gearbox bushes

Hi All
Now, here I have a question. I want to replace the lay shaft bushes on my new motor that I am building, the holes in the case =625thou, the bush = 631thou thats 6thou difference I don't think I can heat the bush in. any help will be appreciated.

All the Best

Les2012

Hello Les,
As no one else seems to have bothered to reply to your enquiry, it seems you are stuck with me, again!
I`ve just drifted the layshaft bearings from a pair of D7 crankcaes, each measures up at around .002” interference on the nominal crankcase bore size of .625”. I cannot think that you could force the ones you have with that huge interference of .006” into the cases and not have the bore collapse inward preventing the layshaft from entering. You may have the option of adjusting the bore size from boring or reaming but if they are genuine sintered oilite ones then the cutting of the bore forces metal into the tiny cavities enabling the lubricant from being released thus destroying the self-lubricating properties. I have made solid bronze bearings in the past but these were to compensate for a well-worn shaft, mind you they did work very well indeed with provision for direct oil feed.
Can`t help more than that I`m afraid.

Regards Trevor.

Thanks Trevor much appreciated, I am amazed at the amount of views on my other posts re:- gears,barrels ect. 350 on one, 212 113 on others so members are looking in so why don't they use the Forum ?. ( better than just looking at pitures I think). Don't know why, maybe somone will post on here the reason and explain.

Had a go today with a bush from Rex, made a complete hash of it so thinking bearing convertion will phone Dan later.

Thanks again Trevor

Les .

Trevor, I should have mentioned your 500 plus views sorry, incidentally that should read pictures not pitures.

Les.

Not much use I suppose -- just an observation -- but I thought there was a general tendency to replace plain-bushes with ball bearings. Some quicker Knut than other Quick-Kniúts did publish something along those line´s about 20 years back, claiming there was a worthwhile reduction of friction drag. Maybe not on layshaft bearing though...?
.... Mumble mumble mumle -- just going back to sleep -- last time I had a most memorable dream experience --- hmmmmmm!! All the best!
Cheers!
JayBee,

Cupped needle roller is an easy conversion for 3 speed layshaft bearings