Help with steering pump flows

HUGE issue with me right now on another vehicle....pump can't run both steering and HBoost.....pulley ratio is the same 1-1 on both the vette and the P30 motor home/camper P30 has a recirc ball steering, vette has a rack both have HBoost....

I have no clue, except to find there is a pump difference....

and a guy I can't get to for a couple weeks yet, who claims he can increase pump flow and pressure....

I have a note into JimL82 Jim Shea here, about this exact issue today...

but to note there is a slight difference between that 10k lbs motor home and the 3300 lbs vette....much less being disc/drum on the brakes...

:hissyfit: so here is a bump for you, I"m all ears too....:quote:
 
when i put my hydro boost on .. the guy i got alot of my info from was selling hydro boost kits for all makes of cars ... told me the stock 79 vette pump will work fine ... then i asked about adding a rack and pinion and he said it was not a problem, using the same pump ... i wound up using a remote ps pump for my tall deck motor transplant ... i will look and see if i can find the specs on the pump i ordered from PCS .... you can change the flow and preasure of a stock Gm pump by changing the valve and sping behind the preasure outlet ... but i have no info on what parts to put in or where to get them...
 
when i put my hydro boost on .. the guy i got alot of my info from was selling hydro boost kits for all makes of cars ... told me the stock 79 vette pump will work fine ... then i asked about adding a rack and pinion and he said it was not a problem, using the same pump ... i wound up using a remote ps pump for my tall deck motor transplant ... i will look and see if i can find the specs on the pump i ordered from PCS .... you can change the flow and preasure of a stock Gm pump by changing the valve and sping behind the preasure outlet ... but i have no info on what parts to put in or where to get them...

THAT is what I thought/remembered....I have not pulled the backside of my vette pump apart to mess with it, but I have a '88 serp drive on it, and so I remember changing the valve for the '72 valve because of mainly the flair fitting on it, and then having stock steering....I left it in place for the rack conversion, and then some years later, the HBoost addition....never touched it....

AND I remember it was a 2+ piece valve setup....this pump on the motor home is a one piece straight through hole down the center, an O ring around the outside, with a tiney side hole.....I have no other parts to it, just that....

I pulled a old pump out, removed the output fitting, and sure enough, same thing....one piece....

:cussing:
 
Gene, going from memory here but the old pumps were .94 cu in.
Depending on the flow oriface size they put out anywhere from less than 2 gpm to almost 3. I'm sure that is still less than the pump max.
Check the hole (hardened) on the inside of the adapter (not the hex end) you pulled out (flow control) and that hole in the end can be as big as .150" for close to 3 gpm flow. You can check and cross over with numbered drill bits. It can be drilled to suit.

Behind the fow control/adapter you pulled out, should be a relief spool with a nut on the end with a big spring behind it. If you remove the nut and play with the shims inside the spool you should be able to get anywhere from less than 1000 to almost 1500 psi.

I think most rack and pinions run well around 1000psi.

Jim Shea should be able to give you the details, my memory is sort of fuzzy.

I do still have an old C30 Chevy that came with power steering and hydraboost. Still works perfectly when both brakes and steering are applied.
 
Gene,
This is the same answer that I posted in your PM to me.
Jim

Behind the discharge fitting you should have a flow control valve and then a spring. The spring pushing the valve up against the discharge fitting.
P-PumpFlowCntrlValve.jpg
I assume you have a Saginaw P-pump on the motor home. Get a pickup truck discharge fitting. If 1980 or later it will be female 16X1.5mm o-ring. If before 1980 it will be 5/18-18 female with 45 degree flare seat. You might actually end up with too much flow and your steering may become too sensitive.

Otherwise, you could try drilling out your current discharge fitting. Every 0.016 inch diameter increase will increase flow by 1/2 gallon per minute. That very tiny hole at the bottom of the groove in the discharge fitting that you mentioned is very critical to the pump regulating flow. If you disturb that hole when drilling it out (burrs, chips, etc) your steering will be quite erratic. Some are successful, some are not.
Jim
 
Jim I'm ruining the GM Type 2 Power Steering Pump - 6175 PS Pump that came with my Zoops serp drive system. Any idea how much flow I might need to get the HB and R&P to function as designed?

