74 with P/S Over Assist

Fuelie74

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Joined
May 7, 2008
Messages
770
Location
Monroe, WI
The power steering is over assisting anytime the engine is above idle. This is not a new problem but, its getting very old. On the interstate you loose all feeling of the road. The pump on the car is from a 92 F body. I am wondering if it is a flow issue. Has anyone encountered this problem before or know of any fixes?
 
The pump bypass pressure is lower than the later Camaro pump. C3 pressure is spec 870-1000psi. Your pump is probably 1500 psi.
 
That's why I use KRC pumps, they have flow valves so you can play with that.

Maybe Jim Shae can help. The 92 F body pump is designed to work with the F body internal assist Saginaw 605
 
IF you have your old shark pump....Take the large brass hex out of it , that is the whole valve assy.....and swap with the 'new pump'......I did that just for the grins of using the old flare fitting, but did notice some difference in the valving construction....since doing the serp drive conversion for years running with stock shark steering, I left the valving alone, then when going for the rack about 7 years later afterwards.....I left the valving alone, and just spliced the lines, having lost the 'new' pump valving....and the rack hose being a O ringy doo/AN fitting........:D
 
I would switch it back but I don't have the original pump. My car was butchered and not running when I got it.

Won't the higher pump relief pressure only effect it on lock to lock?
 
I would switch it back but I don't have the original pump. My car was butchered and not running when I got it.

Won't the higher pump relief pressure only effect it on lock to lock?

I dunno, my only suggestion is go get a '72 pump and change out the valving with your unit.....

NOW, I have to ass ume the F body pump you have and the '88 serp setup I have is the same pump machine work in the body, so as you can use the shark valving setup......I did, and it's a fine for my rack....and so I have less assist, apparently than some other guys on the RACK install....

I found NO diff on the stock steering for the serp drive setup change over....
 
I would switch it back but I don't have the original pump. My car was butchered and not running when I got it.

Won't the higher pump relief pressure only effect it on lock to lock?

The bypass pressure of the later Camaro pump can be reduced. I'f there is a rebuilder in your area, they can do it.
 
The C2/C3 Corvette power steering system was designed for 900 psi. Most modern GM steering systems are designed for 1450 psi or higher. The maximum pressure is generated when you are at full lock.

The C2/C3 hoses were only designed for 1000 psi. They will quickly become leakers if they experience 1400+ pressures. The high pressures will not cause any different steering feel. However, high flow rates from the pump could cause your steerng to feel light. It is best to use the discharge fitting and the flow control valve from a Corvette pump to insure the correct pressure relief and the correct flow rate.

Jim
 
Thanks for the help everyone. I took TT's advice and contacted Jim Shea. He was out of town and won't be back till March but, said he has the information I was looking for at home. He did say that this was definetly a flow issue.
 
Ok we are really slow at work so I have been doing allot of searching over the last couple days. I found a few things and think I have the answer to my problem.
Jim Shea

For a C2/C3 power steering system that really didn't change through the years, the power steering pump high flows and low flows did change. The maximum pressure remained the same at 950 psi for all the years. Here are the flows:

1967-69 1.25 gpm @ 465 rpm 1.75 gpm @ 1500 rpm
1970-73 1.32 gpm @ 465 rpm 1.60 gpm @ 1500 rpm
1974 1.32 gpm @ 465 rpm 2.90 gpm @ 1500 rpm
1975-79 1.32 gpm @ 465 rpm 2.90 gpm @ 1500 rpm
1980 1.32 gpm @ 465 rpm 2.90 gpm @ 1500 rpm
1981 0.60 gpm @ 465 rpm 2.90 gpm @ 1500 rpm
1982 0.60 gpm @ 465 rpm 1.90 gpm @ 1500 rpm

The high flows (@ 1500 rpm) are strictly a function of the discharge fitting. Change the fitting, change the flow. The high flow rates might make your steering feel somewhat lighter.

The low flows (@ 465 rpm) are a function of the cam displacement inside the pump. The pump displacement was greatly reduced in 1981-82 in order to promote better fuel economy. The less oil that is displaced every time the pump rotates the less energy the pump consumes. I don't know if low flow rates at low engine rpms might affect hydroboost braking systems.

For you road racers that continually see high engine rpms, a low displacement pump will reduce your steering temperatures. Any Chrysler minivan built before 2000 will have a Saginaw P-pump with a low displacement 60 series cam ring inside the pump.

The 1974 through 1980 pumps ought to have plenty of flow.

I will try and determine if there is a range of service discharge fittings that will provide from 1.9 to 2.9 gallons per minute (or more).

I will also try and determine if there are service cam rings that will provide higher and lower pump flows at low engine speeds.

I do not know what the flow for my F-body pump is but, Billet Specialties makes a 2GPM Flow Control Valve. http://www.billetspecialties.com/item.asp?cid=7&scid=221&pid=732 It is supposed to be for use with a ford rack but, by the numbers Jim posted on CF along time ago it should give me the results I am looking for. Plus it has a 37deg flair for use with AN line.

Anyone have any thoughts on this?
 
I wonder if there is a way to determine what flow control valve you actually have? Numbers on the valve? I have a rebuilt pump from Autozone. It has the right reservoir and pump mounting but it could have any FCV in it once it is taken apart.
 
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