Clutch Release Clunk

[tgsguitar]

The clutch in my 85 Interstate works fine when upshifting and downshifting, but
when I practice slow riding using the clutch in the friction zone it often will
suddenly release with a bang ( I guess really it's fully engaging but with quite
a clunk, but it's when I'm still trying to hold it in the friction zone and I haven't
fully released the clutch lever. )

It's as if whatever it is that holds it in the friction zone suddenly can't hold it
there anymore and it engages with great gusto.

Whenit does engage it feels as if a five pound item just banged into place with
a shudder from the engine to the rear wheel.

In my non mechanical mind it feels as if the whole clutch assembly is restrained
by a spring or something that suddenly gets overwhelmed by the weight and pressure
of the clutch basket assembly and it releases and suddenly bangs into something.

I had the clutch plates replaced a couple of years ago.

Any ideas what causes this ? BTW the clutch has been bled.

I appreciate any feedback or suggestions !

JimC

[bs175dths]

When upshifting or down shifting, the clutch lever is closed and released in rapid succession.
When holding the friction point, pressure at the clutch master cylinder is held longer than when shifting up or down.
The clutch master cylinder may not be able to hold the pressure of the friction point, but appears to operate fine when shifting.
The clutch master cylinder may need a rebuild.

Just so these can be eliminated as possible problem areas:
Remove the slave cylinder from the back of the engine (3X 10mm I believe) and see if there is any fluid leaking from the seal.
Remove the clutch lifter rod and inspect it. Make sure it is clean and does not have any junk built up.
The clutch doesn’t have a whole lot of springs in there which would suddenly stop pushing back against the hydraulic pressure of the clutch fluid (DOT 4 Brake fluid), so it is not likely a fatigued spring.

While looking for the source of the ‘clunk’, check out the drive train:
With the bike on the center stand, in any gear, engine not running (HAD to add that point), grab the rear wheel and see how much it will rotate before meeting resistance.
Does it ‘clunk’ when it does meet resistance?
The ‘clunk’ may be the teeth of the final drive gear or the teeth of the final drive flange have worn and have some play.

Good Luck!

-Ride On

[ember1205]

Does this clutch have the dog ears inside that hold the friction plates like on the VFRs? I know that when those get rough from use, they will cause a variety of odd behaviors in the clutch, including a heavy vibration when releasing the clutch from a stop under hard throttle. The fix on those is to pull the cover and remove the friction plates then use a file to clean up the rough edges of the basket.

[tgsguitar]

When upshifting or down shifting, the clutch lever is closed and released in rapid succession.
When holding the friction point, pressure at the clutch master cylinder is held longer than when shifting up or down.
The clutch master cylinder may not be able to hold the pressure of the friction point, but appears to operate fine when shifting.
The clutch master cylinder may need a rebuild.

Just so these can be eliminated as possible problem areas:
Remove the slave cylinder from the back of the engine (3X 10mm I believe) and see if there is any fluid leaking from the seal.
Remove the clutch lifter rod and inspect it. Make sure it is clean and does not have any junk built up.
The clutch doesn’t have a whole lot of springs in there which would suddenly stop pushing back against the hydraulic pressure of the clutch fluid (DOT 4 Brake fluid), so it is not likely a fatigued spring.

While looking for the source of the ‘clunk’, check out the drive train:
With the bike on the center stand, in any gear, engine not running (HAD to add that point), grab the rear wheel and see how much it will rotate before meeting resistance.
Does it ‘clunk’ when it does meet resistance?
The ‘clunk’ may be the teeth of the final drive gear or the teeth of the final drive flange have worn and have some play.

Good Luck!

-Ride On

Thanks for the feedback I will make the checks that you suggest.
And I will make sure I don't have the bike running when I grab onto the back wheel
JimC

---

Does this clutch have the dog ears inside that hold the friction plates like on the VFRs? I know that when those get rough from use, they will cause a variety of odd behaviors in the clutch, including a heavy vibration when releasing the clutch from a stop under hard throttle. The fix on those is to pull the cover and remove the friction plates then use a file to clean up the rough edges of the basket.

Yes it does have the dog-ears. Getting the clutch basket in and out is a big job. The clutch basket and plates were out about 18 months ago to replace the plates. Everything looked good then and I have not done a ton of miles since. I will keep your suggestion in mind though if I can't figure out what the issue is, ,thanks !
JimC