ball bearings

[stevemarl]

(Bit of a dull technical query I`m afraid) Just wondering if anyone has any experience with ball bearings? I fitted a brand new QH wheel hub assembly to the Fiat about 10 years ago. Right from the start it had a very strange faint `low rattly` noise which we were unable to fathom. Not loud, no roughness or play (or MOT comments - till last time). Anyway done about 50K since and I noticed I was getting a droning on the motorway, even when Deb paused for breath, like the exhaust except if I put the clutch in - still there. So, put another new hub on (fine) and thought out of curiosity I`d see what was inside the noisy one. The inner race of bearings are a weird golden colour (outers less so) which I thought perhaps overheating?
where we love is home poem

Then I checked the balls (as we all should) and found this:


Hard to photograph with reflections, all the grey is the `inner` material: I can only describe it as, it looks as if it was `plated` and some of that has broken off, as though it had a hard outer shell? Like case hardening that`s broken down? AFAIK ball bearings should be through hardened, the ones I`ve ordered are, is this QH using inferior quality parts to save ££s?
Any thoughts?

[Mc Tool]

Sorta hard to tell but if the bearing still grease around it I would say it was #ucked right from the start.
Gotta ask , was there a spacer between inner and outer bearings ( so when hub nut is tightened there is no axial load on the bearings ) ,. Did you fit the new bearings by beating on the inner race . If you fitted them correctly then I would say you got a dud bearing.
Even with a brand new good bearing the races and the balls ,or rollers deform minutely under load , sorta like a moving ripple on the surface , they are #uckin hard but still malliable . A good bearing will tolerate this for a long service life if preloaded and lubed correctly. It only takes a minute imperfection to start a crack and it all turns to custard after that.

Having said all that I watched a mate (cant be told so I didnt bother trying ) bash a ball bearing into a m/ cycle crankcase half , I could see it wasnt square , had a bit of a job getting the c/case halves together , had to beat on the ends of the crank just to get the crank to turn by hand , still had a massive "tight spot " .....but that motorbike out lasted 4 grand kids .

[stevemarl]

was there a spacer between inner and outer bearings ( so when hub nut is tightened there is no axial load on the bearings ) ,. Did you fit the new bearings by beating on the inner race .

Hamish,
No beating, it`s supplied as a sealed unit, you just slide on, spacer, nut, torque, peen. The 2 inner `tracks,` cones, or whatever meet to prevent overtightening, so the bearings were never stressed.
Rather than a separate bearing as such, the outer `tracks` are machined into the hub, the bearings and cages go in from front and back, then the inner races push in, front & back. The whole hub is then fitted onto the steering (can`t think of the name - the shaft it all spins on?) As I say it was free spinning and smpoth from the off - just made a strange noise. Still loads of decent grease there so I`m assuming it was faulty from the start then? It`s a strange thing, the ball looks exactly as if it was plated and the plating`s come off. Plus, I`ve never seen bbs that colour. Strange too that the NS one is original and still totally silent at 250K (that`s 400k N.Z.)
Thanks for your thoughts.
Steve

[Mc Tool]

Ah yes , I know the bearing you mean , sounds the same as my old MR2 front wheel bearings and they did over 260,000kms . Certainly sounds like it has shed its surface area. You wouldnt think the discolouration would be due to heat as there was still grease which you would expect to burn .
Just one of them things