Dana 300 rear output endplay

[simple man]

I have finally gotten around to rebuilding my Dana 300 and have run into a problem regarding setting the end play on the rear output shaft.  After assembling the shaft and getting an initial end play reading, .005, I added a .003 shim and remeasured the end play and got a .005 reading.  So I added another shim and there was no change in the end play reading.

My assumption is that the the inaccuracies in the end play measurements are caused by user error in setting the dial gauge. In setting up and resetting the gauge I may be getting inaccurate readings. In setting the gauge I am trying to place the gauge against the end of the threaded portion of the shaft.  However, one questions is could the torquing the yoke on and removing it and replacing it be affecting the output shaft.  For example, could I somehow be stretching the shaft?

Is there any trick in setting up the dial gauge?

Another strange problem I have had when installing the yoke is that the yoke will only fit on the shaft in one specific orientation.  If the yoke is placed five splines left or right it will not slide all the way onto the shaft.  I have tried the yoke on the input shaft and it doesn't have a problem.  Any idea of what may causing this, could the shaft be damaged?  Could this be related to the above problem?

 

Thanks

[Moses Ludel]

Check for radial/lateral runout of the shaft.  Make sure the shaft is not rocking sideways, which would make your endplay readings inaccurate.

Threads would not stretch to show this kind of endplay error, but you do compress parts when torquing the nut.  That affects the endplay reading.  Also, the shim(s) must be located properly in relationship to the bearing.  Refer to the illustrations for the parts and make certain that you are removing and adding shim material in a manner that will allow the bearing to move inward or outward.  You should be able to read endplay changes with each shim stack change.

As for endplay readings in general, I use a stout magnetic stand to secure the dial indicator to the iron case.  I also use dial stand rods and clamps rather than a goose neck fixture, although many do use a goose neck with success.   Note that the stem of the dial indicator can stick in the shaft end recess; the stem must be able to float.  I use a smoothly rounded end on my dial indicator or sometimes the roller end.  Make sure the dial stem can move without interference; this can be tricky.  The stem should be directly in line with the shaft, not leaning one way or the other.

I would check the splined hub and flange of the yoke to be sure the parts can seat up completely.  Are you running out of spline length before the yoke seats completely?  This would throw off your endplay by not allowing the stack of parts, including the shims, to crush together flatly.  You would keep getting the same measurement regardless of the shim stack thickness.  This problem would be prevalent when trying to reduce endplay like you're doing here...Also make sure that the bearing can seat fully each time you change the shim stack thickness and tighten the nut.  Is the bearing able to seat properly on the shaft?

Moses 

[simple man]

My reason for my post was my concern that when adding shims the amount of end play would increase and this seemed illogical.  I assumed that adding shims would decrease the amount of end play.  

It has finally struck me me that the amount of end play is reduced by reducing the thickness of the shims.  

It seems  to me now, that reducing the thickness of the shim pack moves the end of the yoke closer to the housing therefore reducing the amount of movement between the input and output shaft, therefore reducing the amount of end play.  

 

Is this correct?  

Rick

[Moses Ludel]

Correct, simple man...Removing shim thickness brings the tapered bearing cones closer together.  This reduces end play.  See this schematic for the parts relationship, it will be clear how the shims affect the end play:

1981-86 Jeep Dana 300 Gears and Shafts.pdf

Trust this helps...You can zoom-in for more detail on the PDF images.

Moses