Hei. When the bike is put away for winter Storage, I'm going to service the engine. One of the items is to check the alternator nut, since I know from this forum that it will generate a lot of trouble if it comes loose. This is how Kaemna deal With the issue at the engines sold by them: " Description!!!!!!! Woodruff key generator rotor ALL our engines up to 98 modell only !!!!are delivered without the wooduff key for the generator rotor!! In case of the loosening of the left-sided crankshaft nut the rotor turns loose and free and the motorcycle stops because of empty battery. But it does not produce any damages like seizing up the rotor or crankshaft. You will notice this immediately and nut can be tightened again without circumstances and costs!!! So this procedure is a safety modification!! The loosening of the left-sided nut from crank is a Ducati typical problem and it is expressly noted on our service sheets, which are attached to each engine,that this nut must be controlled and fastened tight at each service or inspection to minimize the danger of the looosening !! So the missing woodruff key is no mistake ,it is like it should be in our eyes !!! Regards Rüdiger Kämna price on demand " http://www.ducati-kaemna.com/catalog/ducati/motoren-neu-und-gebraucht-engines-new-and-used.html Seems reasonable to me, any toughts ? By the way, does anyone of you have the dimmensions, Outer diameter of the alternator magnet and the sizes of the small gripping tabs at the end of it ? I'll try and make a holding tool.
hi Per748 sent you a pm the key fits inside the 14 spoke magnetic stator r92 r93 type so that it has a drive and not held by the the crank shaft nut setting here is a r93 14 spoke type r92 is same but for the depth of the item some call them g92 g93 i think ducati call them Rs mike
Nichols Engineering in the States make a replacement for the nut that consists of two thin nuts that lock together and this allegedly cures the problem http://www.nicholssportbikes.com/products/NFLYNUT.html
Hi don't know if the nut or lack of a key in the magnetic stator? is the fault yes two lock nuts are on offer even Ducati say not to reuse the crankshaft nut get a new one have never reused the nut cheap to buy Mike
By the way. The bike is a MY99 748 SPS. According to the Haynes manual it should have the 3 phase generator, but this is not the case. It has the single phase generator (2 yellow wires). I mentioned this for the Ducati dealer I have used for servicing, and he confirmed that the SPS's have the single phase generator. The rotor shown in the pics above seems to be the same as in the Haynes manual. I assume the rotor is the same for all 748/916 series of bikes With the single phase generator, or am I wrong ? What about the way Kaemna deal With the "lose alternator nut" problem ?
hello per748 yes 2 yellow wires 1 phase the 14 spoke wheel type magnetic rotor fitted then after 1999 ducati changed to high out put 3 phase some lads change to the two thin nuts, i buy a new nut and set to spec plus some thread lock and check every service on my st2 r92 r93 used across the ducati range inc many other makes used them as to how your ducati dealer service thats up to him the 14 spoke magnetic stator r93 narrow type r92 deep type i think i sent one to you via pm not to worry here it is mike
Not knocking the Nichols nuts but I've had my 916 for 20 years, done 50k miles and have removed/checked the alternator nut occasionally but never has it actually been loose. Correct torquing with loctite seems to work OK, I wouldn't be happy running it without a woodruff key...
According to the owners handbook that came with my 916 it has a 3-phase alternator but it's a lie as it's single-phase. All 916 and 748 up to '99(ish) have single-phase, the change to 3 phase happened with the introduction of the 996 but I suspect Ducati used up any remaining stock of single-phase parts on 748 models...
I'm with you on that It's much less of an issue nowadays than it used to be. New nut, clean up the crank threads and Loctite. Correctly torqued up and job done. Most issues I've seen in the past have been after having it "checked" and not having the correct tools to hand and/or not hitting torque. I've done them to 180Nm for as long as I can recall following a bulletin back in the day. I wouldn't run without a woodruff key in there either. There's some mass in the rotor and spinning round at the rate it does, I could see it causing more issues than it sets out to solve. The motor is rotating counter clockwise and in theory could undo the nut if it starts to spin on the crank. I've fitted a few sets of the Nichols nuts in the past, I can see the idea behind them but to effect a locknut arrangement you need to hold the back nut down whilst tightening against it. It's fiddly.
Actually, looking at the website, can’t see the double nuts listed, so they may not be an option anyway.
My 750SS nut came loose. No enormous damage done but had to replace the pickups damaged by the flywheel as it wobbled
OK. I think I stick with the woodruff key in place. Just got curious about the Kaemna way of dealing with it, but was wondering why its not mentioned other places. Immediately it seemed to be a reasonable solution..... What kind of Locktite should be used ? I have tried the permanent type in other applications were the parts was never supposed to be taken apart again, it worked.... I have seen other places that the alternator nut should be torqued to 220 Nm and 190 Nm for the 748SPS. Is there any reason that 180 Nm is used ?
I use Loctite 270. High strength. No, 180 is a minimum. Tolerance is +/- 10% so top end would be 198. If your wrench will top 200Nm, can't see it being a problem. Make sure the threads are good though.
We are starting to get like the old ducatis.forum great help coming thick and fast keep going what great way to help others Mike
Can I ask, what is the solution to the nut coming loose, its a big ordeal draining coolant and stripping it to check each service Red loctite?
Having had the nut come loose on my 750SS, I was concerned it might happen to my 999. However, I was assured this was very unlikely as the design had been changed on later bikes. If this design change doesn’t apply to your 748 and involved the nut itself, I can’t help wondering if it’s possible or desirable to fit a later nut? Can’t say I’ve ever heard of it though.
