Power steering pressure control valve - where to get? - Team Camaro Tech
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Brakes, Suspension & Steering Conversion questions, Steering & Handling

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  #1  
Old Jan 3rd, 10, 11:55 PM
71rs400 71rs400 is offline

 
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Default Power steering pressure control valve - where to get?

I swapped my power steering pump for a reman. Original pump is now lost to time (oops). The problem is that the new pump has totally ruined the feel of the steering, there is too much assist/boost.

Where can I find a correctly (stock) valved pressure control valve for the pump??
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  #2  
Old Jan 4th, 10, 01:51 AM
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parkbrau parkbrau is offline
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Default Re: power steering pressure control valve - where to get?

Not sure if this will help. But go to Davids site. He has a lot of info regarding Camaro and suspension. Mainly 1st gen, but the info is all good.

http://www.pozziracing.com/camaro_st...and%20brackets

OOOPS Welcome to the site.
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  #3  
Old Jan 4th, 10, 11:53 AM
davidpozzi davidpozzi is offline
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Default Re: Power steering pressure control valve - where to get?

One way is to go to a local parts store and ask who rebuilds their PS pumps, then contact them.
Your original valve would have been set at around 900 psi with a small flow restriction hole in the outlet fitting. The pressue is set by special shims in the pressure valve, the nut on the valve is very tough to remove without damage to the valve.

Lee Manufacturing in Sun Valley California has been a high profile rebuilder of these pumps since forever, you might contact them.

Changing the steering box to a later style with firm feel would be a great improvement over the stock box. You would need to keep the valve you have now in that case.
David
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Last edited by davidpozzi; Jan 4th, 10 at 12:10 PM.
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  #4  
Old Jan 4th, 10, 12:18 PM
jkuro jkuro is offline
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Default Re: Power steering pressure control valve - where to get?

Got mine from here $18.00 plus ship. Look under accessories

http://billshotrodcompany.com/17022.html
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  #5  
Old Jan 5th, 10, 01:54 AM
TMessick TMessick is offline
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Default Re: Power steering pressure control valve - where to get?

I think the following info is for the newer style (metric bubble flare) pumps -- not sure if the part numbers etc. are valid for the early pumps or not.... At least it has neat pics:
http://jeffd.50megs.com/Pump_valve_mod_page.htm


If you want less maximum assist, I guess you'd want to go the opposite of what they did in the link and go to a lower relief pressure spring.
As David mentions, the torsion bar and valving in the steering box will also have a big effect on overall steering feel...
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Old Jan 5th, 10, 05:58 AM
JIML82 JIML82 is offline
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Default Re: Power steering pressure control valve - where to get?

You guys are making a common mistake when you discuss how the power assist works. The pump generates pressure upon demand from the gear valve. What you want to do is to change the whole gear or have someone just change the gear valve. This will directly affect your steering feel. Tom Lee of Lee Manufacturing in California or Jeff Roethlisberger at Turn One in Saginaw, Michigan can perform the service. They also probably have a recommendation on the pump as well.

Another approach is to just go out an purchase a new or used Camaro gear from a later version Z28 or IROC gear. Here is a chart of the various Camaro gears that were used throughout the years.
http://jimshea.corvettefaq.com/wp-co...ev18se2008.xls


Another approach is to reduce the flow (amount of oil) coming out of the pump. You can do this by changing the discharge fitting on the back of the pump. The problem with this approach is that if you have too little flow coming out of the pump, you will not be able to make an evasive steering maneuver (i.e. something suddenly comes in front of your car; when you try and whip the steering wheel to avoid a collision the steering effort will suddenly increase to manual steering levels because of the lack of oil flow.)

Jim
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Old Jan 5th, 10, 09:40 AM
davidpozzi davidpozzi is offline
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Default Re: Power steering pressure control valve - where to get?

Quote:
Originally Posted by jkuro View Post
Got mine from here $18.00 plus ship. Look under accessories

http://billshotrodcompany.com/17022.html
They don't show a photo of it. Is this an external valve or does it replace the internal valve?

I agree with Jim, the torsion valve in the box is the way the factory sets steering effort, and the newer boxes are best. However taking an old box and putting a newer higher pressure valve setup inside the pump will overboost it and make it worse. Most internal valve mods are for more flow and higher pressure, NOT the other way around, but there are some that go the other way that street rodders use, (Heidt). I don't like the external valves because they just bypass extra flow. A stock 67-69 box is going to have poor feel at best, it just doesn't have the right torsion valve inside.
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Last edited by davidpozzi; Jan 26th, 14 at 08:19 PM.
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  #8  
Old Jan 5th, 10, 03:53 PM
jkuro jkuro is offline
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Default Re: Power steering pressure control valve - where to get?

