Dave Plowman (News) wrote:
In article ,
The Natural Philosopher wrote:
I had to fit new big end shells and main bearing shells to a Rover V8
engine about ten years ago.
Only the worst of ignorant ****s would fit new bearing shells to
anything. If the shells need replacing, the bearing surface is also
worn/damaged.


No.

Crankshafts are hard steel,. bearing caps are IIRC lead indium plated,
they wear much sooner.

Fallacy. And I thought you knew something about cars.

http://www.austin-healeys.com/austin...ine-details-2/

says I am in fact completely right.


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.


Having rebuilt more engines than I can remember in my time, I've never
found a case where replacing shells only when there are signs of bearing
problems works. Only time I'll replace bearing shells without a crank
grind is when carrying out other work which requires splitting the
bearings. Because they are cheap, it makes sense to replace them - in much
the same way as you fit new gaskets.

In the bad old BMC days I used to replace big ends at 30k, mains at 60k
and have a bloody good look at the crank and bores at 120k, if the whole
car lasted that long.

You replaced them on spec - or when there was signs of wear?

It turned out to be the same thing Dave, I'd drop the sump and if I
could find any rock in the big ends I'd drop the caps and replace the
shells - not a big job.

at 60K I replaced the mains on spec, and that too is doable - by
dripping the main bearing caps - just.

I did this because the haynes manuals of the time recommended that you did.



--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.