Flywheel/clutch gear torque

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rjk40
Parallel Twin
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Flywheel/clutch gear torque

Post by rjk40 » Tue Jun 26, 2018 1:06 pm

I just wanna be sure:

Since the torque for securing the crankshaft nut holding the flywheel/clutch engagement gear is quite considerable, and since I have the clutch basket assembly off until I replace the disks and thus cannot use the clutch holding tool, I need to hold the crankshaft still while torqueing the crankshaft's flywheel nut on. I am assuming that, since I have the generator stator on the other side of the motor off at present, I can just hold the generator rotor nut with a 30mm socket and long lever, while I use an impact driver to set the flywheel nut into place. If I am missing something here, it is not obvious to me.

Any coments are welcome.

If any of you disagree with this approach, I could just re-install the clutch so that the clutch basket gear hooks up with the flywheel gear, I just don't want to break off a tooth on either piece.

I have acquired new shims for the flywheel side, but have yet to measure the old ones to compare with the new (still looking for my micrometer... likely buried under the Ducati guts strewn upon my workbench). That comes, of course, before torquing the nut on and bending over the tab washer since they go on behind said nut and tab washer.

Still looking for the right torque value for both the flywheel nut and the clutch nut.

Regards,
Richard

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Gardner
Diana
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Re: Flywheel/clutch gear torque

Post by Gardner » Tue Jun 26, 2018 8:20 pm

Hi Richard, remember, the crankshaft is 3 pieces pressed together and trued to less than .001 run out. It does take 30 tons to press together
with .004 interference fit but I don't think a good sized wrench on each end twisting in opposite directions would be the best way to tighten
the flywheel nut. If you feel more comfortable torquing to the specified value then a clutch basket holding tool would be the way to go.
I clean the threads in the nut and the crank, apply a few drops of red loctite and hit the nut gently with an electric impact wrench.
The flywheel is on a taper with a key, it all locks up pretty tight. I don't use the tab washer.

Mark
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wdietz186
Cagiva Alazzura
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Re: Flywheel/clutch gear torque

Post by wdietz186 » Fri Jun 29, 2018 7:21 am

Cross torquing the crankshaft can pull it out of true. Not so much the ign. flywheel as the taper fit doesn't need much torque to hold it securely(too much can damage the crank and/or flywheel)the but torquing alt. rotor holding the flywheel nut or torquing the clutch hub by holding the alt. nut may twist the crank out of true. The crank pin/crank cheek interference fits do vary from the .004" spec. as does anything not CNC manufactured.

rjk40
Parallel Twin
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Re: Flywheel/clutch gear torque

Post by rjk40 » Fri Jun 29, 2018 7:58 am

Thanks Gentlemen.

In my original comments, I had mentioned that I had yet to install the clutch, thus the clutch gear would not be present. I am concluding that your recommendations do, in fact, warrant the clutch reinstallation to give a "stop" to the crankshaft rather than cross-torqueing it from the other (right) side.

I do have the clutch holding tool, and will proceed in the recommended direction by using the clutch to hold the crankshaft stationary whilst tightening the crankshaft flywheel nut with my handy dandy torque wrench. I am guessing from other Forum entries that around 55 ft-lbs. will work.

Again, I thank all of you for sharing your knowledge with me; it has saved my sorry posterior on numerous occasions.

Regards,
Richard

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Craig in France
Cagiva Gran Canyon
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Re: Flywheel/clutch gear torque

Post by Craig in France » Fri Jun 29, 2018 8:34 am

rjk40 wrote:
Fri Jun 29, 2018 7:58 am
In my original comments, I had mentioned that I had yet to install the clutch, thus the clutch gear would not be present. I am concluding that your recommendations do, in fact, warrant the clutch reinstallation to give a "stop" to the crankshaft <snip>
Richard, that's the way the factory manual says do it, so it might seem best ... ;).

(P.s Just for the avoidance of doubt: Naturally, the nut and tab washer are installed prior to mounting the clutch drum. And the clutch drum nut is tightened up before the flywheel nut.)

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rjk40 wrote:
Fri Jun 29, 2018 7:58 am
I am guessing from other Forum entries that around 55 ft-lbs. will work
I can't say for the 750 engine, but, FWIW, here's the values from the Dramah manual. As Mark and Bill have already said, the flywheel is on a taper so the nut shouldn't need to go up super tight. THAT treatment is reserved the gearbox sprocket nut ... :-D

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rjk40
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Re: Flywheel/clutch gear torque

Post by rjk40 » Fri Jun 29, 2018 8:50 am

Thanks kindly, Craig,

As always, your info is very comprehensive, and quite reliably forestalls potential screwups (which I REALLY appreciate), on my venerable 860GT.

Best Regards,
Richard

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Craig in France
Cagiva Gran Canyon
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Re: Flywheel/clutch gear torque

Post by Craig in France » Sat Jun 30, 2018 12:26 am

rjk40 wrote:
Fri Jun 29, 2018 8:50 am
<snip> ... my venerable 860GT.
Woops. I need to correct myself a little, Richard - for some reason I thought you had a 750. My bad.

Errr ...

The method for torquing the flywheel nut is the same. However, I notice that the torque value for the clutch centre nut is different, 860 vs. Dramah: 7 Kgm (=50 ft/lb +/-), says the 860 manual. Dunno why ...

Flywheel nut's the same, mind: 4.5 Kgm.

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