Clutch problem

[Rocketman]

Had a weird one with my clutch on Saturday.  2000 I/S.  I did a mini-course with an experienced rider's MSF instructor.  It was ~70 miles to get there.  Rode two up to get there, but rode solo through the course.  Did 5 or 6 runs through the course, which was your standard MSF style drill (u turns, weaves, etc).  I'm out of practice, so I was riding the clutch hard (Yes, I should have been riding the rear brake instead.  Remember the part about being out of practice?).  Finished my last run, pulled up to the instructor, put it in neutral.  Everything's good so far.  Checked out with him, and was about to ride away.  I pulled the clutch in, and there was zero resistance to it.  Cycled it a few times, no difference.  Pulled it in, popped it in gear to make sure it wasn't my imagination, and sure enough it clunked and died (just like I had popped it in gear with the clutch out and full brake).
I opened up the clutch fluid reservoir to get a good look at the hydraulic fluid (spilling some, because that reservoir is terrible!) but there was plenty and it didn't look too old or crusty.  I closed it back up again, pulled the clutch in, and it felt fine.  Tested it out, and it worked great.  Ran fine the whole way home.

Anybody have any idea what happened?  I'm not 100% sure it won't come back, but I don't know what to look at.  I suppose a clutch fluid change/flush is in order, but wondering if there's anything else I'm missing.

Mark

[HayHauler]

I thought it might be the TINY pressure relief hole under the metal clip in the middle of the reservoir.  But, I think that if it wasn't releasing the pressure, the clutch would remain disengaged, not engaged. 
Did it seem like there was "pressure" in the reservoir when you opened it, or was it just a the weird angle and ran down the low side?

Possibly something with the slave cylinder.

Hay 
Jimmyt

[Rocketman]

I don't think there was pressure in the reservoir, but hard to know for sure.  I had it leaning hard over on the side stand  (I think mine is bent a little and it's sitting low anyway), and it ran out the low side.

Concur that if it was the pressure relief valve it would manifest differently, and not disengage.  I had that problem on an old Suzuki with the front brake, it would slowly build up pressure and lock up the front brakes.

[HayHauler]

I don't think there was pressure in the reservoir, but hard to know for sure.  I had it leaning hard over on the side stand  (I think mine is bent a little and it's sitting low anyway), and it ran out the low side.

Concur that if it was the pressure relief valve it would manifest differently, and not disengage.  I had that problem on an old Suzuki with the front brake, it would slowly build up pressure and lock up the front brakes.

That's the exact problem I had with the front brakes on HotGlue's bike I bought from him.  Front brakes building up pressure and eventually locking up the front brakes.  Thankfully, it never happened at speed, or it would have been exciting to say the least.  The pressure relief hole was rusted shut and I couldn't open it up.  Ended up replacing both reservoirs on the handle bars so they would look the same.

Hay
Jimmyt

[WintrSol]

How long since you changed the fluid? I flush it out every year (two is recommended) because water built up in it over time can cause it to boil. This sounds like your clutch slave boiled, filling the line with steam, then went back as it cooled.

[Pluggy]

I thought it might be the TINY pressure relief hole under the metal clip in the middle of the reservoir.  But, I think that if it wasn't releasing the pressure, the clutch would remain disengaged, not engaged.  
Did it seem like there was "pressure" in the reservoir when you opened it, or was it just a the weird angle and ran down the low side?

Possibly something with the slave cylinder.

Hay  
Jimmyt

 

Hey, guys.  On my 4 cylinder Honda, that little "fluid return" hole clogged.  Locked rear brake and smoked the pads.  The built-up pressure can be relieved by loosening the banjo bolt.  I made it home using front brakes.

A "B" guitar string, .016" diameter, cleaned the hole out.  Rebuilding the rear caliper, cleaning the master and a new set of pads was the result.  Yes, I change the fluid every 2 years, but had not cleaned the hole.

 

[HayHauler]

Mine was the front brakes.  I got home by loosening the bleeder and releasing the pressure.  I rode it like a Harley on the way home, only using the back brake. 

Hay 
Jimmyt

[Rocketman]

Mine was the front brakes.  I got home by loosening the bleeder and releasing the pressure.  I rode it like a Harley on the way home, only using the back brake. 

Hay 
Jimmyt

Be careful doing it that way.  Harleys get away with it because they can never really go that fast anyway, so they don't need much stopping power.   

