[Fot] TR4 crankshaft end play

[Tim Murphy]

When I assembled the reground crank after the center main bearing failed I
put new thrust bearings in, 0.005 oversize in front, standard in the rear,
which is what the old ones were.  The old thrust bearings got particles of
the failed center main imbedded in them which is why I replaced them.  I had
0.003 end play with the old thrust bearings when I put new main and rod
bearings in 2008.  I now have 0.001 to 0.0015 end play with the same  size
new thrust bearings, 0.005 oversize front and standard rear.  I'm guessing
my old thrust bearings were a bit worn, giving the 0.003 end play in 2008.
The book spec is 0.004 to 0.006.  If I take the 0.005 oversize out and put a
standard in front also I'll be right at the limit of 0.006.

 

Am I better off to run the 0.001 end play or the "at the limit" 0.006?

 

I did notice that the new thrust bearings from BPNW, which are the "County"
(I think that's the same as "King") brand, have what appears to be a copper
facing on the bearing surface whereas my old ones looked like Babbitt.
Maybe the copper was worn off the old ones giving the 0.003 endplay?

 

Thanks for any comments and opinions on this.  It would seem that 0.001
would be a bit tight, unless they quickly "wear in" and would give me 0.003
or there about.

 

I'm measuring the end play with a tenth indicator against the ground surface
on the flank in front of the rear main journal and "pushing" the crank back
and forth with a big screwdriver against the center counter balance and the
block.  I get the 0.0015 if I push hard and hold and the 0.001 if I push and
release.  Only the center main bearing block is in and torqued.  The front
and rear blocks are not installed yet.

 

This is a stock crankshaft and the stock thrust bearings.

 

Tim