Someone asked the other day about a problem he was having with his Mustang II rack blowing out seals. He was running a GM pump and a Mustang II IFS power steering rack unit just like everyone else and wasn't sure why he was having the problem or what was causing it.

To begin with the GM pump puts out too much pressure for the Mustang rack. GM power steering pumps operate between 1000 and 1200 psi. Mustang II power racks were only designed to operate between 700 and 800 psi. This difference in pressure requirements can and does cause a couple problems.

First is a very "touchy" feel to the steering at highway speeds. This makes any vehicle a pain to drive for long periods since you can't really relax while driving. You have to pretty much be on top of the car at all times. The second problem is blowing out seals in the Mustang rack. You don't want to see power steering fluid puddling under your car in the driveway but it can and often does happen with this combination.

When he contacted the company that made his Mustang II kit, one of the guys there told him to just "cut" the pressure spring in the back of the pump. This is NOT the right way to lower the pressure of a GM pump. If you cut the spring it's like shooting in the dark. You never know what pressure you'll wind up with because a little taken off the spring can make a lot of difference in the pressure output of the pump. If you cut too much you could wind up with such low pressure it would be like driving with a manual rack. So, how do you correctly solve this problem?

The solution to all this is of course to lower the pressure of the GM pump and there are basically two ways to correctly do this. One is to purchase an Adjustable Power Steering Valve from someone like Heidts . They go for about $125 with all the fittings you'll need and basically mount in the high pressure line and allow you to dial the pressure you want. This method works well but for some people it can be a bit pricey.

The second solution, and the one I recommend, is to pick up a GM Power Steering Pump Flow Valve kit from Borgeson. With this kit you can easily adjust the line pressure in a GM pump to make it compatible with the Mustang II rack. The kit includes simple instructions, shims, and all the parts you'll need to do the job including a tool to hold unit in a vice while installing shims. If you are interested, take a look at page 11 of the Borgeson catalog (there's no picture but that's where its listed). The kit costs less than $30 and takes about 15 minutes to install. Best of all, it reduces the pressure the at the pump and no "add on" in line valve is required so there are less fittings to leak.

So if your Mustang II power steering is making your ride feel a bit skidish on the highway or you're rack is leaking all over your driveway, you now know a couple ways to properly solve the problem.

Centerline

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Centerline
HotRodsAndHemis.com

"Political Correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."

Wow....you're reading my mind. I am in the process of installing a Mustang II rack in my 48 Chevy p/u. I was planning on using the pump that came on the 350 SBC I have. My question would be....are all Chevy pumps putting out that much pressure, and if not, how can I find out what the pressure is given a certain year? Or...do all MII racks only handle 800 psi? thanks

I think they all put out at least 1000psi. In fact some of the pumps in trucks and vans can be up to 1500psi.

This is an intresting thread on trying to get MORE pressure from a pump.
http://westtexasoffroad.homestead.c...ersteering.html

Some of the guys that have done what is in the above link have broken steering boxes and pumps in half from the pressure!

Borgeson is the way to go fast and easy, works great. No change to hose or set up, instructions straight forward and the price is right. Zeke

any chance of doing the install with the p/s pump intalled in the vehicle. If I have access to the fitting on the back side can I do it with out removing the pump. thanks ed ke6bnl

I have been running the GM pumps with stock/rebuilt power racks since 1990 and have had one failure. I did get the pressure reduction kit for my pick up when it I reworked it and am glad that I did. It sure did reduce the noise level, but other than that, I can't tell any difference between it and my coupe which has not been reduced. You can bet I will reduce it when I have to go into the pump or the rack in the future.

Trees

You can do it provided you have enough room to remove the union from the back. That has to be held in a vice using the supplied tool in the Borgeson kit in order to remove the nut and install the shims.

Centerline

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Centerline
HotRodsAndHemis.com

"Political Correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."

Just went to Borgeson's website but couldn't find the flow valve kit mentioned. Ordered their catalog and will see if I can find it in there.

Thanks CENTERLINE for advice, right after your response I was checking the installation of the pr. valve reducer and noticed the pump retaining bolt was sheared off. Had to weld a nut to the left over portion and screwed it out. I also went to the Borgeson site and the there is no part number but only a reference to the need of the pressure reducing valve in the p/s tech. information. I called them and the part number is 899001 and sells for $16.00 plus shipping. Summit will get it for you but they want $19.00 pluse $9.00 handleing. Borgeson will sell it to you direct and I ordered it. It is a heck of job to get it out and hope I do not have to make several attempts to get the correct pressure. Good luck Ed ke6bnl

Hi, I have a Mustang power rack with a remote GM power streering pump. I used the pressure reducing valve from RBs, you just open up the pressure line on the back of the pump, and take out the old valve and put in the new one. I think the price was around $30, but it works fine,
rock

Do i need to get spcial lines from the MII power rack to the GM pump, or do they all have the same fittings on the end?

I had Napa make up the lines, tel them what the end are and how long and how they are to be oriented (Sp) and they worked fine www.gottashow.com has them made up in braided line for more then twice the price maybe under $200. verses about 60dollars.Ed ke6bnl

The Mustang II rack has different fittings than a GM unit so you'll have to do one of two things. Either have lines custom made as has been indicated or you can purchase ready made lines. I purchased mine from Borgeson at a cost of $59.

Centerline

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HotRodsAndHemis.com

"Political Correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."

That is a great price I spent more then that for my Napa fittings but I was limited in space and had no room for ANY excess of the pressure line, the return is just power steer low pressure hose. I just got the ups shipment for the shim kit from Borgeson and it was an easy job while the pump was out and took only about 15 min. I miked the new spacers verses the old washer spacer set up and the old had two washer spacers for .037 in while the new called for 3 at .021 ea. I estimate from there literature I went from 1150psi to 1000 psi. will see tomarrow when I install the pump how it all works. Ed ke6bnl

The Mustang racks seem to work best around 800#. Then they aren't as sensitive going on long freeway drives. I use the shim and RB's valves but also hook up my pressure gauge that I also use on brake problems (pulls). When the gauge is hooked it is in-line so has a return to pump with a shut off valve in-line to really load the pump. Get Max and by-pass pressures. Max should be 800#.