Hydroboost Question

[scorpion1110]

So I continue to wire and clean-up the engine bay of the 55 handyman. A lot of this is rework. I spent a lot of time on this while on a round of Chemo, and I just dont think I was designing with clarity. I am redoing a lot.

So now I am looking at the brakes. I thought id just leave the drums, but now they are going for a set of discs. I think I am going to start over at the firewall too. I am going to ditch the power booster, and replace the master and the prop valve, and go with a hydro-boost. It will save space and eliminate any issues with having enough vacuum.

Rick L has provided info previously about using a circa 95 Astrovan boost unit. CN makes a bracket and the plumbing diagram is available on line. The question is the power steering.

I have a factory PS setup. How difficult to adapt the factory PS? Any diagram on that and can you get hoses for the Control valve? Or do they have to be made?

It would seem the parts list would be:

Boost unit
Firewall mount
Actuator rod modified as necessary
MC disc/drum
Prop valve
Hoses
Hose tee
AN fittings as necessary

BTW, I know it might be easier to swap out the factory for aftermarket but it fits well and works and I wouldnt mind keeping it.

So thoughts?

Thanks.

[chevynut]

I can't comment on the factory PS pump and setup as to compatibility with the HB but if the pump will work the hoses should be a minor issue. The HB has metric thread holes so you'll need some metric adapters for the AN lines. I think the pressure lines are all AN6 (3/8") and there's a low-pressure return line to the reservoir. From what I understand there's a difference in the early 90's and late 90's Astro HB and it's the way the pushrod is configured. I don't know which is better because I just removed the pushrod and planned to use the stock Tri5 one that I modified. The adapter plate I sell bolts to the stock studs and has the hole that's keyed for the HB. Most guys orient the accumulator opposite the engine valve cover so there's plenty of room. I think it's a better setup than the vacuum booster, especially for an engine with low vacuum.

[JT56]

[Rick_L]

As said I adapted an Astro van hydroboost unit on mine. I built a mounting plate similar to Cnut's. The mounting plate height was done in a manner that allows me some adjustability with the pedal ratio without binding. The pushrod from the brake pedal to the unit was modified by cutting the eyelet fitting off and threading the rod to accept a stock 55-57 clevis. The pushrod from the h/b unit to the master cylinder had to be shortened to be able to use a common GM master cylinder (actually I used a Wilwood). Measuring for the pushrod clearance/interference is kind of tricky - I made some Autocad layouts to figure it all out.

I don't see how plumbing the unit is any different with stock power steering than it would be with a p/s box or R&P.

[Gmvette]

If the power steering pump fan belt breaks or comes off do you lose your brakes?

[chevynut]

If the power steering pump fan belt breaks or comes off do you lose your brakes?

The hydroboost has an accumulator that stores pressure to allow for a few applications of the brake pedal with assist. I've never had my PS pump belt fail on any car I've ever owned, not to say it couldn't happen. But that's why they're designed with this safety feature.

[scorpion1110]

Rick, CN, JT thanks. Sounds like a useful mod.

CN, I will be in touch for the adapter plate, as soon as I figure out my parts list.