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Help, I have too much power steering assist, 4.6L DOHC

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6.3K views 20 replies 10 participants last post by  beeman  
#1 ·
I'm running the stock PS pump on my 2004 Mach1 DOHC with a fox body rack. Not using Hydroboost steering. I have way too much assist, my PS pump sounds like a supercharger! I'm thinking the fox body rack likes a lower pressure? Other than a Heidts valve, what are my options? Is there a spring-cut option? Is this written up? Thanks!
Dave
 
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#4 ·
Thanks, acth4347. Does that apply to the mod motor PS pump? I'm ready to slice and dice.
Gordon, thanks for the reply. I am already running a decent sized cooler on the return line, basically an oil cooler.
 
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#5 ·
Beeman,
What are you running for caster? With PS you should be in the 8 degree positive range which will naturally increase the steering effort and make the car track better with more straight line stability and return to center. When going to that much caster be mindful of the thread engagement in the adjusters, particularly of your upper arms have the zero degree ball joint plates:

http://www.ffcars.com/forums/17-factory-five-roadsters/244160-lots-caster-warning.html

Be sure that you are set for toe in, not out (I like about 3/32" total) because toe out can make the car feel twitchy which could be interpreted as being over assisted. These things along with the spring mod should get you where you want to be.

Cheers,
Jeff
 
#6 ·
I got the impression from the original post that the noise occurs at all times. If the system is screaming with the steering wheel in the neutral position, I suspect the rack is plumbed backwards with the pump pressure line going to the rack outlet.
When the wheel is neutral, all fluid entering the rack is returned directly to the reservoir, and should develop minimal pressure and noise. I only hear noise from the pump (stock 4.6) when the wheel is turned to full lock - end of travel. When you have the wheel at full lock, and continue to try to turn the wheel, the pump is attempting to push the rack further, which is at a mechanical stop. Full pressure is developed and flow is relieved thru the pump pressure relief valve, making the squealing noise.
 
#7 ·
Interesting...yes the "whirring" is constant, increases in volume with higher revs. I have 6 deg of caster, could go a little more. I have tons of assist, can easily turn the wheel with one finger at a stop. If I'm plumbed backwards, would I have that much assist?
 
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#9 ·
If plumbed backwards, you would likely blow the high pressure line apart. Ask me how I know!

Alan
 
#8 ·
There are also flow control valves that will reduce the volume output of the pump. Google search. But the spring cut seems to be a proven fix.
 
#10 ·
"Thanks, acth4347. Does that apply to the mod motor PS pump? I'm ready to slice and dice. "

As far as I know the PS pumps are the same (internal spring sets the pressure relief point). I cut the spring on the pump on my mod motor per the instructions in that link. I haven't started the motor yet so I can't say it works but I don't see any reason it wouldn't.

Are you running the PS pump and Fox body rack but no brake boost? I can imagine you might have too much assist that way. Either the internal spring cut mod, a larger diameter PS pulley, or a Heidts valve should work. The Heidts valve along with all of the hoses and fittings is probably the most work/money but you can adjust the assist all you want. Once you cut the spring, you are stuck at that level until you cut is some more. hth, Bill
 
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G
#11 · (Edited)
The loud noise in the pump may be some air still trapped in the system. Upon opening the filler cap, if there is foam or air bubbles present bleed the system again.

In regards to cutting the spring, I just spoke with Detroit Speed and Equipment and they said the control valve is a better solution to controlling the twitchiness of the steering system. The valve maintains the required pressure but slows down the amount of flow. The cut spring lowers the pressure.

In regards to the cut spring, I think you can add a washer under it to increase the pressure again.

I was, at one time, going to use a Heidt valve but am going to try the Control Valve first to eliminate plumbing and more 'stuff' in my engine compartment.
The control valve screws into the high pressure output on the power steering pump. You can get it at Summit Racing or Detroit Speed for about $26. I'll then screw in a -6AN fitting onto the control valve.

Here is a link to the Detroit Speeds Control Valve, with more information:
Detroit Speed, Inc. - Steering - Power Steering Flow Control Valve

As Gordon suggested, :yes:I'm using a small cooler from Derale Performance that has -6AN fittings on it. Stock #13310. It is put between the low pressure output of the steering rack and the return to the power steering reservoir.

Also do pay attention to Jeff's link to adding caster.

George
 
G
#12 ·
One more thought about the Control Valve I mentioned.

The Control Valve is not adjustable like the Heidt Valve is.

However, if you want more assist you can remove the Detroit Speed Control Valve and slightly enlarge the orifice by drilling and trying it out and then drilling it slightly larger again until you get the assist you want. You just can't go back except for another valve at $26. Still way cheaper than one Heidt valve though.

George
 
G
#14 · (Edited)
I do note that. The '97 Explorer Ford pump that I presently have is an exact copy of the Gen II pump. True the insides, possibly the orifice, may well be different and output different also but I think there is some crossover regardless of the name.

I have just looked at the 2004 Mach1 DOHC steering pump and while it has a different mounting system in the casting it 'looks' very similar. I will find out what the output is and if that Control Valve will fit the pump.

I will continue to do some more research. Thanks for the input.

George
 
#15 ·
Thanks for all the info, appreciate it. I actually had to repair 2 hard line leaks on the rack, trackside at European Autosports, at Autobahn CC. Great guys if you are ever out there...even were there for a Sunday morning repair! Maybe I have accidentally mixed up the high/low lines on the rack, I'll look at that first. Glad I wouldn't be the first! If that's the case, have I likely destroyed anything?
With regards to the valves vs spring cut, I am leaning towards the spring cut. Seems the valves would force the pump to work harder than it needs to, just lets the downstream rack "see" less pressure.
 
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#18 ·
beeman said:
Maybe I have accidentally mixed up the high/low lines on the rack, I'll look at that first. Glad I wouldn't be the first! If that's the case, have I likely destroyed anything?
Click to expand...
I mixed mine and the wheels went to the left and I had to fight the pressure to turn the steering wheel. Something inside the rack (Mustang 2.5 turn rebuilt) was damaged and caused the fluid to leak a few drops a day from the rack ends. I replaced the rack rather than trying to rebuild it.
 
#16 ·
I believe the way the Heidts valve works is it allows excess pressure/flow to go back on the return line. The pump works at whatever flow it is and the valve sends extra back. Like a "return" style fuel pump system.
Bill
 
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G
#19 ·
The lower port, on the steering rack is the pressure port and the smaller of the two ports. Run a high pressure line from here to the pressure port on pump (Blue Plug on pump below). The top Return Port runs to your reservoir.



Blue plug is where the high pressure line should be attached and run to the lower pressure port on the steering rack.


The black capped off port at the very top of the above picture, and pointing to the left, is the return port from the reservoir. Make sure you use a good line here that does not collapse as the pump is sucking through this line.

This is how you would hook up the Heidt Valve. Disregard the picture of the pump as it is not yours but think of the pressure out and return line to it.


Now, I don't know if it fits or would work in your case but the control valve would go into the location where the Blue plug is and limit the amount of output flow to the steering rack. There are all kinds of control valves available with different sized orifices.

Here is a site , Speedway Motors, that sells many different ones including the one I mentioned before.
Power Steering Control Valves - Free Shipping @ Speedway Motors

From what I've read on several sites, don't cut the spring as it lowers the pressure to the rack. The control valves and Heidt Valve don't lower the pressure they lower the flow.

George
 
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