From digest.v7.n836 Sun Dec 28 02:10:17 1997
From: "Edwards, Scott" <Scott.Edwards_at_Compaq.com>
Date: Sat, 27 Dec 1997 23:28:32 -0600
Subject: <E28> How to rebuild your P/S box

I had previously inquired about the factory rebuild kits, and receiving no reply went ahead and did it. You need to go to the dealer and order a "repair kit" (32 13 1 126 887) for the P/S box. This kit is for all E28's and lists for $118.22 (figure your discount). When I got it in (ordered) I was shocked to find that it is a small bag with the following contents: 15 O-rings, 3 radial seals, 8 seals, and two plastic caps. I then had to remind myself that I don't drive a BMW to save money. I also ordered the "set mounting parts" (32 13 1 126 655) listed as "in conjunction with" on the fiche and it lists for $47.73. I don't know that you need this as it contains: 3 bolts (replacements in case you need one to replace a bad bolt), several washers, both external lock nuts for the adjustments on the box, 2 plastic dust caps for removing the box, a new thrust washer for the rebuild, a new bleed screw (on top of the box - what is this for?), and a nifty new plate to rivet onto the box to show you've rebuilt it. I also took the opportunity to rebuild my P/S pump and ordered the kit for it (32 41 1 135 880) which lists for $33.78. This kit should be for all E28 pumps from 83-88.

The parts are expensive, but it is much cheaper than a new box or a rebuilt one, and you know it was done right.

P/S pump - My pump was the original '84 and didn't leak, but I figured it wasn't pumping up to spec. It can be removed and rebuilt in 2-3 hours. Nothing fancy - the removal is harder than the rebuild. My original seal was totally worn down and the new one definitely made a difference.

P/S Box - Again, I had the original '84 box (label on outside with date on it) and no obvious signs of ever having been rebuilt which has 172,000 miles on it and a huge amount of slack, numbness, you name it. The parts bag is fairly intimidating, but if you go through the manual several times before beginning, it's not too bad. Removing the box is a pain, and I hate to disappoint you, but I'm not going to spell out the procedure here. I followed the factory manual I have on fiche and would suggest that you get the manual, fiche or paper. It is pretty clear and easy to follow, with these additions.

• - You have to remove the front crossmember, per Bentley, to remove the box from below.
• - When replacing the seals on the piston (there are 4, 3 large, 1 small) it asks you to replace the 4 seals and o-rings underneath. The kit doesn't have an o-ring for the small seal and my original seal didn't have one under it, so I didn't use one there.
• - The kit has one green seal and looking at the factory manual (black & white pictures) it looks like it should go in the position nearest to the small seal on the piston.
• - When I was done I had a large white seal left over! I triple checked and the manual and the parts didn't indicate anywhere one should have gone. I can only assume that the kits are carefully inspected and that I received all the parts I needed (or an extra?).

My box had no noticeable wear on any of the internal components. I also found out what that "other" adjustment at the end of the box (opposite the steering input shaft) is for. It is for adjusting the right hand turn stop point. The left point is the end of the worm/piston travel and the adjustment is simply to make the right end point equal to the left point so that the steering wheel travels equal distances left and right. This is based on my observation of the inner workings, but I can't imagine it could be for anything more. The box rebuild should take a full day for removal, rebuilding, and reinstallation.

The rebuild was a huge success! Only one leak (I didn't tighten the friction point adjustment locknut enough) and the change is astounding. No dead spot at center, much more power assist, more road feel - it's a different car now. I also took the opportunity to change to Redline ATF in the P/S system. I'll let you know how that goes.

If you've got a bad box, $150 bones, and a day, go ahead and rebuild it yourself! It's not that hard and is actually quite satisfying. Also, kudos to Autozone for the free tool rental - yes, FREE. I dropped in and rented a Pitman arm puller and a ball joint puller (my Bavarian Autosport tie rod puller is too small to pop the ball joint off the Pitman arm. Both worked beautifully for this project.

Learning how to steer again,
Scott

ps - email if you've got questions. I'll be happy to expound on anything.