Rumbling with clutch lever pulled in

[toucheturtle]

My CB500 doesn't get a lot of use but I fire it up weekly and let it run for half a hour. The clutch plates tend to stick to one another and I have to rev it and stand on the rear brake to free them. I did that last week but noticed afterwards a rumbling sound when I held the clutch lever in.
I've taken the outer clutch cover off and noticed rubbing on the raised boss on the inside of the cover (I have photographed it). It looks to have been rubbed by the clutch plate cover. Everything seems tight, there is a little bit of in/out movement in the clutch basket but I don't think it is exessive (1mm).
I'm just wondering if I've damaged anything?

[Bryanj]

 1mm is at least 10 times too much!!

[toucheturtle]

Oh dear I don't like the sound of that, it's the clutch outer drum with the in/out movement, the centre & plates and cover have no movement. The outer drum is only held on by a circling so not sure how I would eliviate it or why there would only be movement on the outer

[Seabeowner]

The are listed by CMSNL and special order from DSS, 0.1 (90458-323-010), 0.3 and 0.5. Never seen one that wanted more than 0.2mm. And if the fault has suddenly developed, it is worrying and probably needs further dismantling to see if the circlip is in place correctly.

https://www.cmsnl.com/honda-cb500k1-four-england_model14660/spacer-01mm_90458323010/#.WQHs8NIrLtR

[toucheturtle]

I have taken the basket off, the shaft has 1mm of movement, I had the manual out and did notice the 3 different sized shins. Mine has a .2mm fitted, managed to source a.5mm from PlenterNZ. £11.50 including air mail. Will try that and see how much play remains. Wish I could stop the clutch plates from sticking together in future.

[Bryanj]

The shaft should have zero movement, there is something wrong inside, srry but you are going to have to split the cases and inspect

[toucheturtle]

That is so annoying, the engine is spot on and the gearbox works perfectly. I can adjust the clutch so it doesn't rub but if the end float is excessive I'll have to get it sorted. If the damage was caused by trying to free sticking clutch plates I don't know how I'm going to prevent it happening again

[royhall]

Yep that sounds like a failed gearbox bearing. Full strip down required, sorry.

[mike the bike]

How about a missing thrust washer that fits behind the clutch basket?   That's probably there to take up the end float so if thats missing...

[Bryanj]

Don't remember there being a thrust washer, only thing I can think of is the half ring missing that holds the bearing in place as the bearing is a press fit on the shaft

[mike the bike]

I'm just thinking of the 400 here, its a long time since I stripped a 550.  Best check the parts list.

[toucheturtle]

Well fearing the worst I ordered new bearings, the needle bearing had to come from America as they're pretty hard to get now. I bought a NOS mainshaft as well for £50 also from America. That shaft is the only part of the engine and gearbox which hasn't been replaced in the past so thought I'd go the whole hog.
While waiting for the the stuff to come the shim arrived from New Zealand, I thought I'd just try it with a new circlip. I put on and built up the clutch plates and fitted new clutch springs. There's absolutely no movement, I thought I'd replace the clutch cover and fill it with oil. I've run it and there's no rubbing and the gears and clutch work fine.
The steel plates were a bit grubby and the clutch plates were facing the wrong way. I've cleaned everything but don't know how I'm going to prevent the plates from sticking together in future. I read someone recommended pulling the clutch lever in and securing it in that position.

[hairygit]

Not a good idea, the springs are only meant to be compressed momentarily while pulling away/changing gear/waiting at junctions etc. To keep the lever pulled in for any period of time will weaken the springs, leading to clutch slip under power and that in turn will rapidly wear the clutch plates.