Re: Puch Maxi - Stripped Engine Stud Inside the Engine Bottom

Overpriced Parts /
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> Jeff Parr Wrote:

> -------------------------------------------------------

> Get a bottoming tap and chase the treads or drill it out and Helicoil

> it.

See if you can chase threads first and make sure you chase the threads on your stud

And/or use a good OEM stud not aftermarket

If you can’t make old threads work or a 7mm stud work,

What I do (because I’m a cheapskate) is to take a 8 mm bolt, (it can be a bit larger)(see below) and drill a hole in the end going from a smallerdrill bit for the pilot hole then a larger bit (the size you need to tap 6 mm stud) making it deep enough like 11-12 mm

Iv’e done this by hand putting the bolt in a vice, Iv’e even held the 8mm bolt with a pair of channel locks while stepping on them withmy feet at someone’s house who didn’t have a vice, if you take your time and go slow, checking progress every mm or so you can drill a halfway centered hole but if you have access to a drill press then of course that’s much better.

Bolts are cheep, if you make a mistake it won’t cost you lotta money too.

Take your time tapping end to 6mm slowly back-and-forth removing shavings at every bit of reverse turn and using oil whatever you need to do to get tap down maybe 10-12mm

You don’t need to have a long threaded insert the whole length of the case hole You only need 3/8th (9-10mm) worth of good threads if that,

Drill out the case hole with correct drill bit to use an 8 mm tap with threads that match your 8 mm bolt, Do Not drill the 8 mm case hole out first because if you can’t make the bolt correctly you don’t want to drill your case hole bigger for nothing,

Try the bolt you just drilled out and tapped into new 8mm case case hole and try it making sure goes in easy then see how far it goes down, Mark and cut off the end that you drilled and tapped, that will be your insert/your homemade helicoil,

You will pretty much have to screw it in with your fingers, you don't want to use any Loctite or nothing it because you want to be able to remove it if you have to but you could if you want to,

Again it’s not important that you have a long huge amounts of threads all the way down case to hold the stud because look how thin a head nut is and it holds your cylinder on but to try to shoot for at least double the thickness of a head nut because it’s aluminum it’s going into,

8mm outer threads are stronger then 6mm so could be less then double nut thickness, it only needs to hold 10 ft lbs torque,

You don’t even have to use an 8 mm bolt you could use a standard thread bolt (23/64th-3/8 in) or even maybe a 9 mm bolt if you could find one,

it don't matter what the outer size is as long as you have a inner and outer tap and drill bit that fits the bolt that is going into case and you leave enough for base gasket to seal,

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