uys what can be done to rstripped threads in head?

[rikiwho123]

hey guys what can be done to repair stripped threads on a triumph 1300 head in the rocker tower hole; the torqueing of the tower is 34 ; well just at that setting it went limp i unscrewed it to find the top half of the threads in the head gone; i was able to screw it back down with only half the threads there ;will it be safe being the other 3 towers are all good; the motor runs great but am i safe. thanks rick. p.s. their was some oil in the front tower hole and thats why i thought the it was all the way in big mistake.

 

[luke44]

You have to drill an oversize hole and put an insert in. The brand I am most familiar with is "helicoil" - google it and you will see all sorts of videos on how it works. There are others brands out there as well...here is one example.

https://www.timesert.com/

You're gambling by only going with 3 1/2 bolts.....

 

[DNK]

Nutin wrong with Luke's brand.
If you have the room , check out Keen serts
Nice Insert, used it on my Wedge Headbolt

 

[TR3driver]

I'll throw in a second vote for Helicoil-style inserts (I generally buy Recoil brand, as they are somewhat cheaper and seem to work just as well).

One of the things I like about Helicoils, the required drill is very nearly the same size as the stripped hole, so the existing hole helps guide the drill. In fact, with a completely stripped hole, it frequently isn't necessary to drill at all (but in your case I would recommend drilling out the remaining threads). The Helicoils wind up being stronger than the original threads, because they distort just a bit and spread the load out better.

And, they leave enough 'meat' behind that, if it does go sour, you can still try the solid inserts that Don is talking about. But I have never seen one fail (and I used to work at a company that installed Helicoils as a matter of course, to produce strong, durable threads in alloy castings).

 

[rikiwho123]

thanks guys i guess i'll have to find out the size of the stud that stripped out the threads; if anyone out there has done this to their head and knows the size helicoil please let me know ;thanks rick.

 

[bigjones]

The hole for Keenserts has to be drilled out perfectly vertical.

What do folks do to ensure this?

Cheers

 

[Andrew Mace]

thanks guys i guess i'll have to find out the size of the stud that stripped out the threads...

If it's the rocker pedestal stud, it's 3/8" UNF.

 

[rikiwho123]

Yes it is thank you very much.

 

[TR3driver]

What do folks do to ensure this?

If you have access to a drill press, the easiest method is to take something square and drill a hole the same size through it. A chunk of 2x4 wood will do for a single use. There are also various commercial versions available, Google for "drilling guide".

But I find that usually, I can get it close enough by eye, perhaps with the aid of a machinist's square https://littlemachineshop.com/products/product_view.php?ProductID=2549

 

[DNK]

I did it free hand on the Wedge.

 

[bigjones]

OK, thanks! Hopefully I've never have to do it, ha!

 

[startech47]

You may be able to bolt the rocker arm back on and drill through the pedestal if the required hole size is smaller than the hole in the pedestal.