. Chances are the manual was being printed before production started so there could be minor differences.

Mike B

As far as power accessories go, I wouldn't waste time trying to retrofit the hydrovac brake system. The brakes on these trucks are not difficult to use and really don't require any undue effort to stop the truck.

Adding power steering would be a lot more useful and beneficial, I think