Worn spindle?
 

I am rebuilding the front end of my 72 SL After taking the rotors off I found a grove in the spindle that I can catch a nail on. Time to replace?

Which direction is the groove? Transverse? Some axle spindles have a groove to retain grease, but I don't know if 72 sl's (or any MB's) do. I'm not sure how it would get grooved, though.

If the bearing race fits firmly without wobble, I wouldn't worry about it. The only surface of the spindle that is important are the two bearing race supports.

It is transverse, not scratched or galled very smooth about and inch wide, depth is even the entire way around.

Thanks Steve

Sounds like it is supposed to be there to me. Steve is right (not that any doubt would exist) and his reason is why I wondered how it would get that way on it's own.

A little follow up on Steve's explanation and this is just general bearing information for people that may not know. If you do not have a good bearing fit (or you lose oil flow to a bearing) there is a chance that the bearing can actually spin on the shaft that it is fitted on. This will destroy a bearing and shaft in very short order. In industrial type applications the bearing is the cheap part:( to repair. I have seen it a couple/few times over the course of my career.