Wet clutch slipping

[MonsterHPD]

if you have the censor function on it replaces f*uck with "make the beast with two backs"

I didn't even know there was a censor function. Obviously, I have to get rid of that, don't want to miss out on creative language 

With some luck I will soon have a spring tester, intended for fork springs but maybe OK for some clutch spring testing to compare my 900 springs with my 800 springs.

The steel plates don't look glazed, but I suppose I could glass blast them just in case, maybe fit an extra disc if there's room, look up the springs and maybe shim them a little, throw it all together and see what happens.  Even if my reference for "expensive" has been modified rather thoroughly since I got into the Ducati world, I thoroughly dislike throwing out a clutch that looks perfectly OK like this one does.

     

[ducpainter]

I've used a scotch-brite wheel on a right angle grinder to rough up dry clutch steel discs.

Less clean up than blasting.

[MonsterHPD]

I've used a scotch-brite wheel on a right angle grinder to rough up dry clutch steel discs.

Less clean up than blasting.

Right ... I'll visit the Baumarkt at first opportunity 

[brad black]

you'll need thinner steels to fit an extra plate in.  with my old style 750 i ran the 1.5mm steels from (probably) the stash of old sintered sp/sps style packs, and then added another friction plate.  not sure how much thicker it was now, but they're different design and more restrictive (slave in cover).  it was noticeably heavier, but didn't slip any more.  i later just replaced it with a new pack (the horror) and again it was fine.  the pack in there was what came with it when i bought the motor s/h with 80,000km or so on it.

1098 has thinner steels i believe.

[MonsterHPD]

1098 has thinner steels i believe.

Does that mean a 1098 clutch pack might / would fit in the M800 basket / hub?

[brad black]

1098 has an extra friction plate, and is maybe 2mm or so thicker than an old dry pack.

[MonsterHPD]

1098 has an extra friction plate, and is maybe 2mm or so thicker than an old dry pack.

And it would fit otherwise?

If so, interesting. It sounds like a 1098 clutch in an 800 would last forever ..... 

[brad black]

well, it's a dry clutch material and style, so i'd be wary of it.

[MonsterHPD]

well, it's a dry clutch material and style, so i'd be wary of it.

Ooopps ... forgot that little detail 

Anyway, thanks all for all the input. I'll check parts and consider what to do. Since the bike is perfectly rideable as it is, and since nothing seems to get damaged, some experimenting might be worthwhile.

[MonsterHPD]

Hello Swede 

It's not strange that an eleven year old clutch is slipping at 27,000km. Discs and/or springs....

My first two APTC clutches started slipping at 25,000km at +/- 6,000 revs - after changing from full synth oil to semisynth the third one lasted 40,000km. My fourth is a 750, non APTC, and has ~40,000km on it without slipping, but it also has two extra discs.

Hi again, Norge.

I've been checking up the clutch and am now evaluating options .... you mentioned above that your regular model clutch has 2 extra discs in it (presumably one steel, one friction).
How did you fit that in? I don't see too much room for a thicker clutch pack since the locating tangs on the pressure plate will have too little "stick-in" on the clutch hub, and I don't see much room for machining ..... so I'm curious
   

[stopintime]

Don't know, a mechanic did it. I guess it's possible that he meant washers under the springs, but my impression was and is clutch plates. I'll ask later and get back to you.

[MonsterHPD]

Don't know, a mechanic did it. I guess it's possible that he meant washers under the springs, but my impression was and is clutch plates. I'll ask later and get back to you.

OK, thank you very much 

[MonsterHPD]

Well, time for an update, might be of interest to someone...

Sinc I felt bad about throwing away a clutch that looked and measured perfectly OK,  I decided to see if it could be salvaged. I did the following:

• Took 2 thin steel discs out and replaced them with 2 thick ones, increasing clutch pack thicknes by 1 mm
• Glass-blasted all steel discs; I never got round to the Scotch-brite ....
• Lightly dressed the friction discs with very fine emery paper on a glass pane; on all discs it was obvious that the friction pads were not flat; they all started sanding on a rather narrow part; I lightly sanded the until the whole surface was ground
• I machined ome 2 mm washers to put beneath the heads of the allen screws for the clutch spring, increasing pre-load by 2 mm 

Today was the tradiitional May 1st ride of the Ducati Club, about 250 km in 5-ish°C temperatures. Tested on the motorway, the clutch did not slip as it did last year (6th gear, >6000 rpm). So far, so good .... I'll report when (if ...) it starts slipping again.

Apart from that, re-valved (softer) Öhlins shock worked  great over rutted roads, and the newly fabricated exhaust did not crack up :-)

 

[MonsterHPD]

Hello,
time for another update in case someone might still be interested ....).

The clutch held up all of last summer, incluing some trackdays and quite a bit of road riding.

It was not perfect, though, but instead of "slipping up" when torque got too high, it sometimes "slipped down" on powershifts, slipping down to full grip.

Took the clutch out a few weeks ago, it looked exactly the same as last year, so I made some new washers and now run 4 mm pre-load washer. That's the max I'd o with the stock screws, with any thicker washers I'd use longer screws.

Today was the first ride of the season for me, from a pretty cold spring with even sleetyrain not too long ago we now have had a few days of summer-ish temperatures. The M800 Dark got some pimp over the winter, mostly left-over bits from other bikes (Öhlins forks, turned-down flywheel, semi-radial master cylinder), but also some new carbon fibre.

Dry weightt (with oil) now is something like 169 kg, I'm slightly suprised at the weight  of these Monsters. My 900, with everything taken off that could reasonably be taken off, was something like 179 - 180 kg dry but with oil. The M800, with pretty much the same efforts weight-wise, is about 10 kg's lighter. I had not expected this to be the case.

Anyway, in the background, white anemones (or whatever they might be called in english), there's a billion of them and to me, this is the best time of year.

P5060034 by torbjörn bergström, on Flickr    

[koko64]

Nice bike .