Super Stubborn Flywheel Nut

[ducwiz]

Greg,

afaik the n/c engines have the same thread as the w/c types, it is a metric M20x1/60°. I apply ~100Nm and use Loctite 243 (blue) on the dry and solvent-cleaned thread.


Hans

[gregwils]

Thank you Hans.

[BDang]

100 NM is about 74 ft-lbs, which is the same as wheel lug nut torque for all Lexus cars and Ferrari Testarossa. Does this sound a bit high for our little bike (my is 125 Sport)?
Lexus
All Models 1990-05 75 ft-lbs

Ferrari Testarossa(5 bolts) 1988-91 75 ft-lbs


http://www.discounttire.com/infoCenter/ ... orque.html

Regards,
Brian

[Dave450]

That torque value of 75 ft-lbs doesn't sound too high. As a comparison, Norton specified 70 ft-lbs for the Commando alternator nut, which also secures the primary drive sprocket on the crank, and the Norton camshaft sprocket nut is listed at between 60 and 80. The Ducati nut has a fine thread and can withstand high clamping pressures. One thing I want to try next time I remove the alternator is to put a belleville washer behind the nut and also behind the clutch centre nut, instead of those rather ineffective tab washers.

[BDang]

"instead of those rather ineffective tab washers."

Did it back out with the bent tab?

Brian

[Dave450]

"instead of those rather ineffective tab washers."

Did it back out with the bent tab?

Brian

The clutch centre nut did, yes, because the tang that engages with the mainshaft splines is ineffective. If there is even the slightest bit of slop on the splines, the tang tends to break or bend. Same with the nut for the final drive sprocket. The tab washer is useless there as well. I threw away the factory clutch tab washer and made one that was anchored to the spring posts. I then just bent the tab over as usual. This works. I got rid of the tab washer for the engine sprocket nut and just used a normal thin washer and Loctite thread locker. That works too, but it got me thinking that there could be a better way, especially for inside the motor. The flywheel tab washer is probably less critical because the nut is done up with a high clamping force and the primary pinion is a light press fit on the end of the crankshaft, thus no slop.

Dave

[Ventodue]

The clutch centre nut did, yes,

Ha! Tell me about it ...



Learnt my lesson. Loctite and a lot of torque = no problems since, touch wood. (Mind you, the bike had done several thousand kms, including the Moto Giro, before the clutch centre came lose).

I threw away the factory clutch tab washer and made one that was anchored to the spring posts.

This is the Brancato version

[Dave450]

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Looks neat, Vento. I made mine on the same principle. Glad someone is supplying them.