PDQ Mobile wrote:Brucey, you don't think regular pressure washing may be a cause of bearing failure?....
er, no. This particular bike gets left outside 24/7 and gets rained on, never cleaned per se. In fact it has green stuff growing on it in places.
Besides which the 'experimental pedal' (PD-M324) was one which had been abused to death by someone else. It must have been run with free play in the bearings, and the free play got so bad that the balls in the left bearing of the left pedal started to run over one another and escape from the place where they were meant to be. Since the cone has a hexagon on the end of it there was a certain amount of mangling; the cone was so far out of shape that I wasn't sure that the balls would even stay in place when I first reassembled the pedal bearing. There was a really bad tight spot and ninety degrees away from that the bearing was so loose that I thought the balls could escape again. Just what I wanted to try in fact.
You might be wondering 'why?' Well in my care I find that SPD pedal bearings just don't wear out; typically they need adjusting once (after they run in) and then rarely if ever need anything more than grease subsequently. However I have noticed that pedals which are run with any slack in the bearings (by other folk) do carry on wearing. Often I have had to adjust such pedals two or three times before they 'run back in' again, because the bearings wear to give a slight tight spot and a slight loose spot, which can gradually disappear over time if you keep relubing/readjusting. I was intrigued to see just how bad the wear would have to be before it became impossible to recover the bearings, i.e. so that they spin freely, have no tight spots, no free play and don't need adjusting more than once every few thousand miles/ couple of years. Some years ago I took what I thought were the most worn SPD bearings ever in another set of pedals (which were so worn that the bindings needed repair before I could use the pedals at all...) and gave them the same treatment and to my astonishment, after about four adjustments/regreasings the bearings 'ran back in' perfectly. Another year's use (without adjustment being necessary) confirmed that the bearings had settled down and were no longer wearing at any appreciable rate. Too easy then; I obviously needed a bigger challenge. Hence the current experiment.
In fact the current experiment almost failed because the RH ('control') pedal developed some free play. I hadn't regreased that one and (as is common for PD-M324) the seal on the spindle had deteriorated. So over the second winter some water got into the inboard bearing on the RH pedal so the RH control pedal developed more free play than the 'experimental' LH pedal (*). The RH pedal now has a little fresh grease and some improved seals, and has stopped wearing. The LH pedal bearings are still pretty rough but don't have a really bad tight/loose thing going on and don't seem to be wearing at any great rate. Several of the balls are damaged and when I last looked at them the edges of the damaged parts of the balls were well-rounded, which suggests that the bearing is settling down. Some prior examinations had revealed lots of swarf in the subject bearing. I've only bothered cleaning it out once though and it has done several thousand miles.
(*) from which you can conclude that even a really knackered bearing which is lubed with decent grease (solid lubricants, EP additives, synthetic oils and corrosion inhibitors amongst other things) can wear more slowly than a bearing with 'normal' (for shimano) grease which also has the slightest amount of water in it. The grease was still indentifiably green in places still, and only slightly brown (through corrosion) in others. It really is utterly hopeless grease if the slightest amount of water gets into it; no wonder that freehub bodies clap out so often.
So no, pressure washing has nothing to do with it. The provisional conclusion of this experiment is that if the wear is bad enough, you might not get SPD bearings to run back in again no matter what you do with them. But they have to be incredibly bad before that is definitely going to be the case. There are other experiments underway in the hubs and BB bearings....