[Rocketman]

How long since you changed the fluid? I flush it out every year (two is recommended) because water built up in it over time can cause it to boil. This sounds like your clutch slave boiled, filling the line with steam, then went back as it cooled.

It's been maybe two years, possibly more.  I'd have to check my records.
I thought about it being a boiling problem.  However, I wouldn't think it would go from working perfectly to zero over the course of <30 seconds, and then back again over a similarly short period of time.  I would think it would be a much more gradual transition, where I would feel a change in the effectiveness of the clutch as I went.  Even weirder, it worked great through the time that I was riding it, and then it transitioned to completely failed while I was sitting still, not riding it at all.  (Engine running, but in neutral)  So yeah, boiling makes sense to a point, but not completely.

[Jims99]

I personally think it was the boiling theory. I would change the fluids and not worry too much about it. The weep hole clogged would keep the clutch engaged. (Ride break). Heat can do weird things.

[Pluggy]

I personally think it was the boiling theory. I would change the fluids and not worry too much about it. The weep hole clogged would keep the clutch engaged. (Ride break). Heat can do weird things.

Yes, change the fluid.  After the reservoir is drained, checking (and possibly cleaning) the little hole is real easy.  Two possible causes would be eliminated.

This fluid has a higher boiling point than most.  You may want to consider it.

https://www.autozone.com/brake-and-power-steering-fluid-additives/brake-fluid/p/prestone-dot-4-brake-fluid-32-ounce/1083028_0_0?spps.s=2488&cmpid=LIA:US:EN:AD:NL:1000000:PER:19488533498&&CATARGETID=120054150001289361&CADevice=c&gad_source=1&gclid=CjwKCAjwpbi4BhByEiwAMC8JnXGpoFIhgrDnozIcQdB26bA7_bVncp7tKT9VRLbEecqDaIM34YwVMxoCRoAQAvD_BwE&gclsrc=aw.ds

[Skinhead]

How do you boil the clutch hydraulic fluid?  Where does all the heat come from?  I could see the brake system getting hot, but not the clutch.  I think you got a piece of debris stuck somewhere in the master cylinder.  I would do a thorough cleaning and rebuild of the MC and a fluid change.

[Chrisj CMA]

Did you check the brass bushing in the clutch handle? Maybe it’s not disengaging all the way

[WintrSol]

How do you boil the clutch hydraulic fluid?  Where does all the heat come from?  I could see the brake system getting hot, but not the clutch.  I think you got a piece of debris stuck somewhere in the master cylinder.  I would do a thorough cleaning and rebuild of the MC and a fluid change.

Dragging the clutch a lot, as described, creates a lot of heat in the clutch, much if which is not pulled away by the oil (which may also be pretty hot), and can be transmitted to the slave cylinder. Ours it tucked in behind the back of the engine, so gets almost no air cooling to help.

[Rocketman]

Did you check the brass bushing in the clutch handle? Maybe it’s not disengaging all the way

That would make it so that the final drive would always be disconnected from the engine.  This was the opposite.  I could not disengage at all.  (For that short time)

[98valk]

https://www.goldwingfacts.com/threads/gl1500-why-to-rebuild-clutch-slave-cylinder.372581/

https://www.goldwingfacts.com/threads/slave-cylinder-gl1500.675160/#post-6000573

[WintrSol]

Just the pedant in me, but in reference to the clutch, disengaged means disconnected, and engaged, connected.
I just don't like sloppy terminology, as it leads to misunderstandings.

[Skinhead]

How do you boil the clutch hydraulic fluid?  Where does all the heat come from?  I could see the brake system getting hot, but not the clutch.  I think you got a piece of debris stuck somewhere in the master cylinder.  I would do a thorough cleaning and rebuild of the MC and a fluid change.

Dragging the clutch a lot, as described, creates a lot of heat in the clutch, much if which is not pulled away by the oil (which may also be pretty hot), and can be transmitted to the slave cylinder. Ours it tucked in behind the back of the engine, so gets almost no air cooling to help.

So all that "heat" is transferred to the slave cylinder and boils the brake fluid via heat transfer through the 1/4" x 3" push rod?  I don't think so, but I have no data, so just my opinion.