Would you recommend just to play with flow and pressure until I get the feel I want?

Fittings can be bought for the pump I have to change the flows I believe.


Neal
 
Jim, guys, just a hour before getting Jim's reply I went to the parts house and got a new pump....same thing, so I tore into the HBoost....

and typical ebay....somehow it was slightly RUSTED internally...nothing much or pitted, just brown...so it's been all flushed and cleaned out, the gaskets were still soft, the way they should be, and so I got finished by 5 or so, and am beat to shit...tmrw is another day....

one of the valves in there, the larger one, next to the power piston was stuck in place...

so that maybe it...it's all fine looking now...so will see...


not enough words to explain all this shit...

and yes, you are right, somehow the valve behind the bolt/passage that unscrews, was stuck/hung up and didnt' come out....

at any rate the old pump is in place to be reinstalled, as I suspect it's fine at this point...

I should know by noon, unless wife has other plans....:sweat::huh2::crutches:
 
So was it a chip or something from the hydroboost that caused the flow control valve inside the pump to stick? From your description of adding the hydroboost, it appeared to be a lack of flow.

I looked through some charts that I have on power steering pump useage. On trucks that are available with and without hydroboost, it does not appear that they change flows or pressures when you have the hydroboost option. So there is a good chance that you do not need to change anything when adding hydroboost to a C2/C3 Vette.

Now don't forget that with a production C2/C3 Corvette power steering system you should not exceed 1000 psi because the special Corvette hoses were not designed for higher pressures. So don't start removing the shims in the front of the flow control valve and boosting the relief pressure in the pump.

However, when you change to rack and pinion or change to the Borgeson integral recirculating ball power gear, you will have changed hoses and 1300/1400 pressure relief settings in the pump would be acceptable (assuming that the special hoses for the installation are rated for 1500 psi or more.)

Jim
 
Last edited:
My vette is a result of many separate projects over 15 years, it WAS stock as a stove mechanically, when I got it....
first off was the Serp drive change, using the stock '72 vette p/s pump valving...all I did was switch it over, I think because it had the flare fitting, no other reason....it's what I remember...
then ~7 years later the rack conversion...I cut the line and used a 3/8 compression coupling to the rack setup, just easier to fit the hoses I got with the rack....then maybe 3? years later was the HB conversion...just plumbed it in with the hoses I had with the HB unit....never any issue....

NOW, I have posted already last night...the HB came apart, and I put it all together again nice and neat and CLEAN....it works well, Jed's Clamper will stand on it's NOSE with just a feather touch....I have a 1 5/16th dia master cylinder in there from like a 50 ton 18 wheeler.....gotta LOVE it....

take the damn rotors down to dust before the hydraulics fail.....

:D:crap::friends:
 
Well I found out that I have a 2.5 gpm and 900psi valve in my pump.

Now the question is were can I find the correct fitting for my needs?

Can I just go by the junk yard and take one apart and rob the fittings form it. The question will be what type of vehicle to look for and what parts will I need to get?

Can I drill the fitting in the pump I have? What will this do for the pressure. Sounds like the pressure and flow are set with different parts in the pump.

Looks like I'm looking for 1200psi with 3 plus gpm flow.

Any help out there is much appreciated.

Neal
 
Well I found out that I have a 2.5 gpm and 900psi valve in my pump.

Now the question is were can I find the correct fitting for my needs?

Can I just go by the junk yard and take one apart and rob the fittings form it. The question will be what type of vehicle to look for and what parts will I need to get?

Can I drill the fitting in the pump I have? What will this do for the pressure. Sounds like the pressure and flow are set with different parts in the pump.

Looks like I'm looking for 1200psi with 3 plus gpm flow.

Any help out there is much appreciated.

