Wythnail

Yo yo yo everybody.

Went to service an old bottom bracket, and the fixed cup shows very slight "brinelling" (I don't know if that is a word or if it is spelled correctly).

Question is, in general, how much wear is acceptable for you experienced mechanics to reuse a cup? Or is it one of those things that once you see wear it'll deteriorate quickly and warrent a replacement soon anyway.

This is a general question about all bearing surfaces, but for the sake of an example, here's a pic of the cup I took off today. I plan on reinstalling, as it doesn't look too bad to me, and the bike isn't that special.

Andrew R Stewart 

This is always a judgment answer. The photo shows no pits in the viewed areas. So from this limited info I would consider reusing it. But as cup/cone Bbs are getting scarce it could be argued that it's always better to move onto the current standards.

The finer answer is a result of reassembling and seeing how it all runs after adjustment and arm install. Sometimes I replace the balls other times if they're clean and shinny not. Andy.

Yan 

Cup in picture looks fine. Use run a ball point pen across the cup surface. If there is any pitting, the cup is toast.

FBinNY 

That isn't a wear patter you'd get on a bearing surface with a rotating part. It's a pattern you'd get on a stationary part. I suspect it's the result of a corrosion process rather than mechanical wear, possibly vestiges of rust spots if the bike was left a while after riding in heavy rain.

I'd have no qualms about reusing the cup based on the photo, and would expect wear to make it better over time. OTOH, as AS said above, feel is a better indicator.

If you're interested in knowing more about bearing wear, search for "fretting" and "false brinelling". There are many articles explaining about types of bearing wear from complex ones written for engineers to easy to understand ones for laymen.

BTW- if the spindle has a similar pattern, one trick to reduce vibration or the "index" feel is to change the number of balls by one. This prevents all the balls "clicking in" at the same time, producing a scattering of finer clicks, which might not be detectable.

Wythnail

Good idea, thanks, will do!

cny-bikeman

Is the BB on a cottered crank, and what does the fixed cup look like?

Bill Kapaun

I'd reuse it with new bearings and grease.
However- You might note the "code" on the spindle so that you can determine the "symmetrical equivalent" cartridge BB in case of future problems.

Wythnail

That actually IS the fixed cup. Cotterless cranks, the frame is a 77 but the crankset is shimano600, so im guessing everything was replaced at some point. Its a low end fuji im overhauling to make into my daily abuse bike. I run bike delivery at the restaurant I manage, so I grabbed this off CL so I'd have somthing I wouldn't have to worry about too much.

cny-bikeman

Sorry, did not notice that it was the fixed cup, but wondering if the other cup shows the same pattern. I asked about cottered crank because I thought you were working on the 78 Raleigh listed in your info. The pattern you see is something I occasionally saw on cups on BB's where someone had hammered on a cotter without supporting the crank arm, and doing it so hard that they actually dented the cups.

JohnDThompson 

It doesn't look bad to me. But I think you must be using a 9-ball retainer. You might try either an 11-ball retainer or loose balls if you have a concern.