Transmission Main Shaft Alignment

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Model T Ford Forum: Forum 2016: Transmission Main Shaft Alignment
Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Zahorik on Wednesday, June 01, 2016 - 01:21 pm:

I've been struggling with the alignment of the Main Shaft on my 1926 engine. When I mounted the main shaft to the crankshaft flange, without the flywheel I can easily adjust it so there is less than 0.001" run out.



But when I install the flywheel, the best I can do 0.005 to 0.006" run out. For some reason the flywheel is tilting the main shaft. I've cleaned and de-burred for the past two days, rotated the parts 180 degrees many times.



The main shaft is square, I checked it on a lathe and it will not rock when placed on a flat. Yet why should the shaft move once the flywheel is in place?

In fact I have two main shafts. Both are square and they both show the same effect with and without the flywheel installed.

Any Ideas? Thanks Mike


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Gould, Folsom, CA on Wednesday, June 01, 2016 - 02:43 pm:

First thing that comes to mind is that the outer edges of the trans shaft and crankshaft are not perfectly aligned so when they both insert into the hole in the flywheel the transmission shaft is pushed over some. When you have the crankshaft and trans shaft bolted together without the flywheel, check to see both outer circumferences are aligned. If not, you can put a spot of weld on the trans shaft flange and file it down to 3 thou, then try again.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Philip Berg on Wednesday, June 01, 2016 - 02:52 pm:

I had a similar issue when I assembled my engine. To reduce the amount of runout I took a deburr wheel and deburred inside of the dowel pin holes. It allowed me enough movement to dial in the runout.

I spent hours stoning all surfaces flat and this was a last resort but it worked. After assembly of the transmission I had .005" runout at the output shaft.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les Schubert on Wednesday, June 01, 2016 - 03:12 pm:

Or the easy answer is a "floating " transmission shaft


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Hatch on Wednesday, June 01, 2016 - 03:37 pm:

Les, they are coming! Dan


Top of pagePrevious messageNext messageBottom of page Link to this message  By James J. Lyons III - West Virginia on Wednesday, June 01, 2016 - 04:35 pm:

I have a hard time believing that they left the Ford factory any better than .005 or .006 thou.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les Schubert on Wednesday, June 01, 2016 - 04:42 pm:

Dan
Good to hear


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Zahorik on Wednesday, June 01, 2016 - 05:00 pm:

Philip, I've been polishing the location holes in the main shaft and found that I have reduced the run out to just over 0.003". So.... I'll polish them a some more and maybe I can reduce the run out some more. Thanks Mike


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Wednesday, June 01, 2016 - 06:07 pm:

0.003" TIR means the center is off 0.0015".
I think you are fine, likely better than when new.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Zahorik on Wednesday, June 01, 2016 - 06:33 pm:

Ted, that brings a question to my mind. There are a lot of guys that advocate the end of the main shaft should have 0.001" run out or less. Are they talking a straight 0.001" or would that be the off center number (one half of that)? Currently I have reduced the run out to less than 0.0025". When I had the main shaft on the crank flange without the flywheel I can get to under 0.001". I'm going for the best I can get. Thanks for the help Mike


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Tomaso - Longbranch,WA on Wednesday, June 01, 2016 - 11:00 pm:

Add my name to your list for one, Dan !


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