Neal

I thought I commented that in MY case I felt the stock pump valving for a shark was fine for the rack, works well, I would at least try it seeing what you think....

:amazed:
 
I don't have the stock valving for the vette.

GM used a higher flow and relief pressure, this pump is set up for a Ford rack using lower flow and pressure, somethings Zoops didn't tell me when I ordered this setup. They do offer a pump with GM stock flow and pressure settings now and are checking if they have the parts to upgrade my pump.

Reading on the KRC site and talking with their tech dept a higher flow as GM used would more than likely resolve my issue "pump catch" per the KRC site.

From the KRC site;

Larger flow valves are required when using steering quickeners or 3.4 inch per revolution or faster rack-and-pinions. If you run on smaller tracks, a larger flow valve can give you more assist through the tight corners. Cars with wide tires and a lot of positive caster may also require more fluid flow. If you drive into the corner and feel as though the steering has a slight catch to it, commonly called "pump catch", a larger flow valve may be required.

When I apply the brakes and turn the wheel I can feel a slight catch.

Pump relief pressure may not need to be adjusted, KRC tech suggested increasing the flow and see what happens.

The only issue is they don't think the GM type II has an adjustable flow fitting and indicated that their fitting won't work with this pump.

I've had this setup on the car for a couple years now and while this issue is not a major issue its something I want to resolve and get the feel I'm looking for.

Neal
 
Last edited:
Something doesn't sound right. A Hydroboost unit works like a vacuum booster. There is a small nitrogen filled canister that accumulates fluid from the pump when the brakes are not being used (just like a vacuum booster gets it's vacuum "charge" when the brakes are not being used). So there is no demand from the pump when your brakes are depressed, in fact, the supply port is shut off IIRC. This is why a properly functioning Hydroboost will supply assist for 1 or 2 applications of the brake with the engine (pump) off.
 
Something doesn't sound right. A Hydroboost unit works like a vacuum booster. There is a small nitrogen filled canister that accumulates fluid from the pump when the brakes are not being used (just like a vacuum booster gets it's vacuum "charge" when the brakes are not being used). So there is no demand from the pump when your brakes are depressed, in fact, the supply port is shut off IIRC. This is why a properly functioning Hydroboost will supply assist for 1 or 2 applications of the brake with the engine (pump) off.

No it don't....I don't understand your question/statement, I suppose....

if you look at the diagram of my '72/early shark vac booster, you find a spring between the input and output shafts...it's a tough little bastard like a valve spring on steroids....but it's a spring, after all.....

the HB has nothing like that, the shafts are solid from input to output, there is a valve that hung up on me due to whatever/rust/storage on a unit I put in a camper/motor home last week, and it's fixed now, solid as a rock...

the feel of a HB is totally confident over any vac booster I have ever driven...

IMO...vacuum sux...no other way to describe it....

;):bounce::amazed:
 
All the hydraboosts have an accumulator, most have the external gas filled cylinder but some have an internal one inside the piston and some are spring loaded and not gas.

When you apply the brakes the pump fluid is used by the HB first and the steering gets the residual.

The proper way to plumb the return lines is to have 2 separate ports into the resevoir, some kits that used pressure lines and jic fittings with a tee didn't always work in all situations. The rather tiny holes in some of those fittings can actually work like an oriface and restrict flow.

If you are using a tee in the returns, that would be a good place to start.
 
I have a T in both installs, and yes, I used 1/4" ID fittings to keep flow up...the hose is 3/8.....

I did note that the HB on the vette had a normal looking pin on center to hit the m/cyl piston....never took that one apart....

but the one on the M/Home is different, that pin and surround came off the old vacuum booster, modified the length to fit the install, works fine, the piston looked hollow with a 1" hole in the center, sorta strange, but when looking them up from various applications, what I got for the vette chanced to be just what it would be for in applications at the parts house...similar weight vehicle, the one I got for the camper I got lucky again, and got what looks like for a large truck....dumb luck, I never knew any differences....

look at the options on that from O'Reilly AP.....:amazed::nuts:
 
Top