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Author: Subject: Crack in Crankcase...
scootz

posted on 11/4/14 at 05:34 PM Reply With Quote
Crack in Crankcase...

Was fitting some new rearsets to my Aprilia RSVR which allowed me to junk a couple of brackets that were attached using crankcase bolts. Whilst doing so I noticed what looked like a hairline-crack in the crankcase. I put a little pressure on the bolt... and sure enough - it spun reasonably freely. Someone in the past has obviously tightened the bolt too much and stripped the threads. And possibly (probably) stressed that area of the crankcase causing the crack!

I've only ridden the bike a couple of hundred easy miles since getting it due to the time of year it arrived, and I've not seen any sign of a leak.

So what to do!?

Leave it and top-up with oil if it starts to weep?

Notch a groove along its line and seal with epoxy or chemical metal?










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ashg

posted on 11/4/14 at 05:54 PM Reply With Quote
That won't leak leave it be. If you really want it fixes the only proper way is to strip it tig it and reassemble.





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scootz

posted on 11/4/14 at 05:57 PM Reply With Quote
Cheers Ash. I'm also a bit concerned that the bolt isn't really exerting any pressure in the area. Mind you, it's one of the higher crankcase bolts and the ones either side are good.

[Edited on 11/4/14 by scootz]





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mark chandler

posted on 11/4/14 at 06:06 PM Reply With Quote
Blank it from your mind and ignore
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britishtrident

posted on 11/4/14 at 06:10 PM Reply With Quote
I have seen that exact type of crack caused Byzantine hydraulic pressure caused by oil trapped in a blind hole when tightening the bolt.

[Edited on 11/4/14 by britishtrident]





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scootz

posted on 11/4/14 at 06:22 PM Reply With Quote
quote:
Originally posted by britishtrident
I have seen that exact type of crack caused by hydraulic pressure caused by oil trapped in a blind hole when tightening the bolt.




That makes perfect sense!





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scootz

posted on 11/4/14 at 06:23 PM Reply With Quote
quote:
Originally posted by mark chandler
Blank it from your mind and ignore


Will give it a go.

Hopefully the crack will play its part and not cause a scene!





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pewe

posted on 11/4/14 at 06:35 PM Reply With Quote
If you want to hide it and provide a modicum of seal I'd use use some silver/ali epoxy bodyfiller - search Silver Hook Big Boy body filler.
Whilst I'd agree that it probably won't spread or weep it will catch your eye less.
May be best to wash out the crack with meths or similar first.
I used a similar method on the plastic timing chest case on the hairdressers to pretty good effect.
HTH and safe riding.
Cheers, Pewe10

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Dick Axtell

posted on 11/4/14 at 06:48 PM Reply With Quote
Quote "......Byzantine hydraulic pressure......"?????

What a remarkable description!! So how much would that be - in old-fashioned psi?

[Edited on 11/4/14 by Dick Axtell]





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scootz

posted on 11/4/14 at 07:13 PM Reply With Quote
Cheers all.





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CRAIGR
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posted on 11/4/14 at 07:32 PM Reply With Quote
It would take a very brave man to wash Scootz's crack out with meths.

[Edited on 11/4/14 by CRAIGR]

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scootz

posted on 11/4/14 at 07:48 PM Reply With Quote
It'd be worth it for the lucky chap though as he'd get a nice cuddle afterwards!





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CRAIGR
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posted on 11/4/14 at 07:52 PM Reply With Quote
Hahaha
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ashg

posted on 11/4/14 at 10:33 PM Reply With Quote
Sod that. Next time keep your crack to yourself!

If the bolt hasn't come out it's tight enough.





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owelly

posted on 12/4/14 at 07:14 AM Reply With Quote
Another solution would be to screw a stud in with a bit of sealant on the threads and then fit a nut. You can make sure the stud takes advantage of whatever threads are left in the hole and if you use a OEM typre flanged-nut, it won't look out of place.





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renetom

posted on 12/4/14 at 07:15 AM Reply With Quote
Hi
From the look of it it should be fine , the crack does not look the be
in the oily part of the crankcase.
If you'r worried about the bolt coming out use threadlock on it.
Whatever you choose , good luck.

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scootz

posted on 12/4/14 at 09:38 AM Reply With Quote
Thanks all.





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