[Rannsachair]

I have a 1969 T120, there was a slight oil leak from the tacho drive, so decided to investigate.

The left hand thread in the crankcase has been partially stripped (I suspect a previous owner has tried to remove it at a right hand thread).

I believe it was a right hand thread up to 1969.

Any repair suggestions, I wondered if I strip it all down if I could get a helicoil for the crankcase and rethread it for a right hand thread and fit an earlier tacho drive?

Anyone else had the same problem or suggestions on how best to fix?

Thanks

 

[Mastiff-man]

I would try silicone first, just be sure to clean it first so there's no oil.....Because of the early & late different thread types, you may have to change the tach & cable as well..Good luck

 

[t100rc]

68 and earlier use the standard thread. 69 and later use left-handed thread. (backward)

Is your problem that the engine case is stripped where the drive screws in?

EDIT: duh ... you said that was EXACTLY the problem ...

the threads on that thing are pretty deep ... are they damaged enough that it just won't seal? if you teflon tape the unit, will that seal it? what about some gasket sealer on the threads of the drive unit?

I think helicoiling that will not be fun. If you can even find an appropriate thread coil ...

 

[Mastiff-man]

What about CEI threads on the tach gear & cable??? Wouldn't that be different...

 

[Rannsachair]

Thanks folks

Visited GRIN Triumph in Scotland, they will weld up the damaged thread, make up a drill guide for the other side of the crankcase and re-drill and tap for RH thread. I will then use a pre 1969 tacho drive.

 

[t100rc]

Why not just have them tap it for the correct left-hand thread unit?

 

[Rannsachair]

Why not just have them tap it for the correct left-hand thread unit?

suspect left hand thread tap is rare/unavailable.