Some time ago there was a rather long tread on the subject of too much power steering in some of the early Ford's(70's). I now need the information and can not find it using search. Any input?

 

I don't understand how you are experiencing too much power steering or the idea that these 1970s trucks have too much of it.

 

The power steering doesn't give enough feedback and road feel to the driver.

 

I thought it was the radius arms that gave us that nice road feel???

 

Mattsbox99 is correct, I have little or no feed back or road feel. It is my understanding that the pump pressure is to high and giving too much assistance. From memory ( at my age very ifie) Saginaw pumps put out 1200 1300 psi and and some discussion on the prior thread was on ways to reduce this to 800-900psi.

 

Rob,
Have you done some maintenance/repair in your PS lately?
I have seen a cone shape filter in the low side (return) line.
My guess is: By decreasing low side pressure (NPSH) you can descrease high side pressure significantly. Basically what I'm suggesting is: Starve the pump by restricting the low side line. This should slow things down.
KingFisher

 

KingFisher:

This problem has been with the truck as long as I have owned it (4years).

thinking out loud here... wouldn't restricting the low side give the same results as if turned against the stops?

Rob

 

Pull the pressure spring out of the side of the pump and cut one coil off and re-install. If you still have too much pressure, start cutting it 1/4 turn at a time. Pressure seems to drop quickly.

 

wouldn't that extra pressure be a good thing to have off-road?

 

My .02,
I used to think the same thing about my rig. Then I went throught the front end and replaced EVEYTHING including the steering box over time. It's amazing how much it tightened up. I did use poly bushings everwhere.

 

So how is lowering the pressure supposed to give any more road feel or feedback? All this does is slow down the maximum speed the steering wheel can be turned. I have had power steering pumps that went bad slowly and the ability of them to pump up the proper pressure dropped and all it feels like to me is a dragging steering system or two flat tires in the front.

Won't restricting the pump pressure create heat and cause a pump to work hard all of the time and wear out prematurely?

You can get somewhat of the same results just by installing a smaller steering wheel. The smaller steering wheels require more force to turn them, so you wont need to modify the power steering system.

The geometry of the suspension and steering linkage is where the ease of the steering and lack of road feel comes from.

 

thinking out loud here...With engine off there is no slack in the steering, the alignment is ok as there is no sign of uneven wear in 3 years. I took the rig for a drive with the pump belt off and the rig drives great except for the muscle required. At highway speed it is far easier to control.

what controls the amount of force that the system apllies? at parking lot speeds isn't the amount of applied force going to be greater than that which is applied at highway speeds?

 

All,
I worked for GM Truck & Bus for awhile. They had a variable power steering system. You simply moved a switch from hard to soft. This increased the amount of force required to steer. The highway steering was harder than the city setting.
The harder you have to pull on the steering wheel the less the pump is doing. The power assist is acting as a cushion or insulator between your hand and the feedback coming back through the front suspension to the steering wheel.
By slowing down/ reducing the assist, you allow feedback more time to get back to the driver before he/she has over compensated.
Secondly, by reducing psi entering the pump you do not allow the pump to create as high a pressure on the outlet side. You have not caused the pump to do anymore work or caused the pump anymore strain. By restricting the outlet ( bad thing) you are allowing the pump to work at its upper pressure limits which, i am assuming, would shorten bearing life.
Consider it,
KingFisher
PS What does the spring do? Where is it located?

 

NEVER restrict the inlet side of a hydraulic pump!!! That will destroy the pump!!!

When you cut coils off the relief spring, all you are doing is making the system operate at a lower pressure. You are changing the pressure relief valve. Messing with the relief valve can be very dangerous!!! Some systems use a simple one spring poppet type relief valve like oil pumps. Other systems use a piloted relief valve that has a small poppet valve controlling a larger valve.

PS pumps are very simple things, they do not have variable delivery. They are fixed volume pumps that put out just so many cubic inches of fluid every revolution. When the steering wheel is not being turned in most systems the pumps are pushing their fluid output over the relif valve which builds heat. These systems run HOT so anything you can do to cool them helps!

There are some variable assist pumps that have electric solenoid valves to select relief valves. There are also some that have an orifice in the primary relief valve that increases the pressure with rpm's. We would have to go into some HD hydraulic theory to tell you how that works. You can get fluid power training thru many industrial/mobile fluid power distributors.

The amount of assist you have will depend on the system pressure.

If you restrict the output of the pump it will not affect system pressure but it will make the steering "slow" and will require more effort for fast motions.

Power steering pumps "whine" when:
-The shaft bearings go bad.
-The pump has air in the system causing cavitation. This can be caused by low fluid levels or a restricted pump inlet. This will quickly destroy a pump.
-The pump develops scratches in the valve plates inside the pump that allows fluid to directly bypass from the high pressure side to the low pressure side of the pump.

ANY TIME YOU WORK ON THE POWER STEERING SYSTEM INSTALL A FILTER in the return line from the PS control/gears back to the reservoir.

From my files:
==============
WIX TRANSMISSION/PS FILTER #58964
200 PSI WORKING, PRESSURE RELIEVED, MAGNETIC
CHANGE YEARLY OR 12000 MILES
FORD EQUIVALENT FILTER KIT #XC3Z-7B155-AA
FILTER ALONE #XC3P-7B155-BA

 

would the size of the pulley have the efect that you are looking for?
bob