Clutch Evaluation

Willsmotorcycle

Willsmotorcycle

Ride more...
ST1300 50,000 Mile Badge
Joined
Oct 26, 2020
Messages
440
Location
Makefield Highlands PA
Bike
2016 ST1300P
2026 Miles
001252
Patient is a 2016 ST1300PA, 86k miles, symptoms are clutch lever engaging disengaging at the end of the pull. New bushing 1k miles ago, fluid flush more than required. Happens regularly when hot. Various oils over the years, mostly Rotella and Valvoline blue.

CSC or plates?… or…?

Edit for correct wording.
 
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If the clutch is slipping YOU WILL KNOW IT because the engine will rev unexpectedly. If it slips it's shot.

If the clutch is not releasing 100% you will have to hold the bike from creeping at a stop. Unless something is broken in the clutch packs, no creeping, 100% release and CSC is good.

If both are good:

A. Quit worrying. Just ride it.
B. Bleed it again and again and see all is fine.
C. Change CSC and see very little difference (probably).
D. check out the lever hyd. system real good.

E. Most ST1300 clutches release way far in. Just ride it.

Do you have-how thick are the grip covers?
 
If the clutch is slipping when the engine is hot, then the most likely suspect is that your clutch fluid is not returning to the master cylinder reservoir. This is also the cheapest solution and requires least effort, so is well worth investigating. My brand new ST1300 was delivered from the dealer with this fault. I got 7 miles before the clutch stopped biting and left me stranded.

But - you say the clutch is engaging at the end of the pull of the lever. Not sure what you mean here - Do you mean that as you pull in the lever, the clutch plates disengage - ie they separate so that the engine is not connected to the back wheel? This should happen fully when the lever meets the bars ‘At the end of the pull’. But it should start as soon as you have taken up the slack at the lever.
Or do you mean that the clutch engages when you are letting go of the lever - when you have finished pulling it in. ‘At the end of the pull’ ie not pulling any more ? 😁

Bleeding will not cure the issue if the engine is disengaging - ie no drive without pulling in the lever if there is air in the system. The air stops the lever from disengaging the clutch. I think that you are describing that there is no drive at all. Whatever the cause of that, it is not due to air in the hydraulics.

Three possible reasons for the scenario I suggest - ignoring for now the time consuming and expensive possibility of issues with the clutch slave….

1. The compensation port is blocked - under the chrome clip in the master cylinder fluid reservoir.
2. The plunger on the clutch lever is resting on the side of the brass bush, rather than sitting inside the hole in the brass bush. (This was my issue).
3. The plunger has been put in the wrong way round when reassembling. (Recently seen in another thread on here)

#2 is easy to check. Undo the locknut, undo the screw. Hold the brass bush in place and carefully pull out the lever, watching the plunger emerge. Check the position of the hole. On reassembly check that the hole hasn’t worn through to the other side - ie it is a blind hole that you cannot see through. Mark the position of the hole on the circular end of the brass bush so that you can align it properly on reassembly. Put the screw in position - just snugged up - it’s a pivot, not a bolt. Hold the screw, tighten the locknut.
 
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W0QNX said:
If the clutch is slipping YOU WILL KNOW IT because the engine will rev unexpectedly. If it slips it's shot.
Click to expand...
Not necessarily; if the plunger is inserted backwards, the return (?) port gets closed off when you have to push the clutch lever in slightly to align the pivot bolt and the bike will eventually lose power but there is nothing wrong with the clutch itself. This was my case...and it was very gradual over several miles getting worse with every shift/use of the lever - very similar to @jfheath's description above. The square end goes into the lever brass bushing, the round end goes into the MC piston. It will not work correctly (for very long!) the other way around.
 
W0QNX said:
If the clutch is slipping YOU WILL KNOW IT because the engine will rev unexpectedly. If it slips it's shot.

If the clutch is not releasing 100% you will have to hold the bike from creeping at a stop. Unless something is broken in the clutch packs, no creeping, 100% release and CSC is good.

