Hydro Clutch problem

[Nitrotate]

I'm hoping someone with some hydraulic clutch experience can help me out here. I'm the guy building the reverse trike so this is a little different from just a typical clutch problem and the reason why is that I've replaced the clutch master cylinder with a pedal assembly from a dune buggy. Now in the very beginning I was a little worried about the volume of fluid that the pedal would push compared the volume a standard stock master cylinder pushes. Obviously the pedal is going to push more.

Once I got it installed and working it seemed to work perfectly fine. Almost as if the bike's slave cylinder only pushes so far and then relieves the excess volume. (hopefully that makes sense?) I had pushed the pedal probably 50 times or so and it worked fine, disengaging the clutch and allowing the bike to roll while in gear.

So everything seemed fine until last night while I was doing some testing and shifting gears and using the clutch, all of a sudden the clutch feels different... instead of feeling pressure until about half way down on the pedal and then a slight relief (ease of pressure) the rest of the way in, it's now just tight pressure all the way in and feels similar to a brake pedal (gets tighter).

The odd part is that now, when the bike is in gear it still rolls as if the clutch is stuck in.

So far my diagnosis is that maybe the excess volume of fluid the pedal is pushing has caused the clutch to be stuck in somehow??

Wondering if anyone else has any thoughts or if maybe I could be way off base and it's not even the clutch at all... could the bike have some kind of fail-safe that has engaged and needs to be reset by chance?

Any help is appreciated, I'll be opening up the clutch slave cylinder tonight to see if I can figure it out.

 

[ionbeam]

An early, quick guess is that debris in the new hydraulic system has caused the fluid return passage in the master cylinder to become plugged. This would cause the clutch hose to remain pressurized and the clutch engaged. Or if you used Teflon tape perhaps it has pushed out into the inside the fitting and is now blocking the flow. If you crack a fitting open does unrelieved pressure spray hydraulic fluid all over your garage?



I'm sure you have checked for excessively bent or pinched hydraulic hoses...

 

[wfooshee]

Instead of cracking a fitting, I'd first try the bleed screw. Easier to get to, and you can reduce the mess using a tube and bleed bottle. When it opens, if it's pressurized, it'll bleed the fluid and release the clutch.

I'm wondering, though, about the change in feel of the pedal before you got the clutch symptom. If the master cylinder pumps more fluid on its stroke than the handlebar master cylinder, I would expect the pedal to stop when the slave cylinder is fully extended, like you described as how it felt after a few shifts. The slave cylinder doesn't have any way to bypass excess pressure. I'm afraid you've force the piston out of the slave cylinder far enough to jam it, and maybe bent something in the clutch throwout in the process.

If it's just gunk keeping the fluid from returning, that's great. Pull everything apart, clean it, maybe get new lines, try again.

I'm just wary of a master cylinder that throws more fluid at the slave than it can handle. I haven't had an FJR slave cylinder in my hands, but the automotive ones I've done have nothing in them retaining the piston. The only thing keeping it from travelling too far is the correct volume of fluid being pumped into it; its only mechanical restriction is the throwout arm. Shove that out of the way (bend, break, whatever) and the piston comes out.

 

[ionbeam]

...I'm afraid you've force the piston out of the slave cylinder far enough to jam it, and maybe bent something in the clutch throwout in the process.

I was trying to not be an alarmist and say that... The clutch servo rod is pretty solid and the clutch is pretty solid, if that bent the servo rod or damaged the clutch throwout I think it would be a first for a FJR. Being a leader sometimes sucks.

 

[charismaticmegafauna]

So everything seemed fine until last night while I was doing some testing and shifting gears and using the clutch,

Don't be doing that...!

(without either the engine running or the rear wheel turning)

Many a gearbox (later) exhibits the 'jumping-out-of-gear' syndrome due to bent shift forks because of this. The gears can't find a place to go unless, at least, one of the shafts in the transmission is turning.

 

[wfooshee]

So everything seemed fine until last night while I was doing some testing and shifting gears and using the clutch,

Don't be doing that...!

(without either the engine running or the rear wheel turning)

Many a gearbox (later) exhibits the 'jumping-out-of-gear' syndrome due to bent shift forks because of this. The gears can't find a place to go unless, at least, one of the shafts in the transmission is turning.

It didn't even occur to me that he was doing that while not moving!!!! :blink:

Yeah, in a sequential shift, parts gotta be turning to work correctly. If the cam rotates, it moves the shift fork. If the dogs don't engage, the shift fork can't move far enough. Something gives. It's not like a car which can be shifted very well while not moving - the synchro rings slide right over the gear splines as long as the clutch is engaged.

