Vertical shaft bearings

[davidwheeler]

Whilst rebuilding my VIIth engine I have fitted taper roller bearings to the vertical shaft in the block and am wondering if they should be pre-loaded.  The Tmken wensite   https://www.timken.com/wp-content/uploads/2016/10/5556_Bearing-Setting-Brochure-1.pdf   suggests ideally there should be no lay when the bearing is at operating temperature and suggests setting the bearing so that it is just binding and then "backing off the nut by 1/6 to 1/4 turn" which would equate I guess to a couple of thou slack when suitably packed out with shims.   Can anyone enlighten me further please?

[lancialulu]

That seems standard practice for road wheel taper bearings which could get hotter than an engine.... Its not pre loading - more adjusting for optimum free movement

[davidwheeler]

True enough!    I have installed a shim but there is still a few thou play so I shall put in a little more shimmage I think.

[davidwheeler]

I tried to measure the play with a dial gauge but someone has borrowed my proper kit so I just guessed on another 10thou.   I installed it and there was just a smidgeon of play and the castellations did not line up with the hole so I tightened it up another 1/16 turn and the play disappeared and even there was a suspicion of tightness so I left it at that with a tiny trace of preload.
Of course the castellation still did not line up but I cannot see the nut coming loose!