Washer under the sleeve nut?

I was talking to an engineer friend who has a Commando a few days ago about a recent issue I've been having where one sleeve nut (06.3192) kept loosening off slightly after running the engine. The conclusion to solve this issue was he said that I should be using a plain and sprung washer under the nut, but I have never used a washer there in the last 38 years, and not had a problem until recently.

The parts diagram doesn't show a washer there, so although I could fit one, should I have been doing so all this time? Do others fit them?

Hi Reggie, I had never fit a washer under those sleeve nuts , but I had noticed that some of trhose nuts are "sloppy" fit (ie the thread seemed a bit on the loose side , specially the SS one ! but nevertheless , no one unscrew during riding , may be a touch of loctite , as putting a washer (and more two!) will reduce the depth of the usefull thread .....my 2 cents !

Reggie said:

I was talking to an engineer friend who has a Commando a few days ago about a recent issue I've been having where one sleeve nut (06.3192) kept loosening off slightly after running the engine.

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There's a reasonable chance it's the stud beginning to pull out of the head which is causing the sleeve nut to loosen.

Reggie said:

The conclusion to solve this issue was he said that I should be using a plain and sprung washer under the nut, but I have never used a washer there in the last 38 years, and not had a problem until recently.

The parts diagram doesn't show a washer there, so although I could fit one, should I have been doing so all this time? Do others fit them?

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No.

http://www.boltscience.com/pages/helicalspringwashers.htm

Ok, thanks for that. I didn't think that most people were using washers/ lock washers there. It seems that the possibility of the stud starting to pull out is the likely culprit, although there are no threads showing and I can't get the stud out of the head holding the stud in a vice. I will be able to get it out, but will heat the head a bit in the oven first.

The problem now is on the right front stud, whereas strangely enough, the same symptoms happened on the front left stud last year, so I helicoiled the head with a 3/8" BSW as recommended on this forum by Jim Comstock, and my friend made me an appropriately threaded stud. Again, there was no physical evidence such as threads showing and that stud was very difficult to remove as well.

I never marked the nuts and wondered if I had a rogue nut which had moved position, but it sounds as if it is the stud pulling if nobody else is using lock / spring washers. The nuts I'm using are 12 point quality nuts from Steve Maney so I think it is unlikely that it is the nut at fault.

It looks as if I'll be helicoiling the remaining two studs to 3/8" BSW.

Thanks for your help.

When I had one of these studs fail the stud just pulled out and the alloy thread was still on the stud and just fell away in crumbs once the stud was out. That suggests the alloy fails at the root of the thread but the stud hangs on until the last of the thread gives up.

Similar.

I tightened him several times and he finished by fallen by running, without I notice it, on the return to the international rallye Norton in Bremen and the cylinder head gasket clicked in this place.
It is the stud which was in question, since hélicoïl on 3.
It would not be rare on this head after 40-50 years.

Reggie said:

It looks as if I'll be helicoiling the remaining two studs to 3/8" BSW.

Thanks for your help.

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Here is the.... it ain't broke so don't fix it versus ....one failed, the other ones might!

I'm betting you wish you had done all three at the same time!

Good luck.

Steve A wrote;

I'm betting you wish you had done all three at the same time!

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Absolutely correct.

I had the exact same thing (left front) kept coming loose, after years of not doing so. Nip up, and loosen again. Finally lost it.