bodger
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| posted on 5/3/11 at 03:19 PM |
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Cross threaded 5JJ engine mount
The other night I was bolting my engine back into it's cradle. To speed things up a bit I stupidly decided to use my new Aldi air wrench to run
the bolts in most of the way before nipping them up by hand. Anyway I ended up cross threading one of the engine mounting lugs. (Facing the exhaust
manifold side it's the one on the top right that takes an M10x1.25 bolt.) I'd managed to chew up quite a bit of thread before I realised
it had gone in at an angle. Any suggestions for re-tapping appreciated. I've got a set of taps but they're only standard course thread
ones. Is it possible to drill & tap out to M12 or am I going to weaken it too much?
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David Jenkins
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| posted on 5/3/11 at 03:22 PM |
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Rule 1: locate nuts & bolts two or three turns with your fingers before using power tools to finish them off...
To be more helpful: is this something that could be taken to a machine shop to have a helicoil fitted? That would be the most sound solution,
engineering-wise.
[Edited on 5/3/11 by David Jenkins]
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austin man
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| posted on 5/3/11 at 03:23 PM |
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I would try and tap with the original tap first you may have on damaged a coupl of threads, if you manage to do thid then put thread lock onto the
bolt
Life is like a bowl of fruit, funny how all the weird looking ones are left alone
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britishtrident
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| posted on 5/3/11 at 03:37 PM |
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You may end up with a helicoil but get the correct tap or a thread chaser and try that first.
M10x1.25
Helicoil
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MakeEverything
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| posted on 5/3/11 at 03:40 PM |
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...And you dont need a machine shop to insert a helicoil.
Kindest Regards,
Richard.
...You can make it foolProof, but youll never make it Idiot Proof!...
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David Jenkins
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| posted on 5/3/11 at 04:28 PM |
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Fair enough - I've never had to do it (but I've read the machine shop guides...).
Is it just a case of drilling the correct-sized holes, making a thread with the correct tap, then winding the helicoil in? Is it cheaper to do it
yourself, of better to slip a machine shop a fiver to do it for you (if that can be done)?
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MakeEverything
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| posted on 5/3/11 at 06:29 PM |
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quote:
Originally posted by David Jenkins
Fair enough - I've never had to do it (but I've read the machine shop guides...).
Is it just a case of drilling the correct-sized holes, making a thread with the correct tap, then winding the helicoil in? Is it cheaper to do it
yourself, of better to slip a machine shop a fiver to do it for you (if that can be done)?
The existing hole acts as a guide for your new one - yes, it needs to be the correct size and is normally included with the helicoil kit. You then
use the supplied tap to cut the thread for the helicoil, and wind it in.
Its really easy.
Kindest Regards,
Richard.
...You can make it foolProof, but youll never make it Idiot Proof!...
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bodger
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| posted on 5/3/11 at 06:43 PM |
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Thanks for the replies. It'll be a real pain in the a**se to take it to a machine shop 'cos it's all plumbed in. So I'm going
to try the helicoil. Cheers.
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David Jenkins
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| posted on 5/3/11 at 07:16 PM |
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Just don't strip the helicoil - I know someone who's done that!
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britishtrident
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| posted on 5/3/11 at 08:02 PM |
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If possible replace the bolt with stud and secure with Loctite as this will reduce any danger of unscrewing the helicoil next time you take it apart.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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coyoteboy
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| posted on 6/3/11 at 02:04 AM |
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quote:
Rule 1: locate nuts & bolts two or three turns with your fingers before using power tools to finish them off...
Rule 2: Never use power tools to finish them off.
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TimC
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| posted on 6/3/11 at 08:45 AM |
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There used to be a thread on here, but it's long since gone. You certainly wouldn't be the first to tap a 12mm hole.
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