Found Marks During Clutch Boss Inspection

This weekend I took my clutch apart on my XJ550 SECA as part of diagnoses I have been going through in tracking down a engine noise coming from that vicinity. I still have to do some careful inspection of the plates and take some measurements, but for the most part at least all the parts are there. I suspected the wave spring may have been missing and thereby accounting for the noise. But the spring was there. I did however notice these some marks on the clutch boss and was hoping someone with experience can give some opinions in this regard. To me, these marks seem like they should effect clutch plate movement and therefore function. However, the clutch seemed to have been operating pretty smoothly. I found three different areas on the boss, and are about equal degrees apart. What do you think could cause this?

 

Those aren't normal "wear" marks, but fortunately they aren't in an area that will necessarily be of concern once you smooth them out.

I would suspect somebody had the clutch boss spring in the wrong place; it has three ID "nubbies" on it which would account for the finding of three sets of similar marks.

Note the rest of the small polished spots on the hub; those are normal wear from the plates. Luckily, the damaged areas seem largely removed from where the real contact occurs.

If it were me, I'd replace the hub. However, that being said, if you were to smooth out those divots with a sharp, fine file and polish with a stone, you might get away with re-using it. Be sure the new clutch boss spring doesn't make contact in the same three areas (you might want to swap it and its special plate into the next friction plate position "in") and it should possibly be OK. If you smooth those gouges out, they really aren't where the plates ride.

 

Thanks Fitz, that is good news. I will definitely try what you suggested. I haven't inspected the plates, friction plates and spring yet. But I have left them in the order I took them out and will get to them soon. Do you think the clutch boss spring being in the wrong place would contribute to a noisy clutch?