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Discussion Starter #1
I have an Evolzione clutch slave in my 2004 Ducati ST4s. A month ago, I lost all clutch action when the bearing around the clutch control rod failed and broke to pieces. That allowed the clutch piston to travel too far, and lost all hydraulic fluid. The broken pieces spinning about must have damaged the slave interior because a new bearing wouldn't fit where the old one did.

So I got a new clutch slave and I noticed that the same issues I had before the last slave failed (difficult to get into neutral, clutch not engaging fully) started happening again after a few weeks.

I opened up the slave today, and the new bearing is broken, and about to fail just like the last. The bearings cost like nothing, and I can replace them till the cows come home but that isn't fixing the problem. Could the clutch control rod be warped and is beating the bearing to death? I didn't grease the bearing; could that have caused the problem? (I hope so!)

Pix of the bearing in the slave included. Thanks in advance!
 

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You can pull the rod out and roll it on a flat surface, like a plate of glass to test it. You may be in the market for a new pressure plate, or springs? Something must be binding and causing the rod to spin excessively.

t_bare
 

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Discussion Starter #3 (Edited)
You can pull the rod out and roll it on a flat surface, like a plate of glass to test it.
The rod seems to be true:

Good suggestion about plate or springs! Swell, I'm stuck in Southern CA without a vehicle. Good thing I can walk to work for a few days. There's also a major bearing distributor a few miles away; that will provide a temporary fix until I can repair it properly.
 

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IIRC, the throw bearing on dry clutches is an issue re becoming seized around the rod causing it to spin. If you can't pull the rod out then check the rod-throw bearing interface at the throw bearing end. :) If your aftermarket slave is a wide piston type, you may need to dial in the clutch lever plunger screw a tad if you are having problems finding neutral. :)
 

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Discussion Starter #6
Clutch Control Rod Followup Question

So what I'm getting from the thread here (and elsewhere) is that there is a second bearing on my ST4S clutch control rod. Is that correct?

I'm not able to withdraw the rod, so a seized bearing somewhere in there makes sense to me. The rod spins when the engine is running, but I'm able to stop it with a moderate amount of pressure. I can understand how that rotation could be causing the bearing in the clutch slave to fail.

Should I be able to withdraw the rod? If there is in fact a bearing in there (not the one in the clutch slave) how is it accessed?

Thanks again!
 

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Discussion Starter #7
OK, according to the parts guide there are two bearings in there. I assume I'm not getting to them without getting oily.
 

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If you take off the clutch pressure plate off it may come off with it. Then you can remove the push rod and the (throwout?) bearing with a drift. My guess is your bearing on the pressure plate is toast or tweaked causing the pushrod to spin excessively.

t_bare
 

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Not wanting to seem unhelpful but why start a new thread on it ?
Surely anybody reading this who would like to help, but isn't aware of your previous thread, would like to read back through the problem to see what the story is so far ?

There are 42,623 members on here, and 117,071 (at time of counting) different threads.
Do you think that not only are they all familiar with your previous thread, but also that it is at the forefront of their minds as they wake up on this sunny morn ?

Best of luck with a workaround, but please keep problems to one thread. Not only does it help those that wish to help you, but also in turn it helps you too.
 

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not wanting to seem unhelpful but why start a new thread on it ?
Surely anybody reading this who would like to help, but isn't aware of your previous thread, would like to read back through the problem to see what the story is so far ?

There are 42,623 members on here, and 117,071 (at time of counting) different threads.
Do you think that not only are they all familiar with your previous thread, but also that it is at the forefront of their minds as they wake up on this sunny morn ?

Best of luck with a workaround, but please keep problems to one thread. Not only does it help those that wish to help you, but also in turn it helps you too.
+100%
 

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Not wanting to seem unhelpful but why start a new thread on it ?
Surely anybody reading this who would like to help, but isn't aware of your previous thread, would like to read back through the problem to see what the story is so far ?

There are 42,623 members on here, and 117,071 (at time of counting) different threads.
Do you think that not only are they all familiar with your previous thread, but also that it is at the forefront of their minds as they wake up on this sunny morn ?

