So i’ve been cleaning out some Bottom Bracket bearings, and they were a little bit wet, so I decided to heat out the water by placing them in the oven for a short time
I forgot about them and left my house. Double stupid. So the bearings have now been in the oven at about 200 for around an hour before I sped home to fix it.
One of the bearings has turned a sort of brownish colour, both the balls and the cage have this slight brown colour. The other bearing has balls that have gone purple and the cages are brown.
My question is, is it possible to fix this? I’m worried that I have softened/deformed the bearings, and am wondering if this would be the case.
I tried to use the search function, but “overcooked beaings” yielded no results.
You should always roast bearings for 45 minutes in a medium oven, while basting with Phil grease.
Grease em up and chuck them back on the bike. If they roll fine then it’s all good. Steel ain’t going to soften/melt at 200 degrees.
I’m just worried they might still be a bit pink on the inside
next time try some tri lube to clean out the water and then some light grease
They have probably oxidized, bearings are cheap, just grab some more rather than trying to use rusty bearings
Aaah the ol’ Purple Balls, hey…
If they are purple and brown could this be patination rather rust? If so they should be fine to use, I would just just clean them with isopropyl alcohol (to remove any grease that could have become sticky and coated the bearings), wait for them to dry - but don’t put them in the oven this time - and then regrease them.
I would have thought that 200 degrees would be far too low a temp to distort hardened steel.
The steel needs to get to above 700-800 deg. minimum before the molecular structure will start to change.
This is partly true. Ferrite/austenite phase transformation occurs @~722C
However, hardened steel will undergo tempering (gettin softer/weaker/more ductile) at lower temperatures (somewhere around 350C to 500C).
Won’t happen at any temperature a domestic oven is likely to achieve but heating to temperatures below 700 can still cause softening in steels
lawled my balls off
You only need to use lite grease in a crabon frame. If you’ve got a steel frame you’ll be good with full fat grease.