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Discussion Starter · #1 · (Edited)
Hey Guys,


2 days ago i experienced a slipping clutch. I stopped, called some people, and after that stop somehow no slipping clutch anymore. Could not reproduce it for the rest of the whole day. However i washed my bike the day before that with car shampoo with wax in it. Now this morning 2 days later when i washed it again, and went to get gas, there we go, a slipping clutch again. Because of this i think the car shampoo got into my clutch and the wax is screwing it up (open clutch cover). Anybody that had the same thing happen?

Just to give me some ease of mind i checked the service manual and opened up my clutch to measure my friction plates. The manual states a minimum thickness of 2.6mm, and mine are 2.8mm.

Now i was wondering, does anybody have any idea how thick the friction plates are when they are new? If they are for example 3mm new i know my plates are at half their life. 4mm, then i know its going to be time for some new ones.

Corcerning a Hym1100 from 2008 btw :).

BTW all the friction plates look like the included picture. Fine or time to replace??
 

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The standard test for detecting worn-out clutch plate friction material is to watch for slippage when accelerating in top gear. Some people are just harder on clutches than others, so service mileage will vary over a wide range.

You can often stop slippage by maintaining the force pushing the plates together. The idea here is to maintain the 38 mm new stack height as the friction material wears off and reduces the thickness of each plate. The higher the stack height, the more the springs are shortened/compressed, and the greater the force pushing the plates together. The clutch slips when there's not enough force supplied by the springs or the friction material is worn completely off.

The service limit on 3 mm friction plates is 2.8 mm. For 2.5 mm plates the service limit is 2.3 mm.

The plain metal plates come in stock 2.5 mm or 3 mm thicknesses. When the overall plate stack height wears 0.5 mm, replace one 2.5 mm flat plate with a 3 mm one. At 1 mm stack height wear, repeat for a second flat plate. At 1.4 mm - 1.6 mm wear, replace all the friction plates. Allowable friction plate wear is 0.2 mm (each).

Ducati considers both the plates and clutch basket to be wear items. By the time you need to replace the worn-out clutch plates the basket has been notched from the impact loads of the plates. Ducati specifies the allowable gap between the plates and basket as a quite small 0.6 mm, effectively saying to replace the basket and plates together.

Also check the pressure plate throwout bearing and pushrod for smooth rotation.
 

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2008 HyperMotard 1100S
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Strega covered it all (very) well. The one thing I would like to add is that, if you're inspecting clutch plates and steel plates, you need to check that the thickness is correct and that they're flat!

My dirt bike had nothing but clutch issues. I pulled it apart, and every plate & steel was within the allowed measurements for thickness. And to the naked eye, they all looked flat. But I got a small piece of glass and checked each plate and steel. Sure enough, two steels were warped; I replaced them and the clutch ran great.
 

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I got a small piece of glass and checked each plate and steel. Sure enough, two steels were warped ...
Don't confuse a warped plate with the one or more concave dished plates that are inserted in the stack to smooth out the clutch engagement when the lever is released.
 

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Discussion Starter · #5 ·
Wow what a bunch of information. Thanks guys!

Before i read all of this, i pulled apart the clutch to clean everything. Friction plates with brake cleaner and the steal plates with something like scotch bright. Just did a test drive, and everything works without slipping. Also tried the high gear technique and no slipping at all.

Also measured the stack height and it came in at exactly 38mm. Service manual clearly isnt correct stating 41mm minimum. Also my springs are shorter then the stated 41mm. They come in at around 39mm.

If the problem comes back again im going to use all of you guys information to check it out like bend plates etc.

1 quick thing. I dont have the bike that long, and everybody is writing about the hym1100 as a crazy wheelie machine. That it pulls wheelies in atleast 1st and 2nd gear. Im sorry but 2nd gear wheelies is a no go for me. Cant get it to lift. Am i crazy using this also as a way to check if my clutch is slipping :p ??? Or my technique/position and never really wheeling before could be the issue haha.

Thanks again guys.
 

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Okay, don't take this as Gospel, but a friend who rides a BMW R1200RT (which also as a dry clutch) burned up said clutch last year. If you think Ducati clutches are expensive, consider this: The BMW must be "broken in half" to replace the clutch. Labor is about 12 hours; add in parts and he got a $2500 repair bill.

What his BMW buds told him is that as the clutch wears, the fluid level in the reservoir increases, and if you don't remove some fluid, that excess places some pressure on the clutch (a bit like driving with your foot resting on the clutch pedal) and results in premature wear/clutch slip.

Again, I'd never heard of this, but thinking about it, makes sense. As your brake pads wear, the pistons in the calipers move outward, requiring more fluid--fluid level goes down. In the clutch system, as the clutch wears, the pressure plate moves closer to the slave cylinder, effectively lengthening the pushrod, and pushing fluid back into the reservoir. When the reservoir is full, pressure continues to increase....where does it go? Either causes a fluid leak at the reservoir, or applies pressure to the pressure plate, simulating your fingers pulling the lever just a bit.
 

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Again, I'd never heard of this, but thinking about it, makes sense. As your brake pads wear, the pistons in the calipers move outward, requiring more fluid--fluid level goes down. In the clutch system, as the clutch wears, the pressure plate moves closer to the slave cylinder, effectively lengthening the pushrod, and pushing fluid back into the reservoir. When the reservoir is full, pressure continues to increase....where does it go? Either causes a fluid leak at the reservoir, or applies pressure to the pressure plate, simulating your fingers pulling the lever just a bit.
Very interesting, this makes sense in my head too.
 

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1 quick thing. I dont have the bike that long, and everybody is writing about the hym1100 as a crazy wheelie machine. That it pulls wheelies in atleast 1st and 2nd gear. Im sorry but 2nd gear wheelies is a no go for me. Cant get it to lift. Am i crazy using this also as a way to check if my clutch is slipping :p ??? Or my technique/position and never really wheeling before could be the issue haha.
I have an '09 multi, basically same engine as yours. It is almost too easy to wheelie in 1st gear, have done it a few times without meaning to. I can get it to lift in 2nd but I have to try.

If you want to learn to ride wheelies, I'd recommend buy a 250cc dirt bike and practice in the dirt with armor on. I just priced out a rear fairing panel for my MTS, one of the little ones, as one of mine has a crack: $403 USD + taxes & shipping. Expensive bikes to learn tricks on, these Ducatis.
 

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1 quick thing. I dont have the bike that long, and everybody is writing about the hym1100 as a crazy wheelie machine. That it pulls wheelies in atleast 1st and 2nd gear. Im sorry but 2nd gear wheelies is a no go for me. Cant get it to lift. Am i crazy using this also as a way to check if my clutch is slipping :p ??? Or my technique/position and never really wheeling before could be the issue haha.
Position is everything. Accidental wheelies in 1st and sometimes 2nd are a fact of life with my bike that I’ve had to accept, because that’s when I’m likely to still be transitioning from a standstill position to my riding position. If I’m not paying attention to the throttle, up comes the front wheel. By 3rd I’m usually synced up with the bike and I have to make a deliberate effort with the throttle and clutch to lift the front.

(Yes believe it or not, I don’t particularly like doing wheelies, especially in built-up areas where I’m most likely to be in 1st and 2nd.)

And yes, doing wheelies isn’t really the best way to check for a slipping clutch. Too many variables. Top gear full throttle is the better indicator for clutch slip.
 
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