Too much power steering??

DocDirk · #1 (**permalink**) 06-15-2009, 09:29 PM

Well the power steering rack is in and with a 16:1 ratio I was looking forward to a lot less wheel-wrestling than I had with a blown out power steering rack.

Indeed at low speeds and in parking lots it has been a godsend, but on the freeway it's downright scary!! The steering wheel now operates all auto moves within no more than about 1" of its center position; any more than that and the response is excessive. Moreover, the front end feels "floaty", like if I ask it to go left a bit it starts left and just wants to continue on going left unless I correct it back. Have to do that super carefully or it'll start drifting right! It feels like it has no desire to return to center (straight ahead).

I asked the alignment shop if it were related (I don't have the numbers but I'll get them). Their response was it's not the alignment, that's the way it is with power steering especially if you're running those large (265 / 50 / 15) front tires.

I'm wondering where to start here? The pump puts out 1500psi but is limited by a restrictor to just under 1000psi (tested). The rack is 1000psi rated. Would it help to put in a smaller restrictor? Would it help to use smaller front tires? Should I be looking for an adjustable in-line high pressure output regulator from the pump?

Should I have asked around more and wound up with the manual rack and pinion instead

Thanks for any input,

I know, I go to school at ClubCobra University.

Dirk

Jerry Clayton · #2 (**permalink**) 06-15-2009, 10:01 PM

more caster

FWB · #3 (**permalink**) 06-15-2009, 10:12 PM

dirk,
i found this, there is a link there to chase also. apparently a ford rack and chevy pump issue.

Fred

http://www.justanswer.com/questions/...-steering-unit

FWB · #4 (**permalink**) 06-15-2009, 10:31 PM

dirk it sounds like there is still too much pressure going to the rack. if you don't have a source for different restrictors Heidt's sells them.http://www.heidts.com/index.cfm

a pump will bypass pressure to the rack when the wheel is straight. when you apply resistance (in most cases its turning the wheel) the pump will apply pressure. too much pressure and it keeps steering, or keeps pumping fluid.

DocDirk · #5 (**permalink**) 06-16-2009, 11:46 AM

Thanks Fred, I'll put a restrictor in (as also suggested by kitcarbp in a PM) and try to reduce the pressure to 700psi or so...I'm truly UNHANDY with these hydraulic thingamajigs so we'll see, but it seems the reasonable first step.

The trip through Arizona has been wonderful! No serious heat...but RAIN in Kingman stopping us from going anywhere today unless it dries up a bit...

Fairweather Cobra Pilot - signing off...

Regards,

Dirk

kitcarbp · #6 (**permalink**) 06-16-2009, 12:19 PM

Hey Dirk, I think 1000 psi is still too high. What rack did you decide on and install? The Mustang II racks need 700-800 psi as I understand. If yours is rated for higher psi, its not a Mustang II type. You have at least two choices. Heidts can sell you an adjustable valve that you mount in-line permanently, this is a precise way to dial in exactly what assist you want for road "feel". The other option I PM'd you about is to use a shim kit on the GM pump HP valve, and reduce the pressure that way (I went this route). The down side is you may need to try different numbers of shims before you get the road feel just right, which means a few messy drain and fills of the system. The other downside is you'll build more heat in the PS system with excessive head pressure with the valve mod. Which means shorter component life without adding a PS cooler. The Heidt's solution has a by-pass line that sends excess fluid into return line to keep PS fluid temps down, thats their statement, but I have never tried it. Perhaps others who have done this can chime in here and tell us more pros/cons of the heidt solution.

read this link for details

http://www.heidts.com/pdf/art1.pdf

olddog · #7 (**permalink**) 06-16-2009, 07:27 PM

Doc I have about the same size front tires and power stearing in my Cobra. The stearing is a little too easy for my taste. Especially in an auto cross, but I could handle it well with one hand on wheel, rather than two. I have no issues of drifting around or not coming back to center. I can let go of the wheel after a turn and it will come back to center on its own.

It was in it when I bought the car so I cannot tell you exactly what it is. I think it is a Mustang power rack, and previous owner said he got a GM pump with the least pressure output he could find.

The alignment shop making the comments about the tires is not helping you at all. I think they are just trying to wipe their hands off and hope you go away. Just my opinion.

FWB · #8 (**permalink**) 06-16-2009, 07:36 PM

Quote:

Originally Posted by Jerry Clayton

more caster

absolutely jerry, more castor will give better wheel return, being this is vern's kit (he is a walking murphy's law) i am giving the alignment shop the benefit of the doubt. and knowing dirk would only take it to somewhere he trusted in the first place. the gm to mustang II has always been a touch and go stuation the first time around.

Michael C Henry · #9 (**permalink**) 06-16-2009, 07:48 PM

My car has a Sweet Mfg. 18/1 manual rack. It is a handfull in a parking garage. Driving isn't bad but slow is not that much fun. Kind a like going to the gym.

Tom Wells · #10 (**permalink**) 06-17-2009, 02:51 PM

Dirk,

I use a stock 15:1 1993 Mustang GT rack and a stock 1993 Mustang power steering pump. It works great! If you take it on the track, you definitely need a PS cooler too.

The steering is reasonably light at low speeds and very quick and responsive on the track at any speed. No hint of any quirky behavior.

If you're using the Saginaw pump instead of the Ford pump, the advice above seems spot-on!

Regards,

Tom