Clutch free play changes when bike warmed up

jfheath said:
If the clutch isn't disengaging it could be because:

  1. There is air in the system.
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+1 - there's still (possibly) some air in the system (banjo at MC perhaps), which expands (more volume) with heat, then is compressed by pulling the lever but the force at slave/clutch basket is less (so plates stay in partial contact). I'd still check for that.

If you pull vac at nipple, I'd try moving the handlebar (don't spill) such that banjo is no longer highest point, or pull lever and slightly crack banjo open then close banjo bolt. Some people push fluid from nipple up, never done that as I use your method and never had issues.

Did you use DOT 4 fluid? How has this come about?
 
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draser said:
+1 - there's still (possibly) some air in the system (banjo at MC perhaps), which expands (more volume) with heat, then is compressed by pulling the lever but the force at slave/clutch basket is less (so plates stay in partial contact). I'd still check for that.

If you pull vac at nipple, I'd try moving the handlebar (don't spill) such that banjo is no longer highest point, or pull lever and slightly crack banjo open then close banjo bolt. Some people push fluid from nipple up, never done that as I use your method and never had issues.

Did you use DOT 4 fluid? How has this come about?
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Yes I use DOT4 fluid, after work l'll try the master banjo bolt method and see if that gets me anywhere. I've been keeping the handle bars level everytime I've done it. Would bleed into it when the bike is warm make a difference?
 
Larry Fine said:
What if, like mine used to do, it only happens when the engine is excessively hot, and returns to normal after cooling back to normal operating temperatures?

That must be due to fluid problems, like water vaporizing and then re-condensing, and not due to mechanical abnormalities that wouldn't change with temp.
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My answers 1-4 consider the heat issue. 5 & 6 are probably not the cause - heat build up would disengage the clutch in those cases - but worth mentioning as a side issue.

I've had clutch drag on basket / plates where the plate tabs have worn notches in the basket where the plates moved to separate from each other. The notches prevented the plates from disengaging properly. This was much worse when the engine was hot. It wasn't on a 1300 though but the diagrams look similar to the bike that I had when I experienced this. Expansion of metal and nothing to do with fluid expansion.
 
jfheath said:
I've had clutch drag on basket / plates where the plate tabs have worn notches in the basket where the plates moved to separate from each other. The notches prevented the plates from disengaging properly. This was much worse when the engine was hot. It wasn't on a 1300 though but the diagrams look similar to the bike that I had when I experienced this. Expansion of metal and nothing to do with fluid expansion.
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My experience was with my '01 1100, and it has not recurred since the fluid changes, no matter how hot.
 
Personally I think using a vacuum bleeder on the clutch slave is not the best option if your aim is to flush the slave with fresh fluid. On the 1300 the fluid entry and the bleed are both near the top of the slave, so all you are doing is pulling fresh fluid across the top of the slave. If you do the conventional bleed, you are pumping fresh fluid in and displacing the piston, then the piston spring can push the piston and fluid back out through the bleeder; this means a much better chance of displacing old fluid around the piston.
 
Just a quick update.. the boss was in Canada for 3 weeks so I bit the bullet. £250 on bits, did a full service on the bike - airfilter plugs etc - and master and slave clutch kits. I did the master first - no change and then the slave.
It took a couple of days as I don't have a lot of space in the garage and it take me 5 mins to get off by back to stand up as kneeling is not a function I can do these days.
Anyway - as everyone says, it not technically difficult - its just awkward (slight understatement as I'm polite).

Clutch now sorted.

Lessons learned..

1) I delayed doing the clutch slave for 2 years. If you have the same symptons, don't hesitate, JFDI.
2) Make sure you've a 1/4 drive set.
3) Long ring hinged Ratchet 12mm for the banjo.
4) A little helper - to pass you the correct size socket once you you spent 5 mins trying to youself in the correct position with the wrong one on the end of the drive.
5) Take you time, don't rush it.
6) Find all of you tools BEFORE you start the job!!
7) Clean underneath the bike with a jetwash - with the tupperware removed.
8) get some wd40 on the front lower radiator cowel screws they are a complete bar steward to remove - I had to resort to a bit of heat from my tiny gas torch to free them off.
9) Get some else to do it :)

Good luck

Thanks to all for the advice, hints and tips - at the end of the day, its another ST1300 A9 on the road again :)

PS - the abbreviation JFDI means "Just Do It"

Live long and prosper

Joe - Sunny Newcastle, NE England, Planet Earth.
 
