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 Post subject: 906 clutch mfg. 1989
PostPosted: Tue Aug 15, 2017 12:02 am 
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Joined: Wed Nov 28, 2007 5:19 pm
Posts: 5
Location: Williamstown, MA.
My blue 906 is registered as a 1990, but the sticker on the frame indicates June of 1989 as the date of manufacture. The clutch plate count and thickness on these early 906's seems to be different than the rest of the bikes that have the slave piston on the left side of the bike. The slave piston on my bike is on the clutch cover, at any rate, and replacing the steel and friction disks has been a royal pain, but I think I cracked the code; the key seems to be to save the outside single sided friction plate (3mm thick) when you replace the other plates - you won't get a new one when you order replacement plates. Also save a 'dished' plate from your old stack.

The first plate next to the engine is dished, with the dot facing away from the engine. After that, I alternated the new friction plates with four 2mm steel plates except for one 1.5mm plate buried in the stack. Finally, your second dished plate, dot facing the engine, and the 3mm one sided friction plate next to the big round c-clip in the basket. I am NOT taking that apart again, but I think there is a total of 11 plates plus the single sided friction plate.

When you put the pressure plate back on, make an effort to check with a stable pointer on a magnet or something that the center boss where the slave piston presses against runs true - you can tap it a bit on the edge to budge it. I was all ready to put in a new slave piston because the clutch was squealing when I pulled the clutch in, but that was due to a slight mis-alignment with the pressure plate. Crank the engine with the starter when you check alignment, with the emergency cut-off switch turned OFF; you won't be able to turn the whole assembly by hand.


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 Post subject: Re: 906 clutch mfg. 1989
PostPosted: Tue Aug 15, 2017 9:50 pm 
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paso grand pooh-bah
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Joined: Wed Dec 05, 2007 12:35 am
Posts: 1588
Location: Newzealand
model: 906 Paso
year: 1990
If you didn't get the single sided plate you got the wrong kit . More likely that the bearing inside the slave piston is whats really making the squealing noise ( can come and go ). Have a look at the clutch mods in the F A Q's. :)

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 Post subject: Re: 906 clutch mfg. 1989
PostPosted: Wed Aug 16, 2017 10:34 pm 
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Joined: Wed Nov 28, 2007 5:19 pm
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Location: Williamstown, MA.
Thanks, McTool; I have to admit I was a bit skeptical when the one sided friction plate was not in the kit. I ordered from a well established Ducati dealer who had to get it from Italy ( ! ) For the price I suspected that those little yellow flakes in the friction plates were made out of gold. I told him that the bike was manufactured in '89 but he assured me that the clutches were all the same. I bought the bike used and had some trouble registering when I first bought it. Later clues were that it had the european tail light, so it may have been grey market. Perhaps my clutch assembly was a one-off.....

At any rate the steel and friction plates are the common thickness as mentioned in every clutch write-up, but there is no way all the plates in the box would fit in the basket.

To edit my post, after a 3 mile check with no body parts on the bike, the clutch is as draggy as ever. In the driveway when I first checked, neutral was easy,but after the ride, I had to kill the engine to get neutral.

More news as it happens......


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 Post subject: Re: 906 clutch mfg. 1989
PostPosted: Thu Aug 17, 2017 5:30 pm 
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Joined: Wed Nov 28, 2007 5:19 pm
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Location: Williamstown, MA.
NEWS FLASH !!!!
As a retired machinist, I tend to save mechanical bits. The first clutch overhaul I did years ago was with a Barnett kit, and noticing that their springs were longer than the OEM ones that I took out, I swapped them in, thinking that the originals had lost some of their bounce. During all the many disassemblies of the clutch this summer, I measured the springs that were in there and compared them to the OEM springs I had saved. The difference was about 1/16". Today, rather than play around with plate location and thicknesses, I only changed to the shorter springs ( 1.522 long ) and it made all the difference in the world. My 3 mile test ride included hard accelerations ( Whee !) and many gear shifts on back roads with only the seat and gas tank on, and because of the clutch issues, the bike has not been inspected yet. Of course there was a cop coming the other way, but he didn't pay me any attention ( whew!). Returning to my garage, neutral came right up, there was no dragging in-gear with the clutch pulled in, and I gave my wife permission to give me a congratulatory kiss for my triumph.

The kit I bought from the dealer was Ducati part #19020013A which does not list the Paso as an application. I think I got away with it, but I was on the verge of ordering from Bevel Heaven a Surflex # S1686 which does list the Paso.

I also changed out the needle valve in the carb - had to re-use the seat because the hole in the carb rebuild kit seat was way smaller than the original, though the needle taper showed some wear. The grosjet I ordered was way too long; get the shorter one....something funny about the threads too
. I also put in the longer auxiliary venturis mentioned by Higgy. Jet mods and emulsion tubes had already been done on the advice of the guy at Miller Specialties in Connecticut.

So far, so good. Cheers.


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 Post subject: Re: 906 clutch mfg. 1989
PostPosted: Fri Aug 18, 2017 5:10 am 
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paso grand pooh-bah
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Joined: Wed Dec 05, 2007 12:35 am
Posts: 1588
Location: Newzealand
model: 906 Paso
year: 1990
I think ( memory thing ) that the Paso really only differs in that it needs either a thick steel plate on 1st ( either that or two thin ones on 1st .... cant remember ) the idea being that the 1st steel acts as a flange at the back of the inner hub . if you look at the flange you can see that it aint big enough to support a friction plate by itself .
And there is the single sided plate on the outside has to be thicker as it has no support other than the circlip holding the whole plot together. If push came to shove you could always remove the friction material off one side of a new plate , and both sides of an old plate and chuck it in there if you don't have a proper one sided thick plate.
Mostly , I found that the biggest difference to improve the clutch is to make sure the plates are clean ( no black shit stuck to the friction plates ), and that the hydraulic side it properly bled . The paso has the " slave in the clutch cover " and while I think the other sort ( ah la SS ) is better the Paso set up can be improved/modified to be just as good ...... and we don't get the dreaded " Ducati dry clutch rattle " that the ones with the slave on the left have .

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