Clutch slipping after long term storage

Well Eric, it does sound like you're on the trail of the clutch issue at least.

I had a local mechanic bleed my clutch last summer before a big trip and he reported that he got no fluid out until suddenly, a great big wad of what looked just like <please forgive the graphic image> - snot - came blasting into the reservoir of his vacuum bleeder. That didn't happen with the brakes - but the clutch sure had some bad stuff in the pipes. That was actually the beginning (I think) of my clutch slave cylinder woes (see article on replacing the CSC on this forum) - although it isn't entirely clear to me what the connection between the deteriorated hydraulic fluid and the slave cylinder seal failure might have been.

Anyhow, my bike is an '07 and I think I have determined that the routine maintenance had not been done by the P/O and so last summer was the first bleeding done on either the brakes or the clutch. At that point, the bike was 9 years old and had roughly 33,000 miles on it, although the miles aren't important - its the time that counts in terms of fluid deterioration.

Sooooo....if your bike has been sitting and you've got hydraulic issues, I would clean out the master cylinders (brake and clutch) - FIRST - and then bleed the systems very thoroughly until the fluid runs clear.

Pete

Thanks again everyone for the advice. I have my homework to do this weekend and hope to see some positive progress. I will post the results when I have finished. You guys are the best!

Hi everyone,

I have flushed the clutch hydraulic fluid again, cleaned the reservoir (paying attention to the return pin hole). I took the bike for another test ride and the same issue is occurring. After letting the bike warm up to 2 bars, I start out normally, bike pulls normal, gears shift normal everything is fine. This time a gave it some throttle, enough to hear that Honda growl and the bike responds like it should. Pulls strong with no slipping. However, after about 7 to 10 minutes, when I give it enough throttle like I am going to pass someone, the clutch will begin to slip and gets progressively worse.
Is it possible that the clutch plates have deteriorated after sitting for 5 years to the point that when the oil gets hot enough it will cause slippage? I am still running Rotella T6. Even when the clutch slips, shifting feels normal (smooth).
I did not rebuild the master cylinder piston for what it is worth. There is no visible sign of leakage and the fluid level is not dropping. I am thinking to replace the clutch discs now ( and spring while I am in there).

Eric

Where is the clutch disengage point when the engine is cold? If you accelerate, and pull on the lever slightly, does the clutch slip. If there is no free play, the clutch could slip when it warms up. I dont believe there is a way of adjusting free play, though. Only other thing I might suspect is a sticking slave cylinder. Did any "gunk" come out of the bleeder during the flush? You could pull the clutch and measure the plates and springs.

Dump the shell oil and put in some delo 400 15w-40wt. Oil and try that before tearing into your clutch.

Clutch disengages normally when cold. Shifts smoothly as well. I did not see any gunk coming from bleed valve and I put a lot of fluid through there to flush. Thank you for your response

I think there is pressure building up every time you depress the lever. Just a little. Something is hydraulically wrong somewhere and releasing the pressure too slowly. Gets progressively worse. Then releases the pressure over time while the bike is not in use.
I bet you 50 cents that if, when on a ride and the clutch has gone away, you release the pressure by opening the bleed screw, you will have a clutch again, till it AGAIN goes away from built up pressure.
If I am wrong it's worth 50 cents to me to find out!
May as well put the delo oil in just to take that out of the equation. I use T6 but what do I know.
P.S. I have no experience with any of this. I am just going on theory here.
P.S.S. You will not notice the fluid going down when your clutch goes away. Do you notice it's lower when the lever is pulled in? I don't.

Igofar said:

Dump the shell oil and put in some delo 400 15w-40wt. Oil and try that before tearing into your clutch.

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Yup. Going to do that today. Thanks Igofar!

JimGregory said:

I think there is pressure building up every time you depress the lever. Just a little. Something is hydraulically wrong somewhere and releasing the pressure too slowly. Gets progressively worse. Then releases the pressure over time while the bike is not in use.
I bet you 50 cents that if, when on a ride and the clutch has gone away, you release the pressure by opening the bleed screw, you will have a clutch again, till it AGAIN goes away from built up pressure.
If I am wrong it's worth 50 cents to me to find out!
May as well put the delo oil in just to take that out of the equation. I use T6 but what do I know.
P.S. I have no experience with any of this. I am just going on theory here.
P.S.S. You will not notice the fluid going down when your clutch goes away. Do you notice it's lower when the lever is pulled in? I don't.