Best of luck with a workaround, but please keep problems to one thread. Not only does it help those that wish to help you, but also in turn it helps you too.
Threads now merged.
 

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Discussion Starter #13
If you take off the clutch pressure plate off it may come off with it. Then you can remove the push rod and the (throwout?) bearing with a drift. My guess is your bearing on the pressure plate is toast or tweaked causing the pushrod to spin excessively.

t_bare
Indeed, pressure plate bearing is toast. Well played, Sir!
 

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Discussion Starter #14 (Edited)
However, I seem to have a new problem after having taken out the clutch basket, plates, pressure plate etc.

My clutch is now very grabby. (I believe that's what you call it, the opposite of slipping) For example, on the center stand the rear wheel still turns in first gear, with the clutch pulled in. In neutral, the output part of the clutch still rotates. If I try to ride this way (which I did only around the block) the engine really wants to die while stopped in first gear. I assume this is very bad for the engine from what I've read in part threads.

For the heck of it, I removed one of the pressure plates to see what would happen. The output stopped rotating while in neutral but it slips like crazy, so that's not a fix. There is still a decent amount of material on the friction plates, except for one, which has been stripped clean. Unfortuantely I didn't note it's order in the clutchpack, although I think it was one of the first, if not THE first friction plate inboard.

I'm definitely going to get a new pressure plate bearing and new clutch plates but do you all think that'll fix the problem? Seems like the clutch rod is not pushing far enough. I bled the clutch really well, I don't think that's the problem. The adjuster at the master is all the way in.

One last thing; this comes at a very inconvenient moment. I'm moving from this weekend, and the bike needs to move with me Saturday. In this condition, can the bike be ridden for about 12 miles without hurting the motor? I figure I'll encounter about 15 red lights or stop signs. If you all advice, I have AMA towing that can get the bike to my new place, although this is sort of a hassle that I'd prefer to avoid.

Thanks again!
 

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...Seems like the clutch rod is not pushing far enough. I bled the clutch really well, I don't think that's the problem. The adjuster at the master is all the way in.

Thanks again!
This is an inherent problem with the aftermarket slaves. The slaves have a larger diameter piston in them which makes the pull feel "lighter". As the lever at the clutch master will only move a fixed amount of fluid, the result is that the larger diameter piston in the slave does not travel as far as the stock slave piston. This of course results in drag on the clutch plates with the lever pulled all the way in. The only real cure for this is to either go back to a stock slave, or to get a good set of CRG adjustable levers so you can increase the travel at the lever.

Do not be tempted to start turning in the screw at the master cylinder. Many believe this is an "adjustment" screw, but turn it in too far and you'll block the return hole in the master cylinder. As the clutch fluid heats up while riding, it will not be able to expand back into the reservoir and it will begin "pushing" the slave cylinder. Ultimately this will result in a clutch that slips.

I've lived through these very things with my evoluzione slave, and were I to have to do over again I'd stick with the stock unit.

Best regards,
 

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Discussion Starter #16
I've lived through these very things with my evoluzione slave, and were I to have to do over again I'd stick with the stock unit.
Well darn, it was working fine before I removed all the plates and basket. (aside from the previous problem of bearing failure of course) I've replaced the clutch pack before and everything went fine.

I don't suppose replacing the (well-worn) clutch plates in a different order could affect anything...
 

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The clutch slave cylinder ? when you replaced the bearing did you replace like for like,
so the push rod has the correct location.
The pressure plate bearing have you replaced that one all so?.
as this will spin the push rod and cause heat which gives you problems.
The other thing is what is your worn clutch stack height ?.
The clutch master cylinder if you have adjusted the the screw that works directly on the
piston back it back so you have a tiny amount of free play so the piston returns
fully.
The clutch pressure plate only needs to lift move 2mm/ish to give you a
good free clutch but you have to have the rest of the things set to
achieve this.

brian.
 

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However, I seem to have a new problem after having taken out the clutch basket, plates, pressure plate etc.

