My 300SD has what appears to be a bad steering gearbox (tight steering even after several rounds of loosening of the allen nut, also won't return wheel to center after corners). I happen to have a W123 box. How bad an idea is it to swap the two? Has anybody done this? The reason why I would like to do this is that I know I will have a pretty hard time finding one from a W126. So - how different are those two? Different number of turns lock-to-lock or...?

Thanks in advance for any helpful comments!

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1983 300SD, 1999 200 cdi and 1998 1,6 (gasser)

If the part numbers are the same, it should work.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D

Sorry, forgot to mention that the part numbers on the gearboxes are not the same (but don't have the #s on me at the moment).

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1983 300SD, 1999 200 cdi and 1998 1,6 (gasser)

I have compared (side-by-side-, out of the car) a W116 box to a W123 box and, as far as I can tell, the boxes are the same. However, the attached pittman arm is different, as I would suspect that is the case on the W126 vs W123. So, if the boxes physically look the same, I think you can pull the arms off and use your W126 arm.

Also, if you are LOOSENING the nut, you are TIGHTENING the steering ( sounds counterintuitive, I know- check the manual). If you tighten the nut , you will put play back in the system and it should center. Is your problem "operator error"?

Rick

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80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)

Did you just get this car or have you had it for a long time? Did it happen suddenly or what?

I remember after I changed my tie-rods, the alignment was incredibly off, so the steering wouldn't return to center and the tires would squeal going in a straight line.

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1985 CA 300D Turbo , 213K mi

The story is that I got the car a bit over a year ago and the steering was quite loose (sloppy kind of loose). Not knowing what the PO had done (or not done), I went ahead and adjusted the steering tighter (by turning the allen nut out) being careful not to over do it, in par with warnings that I've read on this site The truth of the matter is that the steering on this car never felt what I thought it should be. Part of the problem definitely has been other parts of the suspension which I am in the process of replacing (the next thing was going to be rear subframe mounts) - also the tires I had on this car until now were on their last leg, so that also contributed to the not-as-good-as- possible steering feel.
So steering feel was 'okay' after the initial adjustment, until, recently I purchased a new set of tires. This was a major improvement in many ways including the steering feel. Well, it didn't take more than a week or so after the tires were installed that I started noticing something weird in the steering. It kind of crept in slowly - the center position started to feel 'sticky' at highway speeds. First I thought it was just the tires getting worn in and what not, but when the stickiness got worse I decided to ease the steering box adjustment. Now, I have the allen nut screwed all the way in and the steering is still tight... Short from saying that the new tires broke my steering gearbox, perhaps they were 'what broke the camel's back' of a gearbox that was getting close to letting go. Then again, I am not convinced that it is the box...but what else could it be? Tie rod ends are renewed and the front has been alligned within less than a year. There are certainly other parts to be replaced in front but they are not that bad at the moment.

I do have a related question - I recall reading somewhere how much the allen nut ought to be sticking out (the service limit for it) but now I don't know where that article/information is? Does anybody happen to know that measurement.

Anyhow, it was good to hear from somebody else the confirmation that W123/W126 boxes seem similar enough so that the swap is worth a try. Thanks...

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1983 300SD, 1999 200 cdi and 1998 1,6 (gasser)

On my rebuilt unit from maval - you can see in post number 2 pic number 3 the part numbers - looks like there is at least one 123 part on that steering box!

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~shell
As of 2/2010:
2001 CLK55 0o\=*=/o0
13.6 @ 106mph
10K mi
1984 300SD
260K mi and going and going...
97 S600
46K miles
1991 Sentra SE-R (extremely dorked with)
www.se-r.net

Did the 123 box go into your 126 ok?

yes - been running it for a couple of years now

Pics of Steering Box Swap

http://www.peachparts.com/shopforum/attachments/diesel-discussion/22007d1100448634-pics-steering-box-swap-numbers.jpg

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~shell
As of 2/2010:
2001 CLK55 0o\=*=/o0
13.6 @ 106mph
10K mi
1984 300SD
260K mi and going and going...
97 S600
46K miles
1991 Sentra SE-R (extremely dorked with)
www.se-r.net

So I'll pitch this question into the steering discussion. Does anyone know of a source for gears and bearings for doing a full rebuild of a steering box? Does anyone know if a $400 "rebuild" box has new gears, or just new seals.
Thanks
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