Vacuum Assist?

[Deleted User]

My neighbor is restoring/building a '67 Ferrari Scalenetti (sp?) and he is using a '54 Cadillac vacuum assist booster for the brakes that will be mounted in the front fenderwell. He was telling me that they only need about 12mercs (sp?) of vacuum to operate and will give you about 5 good strong pumps from the pedal if the motor is not running. After that, its manual brakes, so your never without brakes. He said they can be mounted anywhere with the right set-up. He gets rebuilt ones for about $250 no core. Says they can stop a 10K lb. car and can work with disc or drum brakes equally as well. A bias valve would be needed though for a disc/drum combo. This would prevent having to use a firewall mounted set-up and can be mounted above or below the motor, underdash, etc. He says you can use the '55-56 boosters too, but they are slightly bigger.

Anyone heard of this? I thought it was kind of interesting.

Jay

dwardo99

I imagine what he has is a Bendix Hydrovac or equivalent. I have one on the Hornet and it works great. The brakes can actually be very touchy so it's probably true that it doesn't need much vacuum to work. It's also true that the brakes are unaffected by a loss of vacuum - they just revert to ordinary brakes. Having said that, unless I upgraded to disk brakes I don't think it was worth the effort. A properly set up Hudson has pretty good brakes for drums.

[Deleted User]

I thought this was interesting because I'm going with discs in the front and maybe discs in the rear. Thanks for the info dwardo99!

rambos_ride

jsrail wrote:

I thought this was interesting because I'm going with discs in the front and maybe discs in the rear. Thanks for the info dwardo99!

Jay, since your plan is an everday driver - I'd stick with components that are easy to get replacments for ~ I doubt any parts stores sell new or rebuilt power assist units for a 54 caddy.

I know all too well with my experiences with my daily driver 1976 CJ5 I couldn't buy a new or rebuilt power assist unit from the factory or a parts store - I could only send mine out to be rebuilt.

Just my.02

[Deleted User]

rambos_ride wrote:

Jay, since your plan is an everday driver - I'd stick with components that are easy to get replacments for ~ I doubt any parts stores sell new or rebuilt power assist units for a 54 caddy.

I know all too well with my experiences with my daily driver 1976 CJ5 I couldn't buy a new or rebuilt power assist unit from the factory or a parts store - I could only send mine out to be rebuilt.

Just my.02

Dan, they are rebuilt right here in Phoenix.

rambos_ride

jsrail wrote:

Dan, they are rebuilt right here in Phoenix.

I was just being the "devils advocate" and relating my experiences as there were many, many more CJ5's built than 54 caddies.

I drove that CJ daily for years and many times was hundreds of miles away from home - or worse off road - and and I would have been screwed if the power assist had gone out not knowing I couldn't buy a replacement.

As it was, I was lucky enough to be home when it did go out and had to send it out to get rebuilt after stiking out at the Jeep dealer and all local parts stores.

I just assumed your goal using modern mechanicals would extend to the braking system, but if you're not going to be taking the car outside of your local area it wouldn't be a big deal to worry about.

dwardo99

Those units were used in lots of different cars. Early T-Birds come to mind. Also some GMC/Chevrolet trucks, so they are available from LMC. They come in different sizes to suit different needs. The one in the Hornet is fairly large. So, getting parts isn't a problem but you won't find parts at Pep Boys either.

50C8DAN

Hydrovacs were used even into the 70s on Ford and other trucks!



Dwardo99 where did you mount your hydrovac on the Hornet. I have an extra one and was thinking about putting it on my Commodore.

dwardo99

It is on the left fender liner behind the voltage regulator. We ran the line up from the master cylinder and then the line from the hydrovac goes back down to pick up the original lines more or less. I think I might have tee'd the line to the left front at that point but I don't remember. Also, I plumbed the brake light switch to the hydrovac to get it out from under the car. I put a couple of loops in the lines to allow some shaking without fracturing. We made a reserve vacuum bottle out of a bernzomatic tank and put that on the right side of the radiator and ran mostly solid copper but some rubber over to the manifold. Later took the reserve tank out as it isn't necessary. We found out an interesting thing in that you can vary the amount of brake assist you get by restricting the air intake to the hydrovac. In fact we found a 6v electric valve that we were thinking to put on there to allow us to disable the assist in wet conditions and that would work but we haven't tried it. It will absolutely stand the car on its nose but it doesn't address the brake fade you get with drums of course.

[Deleted User]

Just Push Harder< Yer Mother Had To!