Michael Benno

I am curious to know about the pump compatibility between the 924, 944, 968, 928S4 models. They all look identical (the mounting braces are different and so are the pulleys) The only difference I can see is that there are different pressure ratings (different pressure relief valves). Most of the 924/944 pumps are rated at 100 Bar. My S4 pump is rated at 75bar.

I saw an old thread (https://rennlist.com/forums/928-foru...ing-pumps.html) that discussed the 928 started using the 100-bar pump beginning in 1991 along with some other changes including deleting the high pressure line restrictor.

I am wondering if I can swap out my 75-Bar pump with a 100-bar pump without chaining the hose and receive a benefit and not blow up my system.

Why, I need to source a replacement pump on my '88 S4. The pulley sheered off tanking one of the bolts with it and the spindle on the pump will need some expensive machine work or a replacement of the spindle. I am looking into my options. Used 924/944 pumps are cheap under $100 on eBay. 928 pumps are ridiculously expensive. As far as I can tell the only difference is the pressure release valve. I am considering buying a 944 pump for the spindle parts and rebuilding mine with that spindle. However, if the 100bar pump will work in my car and give more assist, I would consider that since I am running wider rims and a smaller steering wheel and could use a little more assist.

Thanks in advance

Ed Scherer

I'm probably not qualified to answer your questions authoritatively. However, I suggest you read the thread Power Steering - Converting to Higher Pressure System.