Helicoil kit size description
Helicoil kit size description
Author
Discussion

Sensibleboy

Original Poster:

1,168 posts

156 months

Saturday 3rd February 2018
quotequote all
Dumb question but always best to check these things.

I have a M7 bolt with 1mm thread pitch that has stripped the thread in a gearbox.
Do I just need a 7mm helicoil kit or does the kit description refer to the hole size that the helicoil will screw into? I.e. does it refer to internal diameter or external diameter of the helicoil?

It's only the thread that holds the end cover onto the box so nothing stressed.


JonChalk

6,469 posts

141 months

Saturday 3rd February 2018
quotequote all
It should refer to the finished size you want to end up with.

We use a lot of these at work, but I'm less sure of the sizing / calcs, but the kit / helical tools should have a drill size (usually around 10% larger diameter from memory) and a tap to cut a new thread for the insert to screw into with a special tool, taking you back to M7x1.

JonChalk

6,469 posts

141 months

227bhp

10,203 posts

159 months

Saturday 3rd February 2018
quotequote all
You need a 7 x 1 thread repair kit.

Sensibleboy

Original Poster:

1,168 posts

156 months

Saturday 3rd February 2018
quotequote all
Excellent. Thanks guys

GreenV8S

31,027 posts

315 months

Saturday 3rd February 2018
quotequote all
I don't have much experience with either type, but I found that helicoils tended to leave a relatively 'loose' fitting internal thread - as if the hole had been tapped oversize, if you see what I mean. I prefer timeserts because they don't seem to do that. Maybe just operator error, but that's how it seems to me.