One last question that maybe I should have thought of sooner: I've got a
rebuilt rack, but I didn't pay much attention to the part number. The manuals
seem to say that replacement racks are longer end-to-end, and that the stops are
also different. I'm reusing my old stops (the original rubber ones). Are the old
stops the same thickness as the newer ones? Essentially, can I turn the wheel
from stop to stop without any issues? Or do I need to match the stops to
whatever rack I've got? Or is there even an issue if the rack was allowed to
move farther then normal?
'79 Euro 5speed
Any stops will work and any rack will work. I have an S4 rack on my 79 with
S4 stops. Works great. No noticeable loss of turning radius. The replacement tie
rods are now all later model ones so eventually you will be fully upgraded.
The racks are essentially interchangeable. They do require different stops. (BTDT!) The stops fit over the ends of the rack a bit and those are different between the models. (Later is bigger, IIRC.)
Swapping between P/Ns means the toe alignment will be messed up. As the later rack is a bit longer.
1) You need stops, especially if you are using a wider tire. If mama 'P'
did not think steering stops were needed they would not be there.
2) There are 4 different racks for the 928 as follows; two versions of the -22 or "B" suffix found typically through about 1981, one version of the -24 or "C" suffix found through 1990, and one version of the -26 or "D" suffix from 1991 through the last production unit.
Neither one is superior over the other in terms for performance (all have same ratios and feedback). Though you can use either version for any car, if you are buying a remanufactured rack the remanufacturer typically prefers that you buy the same model for your year car.
3) The two versions of the B rack shaft are the same length, approximately 795mm end to end. The C and D are the same length, approximately 810mm end to end.
4) The early version of the B rack had a 25 mm minor OD on the RH side and a 26 major OD on the LH side. In order to allow air to move through the rack as the boots compressed on full turns, the early version B had plastic tube running between the two castings. The early B rack used a two piece stop consisting of PN's 92834732900 and 92834733100.
The early steering stop was a stamped two piece washer with rubber vulcanized between.
The rubber breaks down over time and the washer splits away.
5) The second version of the B rack had a 23 mm minor OD on the RH side and a 26 major OD on the LH side. The external breather tube was deleted as they redesigned the rack shaft to be a hollow shaft allowing air to move between the boot ends in the same manner. The second version used the same two piece stop consisting of PN's 92834732900 and 92834733100
6) The C and D versions have the same size minor OD's on both ends, which is 23 mm. Both the C and D versions used a single piece steering stop part number 92834732904. This steering stop was originally a stamped two piece washer with rubber vulcanized between. In later production is was changed to a solid aluminum design with an o-ring inserted inside.
7) Installing the universal over the input shaft spline "may" normally require a little spreading of the universal; the universal is split and the bolt and nut assembly inserted through it compresses the bore.
8) When you are R&Ring a 928 rack and you find the "center" of the rack is off because the input shaft is not set in the rack as your previous unit,
this is normal. I can take fifty 928 racks out of cars that have the original racks, align the center spot of the shaft through inspection plug on the bottom, and the flat location on the input shaft will not be in the same location for all 50 racks (you will see a triangle cast into the top cap on the pinion where you can not alignment). That is the way they assembled them.
After reman'ing nearly 2000 of these units .... well,
you get to know them very well. Alignment or centering of the steering
wheel during the front end alignment procedure is accomplished by removing the
steering wheel and re-centering it.