Dynamo strap retaining stud, twin, broken

Information relating to the Matchless G12 or AJS Model 31 650cc twin
Groily
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Re: Dynamo strap retaining stud, twin, broken

Post by Groily »

The problem. Tiny issue, big pain!
No short cuts, the thing has to be right, as the bike's a serious rider and we can't have bits falling off every 5 minutes!
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clive
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Re: Dynamo strap retaining stud, twin, broken

Post by clive »

Can you not build some weld up on the remaining stud so that you can get a mole grip on it? This would give much more torque than a screwdriver slot. Got a broken single cylinder head bolt out this way years ago (and since have always used a medium spanner when tightening!)
clive
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Groily
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Re: Dynamo strap retaining stud, twin, broken

Post by Groily »

Thanks for that Clive. Mick D has kindly suggested the same thing pretty much via PM, with a blob and a nut atop it - I'm weighing up the steadiness of my hands and the accuracy of my aim with the MIG (that I don't use often enough to make any claims)! My nervous-ninniness right now is that cack-handedness on my part could dissolve the alloy and put me in worse doo-doo!!
Cheers,
Bill
Andy G
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Re: Dynamo strap retaining stud, twin, broken

Post by Andy G »

Maybe thoroughly degrease the stud remains and a suitable nut. Place nut on casing over remains, and aim your mig down the nut ole. Should keep aim straight and double as a heat sink to protect casing? Several small goes to slowly build up and fill the nut without undue heat, then over fill to be sure?

Edited...

Should have said if it's not obvious: in theory you'll be spannering the nut out with stud welded in it.
Last edited by Andy G on Wed Nov 10, 2021 7:08 am, edited 1 time in total.
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clive
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Re: Dynamo strap retaining stud, twin, broken

Post by clive »

Bill worth investing in one of the modern welding masks if you dont have one. They are clear to allow you to see what you are doing and go dark as soon as the spark starts. If you dont have one it would be worth the investment before you start. Using a nut as protection sounds like an engineering solution rather than my amateur recommendation. Good luck :beer:
clive
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Groily
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Re: Dynamo strap retaining stud, twin, broken

Post by Groily »

Got the bar steward.
Will send some 'blather' to Les in due course which he may think worth bothering with, or not. But here's the offending blighter! 6 turns of good thread left, so 'ok for now' with a replacement stud. But def a point of weakness . . . . I wimped out didn't dare go the weld route in the end on so small a target, just not trusting my aim despite all the most excellent advice, so I hoicked the engine this afternoon to do it the slo-mo way . . .3.5mm pilot hole (to depth of 4mm) after a centre drill to get me going, taking advantage of access for proper tools, 3.5mm sq driver bit rammed in, bit 'o heat . . . and voilà! Actually, only about 2.5 hours start to finish - but do now have some, er, reassembly to do tomorrow! But, no need to split the engine, so that's a big upside as far as I am concerned! Be running again for the weekend I expect.
Thanks to Mick, Clive, Andy G et al for all your thoughts, very much appreciated.
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Andy G
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Re: Dynamo strap retaining stud, twin, broken

Post by Andy G »

Image

Well Done!!
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clive
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Re: Dynamo strap retaining stud, twin, broken

Post by clive »

Great
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Groily
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Re: Dynamo strap retaining stud, twin, broken

Post by Groily »

And to round this out, she's running like an express train again since yesterday.

Slight deviation from plan to address an oil-filled mag (bit of tlc needed but it was still working fine) because it hadn't been looked at since the IJR at Celles-sur-Belle, and also a quick check to make sure the dynamo hadn't been damaged mechanically by running 'loose' before I noticed anything wrong.

First kick, and very happy, nothing broke in a quick (and damp) 20 mile thrash at satisfying rpm this pm. Good so far.

Just to add though, Lucas did say words to the effect that a mag should be checked out every 10,000 miles odd, and with reason. This one had done better part of twice that without anything at all. It had suffered mildly - had to redothe drive end bearing and replace the oil seal and fit a new insulator as oil was working its way in and had got onto the HT pick-ups. The bearing was a half-decent Hoffman, but showing signs . . . Nothing's for ever . . .

Thanks to all for great thoughts and comments.
Cheer,
Bill
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clive
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Re: Dynamo strap retaining stud, twin, broken

Post by clive »

Well done
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