I have tightened up a lot of my 300D steering with upper control arms, tie rods, idler arm repair, etc. I did a complete front end rebuild as well as a rear rebuild

The only remaining problems is a manageable wander at highway speeds, about +/- 1.5" of play and the fact that I have to hold the wheel at 15 degrees to the right to go in a straight line .

I noticed that the steering coupling has a hairline crack all the way through from one edge to the center on one side and another crack just starting on the adjacent side of the coupling. The rubber is very hard, but not dissolving, and appears intact.

Does anyone think that I will gain $60 (partshop price with shipping) worth of benefit from replacing it?

Overall, it seems like my steering is pretty good, though not the same as the first day it was driven. I am not super enthusiastic about adjusting the steering box at this point.

I would, just for the peace of mind. I haven't heard of one coming apart, but I can imagine it would be a hairy day if it did.

If you have a pull to one side you have an alignment problem unless you are driving on a road with lots of camber. An inch and a half play is excessive too. Have you tried adjusting your steering box?

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

+1 for steering box. I just rebuilt my front-end with quality parts and was disappointed by how loose the steering still was.
Adjusted the box a little at a time, and now the steering is excellent.
It still follows the profile of the road a little, but not too bad.

Add checking the rear subframe mounts to the list, especially if it feels like it is steering/drifting from the rear on the highway.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

No, it isn't worth it to replace the steering coupler. I've got a box full of them because they just don't go bad.

If you're concerned that yours is going to fail, then you've got to be able to see the braided cord underneath the rubber and its coming to pieces. These things are unbelievably durable and (take my word for it) hard to cut through.

If the steering box only has a bit of play in the center position (what it sounds like), then you're fine. You're probably well within spec and I wouldn't bother with adjusting it. PM me if you want to go into the rabbit hole on this stuff.

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Onus probandi incumbit ei qui dicit, non ei qui negat

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 147k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]

Interesting... mines has a hairline crack all the way from the top and bottom. It's pretty concerning. I saw your website on your signature you rebuild steering boxes which is pretty cool. I'm going to take your word for it. I can live with a little play

Yeah I've tried unfortunately it didnt really make whole lot of a difference.

Rear subframe bushings are 4 weeks old. Didnt see a difference

Do you have the alignment specs to post? Tires are correct size/profile and aired toward the high side of spec between door placard and max tire pressure?

About adjusting the steering box, remember to do it in small recorded increments and you could go back to the starting point.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

After rebuilding the compete front end and subframe bushings. I took the car for an aligment. here are the results

https://i.ibb.co/f8MWjRy/20200513-144247.jpg

Although the toe is within the range of specification, more toe-in toward the max side of spec may help. Current specs favor the minimal side of toe-in @ 0.17-0.18. I believe 0.29° is the max.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

PM me and I'll send you one.

Imbedded in the rubber is a circle of fibers, so even if all the rubber comes apart the coupler still has enough structure to stay together. I've had to cut through a number of them and they are a PITA.

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Onus probandi incumbit ei qui dicit, non ei qui negat

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 147k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]

Quick FYI: URO Parts recently updated the design of our Steering Coupling 115 460 0510.

Mercedes' engineers originally designed Steering Coupling 115 460 0510 with a feature that locks the coupling to the gearbox and steering shafts, even if the pinch bolts become loose. The pinch bolts pass through a groove near the end of the shafts, which requires the bolts to be completely removed before the shafts can be removed from the coupling. In the past, aftermarket reproductions of this coupling positioned the pinch bolts outside of the grooves in the shafts, accidentally omitting the interlock function.

URO engineers redesigned our coupling to provide the interlock function on both ends of the coupling, making the current URO Parts coupling functionally equivalent to the OEM coupling. Pelican offers our updated coupling 1154600510 here: https://www.pelicanparts.com/More_Info/1154600510.htm?pn=115-460-05-10-M253&fs=0

See Cwmoser's videos showing how the interlock works:
URO Steering Coupler - on the Steering Wheel Shaft
URO Steering Coupler - on the Steering Gearbox

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URO Parts online catalog: https://apaindustries.com/catalog