David, there is a pic of the kit on the link I posted. It consists of 6-shims, 1-oring, 1-flow valve tool. Per the instructions you can change the pressure between 700psi to 1375psi depending on the number of shims used in the internal flow valve. This will change the steering from harder to a softer feel.
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  #9  
Old Jan 5th, 10, 04:51 PM
ccpeat ccpeat is offline
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Default Re: Power steering pressure control valve - where to get?

I pulled my pump and steering box and sent them to Lee Manufacturing, one of the best things I ever did for my 68 ragtop. They can build the box internals with a quick ratio or a variable ratio and rebuild your pump to match. They can even customize the feel.
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  #10  
Old Feb 23rd, 10, 07:17 AM
71rs400 71rs400 is offline

 
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Default Re: Power steering pressure control valve - where to get?

I know that the box is what controls a good portion of the feel; I own both a 91 Z28 (with one of the "good" boxes) and my 71 RS - the 71 was never that bad to me with the original pump, but the parts store replacement pump REALLY sucks.

Wish there was some way to look up how many shims, what orifice size (GPM rating) and spring length were in my original pump and I'd set this new one up the same way. My understanding is that the shims set the max pressure, the spring length sets the min pressure, and the orifice size sets the GPM flow rate.

In addition to the other links already posted, Here's some additional links I came across in my research that may be helpful for anyone else looking into this:

These guys have several calibrated pressure valves for GPM flow ratings:
http://www.totalcontrolproducts.com/...PSP_DS_WEB.pdf

Here's a kit with several shims to save some junkyard diving, and a neat tool for holding the valve without damaging it to get the nut off:
http://www.jegs.com/i/Borgeson/153/899001/10002/-1

Here's a fixed 2GPM flow valve. Too small, but could be drilled out:
http://www.rjays.com/Billet_Spec/billet-tru-trac-01.htm

Here's another fixed 2GPM valve, different style, could be drilled out:
http://www.detroitspeed.com/productp..._flow_prod.htm

Finally, an adjustable external valve here:
http://www.heidts.com/steering_kits_components.html
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  #11  
Old Feb 24th, 10, 06:18 AM
JIML82 JIML82 is offline
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Default Re: Power steering pressure control valve - where to get?

It is a fact that the steering gear valve (or the control valve on C2/C3 Corvettes) is the primary component that affects steering effort and feel. However, the amount of flow from the power steering pump can also have some affect as well.

Cutting back the flow from the power steering pump by changing to a production type discharge fitting from one of the above suppliers is a good idea. Most Camaro systems were probably in the 2.5 gallon per minute range. This would be a discharge fitting with a throat diameter of around 0.130 inch. Too much flow can make your steering feel light and twitchy as you drive down the road.

The only time that you would want to increase the pressure relief of a pump (i.e. remove shims from the back of the flow control valve) would be if you did not have power assist as you turned your steering wheel to near full lock with the car stopped (held in place with your brakes) and the engine running. If you have full assist with this type of maneuver, you have sufficient, or possibly even too much assist from your pump.

When you are driving down the road and making steering motions, you probably aren't requiring more that a couple hundred psi of pump boost. You will not even be close to pump pressure relief. So pressure relief has nothing to do with steering feel.

For the most part you have sufficient flow from the pump if you can make very quick steering wheel motions (such as trying to evade something that suddenly came in front of your car while driving down the road.) If you do not have sufficient flow, you will feel an abrupt increase in steering wheel effort as you try to whip the steering wheel. You can test for sufficient flow by finding a large, empty, parking lot and driving in a straight line at about 15 to 20 mph. Suddenly whip the steering wheel as if avoiding something in the roadway. If you have full assist during this maneuver, you have sufficient flow.

When there is not sufficient flow some people have incorrectly described the abrupt increase in effort as having their steering "lock-up" during that maneuver. It did not lock-up, what you are feeling is the lack of fluid flow to move the piston inside your steering gear (or the assist cylinder on C2/C3 Corvettes) quickly enough for you to make the evasive maneuver.

I do not recommend external by-pass fittings or external components that claim to reduce flow. They cause the pump to continually work against the back pressure caused by the needle valve in the unit. This will cause increased power steering pump operating temperatures. The production pump discharge fitting causes internal recirculation of excess oil and does not increase system working pressures.

Jim
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