Well I ordered a new brass bushing that the master cylinder push rod rides in and a new boot. Fingers crossed that it fixes my clutching issues when warm! That's to the white telephone, I have been directed to several issues that need attention that I didn't know of. I'll update when Ron Ayers ships my new part and see how it goes
 
I have read through these posts with interest, my 1300 A9 has just developed a clutch fault. Currently showing 28,000 miles (I acquired the bike in April showing 20, 000, my third ST1300 after a 6-year dalliance with other bikes)) I was out today in horribly heavy traffic and stopped at one of my destinations after about 2 hours. The clutch was operating normally when I stopped. After about 20 minutes I resumed my journey and immediately noticed much greater free play in the clutch lever, i.e. the lever was 'loose' on first pulling it in and the clutch biting-point was much nearer the bars. Apart from that, the clutch worked normally. I was hoping the clutch lever would return to normal after a few miles but it remained 'floppy' until i returned home, about 90 minutes. After the bike had cooled down, like properly cool, the clutch lever remained the same.
I had a look at the brass bush, it was very tight in the lever with corrosion so I polished it up and reassembled the lever - no change.
As said peviously, the clutch continues to work fine but there is a load of free play where, up to this morning, the lever was taught and the biting-point was much further away from the bars.
All suggestions gratefully received.
 
J.Murphy said:
I have read through these posts with interest, my 1300 A9 has just developed a clutch fault. Currently showing 28,000 miles (I acquired the bike in April showing 20, 000, my third ST1300 after a 6-year dalliance with other bikes)) I was out today in horribly heavy traffic and stopped at one of my destinations after about 2 hours. The clutch was operating normally when I stopped. After about 20 minutes I resumed my journey and immediately noticed much greater free play in the clutch lever, i.e. the lever was 'loose' on first pulling it in and the clutch biting-point was much nearer the bars. Apart from that, the clutch worked normally. I was hoping the clutch lever would return to normal after a few miles but it remained 'floppy' until i returned home, about 90 minutes. After the bike had cooled down, like properly cool, the clutch lever remained the same.
I had a look at the brass bush, it was very tight in the lever with corrosion so I polished it up and reassembled the lever - no change.
As said peviously, the clutch continues to work fine but there is a load of free play where, up to this morning, the lever was taught and the biting-point was much further away from the bars.
All suggestions gratefully received.
Click to expand...
Check and flush the clutch fluid?
 
Your not inspecting the correct problem area of the clutch lever bushing....
You want to inspect/check the depth of the hole in it.
If your plunger rod started wearing a deeper hole, this will prevent the lever from compressing the fluid as designed.
 
Igofar said:
Your not inspecting the correct problem area of the clutch lever bushing....
You want to inspect/check the depth of the hole in it.
If your plunger rod started wearing a deeper hole, this will prevent the lever from compressing the fluid as designed.
Click to expand...
Thanks for the pointer. What depth should the hole be?
 
Stuff a small piece of gum wrapper foil, or paper in the hole to shorten the depth, this will tell you if this may be your problem.
 
J.Murphy said:
What depth should the hole be?
Click to expand...
The hole in a new clutch lever bushing is 8mm deep, or 0.315".
The diameter of the hole is 5mm, or 0.197".
The outside diameter of the bushing is 9.94mm, or 0.3915".
It is 10mm in length, or 0.394".
 
Thanks for the suggestion and the dimensions. If the bush has worn I'm a bit surprised seeing as the bike is almost just run-in (broken-in) at 28k?

I'll put something in the hole and see what happens.
 
It sounds like your clutch builds pressure late as though some air got in the system. Do you notice any leaks or lower fluid level in the MC? Is fluid nice and clear in reservoir?
 
J.Murphy said:
Thanks for the suggestion and the dimensions. If the bush has worn I'm a bit surprised seeing as the bike is almost just run-in (broken-in) at 28k?

I'll put something in the hole and see what happens.
Click to expand...
I'm not suggesting that a worn clutch lever bushing is the cause of your symptoms, I simply provided the bushing dimensions in answer to your query.

The rate at which the bushing, handle, or pivot bolt wears is not really related to distance traveled as much as it is to amount of use. Stop-and-go city traffic results in a lot of clutch lever use. This type of use for 28,000 KM will cause more wear to these clutch lever parts than 128,000 KM of highway use will. Lack of maintenance, i.e. cleaning and lubricating, accelerates the wear rate.

As an aside, when everything is new and has no wear the clutch lever should not move vertically more than 1/16" total as measured at the very end where the round knob is. If you have significant vertical movement of the lever there are worn parts in there.
 
Okey doke. I measured the cavity in the clutch-lever bush and I made it 8mm. I packed the hole with a little Al-foil and the clutch action has returned to normal - hooray and thank you!!

I have ordered a new bush from Fowlers in Bristol, it should arrive in a day or two.

Once again, thanks for the input.
 
Brake fluid is hygroscopic which allows it to retain moisture over time. If you have contaminated or an old unsealed can of fluid, when it heats up it can produce vapor in the lines and that will keep the clutch from actuating. It will do this in brakes as well if the fluid overheats it can cause your brakes to go soft.
 
It’s common for police bikes and escort bikes to have the rod bore a hole all the way through the bushing!
 

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