leigh1322

I ran my 40 year old OEM pump for 27 years of autocrossing, and even some road racing. We did tune the flow in the beginning, and I added a cooler on it. Never touched it after that for 27 years. Never even changed the psi, or the fluid, or rebuilt the thing. It was fine for like a 1000 autocrosses.

To tune it, to get just enough flow, and not too much flow & too much heat, this is the procedure to follow:

Turn One says: "We coach customers daily that 2.2-2.6 GPM and 1350-1450 PSI max pressure relief is our general target."
(These are basically OEM specs). And many aftermarket parts have way too much flow.

"A flow of 2.0 GPM +/- typically results in a no-load gauge reading of 100-150 PSI depending upon the steering gear design."
This is where the psi remains for 98% of the time. And when you change the flow restriction larger for more flow, this no-load pressure also increases, giving you more assist/more power/less feel. If the no-load psi is too high, you will also have over-heating problems. Max pressure usually only occurs when you hold the system against it's stops. This "no-load" pressure is far more important the rest of the time.

To tune the flow restriction here is a procedure: (like if you have too light of a feel, or jerkiness)
KRC Power Steering says:

So how do you achieve optimum steering feel? According to KRC’s Ken Roper you reduce the size of flow valve orifice until you experience pump catch. Characterized by a momentary loss of hydraulic assistance, pump catch can be induced by steering the vehicle in one direction then swiftly changing to the other direction—as oval track and road racers do. The quick change of direction increases the pump flow requirements and the momentary deficiency is caused by a sudden lack of flow of hydraulic fluid. When pump catch is encountered you can increase the orifice by one or two sizes, which will eliminate it and cultivate a better feel. As a result, the steering will be accurate, responsive, and without any tight spots.

For a PS cooler, which any hard driven system should have, you do not need a fancy aftermarket radiator type. Those can be leak prone. On my racing '70 Z28, I used a factory early 70s Trans Am PS cooler. It didn't look like a cooler, it was just tubing. You could make one very easily. It is just a long piece of tubing, maybe brakeline or similar. Put it on the zero psi return line. Before it goes back to the pump, go forward under the radiator, turn right and run it all the way to the right side of the car, then loop it back to the left side, and then back to the ps pump. You will add 8-10 ft of metal tubing that is out in the airflow, vs the zero feet that was there before. And it is robust and will not leak. My long OEM line came directly out of the fitting on the box. I used a factory Trans Am part on my Z28. On my C3, I will build one myself. It needs to get some air movement, so not behind the spoiler, but in front of it. Probably I'll put mine inside the fiberglass, under the headlights, in front of the radiator. You can measure the pump temp with an IR gun. I did a couple times while racing. Never got more than warm / rad temp. Over 200*F is too hot. I have seen many autocross cars boil their PS over with way too much heat, and those guys burn up pumps all the time. Vs mine lasted 40 years, and I did not baby the car LOL! I ran 11" Hoosiers and such. I just looked at my C3, I will either put the double tubing pipes right in front of the rad, or a little more forward and near the two bottom air intake holes. I'll build a little bracket of some sort. Best part is you almost don't notice the little run of double tubing, vs a little radiator/cooler sitting there.

Chagjr

I purchased a new one. Great price! Works fine.1968


https://www.topflightautomotive.com/...w-w-reservoir/

leigh1322

Just found this on the steroids site. They recommend no more than 2 gpm flow, unless you need extra flow because of a hydro boost.
On pressure they say the rack is designed to work with normal pump pressures of 600-1400 psi, but they prefer 900-1200 for the best driving feel.

Anyone know of hydroboost requirements?

leigh1322

I am no hydroboost expert, but it seems the gm system is designed for 2.2-2.6 gpm and 1300-1600 psi. And as little as 2 psi back pressure on the return hose will apply the brakes, so a separate return line is recommended. The two systems have different flow & pressure requirements. Running the steroids that high would cause it to be over sensitive.

leigh1322

Well I see that Paul has no comment, but I was also thinking thru this setup for myself, in case I head in that direction...
I have carefully tuned the PS, I know how to do that, and I will not foul that up for whatever benefits a hydroboost offers, no matter what.

