Firstly DEREK
It's very difficult to get Zero tolerance but you can quite easily get as true running shaft as possible by,
1. When buying brass tube at the Model shop run the piece of tube over the glass counter and check for truth
2. Make the bearings .002 undersize to the inner dia of tube.
3. Assemble the shaft in the bearings and fit them all into the tube, smear some Locktite 601 on the bearings and push them into the tube and leave for 24 hrs and you will have a good running shaft.
4. Machine the end of the shaft that goes into the taper collet at 45 deg, this allows you to feed the shaft up through the bearings and into the collet.
It works for me.
5. I dont't think the running temp of the shaft comes into the equation as it's the only thing in the water when the boat is running and the grease coming out of the motor end bearing is lubrication enough.
Secondly HS93.
It's too late to start digging out the shaft to ball race it, in retrospect if I build another fast electric I will consider ball racing the shaft.
I know that grease isn't recommended but the Lithium Poly is very light and as the boat is running at 35 mph in a straight line I am not looking for any more speed,
Thirdly, Bunkerbarge.
Yes I think you could be correct about the grease sticking to the shaft, but it still puzzles me as to how the water can get into the shaft through the thrust bearing
I find at present that if I grease the shaft using a small syringe I can have an afternoon running, 2-batteries each giving about 12 mins running and the boat is dry,
The next time I bring it out without pre greasing I get a small amount of water up through the shaft
As I have said I know that for Racing Fast Electrics grease is a NO-NO but this K7 is exceeding all my expectations and is fast enough see ----
http://www.youtube.com/watch?v=mjckMFo6TUE Thank's for your input.
George.