Does anyone know what the running clearence should be for the bush in the 1st motion shaft. I have recently experienced a seizure (and yes it was a b---tch to free up). I am using a 17/25 convesion and a 4.9to1 rear axel and 19 inch wheels. Lot of clutch slipping to get moving on a hill so I have now fitted cast iron linings to disperse heat.

All seems quiet on this thread at the moment so I'll pitch in and suggest a running clearance of one to one and a half thou should be sufficient. Let's see what other figures this prevokes!
Were these freshly assembled components, with possibly over tight clearances, or had they run for some time?
Getting a flow of oil through the bearing is paramount and that is what the radial holes in the gears are for. They allow oil to be "flung" out of the bearing thereby drawing fresh oil in. Were these blocked or restricted at the time of the seizure?
Ron

I think I have found the problem. When I assembled the box I put in one shim too many over the 1st motion shaft bearing --forcing the 1st motion shaft in to the 3rd motion shaft-- I will be more careful next time.