twybrow
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| posted on 26/3/13 at 12:06 AM |
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How to undo a rounded cap head bolt!
Having tracked down the plug for the oil gallery on my ZX12 engine, this evening I have attempted to undo it. It looked and felt like an 8mm cap, but
after some major heaving, the cap is becoming increasingly rounded. Do I just give up the idea of fitting an Accusump, as this is turning into such an
ordeal, or do I press on, and attempt to weld something onto/into the Hex cap and have another heave to undo it (possibly using an air powered impact
wrench)...?
 
Oil gallery rounded plug
[Edited on 26/3/13 by twybrow]
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chicade
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| posted on 26/3/13 at 12:32 AM |
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I always find a torx bit knocked in or even better a spline drive bit knocked in always un does rounded Allen screws
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spiderman
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| posted on 26/3/13 at 12:39 AM |
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Cut your Allen key so you have a straight hex bar, weld it onto the cap bolt, lots of amps to get some heat into it as it will help break the bond
between the bolt and casing. You will be able to get a good fit with a socket onto the hex bar to give you plenty of leverage.
I have also been known to use an old ring spanner tack welded onto rounded off hex head bolts until I have broken the bond between the threads and
then levered the ring spanner off breaking the spot weld so that the offending bolt can be spun out.
Spider
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twybrow
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| posted on 26/3/13 at 07:06 AM |
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quote:
Originally posted by spiderman
Cut your Allen key so you have a straight hex bar, weld it onto the cap bolt, lots of amps to get some heat into it as it will help break the bond
between the bolt and casing. You will be able to get a good fit with a socket onto the hex bar to give you plenty of leverage.
I have also been known to use an old ring spanner tack welded onto rounded off hex head bolts until I have broken the bond between the threads and
then levered the ring spanner off breaking the spot weld so that the offending bolt can be spun out.
I might have a problem with welding, as the bolt is actually recessed into the engine, so that only about 2mm protrudes above the aluminium housing. I
might still give that a try, although perhaps I should try hammering all manner of items into the bolt head first, as if they get stuck, that would
still allow a weld (possibly!).
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owelly
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| posted on 26/3/13 at 07:17 AM |
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+1 for hammering a Torx bit into the cap head. Dip the Torx into grinding paste first. If you don't have grinding paste dip the Torx in oil,
then sand. Plenty of tapping with the hammer as you turn the Torx.
http://www.ppcmag.co.uk
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fesycresy
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| posted on 26/3/13 at 07:52 AM |
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Last chance would be an 'easy out' if you have room to drill and some heat.
Just don't drill too deep.
-----------------------------------------------------------------------------------------------------
The sooner you fall behind, the more time you'll have to catch up.
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britishtrident
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| posted on 26/3/13 at 08:04 AM |
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Are you 100% it isn't a Torx head --- Allen style hex heads are increasingly rare.
[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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Peteff
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| posted on 26/3/13 at 08:51 AM |
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quote:
Originally posted by britishtrident
Are you 100% it isn't a Torx head --- Allen style hex heads are increasingly rare.
Jap bikes still use mainly Allen heads, only car manufacturers have gone over to Torx. How hard is the bolt head ? Knock an oversize Torx well down
into it then if everything else fails try welding the key in.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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loggyboy
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| posted on 26/3/13 at 08:54 AM |
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Its not a reverse thread to stop people from undoing it without good knowledge/reason?
Mistral Motorsport
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BenB
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| posted on 26/3/13 at 12:59 PM |
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I completely wouldn't use an easy-out. Easy-outs are designed to remove sheared (but not stuck) things. If you try removing a stuck bolt (voice
of experience here) you'll shear the easy out and then end up drilling that out as well. Been there, got the t-shirt, broke an entire set of
drills and used up four hours of my life getting rid of a bastard easy-out.
What I've always done in these circumstances is welding. Personally I'd weld some hex bar into the hold in the bolt (or put a nut over the
top and stick a load of weld down the hole) and then get once it's cooled down get swinging with a big old breaker bar.
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twybrow
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| posted on 26/3/13 at 01:13 PM |
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Thanks chaps - some great suggestions there.
- I don't think it is reverse threaded - but there may be enough thread visible to take a closer look.
- The bolt head isn't as hard as the allen adapter I am using! I hope my Torx bits are just as hard!
- I am really hoping not to have to use easy outs - if it gets that far, I will make do without an accusump, or find another way to plumb it. I dont
want to risk any metal fragments into the oil ways.
- Good tip with the idea of dipping the Torx fitting in grinding paste before using them - I wouldn't have thought of that!
Thanks again chaps - I have some hope that it wont need welding just yet (especially as it normally takes a few goes to get my eye in when
welding!).
Would you suggest trying an air impact wrench?
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blakep82
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| posted on 26/3/13 at 01:21 PM |
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I'd use an impact wrench, just to give it that impact to break the stick its got. Even just 1 or 2 thumps, before using a spanner or ratchet
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Vindi_andy
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| posted on 26/3/13 at 01:33 PM |
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Id try an old manual impact drive as this shocks in 2 directions, downwards i.e. into the hole, and twist. this helps break the bolt thread bond.
I think thats what balke was suggesting too.
[Edited on 26/3/13 by Vindi_andy]
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T66
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| posted on 26/3/13 at 01:46 PM |
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Good quality bolt, grind it down to fit the allen head lands . Weld a pair of nuts onto the bolt, then weld the bolt into the allen head.
And slowly lean on it with a bar and impact socket.
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