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From bad to worse

Technical help for Series one, two and three Lambrettas. Models include the Li, Li Special, TV, SX, GP, Serveta and API/SIL models

From bad to worse

Postby mickey c » Wed Jul 11, 2018 11:13 pm

I’m sure there’s some others feeling deflated this evening by sporting events, mine got worse! I tried to cheer myself by carrying on with my engine build. Lots of nice new good stuff in there and I fit my new chain, then tighten my front sprocket. New bolt into a new crank and the bolt shears 1 mm below the end of the crank! Getting the snapped bolt out will be a flipping nightmare / impossible!
Ah well, at least it’s sunny!
mickey c
 
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Re: From bad to worse

Postby Warkton Tornado No.1 » Wed Jul 11, 2018 11:34 pm

It shouldn't be impossible but you do need to be methodical. The trouble is that the sheared face will be even harder than the material was originally.

It may be possible with a good, sharp punch to tap it around, as there is no load upon it (unless the bolt bottomed out like the MBD one I bought once.....) Hopefully, it was just an Indian bolt, which I would never recommend using over a 'proper' type.

Failing that, drilling using a small, sharp drill bit @ slow speed with copious cutting fluid may enable you to gradually increase the hole size until you can extract it/remaining threads collapse inwards. If you possess a die grinder or Dremel type tool, you may be able to give the drill an easier start by getting below the work hardened surface, but you'd need a steady hand & good, small grinding points.
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Re: From bad to worse

Postby Adam_Winstone » Thu Jul 12, 2018 12:29 am

NB: If this happened when you were trying to pull the crank home into the bearing using a pulling sleeve then you'll not be the first or last to do this! Unfortunately, the sleeves are typically made a little shorter than they need to be, to allow you to reach the thread before the crank is well home into the bearing, but this shortness then means that the bolt bottoms out on the bolts shaft before pulling the crank fully home. To get around this you need to remove the bolt when it starts to go tight so that you can fit a washer between the two to give it the length that it needs to pull the crank fully home. If not, bolt shearing in the crank is a common result. No, the sleeves are not sold with a washer or this instruction :(

If sheared through another method... unlucky.

Adam
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Re: From bad to worse

Postby mickey c » Thu Jul 12, 2018 12:54 pm

thanks for the sympathy and advice chaps.

I'm sure it has bottomed out but the crank and everything was already fitted. I've not set foot in a gym for 20 years and not applying huge amount of force for it to snap. I'm just trying to work out whether its best to try to remove with the crank left in or if I need to remove it? I'm hoping the former as It will be supported in the engine and obviously saves me time having to strip the engine down from where I have got to.
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Re: From bad to worse

Postby davej » Thu Jul 12, 2018 1:02 pm

I'd go for the drilling hole down through the middle option, You may be lucky and need only an 'easy out ' to wind the broken piece out with a smaller hole rather than drilling right out to the thread core size.
Good Luck
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Re: From bad to worse

Postby Warkton Tornado No.1 » Thu Jul 12, 2018 1:06 pm

If it were me, I'd try with it in situ, but not to the point of wrecking anything.

Then, if it proves impossible to drill out in stages, take the crank out & get it removed by somebody with either a spark eroder or a decent vertical milling machine, though the days are gone where we all had a mate that could sneak in a bit of "guvvo" for the cost of a pint or two.....

(Just make anybody taking the job on that the crank can be easily knocked out of alignment just by overzealous clamping)
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Re: From bad to worse

Postby mickey c » Thu Jul 12, 2018 11:12 pm

Thanks again for the advice. Having thought about it, an amateur has caused this mess. I’m going to try a pro to get it out! I imagine it will cost more than pint but best chance of saving my crank!
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Re: From bad to worse

Postby Norrie Bodge » Fri Jul 13, 2018 12:37 am

I’ve snapped one in before
The snapped in thread... It just turned out with a small screwdriver
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Re: From bad to worse

Postby mickey c » Sat Jul 14, 2018 11:21 am

Alas i’ve Not been that lucky Norrie, mines well stuck (as my teenager would say!) i’ve put some penetrating fluid in & hopefully a biker engineer I know can work his magic!!
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Re: From bad to worse

Postby paul213 » Thu Jul 19, 2018 7:57 pm

try a left handed twist drill, you run the drill in reverse and as you drill a hole in the centre it normally catches and spins the snapped bolt out. if it doesn't catch you have a hole for a extractor but you haven't rammed it in tighter while drilling
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Re: From bad to worse

Postby holty » Sat Jul 21, 2018 7:41 am

thats good advice from paul, if all else fails i would weld a blob onto the broken end so i could use grips on it, or then weld another bolt to it, i had to do this a few weeks ago to get some driveplate seal screws out of a mates engine, he had rounded them all off, good luck.
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Re: From bad to worse

Postby mickey c » Sun Jul 22, 2018 8:19 am

Thanks for the suggestions. The left handed drill option sounds good to me & I'll use for my next cock up!
For this one, I took it to a pro who did say it was difficult to remove but £40 to get it sorted seemed more than ok to me!
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