My clutch is now very grabby. (I believe that's what you call it, the opposite of slipping) For example, on the center stand the rear wheel still turns in first gear, with the clutch pulled in. In neutral, the output part of the clutch still rotates. If I try to ride this way (which I did only around the block) the engine really wants to die while stopped in first gear. I assume this is very bad for the engine from what I've read in part threads.

For the heck of it, I removed one of the pressure plates to see what would happen. The output stopped rotating while in neutral but it slips like crazy, so that's not a fix. There is still a decent amount of material on the friction plates, except for one, which has been stripped clean. Unfortuantely I didn't note it's order in the clutchpack, although I think it was one of the first, if not THE first friction plate inboard.

I'm definitely going to get a new pressure plate bearing and new clutch plates but do you all think that'll fix the problem? Seems like the clutch rod is not pushing far enough. I bled the clutch really well, I don't think that's the problem. The adjuster at the master is all the way in.

One last thing; this comes at a very inconvenient moment. I'm moving from this weekend, and the bike needs to move with me Saturday. In this condition, can the bike be ridden for about 12 miles without hurting the motor? I figure I'll encounter about 15 red lights or stop signs. If you all advice, I have AMA towing that can get the bike to my new place, although this is sort of a hassle that I'd prefer to avoid.

Thanks again!
Dry clutches are naturally grabby and difficult to modulate. They may be great on the track re light weight, more power, easy access etc and so on, but for everyday rides, wet is best, so that grabbines you describe may not be abby-normal. :)

The clutch basket always rotates. It is driven by the crank and rides on a bearing on the main shaft. Whether or not the power of the pistons as they rotate the crank and then the clutch basket is passed through the gear box is determined by the clutch drive plates, ie tabs in the outer basket/friction plates, and the driven plates, tabs in the clutch hub/steel plates and whether or not the bike is in gear. When you"engage" the lever, you "disengage" the clutch, ie interput connection between drive and driven plates/power transmisssion, but the basket always spins. The push rod creates the plate separation and the clutch spring/pressure plate creates their re-engagement/power transmission. :)

The adjuster screw in the clutch lever should NOT be adjusted all the way in, but rather a "tad", which means just enough movement in the rod by the slave to separate the plates. When it is adjusted too far in, it will block a fluid return hole and the rod will not be pushed back by the pressure plate/clutch springs all the way and will cause slippage/hard shifting.

That the wheel rotates on the stand when first gear is enaged is not a problem. If when you are on the bike, and engage first gear, of course it will clunk, but it should not stall, nor should you feel any drive. If it just spins on the CS, it's okay. :)
 

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Discussion Starter #19
If when you are on the bike, and engage first gear, of course it will clunk, but it should not stall, nor should you feel any drive. If it just spins on the CS, it's okay. :)
This is exactly my problem though. For some reason, my clutch is not fully disengaging, therefore the bike wants to stall when stopped in first gear with the clutch disengaged.

I assume this is because the pushrod is not traveling far enough. It was before I disassembled my clutch, the only logical thing I can think of is that the replacement bearing in clutch slave is not "tall" enough. It's not an OEM bearing, but it supposedly conforms to the correct specs. The original disintegrated so I can't directly compare them.

Whatever the reason, how bad is it to ride for 30 minutes with a clutch that is not fully disengaging? While stopped, I have to keep the motor revved at about 1.5k to keep from stalling.
 

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This is exactly my problem though. For some reason, my clutch is not fully disengaging, therefore the bike wants to stall when stopped in first gear with the clutch disengaged.

I assume this is because the pushrod is not traveling far enough. It was before I disassembled my clutch, the only logical thing I can think of is that the replacement bearing in clutch slave is not "tall" enough. It's not an OEM bearing, but it supposedly conforms to the correct specs. The original disintegrated so I can't directly compare them.

Whatever the reason, how bad is it to ride for 30 minutes with a clutch that is not fully disengaging? While stopped, I have to keep the motor revved at about 1.5k to keep from stalling.
No neutral?
 
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