 

[Nitrotate]

Thanks for the ideas so far guys, I'll pull it apart and check it out. I have not been overly hard on or rough with the pedal mainly because of my initial concerns so I hope and didn't bend anything, I don't think I did but I'll find out tonight. I can get a proportioning valve if the higher volume is the problem or restrict the pedal movement so I'm not too worried about that once I get it figured out.

I did crack the bleed valve and it didn't spray out so I'm pretty sure there's no pressure build up prior to the slave.

 

[Nitrotate]

So everything seemed fine until last night while I was doing some testing and shifting gears and using the clutch,

Don't be doing that...!

(without either the engine running or the rear wheel turning)

Many a gearbox (later) exhibits the 'jumping-out-of-gear' syndrome due to bent shift forks because of this. The gears can't find a place to go unless, at least, one of the shafts in the transmission is turning.

It didn't even occur to me that he was doing that while not moving!!!! :blink:

Yeah, in a sequential shift, parts gotta be turning to work correctly. If the cam rotates, it moves the shift fork. If the dogs don't engage, the shift fork can't move far enough. Something gives. It's not like a car which can be shifted very well while not moving - the synchro rings slide right over the gear splines as long as the clutch is engaged.

Oh, no I wasn't doing it without the bike or the wheel moving. I had the motor running and the back wheel moving. I would roll the bike forward if the motor wasn't moving while I tried shifting.

 

[wfooshee]

Thanks for the ideas so far guys, I'll pull it apart and check it out. I have not been overly hard on or rough with the pedal mainly because of my initial concerns so I hope and didn't bend anything, I don't think I did but I'll find out tonight. I can get a proportioning valve if the higher volume is the problem or restrict the pedal movement so I'm not too worried about that once I get it figured out.
I did crack the bleed valve and it didn't spray out so I'm pretty sure there's no pressure build up prior to the slave.

Hmmmmm. . . . . . That means there's another reason the clutch is staying loose, doesn't it? To quote a 5-yr-old I once knew: Poopie!

 

[Nitrotate]

Thanks for the ideas so far guys, I'll pull it apart and check it out. I have not been overly hard on or rough with the pedal mainly because of my initial concerns so I hope and didn't bend anything, I don't think I did but I'll find out tonight. I can get a proportioning valve if the higher volume is the problem or restrict the pedal movement so I'm not too worried about that once I get it figured out.
I did crack the bleed valve and it didn't spray out so I'm pretty sure there's no pressure build up prior to the slave.

Hmmmmm. . . . . . That means there's another reason the clutch is staying loose, doesn't it? To quote a 5-yr-old I once knew: Poopie!

That's sure what it seems like so hopefully I'll find out by pulling the slave cover off tonight...

By the way, how do you get the trouble codes from this bike? Do you have to have a reader or is there another way?

 

[ionbeam]

...By the way, how do you get the trouble codes from this bike? Do you have to have a reader or is there another way?

Look >>here<<

 

[Nitrotate]

...By the way, how do you get the trouble codes from this bike? Do you have to have a reader or is there another way?

Look >>here<<

Ahhh, perfect thank you very much! I had a feeling there would be a self diagnostic mode these bikes had.

 

[Nitrotate]

Ok guys so there's no restrictions in the line, I pulled the slave cover off and the piston is moving just fine. I pulled the rod out and it's not bent and doesn't have any visible damage or dirt. So basically I've narrowed it down to something being jacked up on the other side with the clutch and plates etc.

I have a HUGE favor to ask of someone who might have the time... If someone would be able to pull that cover off their bike real quick and just measure how far the push-rod sticks out from the opening on the case, it would tell me a lot!

I'm wondering if maybe the plates or pressure plate or something got jammed or wedged on the other side and if the push-rod is not sticking out as far as it should then I know I need to drain oil and pull the clutch cover to inspect it.

If someone has the time I would greatly appreciate that measurement but if not no worries.

Thanks guys!

 

[radman]

Ok guys so there's no restrictions in the line, I pulled the slave cover off and the piston is moving just fine. I pulled the rod out and it's not bent and doesn't have any visible damage or dirt. So basically I've narrowed it down to something being jacked up on the other side with the clutch and plates etc.
I have a HUGE favor to ask of someone who might have the time... If someone would be able to pull that cover off their bike real quick and just measure how far the push-rod sticks out from the opening on the case, it would tell me a lot!

I'm wondering if maybe the plates or pressure plate or something got jammed or wedged on the other side and if the push-rod is not sticking out as far as it should then I know I need to drain oil and pull the clutch cover to inspect it.

If someone has the time I would greatly appreciate that measurement but if not no worries.

Thanks guys!

