Britbike forum Forums British Motorcycle specific Brands Triumph bulletin board T120 main bearing journal

Good evening all,
I am currently doing parts inspection on my ‘67 T120 TT project. I was taking measurements on the crankshaft surfaces and found the drive side main bearing journal to be slightly under spec and somewhat oval. A photo with the measurements is below.


If I try to reinstall the old roller bearing onto the journal it goes on pretty easily with a slip fit. The manual calls for journal dimensions of 1.1247-1.1250” and the bearing to be a “tight push fit” on the crank. So, what are my options to remedy this situation? Any and all advice is greatly appreciated. Thanks.

Here’s a couple of pictures showing the crank journal and bearing .

I have looked to see if I can locate any of the bearing size markings such as O, OO, OOO, etc. I found this marking etched onto the inner and outer races. Not sure what it means, maybe someone with intricate knowledge can explain.

Send it to Marine Crankshaft and have it welded

I have done this a few times

See my post on this very subject

https://www.classicbritishspares.co...-bearing-on-a-vintage-triumph-crankshaft

Thanks very much for that information, extremely helpful.

No worries

If you do send your crank out for welding, make sure they DO NOT grind the face of your crank

Tell them to leave the depth (length) of the journal the same with the proper radius

Ask me how I know.....