Etched Races

[Chris KC]

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?

[bob46320]

I think a photo of the damage may help in a decision. If you can afford a top quality one, bin it so that others aren't faced with the same dilemma ?

[Chris KC]

Good point Bob but I regret that's not immediately easy to do on account of it being in the bottom of a trunk somewhere in my icy garage and me having the flu.

I guess that was my point really - I'd venture that the Hoffmann (spelt right this time) if unmarked was probably the best quality bearing to be had nowadays.

[Charles P]

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

[Chris KC]

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

[Charles P]

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

[Chris KC]

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

It's hard not to agree Charles. It might very well see me out, but if building an engine I like to give it the best possible chance of success.

I suppose I might be swayed if someone can offer knowledge gleaned from many years in the trade - as others have commented, there's some impressive experience on tap here on A7F...

[Alan]

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.

[Chris KC]

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.

That's the sort of knowledge I mean Alan!

[Robert Foreman]

I agree with Alan, 
   It's exactly the same kind of test I would perform . You can polish race tracks and remember a roller race outer track is not that hard.