I found the solution the disparate flow & pressure requirements of a Hydroboost and PS.

Ken Roper, founder and master engineer at Hydratech Braking Systems with 35 years experience with these hydroboost units, recommends a Heidts adjustable power steering valve after the Hydrosboost, but before the PS, to blow off some flow/pressure to allow you to tune the PS feel, while leaving full flow/presssure/power for the brake unit. That allows you to run and tune both units, without resorting to some "compromise" setting somewhere in the middle, where neither unit is optimized.

Link to Heidts Valve

Link to Ken Roper discussion on "Overboosted Steering with Hydroboost" posts 20-22

leigh1322

I found Jim Shea's paper on how to determine your pressure and flow for GM C3 power steering from 2013.
Jim Shea was a GM engineer who helped design this system, and was active on this forum for many years.

http://jimshea.corvettefaq.com/wp-co...s-09OC2013.pdf

pauldana

not checked out of this thread,,, just reading intently... i was looking at that valve a few days ago... or one like it.

leigh1322

I hope the research helps you.
It certainly helped me.
I may actually consider one now.
What was your experience Pual, how much did the Hydroboost change your braking?

pauldana

When the HB is working properly,,, it truly id the cats meewoo... There is NO better braking... Keep this in mind about my brakes, it is. full willwood big brake system. including the wilwood knee-brake proportioning valve. nothing stock here.. nothing.
The steering... pros, when tuned in, is fast and articulate steering... but getting both in harmony has been an ongoing process...

leigh1322

Sounds like awesome brakes!
My solo car had 1.3G brakes, the lift the passenger off his seat and throw him into the shoulder belts kind.
That was fun for the unsuspecting!

pauldana

https://bobistheoilguy.com/forums/th...advice.371915/


this guy seems to have the same problem... swapped out pump.. worked.... it seems the internal vains may be worn-out, thus giving little to no boost at idle...

i have not always had this problem like i do now...

will keep posted..... but I think i will purchase a new unit... with tight tolerances.. i can see how a rebuilt would have problems with this..



"​​​​​​It’s full and quiet. Works good until rpm drop substantially, like lugging it(manual trans)in granny low pulling into the garage. After which it will continue not working until I rev it to like 1500-2000 rpm."

this^^^^^^^

leigh1322

The vanes do wear, eventually, and faster if there is air in the system or frequent "shudders" from cavitation from not enough flow.
A worn pump will put out low flow, and that would cause lower pressure at idle. Which should be around 100-150psi.
Raising the rpm increases the flow, so yes that confirms you have a low flow problem.
Now was it always low, or did it change?
If it "did not always do this" then a new pump would likely help.
But I would attempt to determine what flow restrictor you have in there now, and either re-use it, or get another one that size or slightly larger.
Many of the aftermarket pumps have random flow rates, or ones that are far too big, and that causes other problems.....
Or get a pump from a place like like Turn One, with a known orifice size.
Normal pressures should be at least 100 or idle, and will go up to around 400psi when using them hard. They rarely ever go higher....

ctmccloskey

When there are questions regarding anything to do with your Power Steering then you go to the best. Turn One is the very best in the business of power steering! These guys have the experience to answer some strange questions and help solve the strangest problems. They know enough about Power Steering to get your Steeroids systems working their best.

pauldana

ok... ive decided to buy a new pump.... any brands to stay away from? and any good brands with a good price? happens sometimes:-) lol

pauldana

ordered a lars new pump...

Lares 12020 - Power Steering Pump

new... will update in about a week...

ctmccloskey

IF you have any questions about getting the flow rate correct call the folks at TURN ONE. They have the parts to make your pump flow exactly what it needs. I tried buying new pumps after the installation of the Steeroids Rack and Pinion conversion. The steering was making a whine and all sorts of noises when you tried to move the wheels. It turns out that the flow rate is the magic number and the folks at Turn One have the parts to get the precise flow you desire.

I even bought an all aluminum NASCAR style power steering pump, I still had to adjust the flow with a part from TURN ONE and then it worked fine.

leigh1322

877-468-8761
I talked to Mark at Turn One just yesterday.
Just got my re-valved Borgeson box back!
42in-lbs now, used to be 28
Woo-hoo!