Transmission gear shaft questions

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Model T Ford Forum: Forum 2008: Transmission gear shaft questions
Top of pagePrevious messageNext messageBottom of page Link to this message  By Gaylen Gammons on Friday, January 23, 2009 - 07:49 pm:

Hi, working on my '15 project. Had checked three tranmission gear shafts that I have. All of them are worn where the bushings have worn them,and the average run-out at the end is about 6/1000ths. Was wondering what it should be, zero, most likely. As for wear, I do not know how I would overcome that, as there are no reproduction part listed in the catalogs I have. I could possibly have it sleeved to the proper thickness after turning it to be straight? Problem is I do not know the proper dimensions for the shaft to start with. Any other ideas out there? I suspect that this is a common problem. I am almost sure that the worst shaft I have is the one that ruined my transmission bushings before, on another transmission. So, need some ideas, or solutions. Thanks MTFCA!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Adam Doleshal on Friday, January 23, 2009 - 08:13 pm:

.0006" would be acceptable runout .006" would not... .006" is quite a bit. That would equal about .020" off center at the fourth main journal. How are you measuring it? In a lathe, or on v-blocks?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gaylen Gammons on Saturday, January 24, 2009 - 01:07 am:

These were checked using a lathe run by a machinist. With three in similar condition, I am not sure about my chances of finding a good one! When I bought two of them,the best in the bin, the seller tried to run them on an older lathe to verify the trueness. I think that old lathe needed bearings... Wobble could not be acurately checked until I had them checked at a machine shop. Does anyone make new ones? Anyone got a real good one for sale?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Adam Doleshal on Saturday, January 24, 2009 - 11:49 am:

A good transmission shaft has to meet the following criteria in my book...
1- The pilot for the driving plate needs to be smooth and true.
2- The area the clutch disc drum presses on needs to be the proper size and not worn from a loose disc drum working back and forth on it. The disc drum needs to be a good press fit on the shaft.
3- The surfaces on the shaft where the brake drum bushings run need to be smooth without excessive rust pitting. A little pitting in some situations will not hurt. (The closest clearance you will be able to set the bearings to is the difference in measurement between the area the disc drum presses onto and the area the bushings will ride on.)
4- The flange needs to be 90 degrees to the shaft on both sides. If it isn't, it can be re-machined. Take off as little material as possible!
5- The area the driven gear "bumps against" in the inside face of the flange does not have to be absolutely smooth. It can be polished in the lathe with a little oiled fine emery cloth to "smooth out any high spots".


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