Jim Shea

Here is the history of power steering fluid. This paper has all you will ever want to know about power steering fluids.
http://jimshea.corvettefaq.com/?p=861

I can't speak on the truck fleet. They may have struck upon a combination of ATF and Lucas oil that works for them. I would still recommend genuine GM power steering fluid.

Jim

Lil" Red Corvette

Thanks Jim, I'm going to buy some today. What is your recommendation about a good replacement pump for my car? Since I don't have the original pump anymore I'm thinking about having Lee's build one as close to original specs as possible and using a smaller pulley to get the RPM back close to original. I have a newer model serpentine system on the car and I did the math and it turns the pump about 200 RPM slower than the 75 setup did at idle.

Jim Shea

If you are going to have Tom Lee build you a power steering pump, make sure that you let him know that your serpentine drive system is turning your pump slower than a production C3 setup. Saginaw made different displacement power steering pumps by making the cam rings thicker and/or more rise in cam ring profiles. You want a higher displacement pump to compensate for the slower rate that your pump is turning.

I would think that Tom Lee will be familiar with pump displacements so as to be able to help you. I am quite sure that he has a machine to flow rate a pump before shipping it to you.

BTW, I continue to read more and more problems with "remanufactured" or rebuilt power steering pumps. I am getting to the point where I would recommend a Saginaw power steering pump out of a salvage yard before purchasing one that was remanufactured.
Jim

Lil" Red Corvette

I'm in the process of compensating for the serpentine system reduction in RPM by replacing the 6.45 inch pulley with a 5.2. The original 75 crank pulley was 7.75 with a 5.75 inch PS pulley (somebody please correct me if I have that wrong) the GM serpentine system is 7.50 and 6.45. The smaller pulley brings the RPM up to just a little more than the original set-up.

Do you know what the pump displacement was for the 75 pump? Which pump could I buy that has the same displacement? If I get the right displacement pump and use the correct flow control valve and pressure fitting would I pretty much have the correct pump for my car? I'm going to the local pick-a-part tomorrow and may just go ahead and get me a good core.

Lil" Red Corvette

I ended up putting a used pump from a 89 Firebird on my car and it works better than the two remans I've installed so far. I used a 5.5 inch pulley to bring the idle RPM up a little. I didn't even take the pressure fitting off. I used the flow control valve and pressure fitting from the 89 Firebird and a high pressure hose from a 1980 model (metric). This was supposed to be just a temp fix until I get the right spec pump but it is working pretty good.