Larry,
I think the key to proving that the two axle shafts are interdependent is
the statement from the Shop Manual:
"Remove or install an equal thickness of shims at each end of the axle in
order to retain the axle shaft spacer in a central position."
Obviously, if they were independent, you would add/subtract the shims
independently. Also, I guess the assumption in putting equal shims on both
sides is that the axles and housing have the same relative lengths on both
sides. I guess you could check this if you aren't sure.
I have wondered what the criteria are for arriving at the .006-.008"
specification. I would assume it simply has to do with the thermal
expansions of the axles versus the axle housing. I can't imagine any reason
why zero end float would be bad, except that if the axle gets hotter than
the housing it would create stress. You might calculate the expansion of
the axle for, say, a 100 F increase in temperature. I would be very
surprised if the temperature difference between axle and housing would
exceed this. In any case, it would give you a ballpark idea of the
magnitude involved. Now, with drum brakes, .006-.008" end float is no big
deal. However, with disk brakes, end float adds to the free pedal you have
so you have a good reason to keep the end float to a minimum.
I assume you are making metal shims that essentially don't compress.
However, as you suggest, a gasket sealer like Permatex will surely increase
the thickness somewhat. Sorry, I don't have any experience with how much
that might be and it probably depends a lot on how much you use and how
tightly you torque the retaining bolts. I would think using any kind of
fiber gasket would be inadvisable and unnecessary in this case. I think I'd
be inclined to shoot for .003-.004" end float before you add the Permatex
or whatever. (I'm assuming this is consistent with what you calculate the
thermal expansion to be.) Maybe you should consider using a lower viscosity
sealer; perhaps use Loctite 601 adhesive/sealant (red bottle). It shouldn't
take much to get a good seal in this circumstance.
Good luck,
Bob
At 07:31 AM 9/22/99 -0400, Wright, Larry wrote:
>I wrote:
> >How the heck am I supposed to arrive at 6 to 8 of
> >end play with those materials? Why not demand
> >clearances in microns? And, so far, I have not heard
> >of a source for the shims. Betcha making them would
> >take forever. Oh, yes, with the one-axle pushing against
> >the other, doesn't end play at one end affect the other?
> > BTW, this is with no gasket back there whatsoever.
> >I'm planning on using Permatex in a thin film. But: where?
> >It seems like every two pieces in the "stack" would need
> >a gasket or Permatex, and that could really add up. Am
> >I wrong? They only used one gasket per side originally,
> >right? If so, where and why?
>
>Actually, I _am_ making the shims, and making headway. If anyone has
>been inside one of these before, and confirm that the end float on each
>side is interdependent, please e-mail me. Also, I'm really curious about
>gasket location/quantity; my plan still calls for Permatexing
>everything, but I'm guessing 3 to 4 layers per side, this could affect
>end play as well. Thoughts?
>
>Lawrence R. Wright, Purchasing Analyst
>U S Office Products, Mid-Atlantic Division
>Formerly Andrews Office Products
>larry.wright@usop.com (new)
>Ph. 301.386.7923 Fx. 301.386.5333
Robert L. Palmer
UCSD, Dept. of AMES
619-822-1037 (o)
760-599-9927 (h)
rpalmer@ucsd.edu
rpalmer@cts.com
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