Axle and gear diameter and fit

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Model T Ford Forum: Forum 2018: Axle and gear diameter and fit
Top of pagePrevious messageNext messageBottom of page Link to this message  By James A Bartsch on Thursday, December 27, 2018 - 11:11 am:

I dug up many threads on installing rear axle gears, and carefully read the Chaffin Bible on axles but cannot find the Ford recommendations for shaft OD and gear ID. Specifically, will someone who knows, please share with me the clearance required to achieve the Ford recommended press fit for the axle gear? Previous posts are filled with horror stories of bent axles from too great interference press fitting, to axle gears being too loose. What's the happy medium used by Ford?

Thanks, jb


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Thursday, December 27, 2018 - 02:06 pm:

James

This older post has data on the OD and ID that may help.

Remembering one install a friend helped with, we used some crocus cloth and took a bit off the OD of the new axle shaft, that let the used gear go on with his press.

http://www.mtfca.com/discus/messages/411944/501790.html?1419095968


Top of pagePrevious messageNext messageBottom of page Link to this message  By john kuehn on Thursday, December 27, 2018 - 03:33 pm:

James I went through the same thing a few years ago as you can read in the above thread that Dan refers to. Trent Bogess is right about why this be a hard thing to do sometimes.

I would bet that in Fords factory this would also happen if the assembly line people would pick up a a gear tha was in the high end of the accepted tolerance and try to press it on an axle that was in the same range.
In other words you can't make a an exact 1" shaft go into an exact 1" hole!
Something has to ha sanded or filed to make it fit.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Adam Doleshal on Thursday, December 27, 2018 - 05:05 pm:

I use a dial bore mic to check the inside diameter of the gear all over and have found that a bore .0010" to .0025" smaller than the shaft works okay. If you have a low cost press that isn't very rigid, you will want to be very close to .001". A larger, better quality (industrial) press may be required for the tighter press fit.


Top of pagePrevious messageNext messageBottom of page Link to this message  By jeff cordes on Thursday, December 27, 2018 - 08:35 pm:

I keep a pile of rear axle gears handy to find that perfect fit.


Top of pagePrevious messageNext messageBottom of page Link to this message  By James A Bartsch on Thursday, December 27, 2018 - 09:03 pm:

Thanks, everyone. I failed to find the post Dan cited.

Adam, if it turns out my vender manufactured replacement axle is 'soft' (Rc~25) should I even consider using it? I bought two of these as spares some years ago.
Best, jb


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