May have overextended the spring plate (overcenter), and it's stuck released. May be able to pop it back, or replace it. Seen it on this style of clutch before. GM clutch diaphragm plate can bend or collapse if mis-adjusted pedal over-extends the plate.

 

[Nitrotate]

Ok guys so there's no restrictions in the line, I pulled the slave cover off and the piston is moving just fine. I pulled the rod out and it's not bent and doesn't have any visible damage or dirt. So basically I've narrowed it down to something being jacked up on the other side with the clutch and plates etc.
I have a HUGE favor to ask of someone who might have the time... If someone would be able to pull that cover off their bike real quick and just measure how far the push-rod sticks out from the opening on the case, it would tell me a lot!

I'm wondering if maybe the plates or pressure plate or something got jammed or wedged on the other side and if the push-rod is not sticking out as far as it should then I know I need to drain oil and pull the clutch cover to inspect it.

If someone has the time I would greatly appreciate that measurement but if not no worries.

Thanks guys!

May have overextended the spring plate (overcenter), and it's stuck released. May be able to pop it back, or replace it. Seen it on this style of clutch before. GM clutch diaphragm plate can bend or collapse if mis-adjusted pedal over-extends the plate.

Yeah you know what, you may have hit it on the head man! After looking at the parts schematics that makes a lot of sense. Hopefully that's all it is... I'll let you know.

 

[pmk6v]

PM sent

 

[Nitrotate]

got it thanks for the info, I'm going to pull the clutch cover off and I'll bet the spring plate is popped backwards... I'll let you guys know.

 

[wfooshee]

If it would help anybody else with this, why put it in a PM rather than posting something someone else might use? And if the PM is really private (assumption: copy of page of service manual, copyrighted material and against the rules to post) why post that you sent it?

I've never understood that. Send the PM and be done.

To Nitrotate. You've still got to figure how to get the correct amount of fluid sent down the line to the slave cylinder.

Once you get the clutch functional again, my suggestion, which may be overly elaborate, would be to assemble the system with the bike's master cylinder and clutch lever, bleed the system so it works normally. Remove the slave cylinder so you can watch the extension of the piston as you work the clutch lever ONE TIME. You'll have to reset the slave piston manually when you release the clutch lever, as it won't have the clutch's spring pressure on it. Anyway, that tells you how far the piston should extend.

Now put it back to your pedal arrangement, bleed it, remove the slave cylinder so you can watch the piston extend, and have someone SLOWLY depress the clutch pedal, stop when the piston reaches your previous measurement. Note the pedal position and find some way to limit its travel to that point. If you're not comfortable with that distance, i.e. it's way too small, find some way to reduce the amount of fluid being pumped. You mentioned a proportioning valve, but you'd have to have a second destination for the diverted fluid that would return the fluid on the upstroke of the pedal. You could rig a second slave cylinder against a spring, I suppose. . . . .

 

[Nitrotate]

If it would help anybody else with this, why put it in a PM rather than posting something someone else might use? And if the PM is really private (assumption: copy of page of service manual, copyrighted material and against the rules to post) why post that you sent it?
I've never understood that. Send the PM and be done.

To Nitrotate. You've still got to figure how to get the correct amount of fluid sent down the line to the slave cylinder.

Once you get the clutch functional again, my suggestion, which may be overly elaborate, would be to assemble the system with the bike's master cylinder and clutch lever, bleed the system so it works normally. Remove the slave cylinder so you can watch the extension of the piston as you work the clutch lever ONE TIME. You'll have to reset the slave piston manually when you release the clutch lever, as it won't have the clutch's spring pressure on it. Anyway, that tells you how far the piston should extend.

Now put it back to your pedal arrangement, bleed it, remove the slave cylinder so you can watch the piston extend, and have someone SLOWLY depress the clutch pedal, stop when the piston reaches your previous measurement. Note the pedal position and find some way to limit its travel to that point. If you're not comfortable with that distance, i.e. it's way too small, find some way to reduce the amount of fluid being pumped. You mentioned a proportioning valve, but you'd have to have a second destination for the diverted fluid that would return the fluid on the upstroke of the pedal. You could rig a second slave cylinder against a spring, I suppose. . . . .

Oh he was just giving me a measurement is all no worries. Basically telling me that the rod is approximately flush with the face of the case where the slave cover bolts on and the rod on my bike is actually in quite a bit so I pretty much determined that it probably is that clutch spring plate ended up popping over backwards so I'll have to pull the clutch cover and fix or replace it.

Now to your other comment, yes I thought about doing that and I have two options I'm considering, I might be able to shorten the pushrod OR like you said go with a proportioning valve and somewhere else for the additional fluid to go. Or yeah I could limit the pedal. Not sure yet which way to go but I'm definitely trying to go the most reliable route.

Thanks for the ideas!