What is helicoiling?

Sat Mar 09, 2013 5:52 am

Hi All,
I never was aware of a procedure called helicoiling. I never came across it until I became a 1st time Cub owner and joined the forum. Explanations /videos / pics very much appreciated. Needless to say I am a greenhorn mechanic :oops: I am of the opinion,from what I have read, that it is some type of method to repair threads in a bolt hole. Looking forward to replies from the experts,
Many Thanks, to all the guys who have advised me on oil changing and cleaning & setting points.
Donegal Cub. :D

Re: What is helicoiling?

Sat Mar 09, 2013 6:13 am


Re: What is helicoiling?

Sat Mar 09, 2013 6:20 am

Rudi has made a documentation that is a very good instruction page. The Helicoil is the name of the kit to repair threads. There are other thread repair methods as well but Helicoil seems to be pretty good way to do it.
Check out this link.

Re: What is helicoiling?

Sat Mar 09, 2013 5:23 pm

Hi All,
Great info re helicoiling,
Many Thanks,
Donegal Cub

Re: What is helicoiling?

Sat Mar 09, 2013 7:45 pm


It really is a lot cheaper than replacing a perfectly good final or any other part. Works on carbs, blocks and just about any thread that has been ruined. Once attempted and the 1st one is successful, it becomes familiar like an old friend as you keep doing them. Rots of fun :D

Re: What is helicoiling?

Sun Mar 10, 2013 3:00 pm

One common place to need to Helicoil is the 5/8 implement bolt holes in the finals. The two main causes of these are loose bolts or improper bolts. The helicoil is a coil spring such that the inside hole matches a 5/8 bolt thread. The external thread is some non standard larger size. The drill bit required is 21/32 inch which is not a comon size but they are available. After carefully drilling out the defective bolt hole, ( I say carefully drilling it out for we don't want to drill all the way through the final for fear of an oil leak.) we will tap the hole (cut threads) with the special tap included in the helicoil kit. The next problem is that with a blind hole (one where the threads do not go all the way through) one must use a second bottom tap to get threads to the bottom of the hole. I found it necessary to buy a second kit and grind the end back of the included tap in order to remove the starting threads, that I may tap to the bottom of the hole.