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Transfer Case Rear Cap Shims

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Howard View Drop Down
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    Posted: 17 Jan. 2010 at 6:13pm
Hi Folks,
These shims are used to adjust the proper bearing endplay on the output shaft. The shaft is supported by tapered roller bearings and must have some play for the bearings to work and carry the load properly. These shims are located between the rear cap and the transfer case main housing.
I have rebuilt or repaired more than one model 18 Transfer cases at this point, all of them have been the early 3/4" intermediate shaft models. Each one has taken a different amount of shims. My cases have required between 40/1000 and 85/1000 worth of shims to achieve the endplay required by the specs of .004 to .008 endplay, as listed in the manuals. If any parts are replaced in the output shaft(s) area then this measurement will need to be made. This should be checked in any case of reworking the transfer case. It is a critical measurement to make.
Improper adjustment will cause premature bearing failure, seal failure, gear malfunction /failure, overheating, etc,etc.
Group 18-02
Part # A-982 .003 Thickness
Part # A 983 . 010 Thickness
Part # A-984 .031 Thickness
Spicer # SP-18-228-7 and -8 and -9 respectfully for the various thicknesses
I use a good caliper or micrometer to measure the thickness of these shims, however it is rather obvious once loose and in hand which one is which. Interesting that I did find one in my pile that measured .007 in thickness.
There is more than one way to set up and measure the endplay of the output shaft as adjusted by these shims. I use a dial indicator and a magnetic base, some do it by feel.
I set this one with a final reading of about 3.5/1000 endplay,dry, no sealant no lubricant. Then disassembled the front bearing cap and the rear cap, applied sealant to the shims and gaskets lubed the bearings and reassembled. This added 2/1000 to my final reading of endplay. Which is now about 5.5/1000.
For referance, this is my setup to measure. This is with the shaft pushed forward in the gearcase and setting the dial to zero.
Then forcing the shaft rearward, as instructed in the service manuals, taking a reading again.
In this case I had to many shims in place. I had just at 9.5/1000 endplay. I removed two 3/1000 shims, reassembled and had just at 3.5/1000 play, dry.
Just to put things in perspective, a typical sheet of paper is about 2.5/1000 thick.
Also as a personal side note...I have always had some trouble with writing these measurements down, and reading them on paper. I do not know why...40 years later I still will write 40/1000 instead of is just easier for me to read. I still have to think about it when reading the various specifications.Embarrassed

Edited by Howard - 17 Jan. 2010 at 8:46pm
Howard F Jewett

1946 CJ2A #23353

43 GPW 106505 USA #20366014

43 Bantam Trailer T3 #14844

52 M100 K1119
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