In article ,
The Natural Philosopher wrote:
If you let them wear to the coppper backing of course you WILL score
the crank.
And copper is harder than hard steel?

Dont be silly, the copper is plated on the steel shells first then the
lead-indium is plated onto that. But if you can see the copper the
bearing is finished and its LIKELY the steel shells have started to
score the crank.

So one softer metal doesn't wear the crank while another will?


essentially the shells are hard carbon steel. The same as the crank so
they wear the crank as fast as the crank wears them.

You have steel shells in contact with a steel crank? I'm not surprised you
need to change things so often.

Even water will in time wear away much harder rock. Its not a binary
thing Dave, despite your brain being wired that way.

Think your wiring is confused...

Cranks are hard, shell casings are hard, a sacrificial layer of lead and
indium is plated onto the shell inners to provide a lower friction and
sacrificial surface for the crank to run in. Get it?

Sacrificial? Not a word I'd use.


IF you replace
shells before they are totally worn out the crank will NEVER need
regrinding until well beyond the engines other lifetime limity, like
having been rebored a dozen times.

********. Plain and simple. What you seem to be suggesting is the only
time you'll get crank wear is after the shells are worn. This simply isn't
so. But perhaps you've never had the tools to measure it.

--
*On the other hand, you have different fingers*

Dave Plowman London SW
To e-mail, change noise into sound.