Clutch Grabs Violently on Fresh Engine

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herbg
Diana
Posts: 51
Joined: Thu Nov 10, 2011 4:56 pm

Clutch Grabs Violently on Fresh Engine

Post by herbg »

Rolled the bike out today for the 1st time after a fresh engine rebuild (thanks to Guy Martin of MBP). Once I got it started, I put it in 1st gear and slowly let out the clutch lever while rolling on the throttle.

However, once the clutch handlebar lever was almost fully out, the clutch engaged violently with the bike lurching forward.
A bit startling so I tried it again in my attempt to ride up the driveway. Unfortunately, it grabbed again - this time stalling the engine.

I realize a new clutch might need to be broken in but I didn't expect the "on/off switch" engagement I'm getting now. There is no ability to ease out the clutch while rolling on the throttle - making it impossible to slowly ride the bike.

Clearly something is off. So, before I begin to fiddle around with the clutch adjustments, I'm looking for tips on where to begin and what might be going on. Looking for some guidance on setting up the clutch engagement correctly.

The clutch is a S1425 SURFLEX competition ALLOY clutch kit including springs, alloy friction and steel plates. I'm also using a Brancato extended clutch lever.

Any idea on what might be going on?
_________________________________
2013 Ducati 1200S Multistrada
1985 Ducati Mille S2
1978 Ducati 900 SS (Blue/Silver Borrani)
1972 Ducati 350 Desmo (Silver Shotgun)
1969 BMW R69S (Earles Fork)

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Craig in France
Cagiva Gran Canyon
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Joined: Tue Mar 23, 2004 3:58 pm
Location: Montpellier, France

Re: Clutch Grabs Violently on Fresh Engine

Post by Craig in France »

Well, it's basically the springs that control the clutch engagement, so that's where I'd look.

Also, you say you've fitted a competition clutch (why?), and that probably explains things a bit too. If you gave it more revs, it probably wouldn't stall. But it will send you down your driveway like a bullet. Which is kinda the idea ...

herbg
Diana
Posts: 51
Joined: Thu Nov 10, 2011 4:56 pm

Re: Clutch Grabs Violently on Fresh Engine

Post by herbg »

This is normal behaviour for a competition clutch? There's nothing on Steve's site that says this is "Not for Street Use":

https://store.bevelheaven.com/Engine-Re ... quarecase/

I assumed the "competition" part refers to the "alloy" - thus lighter and less centrifugal force.

I'm thinking it has something to do with the setup of the clutch (adjustments, etc) BUT, not having any experience with this clutch, I am prepared to replace it. UGGHH !!
_________________________________
2013 Ducati 1200S Multistrada
1985 Ducati Mille S2
1978 Ducati 900 SS (Blue/Silver Borrani)
1972 Ducati 350 Desmo (Silver Shotgun)
1969 BMW R69S (Earles Fork)

ducadini
860 GT / GTS
Posts: 256
Joined: Sat Jul 31, 2004 9:54 am
Location: Antwerpen

Re: Clutch Grabs Violently on Fresh Engine

Post by ducadini »

I think We can find the reason in the first sentence :
Rolled the bike out today for the 1st time after a fresh engine rebuild
With new clutchplates and springs and a new setup (extented lever) it was SURE to get exciting :-D :-D

Give the plates some time to oil up and VERY probably it will become softer to control.

I don't recall anyone saying that using a Ducati for daily use with some "competition" parts in it was easy.
Fitting some Blue/white cams just made it more exciting :-D :-D :-D :-D

Anyway : happy to see You're using the bike, hope You get used to using it's potential.

ciao
ducadini
Nego i ricordi peggiori
Richiamo i migliori pensieri

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geodoc
750 GT
Posts: 179
Joined: Thu Jul 18, 2013 3:57 pm

Re: Clutch Grabs Violently on Fresh Engine

Post by geodoc »

Not saying that my clutch problem cure would also cure yours, but. After I got my GT engine back from a complete re-bop by Guy, the clutch stuck & grabbed horribly. I tried all manner of things to rectify with no effect. Finally, in desperation I took one of the steel plates and even though it looked flat enough checking against a glass surface, I shot it with machinist blue and sanded it with 600 wet or dry emery paper on plate glass. It was pretty flat, but not quite perfect. I ended up taking all the plates and wet sanded them on both sides until they showed perfectly flat with the machinist blue, re-assembled and the clutch then worked perfectly. I had a stock clutch with Surflex plates.

I fall else fails ....................




