Helicoil vs Tap

[AmDaMan]

Hi, basically my mate got his gearbox helicoiled the other day where the gearbox mount stripped the threads. and while putting the bolt on today (and then taking it off to check it was ok) the helicoil came off :evil:

So basically how difficult is this to tap, seems easy enough but worried about getting it 'straight'

Is the current bolt size m10? so if I tap that to m12 everything should be sweet as a nut?

cheers.

[Clio_GTT]

you'll need to drill it before tapping to m12

[snowman]

Youll need a 10.2mm drill for a 12mm thread,also the thread pitch is different, 1.5 pitch for M10 & 1.75 pitch for M12,plus its alloy youll be tapping into so the thread wont be that strong as youre repairing rather than threading a new thread,if that makes sense.

[AmDaMan]

The alloys is pretty soft plus it's completely stripped so can it not just be tapped straight away?

Do all m12 bolts come in a 1.75mm pitch?

[snowman]

The tapping hole size must be 10.2 optimum,otherwise the pitch and thread profile for the 12mm wont form properly and wont grip the bolt.

You can get M12 1.50 pitch bolts aswell tho.

Where abouts is the damaged hole,is it in a place where it could be cleaned out and have ally weld to fill it in and re-thread from new?

[Lunner]

It's on the top of the gearbox, might be easier just to swap the case, don't have to take alot out at all to swap that side