300SD Loose Steering Adjustment problem solved!
 

I've made the steering box adjustment on my 240D to remove most of the play (loosen the 19mm locknut on the steering box and turn the allen CCW (UNSCREW) a quarter turn and try it).

When I bought Hans, one condition was that the PO get it Maryland state inspected - usually a huge pain and often expensive since it's only done once at the time of purchase and not yearly. The poor guy spent nearly a grand to have it pass, and one of the things it initially failed for was loose steering.

The indy shop tried to "fix" it and apparently knew the guy in the inspection shop well enough to get it to pass, despite the fact that it was actually worse to me after they "adjusted" it.

This weekend, I decided to see if I could take out some of the 2 or so inches of play. I turned the screw CCW a quarter turn and tried it - same. Did it again - same. Turned it a whole freakin turn - same. Hmm. Wandered over to Penelope, the wife's 1982 300SD (practically perfect in every way) and noticed the allen screw protruded about a half inch above the locknut. Hans, on the other hand had only a quarter inch protruding. Then it dawned on me - the idiots at the indy shop TIGHTENED the allen thinking that was tightening the steering. It seemed strange that when I turned the allen that I felt no resistance, like nothing was happening. So, I turned the allen TWO more full turns CCW to match roughly what Penelope had and drove it. Voila! - tight steering! I checked to make sure the steering didn't bind on hard-over turns and still wanted to center - no problem. The steering has only a small amount of play and I'm not adjusting any more since I don't want to get into binding it, but what a difference!

I don't recommend adjusting the screw this much, and there's lots of sky-is-falling warnings on the web about what will happen, but it could be that someone tried to adjust your steering by tightening the allen (common instruction by some know-it-alls on the web). In my case I had little left to loose since I was going to have to buy a new box anyway (I wondered if a rebuild would actually fix the looseness. I got this email from one source that I will reveal if anyone wants to email me so as not to step on anyone's toes - the price is about $325):


"All of our parts are fully remanufactured in house by our own builders. All wear parts (bearings, bushings, and seals) are fully replaced with Mercedes parts, and all other parts are either inspected or replaced as necessary. It is then pressure tested on a hydraulic simulator to assure no leaking, binding, or other problems. It is covered by a 3 year part warranty, so if you have any problems at all you can call us up and we can send a replacement._

Excessive play is a common problem with older Mercedes steering gear boxes, and a remanufactured box will definitely take care of that problem."



_

good post, it's good for you to point out as this I for one would have assumed the adjustment screw went the other way. However, I would have consulted my FSM and discovered otherwise but not everyone has one, and so your post sheds some light. Thanks

not too tight
 

Ten...

I've not adjusted a MB steering box, but plenty of domestics. The caution is the steering gear wears more in the center, less at the extremes. So if you adjust it to be tight on center it may stick at the extremes. Adjust, test to the turning limits and make sure it is safe.

Chuck

not too tight is right, although some of these (mine anyway) are tightest slightly off center from either side. The FSM has a nice torque-displacement graph depicting the spec

My 300d w/156K centers at 11am on the steering wheel. In other words, if I attempt to drive straight, I have to hold the wheel at 11am. If I center it, it goes off to the right...

Is there a simple repair for this, like tightening the box??

Where is the steering box located? I think I might try it. I have too much play.
-Joe

fj - IF the car is aligned and drives straight when you take your hands off the wheel (with it at the 11 o'clock position) AND the blinkers work properly then you can remove the allen head fastener holding the steering wheel and reposition the wheel to center it. The right way to do it is to have someone align it that knows what they are doing but you can do it this way if you get in a bind with it. Adjusting the steering box will not correct this issue.

engatwork: thanks!! I was getting ready to have the car aligned as the inside of my P400's are wearing unevenely. Guess I will try to do both.

If you are fixing to get an alignment just make sure the shop knows about the centering pin, which centers the wheel straight while the tires are dialed into spec.