Play in steering coupling

[Earlybird]

When the steering coupling in my 1985 380sl came loose, I tightened it up. It is loose again 2 days later. Does anyone know what is wearing out here? Is the coupling splined to the shafts or is it keyed or scalloped keyed in place by the clamp bolts? I just wonder which part gets the wear. I would hate to buy a coupling and find that the steering column shaft was the root cause.

[Strife]

Frightening! Both sides of the coupling are splined. Something is clearly wrong - I read on another board where a bent steering column shaft (surprisingly thin and delicate) can be bent by carelessness during steering box installation. This causes the coupling to become loose fairly quickly. The person that this happened to was very fortunate not to get into an accident!!!

Obviously, I would not drive this car until the root cause was found.

[Richard Wooldridge]

Hi there,
Keep in mind that the steering coupling itself wears out and develops play internally. What happens is that the flexible plastic, or rubber, or whatever it is, goes bad and starts falling out. This happened to me, the only fix is to replace the steering coupling. The spline on the steering gear end has many splines, 20 or so, and the top is actually a flatted piece, only goes two ways. There are several threads on replacing this coupling. The easiest way is to do it from inside the car- raise the boot covering the spline, lift the steering shaft a bit, and the coupling comes out fairly easily. You could also inspect it from this location.
To check the coupling for internal failure, have someone very gently turn the wheel through the play part of the motion, and look to see if the play is "inside" the coupler.