New thread bushing inserts on some engine parts, p.e. at tensioner housing...

One of the most common problems when working on motorcycles is the all-too-common thread damage. This is especially true for internal threads, which are frequently used, for example, during adjustment work or engine service.

In my case today, it was the internal thread of the timing chain tensioner. This is something that often happens over a long engine life, as it undergoes quite a bit of movement (at least in a well-maintained engine).
I didn't have a "ready-made" replacement part, such as a "timesert," so I made a threaded bushing myself on my lathe.

When making this kind of thread, it's important to make the external thread first (because the greater forces occur during cutting, and it can quickly break if the hole with the internal thread is already finished!).
So always start with the larger external thread!
So I made this bushing with an M8 on the outside and an M6 on the inside, and deliberately made a bushing with a "collar"!

Then I drilled the housing to 6.8 mm and cut an M8 internal thread.
The final step was to screw the cleaned bushing into the housing using a "setting tool" with Loctite.
(When drilling, I inserted an 8 mm drill bit into the tensioner channel to ensure it wasn't drilled too deep!!!)


Now the chain tensioner is ready for use again, and can withstand more stress than before...

At the end of the morning, I made a holding tool for the chain sprocket on the engine. It will be very useful when removing or installing the sprocket...(Of course, I didn't invent such a "sprocket holder"; you can buy one here in Germany, for example, from "Z-fever" for €26.95, but I love making such tools for myself, just like I did with my alternator rotor holder... something like that fits perfectly, nothing gets damaged, and it makes assembly much easier!)
 


 
 
 
 
 
 

Well done, but why did you not just use an M8 bolt in the M8 thread?

...just to use the "original-screw" and the "original-looking",...and not to "disturb" the 8mm channel for the spanner-rod with the same size of screw.....and i like the work  ...( But sure, you can do it also like you´ve mentioned..!)((...and to be honest: With the simple M8 screw solution, the "soft aluminum" is used as a "movement thread"...with a bushing it lasts forever...but that's just my opinion.))
 

Why not use a Helicoil?  Cheap and simple.

Hi Ed,I don't like these simple and cheap helicoil "springs" at all. I've had too many bad experiences with them over the past 40 years, especially on threads that are frequently used by screwing them in and out! They tend to come out with them!

I would only use helicoils on threads that stay fixed, not on parts that are often unscrewed!!!
 

Timesert!

Loctite too
Some inserts are supplied with the locking compound on them.

MFP-Joe wrote:

Hi Ed,I don't like these simple and cheap helicoil "springs" at all. I've had too many bad experiences with them over the past 40 years, especially on threads that are frequently used by screwing them in and out! They tend to come out with them!

I would only use helicoils on threads that stay fixed, not on parts that are often unscrewed!!!


 

I respect your decision.  Have to say, though, that working in the aircraft component manufacturing industry for 19 years taught me that a properly installed Helicoil is just fine.  We used them by the thousands.  A drop of red loctite works wonders.  All of our parts made from aluminum, that got an insert, required a two part epoxy primer down the hole before installing the insert.  That help hold them in place also, but mostly it was for corrosion (stainless and aluminum don't get along).  One place where I'm not a fan of helicoils is in spark plug threads.  There are exceptions to everything...

I used to use Helicoil in the chain tensioner housing, but I always had problems with the thread spiral moving again and rotating when loosening the tensioning screw. Sure, there are applications for Helicoils, but I prefer either "timesert" or self-made, precisely fitting bushings, i.e., "custom-made" for the respective purpose.