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Stripped back plate threads

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Old 07-17-2012, 05:08 AM
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mustangman177
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Default Stripped back plate threads

Was putting on a replacement needle valve stay on my .46 AX and over tightened and stripped the threads on the backplate so now the 3 x 8 mm hex screw will not tighten. With this, it will not run correctly (air leak). Is there a fix for this ? Is there another screw (larger) that can be substituted here if tapped for it ? Another option would be to purchase a replacement crankcase.

Thanks

Cary
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Old 07-17-2012, 06:23 AM
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Default RE: Stripped back plate threads

If you can do it, tapping for a slightly-larger bolt will work nicely. You cannot lose by trying, since a new case would be needed anyway.
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Old 07-17-2012, 09:49 AM
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Default RE: Stripped back plate threads

What size should I try and tap up too ??? A .46 crankcase sells for roughly $40.00, so no big loss here.
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Old 07-17-2012, 10:43 AM
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Default RE: Stripped back plate threads

Check the depth of the hole against the screw. You may be abll to use a slightly longer screw to catch some remaining threads in the bottom of the hole.
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Old 07-17-2012, 04:22 PM
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Default RE: Stripped back plate threads

The largest ANSI thread would be a 6-32 but that might be too large. If you don't mind buying a metric tap, try a M3.5 or an M4 and tap it with a bottoming tap. But to be realistic, by the time you get all of this done, you're probably better off to get a new case anyway. $40 isn't that big a hit when you consider all the things that we all buy and never use over a year's time.

Just my $.02

Bob
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Old 07-18-2012, 08:48 AM
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Default RE: Stripped back plate threads


Quote:
ORIGINAL: SrTelemaster150

Check the depth of the hole against the screw. You may be abll to use a slightly longer screw to catch some remaining threads in the bottom of the hole.


As luck would have it, only the top threads were damaged. I was able to use a longer bolt and reach the bottom threads to tighten the back plate firmly against the needle stay. Was careful this time not to over-tighten and strip again.

Thanks to all who offered advice. Hope I can return the favor some time.

Cary
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