Rear Axle Question
Posted: Tue Sep 26, 2006 5:47 am
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Tom,
The answer to your question is the same answer you recieved on the G503 site. The shims are used to maintain the correct end float of the axle shaft. When you mass produce a mechanical assembly as complex as a complete drive axle assembly you must allow for variables in production tolerances. No mass production facility is capable of producing several thousand parts to an exact 0.0000 dimension. So engineers specify a max and minimum dimension for each part. Then they insure that any combination of parts with any max or min will collectively fit in the total available assembly space. That is why the engineers plan in a small additional space to accommade an adjustment to correct for pileups of adverse tolerances. For a simplified example suppose you were to end up with a housing that measures at the extreme narrow dimension and an axle shaft that measures out to the extreme long dimension. With several thousanths allowed in production tolerance margins this could create a need for 2 or 3 times the number of shims you have. Now if you get a housing measured at the maximum length and an axle shaft measured at the minimum length in tolerance allowances then the engineer's plan allows a little remianing room to be filled with the appropriate size shims.