(14-12-2018, 03:53 PM)Chris KC Wrote: I have a new old stock Hoffman rear main roller bearing, only thing is it has slight corrosion etching (dark discolouration) on the outer race. My 'received wisdom' is that etching can bring about premature failure, but unsure just how big a threat that is in an A7. I read somewhere that if you can polish it off it's OK; needless to say I can't.

Part of me thinks it's a darn good bearing with a minor defect; and part thinks why use a defective bearing when new substitutes are to be had?

So, anyone out there have the necessary expertise / experience to say whether it belongs in my engine or in the waste bin?

(14-12-2018, 06:24 PM)Charles P Wrote:

(14-12-2018, 03:53 PM)Chris KC Wrote: I have a new old stock Hoffman rear main roller bearing, only thing is it has slight corrosion etching (dark discolouration) on the outer race. My 'received wisdom' is that etching can bring about premature failure, but unsure just how big a threat that is in an A7. I read somewhere that if you can polish it off it's OK; needless to say I can't.

Part of me thinks it's a darn good bearing with a minor defect; and part thinks why use a defective bearing when new substitutes are to be had?

So, anyone out there have the necessary expertise / experience to say whether it belongs in my engine or in the waste bin?

Within the rolling surface of the race or elsewhere on the metal?

C

(14-12-2018, 06:34 PM)Chris KC Wrote:

(14-12-2018, 06:24 PM)Charles P Wrote:

(14-12-2018, 03:53 PM)Chris KC Wrote: I have a new old stock Hoffman rear main roller bearing, only thing is it has slight corrosion etching (dark discolouration) on the outer race. My 'received wisdom' is that etching can bring about premature failure, but unsure just how big a threat that is in an A7. I read somewhere that if you can polish it off it's OK; needless to say I can't.

Part of me thinks it's a darn good bearing with a minor defect; and part thinks why use a defective bearing when new substitutes are to be had?

So, anyone out there have the necessary expertise / experience to say whether it belongs in my engine or in the waste bin?

Within the rolling surface of the race or elsewhere on the metal?

C

Yes Charles, on the rolling surface

(14-12-2018, 06:38 PM)Charles P Wrote:

(14-12-2018, 06:34 PM)Chris KC Wrote:

(14-12-2018, 06:24 PM)Charles P Wrote:

(14-12-2018, 03:53 PM)Chris KC Wrote: I have a new old stock Hoffman rear main roller bearing, only thing is it has slight corrosion etching (dark discolouration) on the outer race. My 'received wisdom' is that etching can bring about premature failure, but unsure just how big a threat that is in an A7. I read somewhere that if you can polish it off it's OK; needless to say I can't.

Part of me thinks it's a darn good bearing with a minor defect; and part thinks why use a defective bearing when new substitutes are to be had?

So, anyone out there have the necessary expertise / experience to say whether it belongs in my engine or in the waste bin?

Within the rolling surface of the race or elsewhere on the metal?

C

Yes Charles, on the rolling surface

I wouldn't use it.
Yes, most of the bearings in a car show wear after time and we don't routinely strip the engine down to check. However the idea of putting an engine together with a known weakness would always have me waiting for the problem. 

Perhaps it would be fine if you're building a bitsa budget engine rather as Martin Prior did not so long ago but otherwise, no.

C

(14-12-2018, 07:22 PM)Alan Wrote: Years ago, on bearing tracks, we used to use a rule - if you can’t feel it with the tip of a ball point pen, it will be ok. That worked for aero engines.