.

jockduck
Mariana
Posts: 32
Joined: Sun Jan 17, 2010 3:21 am
Location: South Australia

Re: Clutch Grabs Violently on Fresh Engine

Post by jockduck »

Sorry to hear of your problem but I also have similar problems with the Surflex upgrade kit, I grabs badly when cold improves after a few kilometers and is normal once the engine is at normal working temp BUT then it slips when giving the motor a handful at 4000+ rpm, my other two bikes have stock clutches and behave well, I'm thinking of swapping back to stock if I have enough bits.
Jock

wdietz186
Cagiva Alazzura
Posts: 703
Joined: Sun Sep 10, 2006 5:40 pm

Re: Clutch Grabs Violently on Fresh Engine

Post by wdietz186 »

You might try soaking the plates in engine oil for a couple of hours, many clutch materials need to be fully saturated to work properly.

herbg
Diana
Posts: 51
Joined: Thu Nov 10, 2011 4:56 pm

Re: Clutch Grabs Violently on Fresh Engine

Post by herbg »

All very good suggestions. I spoke with Guy Martin on Monday and told me the clutch is probably sticking from sitting all winter. He did say that he test rode the bike extensively before it was shipped back to me and, while the clutch is a bit more aggressive, he had no difficulty negotiating stop-and-go traffic with the bike.

He gave me a few tips to try to "unstick it" so I'll give that a go when I get a chance to get back at it. Last resort, he also suggested taking the clutch cover and pressure plate off to inspect the plates. Hopefully, I don't have to resort to that.
_________________________________
2013 Ducati 1200S Multistrada
1985 Ducati Mille S2
1978 Ducati 900 SS (Blue/Silver Borrani)
1972 Ducati 350 Desmo (Silver Shotgun)
1969 BMW R69S (Earles Fork)

Lumpy
SD900 Darmah
Posts: 327
Joined: Sun Mar 25, 2007 5:49 am

Re: Clutch Grabs Violently on Fresh Engine

Post by Lumpy »

Did you get this issue sorted Herbg? Interested to know the outcome as I will be fitting a new clutch to my 860 in the future and was thinking of the 1425 Surflex upgrade. Still wondering if to re-use my metal plates and just put new fibre plates in.

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BevHevSteve
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Re: Clutch Grabs Violently on Fresh Engine

Post by BevHevSteve »

By default, you need to ALWAYS soak the fiber plates in your engine oil before assembling them. All WET clutch kits, that is. You have a lot of NEW stuff. Your old motor you probably got away with just giving it a bit of gas and letting the clutch out.... This is all new and will take time to figure out what she needs to get her going,

Put the bike on the center stand, start and put into gear. Let the clutch out and rev the motor, and go through the gears several times up and down. Now the the same and put a VERY LIGHT pressure on the rear brake... just barely push the pedal down. Do the same thing as before, up and down through the gears.

Put her back in Neutral, stop the rear wheel, bike off the center stand and this time, give her a bit more gas (rev it up a bit higher than you can image required) and let the clutch out SLOWLY. Just go ride the bike around. Pull over and stop a few times practicing starting and stopping, it won't take very many times and you will have your new motor, new clutch and new extended clutch arm figured out.
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herbg
Diana
Posts: 51
Joined: Thu Nov 10, 2011 4:56 pm

Re: Clutch Grabs Violently on Fresh Engine

Post by herbg »

So, it appears that the clutch basket that was installed in the rebuild is not the same as the original (which was cracked). The new basket is slightly shorter and, upon inspection, only 7 clutch plain and lined plates installed. The special driven lined plate, with teeth bent outwards, is also not installed.

Fortunately, I was able to retrieve the special driven lined plate and plain plate.

However, now I am faced with finding a replacement clutch housing for my bike. Evidently, there is a difference among 900SS clutch housings. My bike is a pre-Bosch ignition 1978 900SS - a 1977 carryover model.

Not sure where I can find this housing. And, if I do find the right one, I'm assuming the teeth on the clutch baskets are all the same, right?

Hoping someone has some experience with this topic.

Thanks,
Herb...
_________________________________
2013 Ducati 1200S Multistrada
1985 Ducati Mille S2
1978 Ducati 900 SS (Blue/Silver Borrani)
1972 Ducati 350 Desmo (Silver Shotgun)
1969 BMW R69S (Earles Fork)

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81mhr900ss
Mach 3
Posts: 92
Joined: Tue May 31, 2016 3:49 pm

Re: Clutch Grabs Violently on Fresh Engine

Post by 81mhr900ss »

Hi Herb: My go-to site for this kind of information is Ducati Classics: https://www.ducaticlassics.com/parts/75 ... -sport/all

It shows the two different gear change and clutch layout pages but the clutch housing and drum have the same part numbers; it looks like the clutches are exactly the same for 75-77 and 78-82; I think the only differences between earlier and later models was left or right side gear change. I went back to the 75 860GT and it is the same part numbers too. Going back further, the 74 750SS has a different part number for the housing but the drum is the same as later models. Surely if the outer housing is shorter, the inner drum would stick out?

You are right about the teeth on the housings; all the same. I can't find any reference to a shorter housing. I had a 75 860GT and still have an 81 MHR and as far as I can see from the drawings and remember, the clutches are identical. Are you sure that the new housing is shorter than the original? With all 16 plates installed, it's a tight fit.

I'll scan my usual sources and see if I can find a housing. Good luck.

Here's one on this site: https://store.bevelheaven.com/Engine-Re ... S-etc-NOS/
another: https://www.ebay.com/itm/Ducati-Bevel-9 ... 2922700848

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