auto a/r problem

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1608
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auto a/r problem

Post by 1608 »

How hard is it to replace the extractor bolt on my auto a/r unit. The threads have stripped I have had to resort to levering the unit off using a claw hammer-not ideal. :headbang:
Mick D
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Re: auto a/r problem

Post by Mick D »

Hi

It's not difficult but getting the old one off can be a bit of a fiddle - the bolt has a LH thread which winds it into the ATD shaft and then comes out of engagement so in normal use this thread functions to extract the ATD, (this can damage the end of the LH thread making it difficult to start when trying to remove the bolt. Persevere in finding the start of the LH thread and it will unwind the bolt from the ATD - finding a replacement bolt may be more problematic.
ATD Extractor.png
Regards Mick
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Groily
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Re: auto a/r problem

Post by Groily »

As Mick says - but sometimes the little swine just will not start on the first turn of a butchered left hand thread.
Almost always the female bit, in the AR central pillar, is OK, but the bolts can be hell. Tis an awful design, with the benefit of 60 years worth of hindsight! WhoEVER thought it was a good idea to use the first turn of a thread as the shoulder for an extractor!!??

Different lengths on different ATDs / bikes, and it is crucial that the dimensions are dead right (not roughly right!) or it won't work in one way or another. BSA are 40mm end to end, Triumph 32mm.

Some parts are available new - see for example https://sites.google.com/site/priorymag ... atd-spares. Or http://www.davelindsley.co.uk/assets/pd ... 1.2017.pdf page 10. Not sure if on the sprocket-drive mags the ATD bolt is the same length as either on the Triumph or BSA fibre gear ATDs and don't have one to hand to measure unfortunately . . . if it were, the gods would be with you. Medium case it's a mod to an available part; worst case, it's a make. From Mick's pic though, could it be the BSA one is the same . . .?

Alternative case is to do without and figure a safer way than a claw hammer to get the darn thing off! At least sprockets are metal . . . but they still bend if you can't get a good hold on them, and so do magneto shafts . . .
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Re: auto a/r problem

Post by 1608 »

It wasn,t too difficult with the hammer as I used a heavy flat bar across the face of the timing case as a fulcrum for the hammer, I know it sounds a bit heavy handed though. The hammer claw gripped under the bolt head. I was worried that pulling on the mag shaft might cause internal damage. I'm sure that if I can remove the bolt somebody I know could make one if they are unobtainable. Just need to remove the bolt. Thanks for the advice.
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Re: auto a/r problem

Post by Mick D »

Hi

In the interim, I'd use a two leg puller under the drive gear and reacting on the extractor bolt - no chance of damaging the mag that way ;)

As Groily guessed - the bolt in my photo is from a BSA type ATD

Regards Mick
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Re: auto a/r problem

Post by 1608 »

Thanks Mick, this is for my Huntmaster, same as A10. By drive gear do you mean the fibre pinnion, surely too fragile. Don't think I'd get a puller in the space available either.
Mick D
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Re: auto a/r problem

Post by Mick D »

Hi John

Sorry, I assumed it was your G12 - no I wouldn't attempt to use a puller on an FH fibre gear.

Good luck in repairing yours.

Regards Mick
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Re: auto a/r problem

Post by Groily »

I assumed AMC single. So, no prob to replace when it is off, same as Beesa part.
39speedtwin
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Re: auto a/r problem

Post by 39speedtwin »

There is one on EBay under AJS & Matchless parts, £25 buy it now.
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