Mini steering pumps, Hydraboost, and Unisteer Rack.

[ItsA68]

I bought the Unisteer rack in the GP a little while back. I also got the modified aluminum mini power steering pump with integral resevior that will fit my Vintageair Front runner setup. Unisteer says their pumps are modified to provide reduced pressure and flow to give the correct feel for the rack.

The problem is that I also want to run Hydraboost brakes because I plan to use an IR manfold for massive torque output. The hydraboost brake setups don't work well with reduced pressure. They recommend the stock saginaw type pumps with no modifications to avoid slow pedal return, and general overall problems with the hydraboost.

BUT, even if I could get a regular saginaw pump to work with the frontrunner, I would have too much pressure/flow for the rack.

So the solution seems to be, run an unmodified mini pump to the hydraboost, and then before the rack install a pressure reducing valve from heidts to taylor the flow/pressure for good road feel on the rack.

I've been talking to the guys at Mavel (Unisteer) about what an unmodified mini pump can do....my question is, what pressures and flows are produced by the stock saginaw box? and can the aluminum mini pump make the same amount in an unmodified form?

DSE installs a pressure reducing fitting in their pumps (same type pump as what Unisteer sells), and Unisteer modifies the pump in a different manner to reduce the pressure/flow. I need the right amount of flow and pressure for both systems, the hydaboost, and the rack.

Opinions? Those with direct experience with both systems are required to respond :)

TIA for your replies.

~~fred

[David Pozzi]

That's odd because many new cars come with rack and hydroboost. I don't see why you need to reduce pressure to the rack unless they are trying to improve steering feel over the rack's original calibrations.

I've heard the old sag pumps when used with PS and a hydroboost can break the pump shaft! Craig Boone had it happen resulting in no steering and no brakes at the same time!

He's installed a crome molly shaft from Lee. I installed a rebuilt pump on an 81 pickup a while back and the included instruction sheet said something like: "Warning if your vehicle is equipped with hydroboost do not apply the brakes hard while turning the steering wheel, it can result in pump shaft breakage".
THAT didn't sound good!
I have no idea if the small pumps have the shaft failure problems.

[rcotteleer]

The Heidt's valve is a Bypass style regulator and, as such, will reduce pressure everywhere in the system. It basically does the same thing as a re-valved pump, the difference being it's adjustability. Unfortunately, what you need is to isolate the 2 systems: Hydroboost @ 1100-1300psi and the rack @ 700-800 psi. (pressures are estimated, obviously Unisteer and Hydratech would have the appropriate #'s)

[steeryourite]

Fred,
Dave from Unisteer here. The pump you got isnt modified, its a stock C-5 Vette pump. You see the GM TC pump is very common in lots of different vehicals. The problem is they all look exactly alike,but have several flow rates. Im not sure who you talked to here but the pump you got was like 1200psi(al pumps vary 30-40lbs). The thing we do is change the flow. Yours was probably around 1.8 gallon per minute. This is very close to the stock Camaro pump. In fact we have installed our kit using the factory pump with good results. What does the hydroboost company recomend. What vehical was it orignally designed for. We can give you more or less pressure, and flow if thats what you need.
Dave

[ItsA68]

Dave,
I've been talking to a guy named Steve there....we've talked several times. At this point I really need to get more detailed info from the Hydraboost guys. They were the ones that recommended the Saginaw pump, and Heidts valve, which I didn't know was a bypass type setup. I didn't think that the latest Camaro's had hydraboost did they? The Unisteer kit I got was for my first gen Camaro. I guess my other problem is that I don't have any of this installed and running in the car, I'm just attempting to get all the right stuff together so that when I do get it all going, I shouldn't have problems. I can't possibly be the first person to use a rack setup with hydraboost. Possibly I can get Hyratech, and Unisteer together to help me? Admittedly, I haven't purchased the Hydaboost system yet, but I can and will do so as soon as I know it can all work together though...


have a call in to Hydratech.....we shall see.

[ItsA68]

talked to Hydratech this morning...They said that I need to look for a minimum of 2.7 gpm, and 1200+ psi. Dave, Can the mini pump do that much flow if you open it up? What is the specific modification that is made to the pump to reduce the flow? (if its reduced) What is the specific mod to be made to the pump to increase the flow? Hydratech also stated that the feel that you get at the rack is somewhat subjective, and that an increase in flow may/may not be desireable. What I don't want is the steering to loose assist when I'm braking, NOT GOOD, and I don't want my new great rack to feel like the old no-feel stock PS setup. It would seem that a pump with an easily modified output would be the best situation. I think I need to start with decent flow from the pump, and then reduce from there to suit my tastes at the rack.