Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 998 / 996 / 916 / 748 > alternator rotor retaining nut

[disco stu]

Hi all,has anybody had one of these come loose,ducati recommend to get tightness checked every 6000 miles.
i have a 748 bip 1995 and i am not sure if this has been done the bike has done 16000 miles,should i be worried,all the best stu.

[JPM]

Mine came loose, started misfiring badly, bike out of warranty, Ducati UK didn't want to know at all. Was only by posting on here and various US forums when someone emailed me, and said they'd had their Monster I believe repaired outside of warranty several times with this problem. I then passed this information onto Ducati UK, and within 30 minutes they honoured the claim funnily enough, even wrote me a nice letter

Bike went into JHP, turns out it would of cost me over £1000 in parts I was lucky the crank wasn't damaged.

I believe though it's every 12,000 miles, not 6,000 although the Bostrom did have it checked and retightened at 6,000 miles as stated on the service book by JHP.

Food for thought

[disco stu]

Originally posted by disco stu
Hi all,has anybody had one of these come loose,ducati recommend to get tightness checked every 6000 miles.
i have a 748 bip 1995 and i am not sure if this has been done the bike has done 16000 miles,should i be worried,all the best stu.

Thanks i will put it on the list when the bike is in for service,stu

[keefer]

its certainly worth having a look at.
I check mine every two years, as JP says if you don't and it does come lose its a big bill.
Reliability stories of ducati's tend to be down to this nut

[Steve]

Being less than mechanically minded how do you check the nut?

Steve

[Felix]

You have to take the left side engine cover off and use a torque wrench, which means you need to drain the oil, maybe the water, and then reseal the casing afterwards.

[Steve]

Blimey

[Mr C]

Does this get done on the 12k Service??

[keefer]

don't know if it gets done on the service.
But a word of warning if you do attack it yourself.
Don't just try and tighten it up, you need to undo it first to make sure that it is all located properly before being torque'd up. there is a very slim washer at the back which can slip out of place if lose, and if you just crank it up the hole lot could be askew

[Shazaam!]

Whoaa, slow down here. It's a '95 bike that has never had the nut removed.

1999-2000 Flywheel/Alternator Rotor Retaining Nut Problem

For the 1999 models, Ducati redesigned the electrical system, going from a 350 watt design to a 500 watt three-phase system. This resulted in a new flywheel retaining nut design that unfornunately also had an oversized thread depth that would loosen-up, even when properly torqued and Loctited.

Ducati issued a service bulletin concerning the stock nut. If the nut spins-on with little resistance it’s out of spec and must be replaced with an upgraded nut from Ducati. An different rotor was introduced for the 2001 model year that put an end to the issue.

Alternatively, Nichols Manufacturing offers a replacement self-locking double-nut similar to what Ducati used in the early ‘90’s.

Prior to 1999, the factory-installed nut did not commonly loosen, but they present a more serious problem if not properly torqued during (say) an aftermarket flywheel replacement. When they come loose, they’ll often damage the crankshaft splines. On pre-1999 models, you just need to replace/retighten the nut to the correct torque.


Symptoms

The first indication of a problem is a knocking noise from the left side of the engine that doesn’t go away when you pull-in the clutch lever. (The knocking noise sounds similar to the clutch knock at idle.) Excessive clutch tang wear and a broken clutch pushrod at the o-rings are also an indication. If you look into the timing inspection window on the left cover you can see if the flywheel is wobbling. Another apparent symptom is sluggish initial turnover when starting the engine because of interference caused by loose parts.

Solution

The solution is to replace the castellated nut and retorque. If the nut spins-on with little resistance it’s out of spec and must be replaced. Alternatively, Nichols Manufacturing offers a replacement double-nut (similar to what Ducati used in the early ‘90’s) that is self-locking.

http://www.www.nicholsmfg.com

Procedure

http://www.mad-ducati.com/Technical/...torCover2.html

Place a piece of soft metal (like a copper coin) between the starter pinion and the first idler gear to immobilize the shaft while you tighten the flywheel nut.

Best way is to actually make a tool to hold rotor. Some ingenious designs on this list, all other methods are inferior if you ask me. Course, the tool
takes some making, a fair machinest is required.

On engines with a solid countershaft drive gear (the gear behind the flywheel assy,) Ducati now recommends torquing the nut to 270Nm. On SP/SPS and other models where the countershaft drive gear is grooved where it sits on the crankshaft, you can only torque to 190Nm, to avoid damaging the gear.



[Edited on 1-7-2005 by Shazaam!]