This is the diagram of a BMW ZF-rack. Very similar. ZF Rack BMW.pdf
And one for a Volvo: Steering Rack and pump Volvo.pdf
If you're considering what it takes to fix
your Porsche power steering then this is a good place to start. Its a very
good idea that you do some research because this little job is easily and
often underestimated. I know this because I've made every mistake possible
and am therefore somewhat qualified to warn you of the many pitfalls. The
information on this page is NOT complete - I do not have re-assembly
instructions. Those would require many more hours of work than I have to
offer. Still, you can get a good idea of what is involved by reading through
the disassembly areas that I have here.
At the outset, I should tell you that resealing a rack will be somewhere between moderately difficult and I'm-so-pissed-at-this-I'll-just-get-rid-of-the-car. I'm tempted to tell you it is sooo easy and that all you need is a little determination but I'm afraid this casual confidence will get a few of you in over your head and if that happens you'll be looking to lure me into a dark alley. Please review these "Ten Things to Know ... " before you begin stalking me.
====== Ten Things to Know before Attempting to Reseal Your Steering Rack =====
1) It is moderately difficult to get the rack out of the car and this provides potential for a fair amount of exasperation. Its even worse on the turbos. Even if things go very well, it will take over an hour just for removal. Another hour (plus) to get the rack re-installed. Expect to double this time if you haven't done it before. yes, there are people that can do if faster. Working fast doesn't work well for me though.
2) Unless you have a hydraulic test stand, you'll have to re-install the rack in order to test for leaks and to make sure the rack works. If problems arise, you may have to remove it a second time to correct. This sucketh greatly.
3) Its possible that once you get the rack apart, you will find that you need parts, part that are not included in your reseal kit. ZF, (a German company with a long name) makes the rack and pump for our cars. ZF will not deal with anyone other than Porsche dealers for mini-parts. This means that your source for parts is very limited. No, the popular reseal kits that are currently on the market do not include all of the little parts. Yes, extracting those parts is needed to do a reseal and yes, extraction often damages them.
4) The new seals are delicate and can be easily damaged during installation, ordering replacements will postpone re-assembly.
5) Some tools are needed, a clean place to work, a way to clean up the rack and parts, some sort of vice, and a variety of sockets, extensions and tools to replace the seals.
6) Some machine work is needed to polish the main shaft. If the main shaft is not defect free, your reseal will probably last about a month.
7) It is easy to make mistakes in inspecting/reassembling the rack. Mistakes cost time and money.
8) There is a chance that you will need to have the steering re-aligned after reinstalling the rack. There is a very good chance that your steering wheel will not be centered and will require an additional adjustment.
9) With so many law suits over the past few years, it is difficult to find people willing to refit hydraulic hoses. Any parts purchased from the dealer will be very expensive.
10) Steering racks are a relatively simple mechanism but one which relies on hydraulic pressure. Many "reseals" fail because problems with particulate contamination are not corrected. This is one reason that even "professionally rebuilt" racks are warranted for only 12 months.
Seal kit for a 928: