Firstfives.org

I was reading some threads on mye28 about power steering feel. It seems that a lot of effort has been spent by folks trying to tweak their cars with mixed results. The one constant appears to introducing some overpressure.

I have a ZF power steering pump from an E23 rated at 130 bar. The E12 pump is rated at 100 bar. That's about a 435 psi difference in pressure. That got me to thinking whether it would be possible to use the higher-pressure pump. Ever.

Has anyone been down this road before? A swap would entail all new hoses and seals but the internals of the steering box are the chief concern. My understanding is that the rated pressure of the pump is probably not drawn on except during a quick maneuver or if the steering is held at lock. My E12 at idle has heavy steering, which would be nice to improve, but not at the expense of dynamiting the steering box.

As an aside, I saw that the E28 (non-exchangeable) had a higher-pressure pump rated at 110 bar, and that there was a “handicapped version” of the steering box. Anyone know what that is?

Cheers,
Eric

If you've been thru the Mye28 threads on steering you have probably seen this one, https://www.mye28.com/viewtopic.php?t=145054 but I'll post it in case you haven't. Phil has spent a lot of time and money on steering (and the car itself for that matter) with little success on steering. I would pay particular attention to the engineering link Gadget posted a ways down, there seems to be some very good and hard to find tech info it in.

Yes, sir, that is exactly the thread I was reading. That linked article was very helpful. It looks like the pressure control valve would be circulating more fluid back to the inlet with the 130 bar pump than with a 100 bar pump. That _could_ have a negative effect, or maybe the pump wouldn't work as hard. It doesn't appear that it would have any positive effect on steering without a modification to the pressure control valve. On that thread, somebody (maybe Phil) added a washer as a shim under the control spring to increase the set pressure.