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Thanks Jim,

I was thinking the same thing about the releasing the pressure once slipping occurs. First I plan to change oil and if it slips again I will release pressure and see if that helps. I may not have cleaned the return "pin hole" in master cylinder good enough as it IS very small.

Eric

JimGregory said:

I think there is pressure building up every time you depress the lever. Just a little. Something is hydraulically wrong somewhere and releasing the pressure too slowly. Gets progressively worse. Then releases the pressure over time while the bike is not in use.
I bet you 50 cents that if, when on a ride and the clutch has gone away, you release the pressure by opening the bleed screw, you will have a clutch again, till it AGAIN goes away from built up pressure.
If I am wrong it's worth 50 cents to me to find out!
May as well put the delo oil in just to take that out of the equation. I use T6 but what do I know.
P.S. I have no experience with any of this. I am just going on theory here.
P.S.S. You will not notice the fluid going down when your clutch goes away. Do you notice it's lower when the lever is pulled in? I don't.

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This is a good idea and I would try this before changing the oil... it doesn't cost a dime.

Many of us have used T6 for years with no problems. I'm about to put in my second gallon of Delo, and while I like it better, it's not likely to solve your problem.

My suggestion would be to remove the fairing, ride the bike until the clutch slips, limp it home, crack the bleeder very briefly and see what happens. If you get a good squirt of fluid and the clutch works again, you have pressure buildup in the system that isn't being properly relieved into the master cylinder. My money is on that; if the valving has silt in it, it's not going to work properly.

--Mark

I have had my st1100 for a couple months now and got it back together from a purchase out of nh. It had been stored for some time. I had a no clutch release, no pressure in mine until it warmed up. So I bled it and flushed the fluid. It worked until 2 days ago, I went to ride it and clutch slipping and barely no release. So I cracked the slave cylinder bleeder and had pressure. I knew exactly what it was. I removed master cylinder and pulled it apart and sure enough, the pressure release hole got plugged. So...check that as bdalameda just suggested. I am riding now with no issues.

Today I changed the oil... just because... Same thing happened after about 10 minutes of riding. Clutch started to slip under moderate acceleration. I played with the clutch lever a bit and the engine revved as soon as I pulled the lever in. As soon as I pulled the bike into the garage, I cracked the clutch bleed valve and I got a little spurt of fluid. Not a lot but a burp. ST-Owner Igofar called me at this point to see how things were going. With phones on speaker he guided me to remove the clutch lever and had me remove the boot, which was torn and remove the piston plunger. Besides the rubber boot being trashed, everything else seemed...ok. While Igofar was describing where the slave cylinder was, I was already on the ground looking at it and discovered a yellowish dried up mess, at the clutch slave housing. Well, that pretty much sums it up for me. Time to change the slave cylinder assembly. Parts are already on order and I should be replacing it by next weekend. Ordered the master cylinder rebuild kit as well. Thanks to MaxPete, I will be using his writeup as my guide. Definitely a doable project. Thank you Max for the effort you put into that.
BTW, I changed the EBC brake pads in the front for OEM pads. The front wheel spins much easier now.
Thank you Igofar for your phone calls. Your wealth of knowledge is greatly appreciated.

Eric

Update for the clutch slipping issue.

Master and slave cylinder was changed. Fluid was bled so many times, It feels like a daily routine for me. No matter how many times I bled the fluid and purged the smallest of bubbles (which were probably coming from the bleed screw anyway) the clutch would start to slip after about 5 to 7 minutes of riding. I would keep a 10 mm wrench with me to relieve the pressure that built up, so that I could make it back home. I tried relieving pressure at the banjo fittings, shaking the lines, banging on the bike, turning the handles, talking sweet to the bike, threatening to sell the bike and then making up with the bike. (A Triumph Thruxton was becoming attractive to me during this time.)