If both are good:

A. Quit worrying. Just ride it.
B. Bleed it again and again and see all is fine.
C. Change CSC and see very little difference (probably).
D. check out the lever hyd. system real good.

E. Most ST1300 clutches release way far in. Just ride it.

Do you have-how thick are the grip covers?
Click to expand...
I love "A" Raymond, thank you for your input. I have heated grips with puppies on them. My comparison is from a 2010 with 20k miles on it. The lever on that starts to "activate" with little pull, my 16 has to be pulled all the way to the grip.
I will be doing B as well.
It may be a bad plunger boot/install
 
jfheath said:
If the clutch is slipping when the engine is hot, then the most likely suspect is that your clutch fluid is not returning to the master cylinder reservoir. This is also the cheapest solution and requires least effort, so is well worth investigating. My brand new ST1300 was delivered from the dealer with this fault. I got 7 miles before the clutch stopped biting and left me stranded.

But - you say the clutch is engaging at the end of the pull of the lever. Not sure what you mean here - Do you mean that as you pull in the lever, the clutch plates disengage - ie they separate so that the engine is not connected to the back wheel? This should happen fully when the lever meets the bars ‘At the end of the pull’. But it should start as soon as you have taken up the slack at the lever.
Or do you mean that the clutch engages when you are letting go of the lever - when you have finished pulling it in. ‘At the end of the pull’ ie not pulling any more ? 😁

Bleeding will not cure the issue if the engine is disengaging - ie no drive without pulling in the lever if there is air in the system. The air stops the lever from disengaging the clutch. I think that you are describing that there is no drive at all. Whatever the cause of that, it is not due to air in the hydraulics.

Three possible reasons for the scenario I suggest - ignoring for now the time consuming and expensive possibility of issues with the clutch slave….

1. The compensation port is blocked - under the chrome clip in the master cylinder fluid reservoir.
2. The plunger on the clutch lever is resting on the side of the brass bush, rather than sitting inside the hole in the brass bush. (This was my issue).
3. The plunger has been put in the wrong way round when reassembling. (Recently seen in another thread on here)

#2 is easy to check. Undo the locknut, undo the screw. Hold the brass bush in place and carefully pull out the lever, watching the plunger emerge. Check the position of the hole. On reassembly check that the hole hasn’t worn through to the other side - ie it is a blind hole that you cannot see through. Mark the position of the hole on the circular end of the brass bush so that you can align it properly on reassembly. Put the screw in position - just snugged up - it’s a pivot, not a bolt. Hold the screw, tighten the locknut.
Click to expand...
Thank you for the reply John, as always very detailed.

I was using the wrong terminology, Larry called and explained the right way to describe this. The clutch doesn't disengage until I pull all the way to the grip. There is no "friction zone", or at least very little. There is seemingly no slack in the lever. Sorry for description error.
 
ST1100Y said:
Well, I usually don't post in the 1300 section, but police spec + mileage + engaging at the end might add to worn down friction plates... :unsure:
Click to expand...
Thank you Martin, after talking with Larry, we are probably having a plunger malfunction, possibly clutch springs. Will be trying the simple solution first.
 
Larry Fine said:
As John said, please clarify whether the clutch starts engaging close to the grip or fully away from it, and if this is a change from normal.
Click to expand...
Thanks for replying Larry, dumbness on the words from me. The clutch doesn't disengage until the very end of the pull and sometimes I have to squeeze super hard. As for normality, it's been this way for a while, 10 of 1000s of miles, just thought it was bad oil or what not. I changed the bushing and hoped it would help, it did not. Moving the 2010 around I noticed disengagement at the beginning of the pull, and now realize my 16 is not normal.
 
It sounds like it's low on fluid, or a mechanical issue with similar symptoms.

My '01 did that when hot, to the point of stalling when stopping, until I did two fluid bleedings.
 
OK thanks for the update. If it isn't disengaging very well, even will pulled back to the lever, then that could be air in the lines or failing master cylinder or slave cylinder - in order of difficulty to fix !
It could also be that the hole int he brass bush has worn all the way through to the other side.
 
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