Scott,
>I'm not a machanical engineer or anything, but i know my way around engines
>fairly well, and have this question. The factory manual states crankshaft
>endfloat to be .006-.008, I know some engines use a tighter clearance (.002
>or so) than this on the endfloat. Are there any reasons that it would be
>unadviseable to run with endfloat at .003-.004 by using a combination of
>stock & oversize thrust washers? Has anyone tried running a tighter end
>float than the specs call for?
Why run tighter? Specs are there for a reason. I had to fit a combination
of std and oversized thrust washers to my TR3. Even with the mixed sets I
couldn't get within tolerance. Two standard washers resulted in 0.0015 over
tolerance and a standard and a 0.005 oversized was 0.002 under tolerance.
In a half an hour I was able to hand lap the oversized thrust washer set
down to meet my specification. All you need is a measuring device (caliper,
micrometer, etc.) good quality sandpaper and a very smooth surface, like a
piece of glass.
I used double faced tape to secure the thrust washer to a large block of
wood to maintain flatness, and also secured the sandpaper to the flat
surface. I started with medium grit paper and finished with fine grit.
I measured the gaps with thrust washers which were too small (I used the new
standard thrust washers) and was able to determine how much too small with
feeler gages. It is simple math at that point to determine how much you
should take off the oversized washers to get them right. I targeted the
bottom of the allowable tolerance range, so that I would have the tightest
possible configuration an well as the most bearing "meat" still available
for wear.
NOTES:
1. Make sure to take the material from the steel backing side only.
2. I don't know why, but everyone says to put the thicker washer on the
surface that takes the most pressure, the back washer; probably because it
has a thicker bearing material.
3. Check your work frequently to make sure you are removing material evenly.
4. Change sanding directions and part orientations frequently to insure
flatness and uniformity.
It is really pretty easy and very rewarding when you install them and verify
that they are done correctly.
BTW - If you are uncomfortable with this procedure, a local machinist could
do the work for you very easily, if you can provide the measurements. I'd
say give it a shot yourself. It really is pretty easy and if you blow it
with the first oversized thrust washer, you get a free second shot with the
other half of the oversized washer.
Jack I. Brooks Brooks@Belcotech.com
Project Manager http://www.Belcotech.com/
Belco Technologies Corporation '60 TR3A
201-560-8861
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