[WintrSol]

Well, the clutch will transmit its heat into the oil, which could be over 220F and given the operating conditions 250F before being damaged, and the rear housing, with the maximum heat source centered around the throw-out rod. 'Wet' brake fluid can boil as low as 311F, for Prestone DOT4, so I still think it possible it will get hot enough.

[jnicks01]

try pulling the slave cylinder and see what it looks like.  Then do a complete bleed and new fluid.

[Rocketman]

Update:
I'm not sure this is related, since the full on failure didn't happen until this spring, but:  After the issues described above, it behaved quite well for months.  And no, I didn't park it over the winter, I live in Texas.  But in the spring, it started acting wonky for a few weeks.  The grab point (what the MSF course calls the "friction zone") on the clutch was unpredictable.  One time, it might be in its normal spot, the other time it might start to grab right up against the handlebar.  It was becoming impossible to ride smoothly when I didn't know where it would grab until after I had done it.
Then one morning it just wouldn't disengage.  At first, with the engine running and the trans in gear, clutch pulled in, it was noticeably dragging and trying to move the bike.  Then while I was trying to troubleshoot it, it got worse, and then would not run in gear, it just stalled out.  Little to no resistance in the clutch lever.
It has taken me a long time to do all this work, just due to a complete lack of time to do it in, but I pulled the clutch slave cylinder, inspected it, and decided to replace it even though I didn't see anything glaringly wrong with it.  Installed the new one, filled and bled the fluid, and was getting good resistance on the clutch lever.  
But, it's still dragging the clutch, like I'm running it with the lever halfway out.  I bled it three times, and unless that system is inherently un-bleed-able, I'm confident that I have all the air out.  I have pushed several pints of fluid through it at this point.
The weird thing is that it made lots of progress, but not 100%.  I figured it would either do no good at all, or fix the problem.

So:  Did I have two problems?  Did the slave replacement fix one of them but not the other?  If so, I guess I'm left with either master cyl. or internal clutch pieces.  I really don't want to pull the clutch out.
Do I still have air hiding in there despite pushing that much fluid through?

Thoughts?

[HayHauler]

I had front brake issues with the bike I bought from HotGlue.  The issue was that the VERY SMALL hole, under the tiny stainless clip in the bottom of the reservoir was rusted shut.  This is a very slow bleed hole to equalize the pressure after releasing the lever.  MY issue was that the front brakes would operate sort of normal for a while, then they would start locking up (applying full pressure).  I had to pull out the 10mm wrench, crack the bleeder screw on the caliper to drain some fluid, just to get home.

This might not be your issue, but it sounds like it could be a contributing factor.

Hay 
Jimmyt

[Rocketman]

I had front brake issues with the bike I bought from HotGlue.  The issue was that the VERY SMALL hole, under the tiny stainless clip in the bottom of the reservoir was rusted shut.  This is a very slow bleed hole to equalize the pressure after releasing the lever.  MY issue was that the front brakes would operate sort of normal for a while, then they would start locking up (applying full pressure).  I had to pull out the 10mm wrench, crack the bleeder screw on the caliper to drain some fluid, just to get home.

This might not be your issue, but it sounds like it could be a contributing factor.

Hay 
Jimmyt

I had someone suggest that, and I had that issue on a different bike years ago, but the symptoms would be exactly as you describe, and my issue is the opposite.  Not enough pressure rather than too much.

[Rocketman]

Another update:  And yes, I'm moving very slowly on this, I just don't have the time I need to really work on it....
I found hydraulic fluid under it, and the slave was wet.  Not a lot, but some.  I have a very small drip.  I will tighten up those connections and possibly replace the crush washers.  Anyone know the size, so I can buy some?

[97BLKVALK]

https://www.ronayers.com/oemparts/p/honda/90545-300-000/washer-oil-bolt

Here is the Honda part number for the crush washers.

[ridingron]

If the local Honda dealer doesn't have one in stock, take one to Ace Hardware or just about any auto parts store. I doubt they are more than 50¢ maybe a dollar. 

[SPOFF]

I'm following this thread with interest. My slave cylinder has been leaking for a decade. Usually I bleed it in the spring and it's good for the season. This spring the lever is doing nothing. I suspect the slave cylinder is completely drained of fluid. I have a new unit in hand and will install it soon, but what a miserable place to get to. And I have other bikes to work on first. The Valkyrie is fourth on the runway.