I have quite a few stripped threads on my primary chain case.

What is the best way to repair these, helicoil inserts or braze on new captive nuts?

Also, what is the thread for the screws?

Regards

Pat

email (option): sacombsashtrees@hotmail.com

I have to confess to having run a 5mm tap down the stripped threads on my cases and used metric screws.

They should be 2BA I think (0.185 Inch Diameter vs 5mm -1.95 Inch)

Cheers

Pete

Yes 2BA they are.
If they are not too bad put a strand of copper wire through the nut then run the screw through.
You might need to do it a couple of times.
You will not find BA inserts and if you do it will be BSF not BA.
You can also tin the hole if you are good with solder then run a tap down them.
30/70 solder commonly called radiator solder will do the job just fine.
Don't forget the outer.
Most of the holes will be dimpled a little so will require a few taps with the hammer with a dolly ( commonly called bolt head ) underneath to return the hole to being flat with the cover.

email (option): bsansw1@tpg.com.au

Thank you for the responses.

Ebay has some inserts which are advertised as 2BA, the taps seem available too.

I wasn't sure what you meant by "don't forget the outer [cover]"

Kind regards

Pat

email (option): sacombsashtrees@hotmail.com

Hi Patrick
I have just done these on mine, I had four nuts that were missing altogether!

I got a piece of 3/8 square keysteel, cut a short length then drilled and tapped it 2 BA.

I then cut it into four slices and brazed them into place. Finally running the tap through to finish the edges where sawn off.

Good as new !
D

email (option): dwrudd at lineone.net

The BSA parts books identify them as 3/16" so I think that they were originally 3/16" Cycle (32 tpi) .
2BA is very close to that but slightly smaller in dia and has a slightly sharper thread form.
Once manufacturing tolerances come into play 2BA will fit fine with good female nuts but I have personally had good success with using 10-32 UNF which is slightly larger than 3/16" and has a 60degree thread form and 32tpi.

My primary now has all 10-32 UNF Fillester head screws and they fit very nicely without touching the female nuts - worth a try given they are relatively common screw size.

Great tip Trevor. I'll definitely try that.

email (option): cas.vanderwoude@gmail.com

Hello Patrick,

I had a nice inner case with few of the nuts missing,
And I noticed that the holes there are all nice and round, of the same size.

It turns out that these nuts had a round shoulder, and they are pressed in.

I tapped out few nuts from another rubbish inner case,
Using a drift and a hammer,and in the same manner installed it to the better inner case.

Cheers,
Noam.