Topic: Why would my clutch be rubbing on my clutch cover?

[coma13]

Any clues on this? The other day I was riding and heard a loud "kLUNK" followed by intermittent gear grinding noise that became constant when shifted into neutral. I pulled my clutch cover off and found this. (see photos).

I had my clutch cable tension adjusted to the max at the perch and clutch cover and when I removed the outer cover I noted that there was slop in the clutch actuator arm and I could rotate it back and forth (rolling the balls in and out f their detents) by hand.

I pulled the clutch cover off a while back to powder coat it and I have put a hundred or so miles on it since then until this most recent incident.

[coma13]

To clarify, in case it isn't clear, the first picture is wear on the inner edge of the clutch basket, the second is the corresponding worn down part of the clutch cover, and the third is a small ring of wear on the back of the plate that attaches to the actuator arm that appears to correspond to the inner bearing race at the center of the clutch.

[MoMo]

It looks like the clutch basket is loose.  Can you grab the clutch basket and see if there is free play side to side?...Larry

[coma13]

It looks like the clutch basket is loose.  Can you grab the clutch basket and see if there is free play side to side?...Larry

Reaching around the sides of the basket with my fingers on the outside of the plates I can get about 1/16" play in and out in relationship to the inside of the basket, but the basket itself appears solid.

[coma13]

I still haven't dropped the oil pan, which I should probably do and see if there is something sitting in there that ought not be.

[madmtnmotors]

What bike are we talkin' about? I know the later 750's (77-78, and all the F's I think) use a thicker clutch pack. I had an issue similar to what you have with my CB750K8 when I swapped out an earlier clutch cover (because it was chrome and looked purty). The earlier covers have a deeper screw boss (the one that is ground down in your photo) where the outer tin cover screw is (the one closest to the kicker), that is deep enough to contact the clutch hub where yours is gouged. Mine was actually "pinned" in place after reassembly and would not budge. I had to take the cover back off, compare the two covers, along with the gouges on the clutch hub I was able to determine that this deeper screw boss on the earlier cover was too deep for the later model clutch. I cut away about a 1/4" from this screw boss to eliminate the interference, but learned that this cover is not a direct replacement without this modification. It looks to me as though a P.O. may have put an earlier cover on a later engine, or updated an earlier engine with a later model (thicker) clutch pack and forced the interference until it ground itself away. What year/size engine are we talking about and how many disks does your clutch have (both steel and fiber)? You may have damage as a result of this interference which could include bearing damage (from the sound of it) and that clutch hub looks like it should also be replaced based on the depth of the gouge in the surface. This part of the clutch hub holds all the disks on the hub and has a fair amount of force being exerted upon it.

[coma13]

CB750K7. As far as I know, it is the original clutch cover, though it was chromed. (hmmmmm) I haven't pulled the clutch pack out yet.

The only thing is that I am pretty sure that this damage wasn't there when I took the cover off before.

[madmtnmotors]

Yep, the 750K7 has the thicker clutch pack and the damage you have is the exact interference I had with mine. Fortunately, the only thing I had done at the time was new friction disks along with the chrome cover. My engine would not even budge in this condition. After taking the cover back off, comparing covers, and seeing some scoring on the hub, I was able to correct the problem before it got to the extent yours has. If you are certain that none of this damage existed when you last had the cover off, then I would suspect too much endplay in the clutch assembly allowing it to reach out and "touch" the cover.

Keep us posted.

[coma13]

I am definitely second guessing myself now about the interference existing before, I am just curious as to what would have resulted in that nasty KLUNK and the subsequent grinding noise. The bearing visible from the outside of the clutch appears to spin freely without any indexed feeling or anything.

[madmtnmotors]

I am definitely second guessing myself now about the interference existing before, I am just curious as to what would have resulted in that nasty KLUNK and the subsequent grinding noise. The bearing visible from the outside of the clutch appears to spin freely without any indexed feeling or anything.

There could be a couple of things:
*The undue stress from the previous interference my have caused other problems, or....
*There could be another, totaly unrelated, problem.

I would recommend filing down the offending screw boss iside the clutch cover a little bit to eliminate a further interference (shouldn't need much, most of the interference has already been ground away). If you go too deep you could expose the threads from the outside. I think if this screw boss is flush with the outer edge (the gasket surface) of the clutch cover then you should be alright. I would also disassemble the clutch for inspection and start shopping for a new clutch hub. The grinding into neutral is symptomatic of the inherent poor oiling of the clutch as described in Hondaman's fix by drilling more oil holes in the clutch hub. You might drop the oil pan and look for some of the shavings from the hub, along with a new oil filter too. Slop in the actuatur arm could be a result of loose adjustment of the secondary clutch adjustment which would also contribute to grinding into neutral. There are two clutch adjustments, one at the hub, and one at the cable. After inspecting the clutch and changing the oil you might try putting it back together (if everthing seems to look okay), make sure both clutch adjustments are properly made, and see if the problem persists.

Keep us posted.

[mrrch]

Silly question, are you using a gasket for the clutch cover?

[scottly]

Did the nut that locks down the clutch center come loose?

[coma13]

Yes, using a gasket.

Which nut are you talking about, Scottly?

[scottly]

The nut that takes the special socket, under the lifter plate. Part number 13 in the exploded view of the clutch in my old Clymer's manual. Might be the same number in the fiche?

[scottly]

Scanned it: