Author Topic: Broken barrel fin  (Read 482 times)

Online Minto

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Broken barrel fin
« on: 24.04. 2020 00:33 »
Hi all,
Now I can only claim 50% responsibility for this cock up as I'd noticed a crack in the bottom barrel fin on the timing side a while ago, unfortunately I completely forgot about it and while attempting to lift the very reluctant barrels off, finished the job of breaking the fin altogether.
What are my options? I might have someone who can weld it, but it might be some time before they're back at work.
Is there any chemical metal option that would work in this application?
It's a fair old sized piece that's broke off, but at least it's the bottom one so accessible for a weld if appropriate.
The only other issue was the drive side footrest bolt sheared off and now needs to be drilled out. But the engine is now on the bench.
Thanks all
52 A10 plunger
Aprilia RSVR

Online RichardL

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Re: Broken barrel fin
« Reply #1 on: 24.04. 2020 00:57 »
Minto,

May be a blessing in disguise that the fin broke off when you tried to lift the barrel. Had you been riding and it broke off on the ride you would not have the piece to weld back on. Also, the cracked piece in place would be no help to the welder, as it would need to come off anyway in order to be chamferred to accept the weld bead. I'd skip trying adhesive because it could still come off and get lost. Though, if you wanted to try adhesive,  I suspect JB Weld would be the likely candidate. You could drill a very small hole in the fin and add a fine safety wire that saves the fin if the adhesive did not hold. You could just run without the fin until the next time the barrels need to come off, which , we hope, would be after the world returns has returned to us.

Richard L. 
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Online Minto

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Re: Broken barrel fin
« Reply #2 on: 24.04. 2020 01:52 »
Hi Richard
That was "almost" my first thought when it snapped off. I have a mig welder but can't get hold of any gas and would rather someone who knew what they were doing did it.
Not a bad shout with the safety wire in case the glue fails but I'll try to get it welded first if I can.
Thanks
52 A10 plunger
Aprilia RSVR

Online Brian

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Re: Broken barrel fin
« Reply #3 on: 24.04. 2020 03:57 »
Have a read through this post from some time ago when I repaired a set of barrels, it might give you some ideas.

https://www.a7a10.net/forum/index.php?topic=10186.0

Offline BSA_54A10

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Re: Broken barrel fin
« Reply #4 on: 24.04. 2020 07:18 »
LEAVE IT ALONE .
The engine will not blow up.
Put the piece some where safe till you have the time / money / enthusiasm o get it welded on properly.
Most of the goos make getting a good weld later on near impossible
Bike Beesa
Trevor

Offline Tomcat

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Re: Broken barrel fin
« Reply #5 on: 24.04. 2020 07:29 »
I copied Brian's idea, mild steel fin, MIG weld, don't get it hot. Worked a treat and saved a set of thick flange barrels. Did it at work and the boiler maker there said that won't work. Has been back on the road 3 years now and not fallen off.  Thanks Brian.  *smile*
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Online Brian

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Re: Broken barrel fin
« Reply #6 on: 24.04. 2020 07:38 »
Although I havent used that particular set of barrels yet I have repaired lots of fins with the mig and it has been very successful. Over the years I have tried brazing and nickel rods in a arc but the mig beats the lot of them. I think the fact you can weld short bursts with minimum heat is why it works so well.

Offline BSAmoto

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Re: Broken barrel fin
« Reply #7 on: 24.04. 2020 07:56 »
I spotweld the fin pieces just for position, then braze them on with a high silver content rod. No hard spots and even fins between other fins could be brazed. Works for me. The A10 barrel here has a lower fin missing as well so I will replace that with some steel sheet. Will take a couple pics - if I donĀ“t forget...

Online beezermacc

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Re: Broken barrel fin
« Reply #8 on: 24.04. 2020 08:03 »
I've always had success with standard brazing equipment.
Priory Magnetos Ltd - A10 spares, magneto and dynamo refurbs. www.priorymagnetos.co.uk

Online berger

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Re: Broken barrel fin
« Reply #9 on: 24.04. 2020 10:13 »
minto I used araldite on a big piece of ally cylinder head fin 30 years ago and it is still on. I did try gentlyish to break it off it , it didn't want to break. the advert used to say it would pick up a ton or more, maybe it was good araldite before elf and safety police removed some of its make up. I would say its worth a try worked for me

Offline Guy Wilson

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Broken barrel fin
« Reply #10 on: 24.04. 2020 11:14 »
I recently replaced / repaired several fins on my TR6P barrel. I had set with decent bores that had several fins broken and missing. I cut the missing fins of the original barrels and MIG'd them. Its mixing cast iron and mild steel although not structural. MIG doesn't get the cast iron too hot its easy to dress back the surplus weld. I was happy with the results. I've not ridden the Triumph enough to guarantee the repair holds, although it all looks good so far..
Guy

Online RDfella

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Re: Broken barrel fin
« Reply #11 on: 24.04. 2020 11:42 »
Duct tape. Just don't start it up .....
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Online RichardL

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Re: Broken barrel fin
« Reply #12 on: 24.04. 2020 12:53 »
Most of the goos make getting a good weld later on near impossible

Excellent point I should have thought of.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Online Minto

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Re: Broken barrel fin
« Reply #13 on: 24.04. 2020 15:52 »
Thanks everyone, mig it is then. I'm not in a massive hurry as the motors on the bench for the next couple of weeks, and my mate is back at work after this weekend so I'll leave it with him.
Sorted!
52 A10 plunger
Aprilia RSVR

Online Minto

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Re: Broken barrel fin
« Reply #14 on: 24.04. 2020 16:15 »
Brian, that is very impressive work.
Thanks for posting, I'll pass the advice on to my friend before he starts at it.
Cheers
52 A10 plunger
Aprilia RSVR