Today, after going through so many containers of fluid, i just put a check valve in-line with the hose coming from the bleed valve and ran the output to the master cylinder reservoir and pumped the clutch lever away while enjoying my 3 cups of morning coffee. After about 30 to 40 minutes of doing this, the lever felt solid and absolutely no air bubble were present. I was feeling confident in my technique and happy that I was no longer supporting the auto parts store with my insane amount of DOT 4 brake fluid purchases.

Time for another test ride and put this issue to bed.

FAIL!!!

What the hell! Why not bleed it again, right? So while I routed my hose to continuously run fluid through the lines, pumping away at the lever and thinking about the Triumph, I noticed a little bit of fluid coming up from the large hole in the reservoir. What about the little pin hole inboard of that? Isn't that supposed to squirt fluid in my eye? I have cleaned the crud that was around it but never noticed any fluid coming from it, certainly nothing that would make it to my eyeballs. I just bought a new shirt the other day and it came with one of these

View attachment 183266

A little pin.

So I stuck that in the "pin" hole, wiggled it around a bit and pulled the clutch lever.

I almost got an eyeful of clutch fluid!!! And... a few tiny bubbles came out of the pin hole. So for good measure, I flushed the system for a couple of minutes, after putting the "spoon" on the pin hole. I am really feeling confident now because of my close call with going to the hospital to get my eyes flushed. Time to get back on the road.

20 miles later, absolutely no hint of clutch slippage! All of that work for a little blocked pin hole. Well, the slave cylinder did need to be changed anyway. It was in really bad shape.



Thanks to everyone who replied to this and especially thanks to member Igofar for the many phone calls and support. This has truly been a learning experience.

Eric

Well done Eric - so pleased you got this worked out! Hydraulics are my "thang" but I have never looked at that pinhole closely enough to figure out how it all works - I must do that soon. Anyhow, sometimes these journeys are long and hard but it sure feels good when everything is working nicely again.



Kind regards,

Pete

That is exactly the orifice I had described that needed to be cleaned. I guess my description was not good enough. Oh well I'm glad it got worked out. I was certain that was the problem.

Wonderful news! So glad you got it resolved! I found that sometimes a high E steel guitar string is perfect for cleaning out this hole (and also for cleaning out the jets in carbs).
Glad you didn't get a face full of fluid. I can tell you first hand that brake fluid quickly destroys the lenses on eyeglasses.
Oh, and as far as your insane amount of DOT 4 fluid....I have filled 5 Gal water bottles to the top with the stuff in a month or so, and normally I can bleed an entire brake and clutch system with 3 small bottles.
Buy yourself and drink and pat yourself on the back, you deserve it for not giving up!
Good job my friend.
Larry

bdalameda said:

That is exactly the orifice I had described that needed to be cleaned. I guess my description was not good enough. Oh well I'm glad it got worked out. I was certain that was the problem.

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I did clean this out after your post (but apparently not good enough) I did not fully understand the function of this hole at the time and to be honest, kind of forgot how important it is because I was so obsessed with getting every last bubble out of the system. Having reread your post now that my mind is clear again, yeah, you did exactly describe what needed to be cleaned. Now I am sitting here in reflection pulling a stupid look on my face... But hey, I got to know the hydraulic part of the system well and learned something in the process. Thanks bdalameda!!!

Igofar said:

Wonderful news! So glad you got it resolved! I found that sometimes a high E steel guitar string is perfect for cleaning out this hole (and also for cleaning out the jets in carbs).
Glad you didn't get a face full of fluid. I can tell you first hand that brake fluid quickly destroys the lenses on eyeglasses.
Oh, and as far as your insane amount of DOT 4 fluid....I have filled 5 Gal water bottles to the top with the stuff in a month or so, and normally I can bleed an entire brake and clutch system with 3 small bottles.
Buy yourself and drink and pat yourself on the back, you deserve it for not giving up!
Good job my friend.
Larry

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Thanks Larry. I can't thank you enough for all of the help you gave me over the phone. I really appreciate the time and attention you gave and I think most important was the moral support you gave as we all know that little aggravations with maintenance can get the best of us sometimes.

Cheers!

I'm having the same issue that you described. Where is this pin hole of which you speak?