brussel Posted August 30, 2009 Posted August 30, 2009 OK so my spd's are not well after saturdays river crossings. The bearings are smooth but a lot of play...hmmmm so I open them up and the plastic sleeve that runs on the axle is worn oversize by more than a millimeter as you can see arrowed in this image. So what to do? a bit of a boer maak 'n plan for an ex-engineer, I am sure we can make this work. Luckily I have some tools on hand. So I bored the worn surface to a good finish and a known dimension. Then I turned up a nylon plug to fit oversized and press fit it into place. I then bored the plug to 14mm to fit the pedal axle and voila!! another couple of thousand km's I hope!!
Procrates Posted August 30, 2009 Posted August 30, 2009 Lovely when you have access to machines like these.
Johan Bornman Posted August 30, 2009 Posted August 30, 2009 Very nice. But your project is not finished yet. Now cut a half-round groove along the inner circumference of the bush and fit an O-ring to seal the pedal's guts from the outside elements.
brussel Posted August 30, 2009 Author Posted August 30, 2009 Ok Johan let me do that - good idea, should add a bit of friction but at the value of really keeping the crap out. Why don't they do that from the go??
jugheaddave Posted August 30, 2009 Posted August 30, 2009 nice work, well done, I like the idea of the o ring seal. Just make sure its nicely lubed, and you should fell a huge difference.
Johan Bornman Posted August 30, 2009 Posted August 30, 2009 Pedal seals have always intrigued me. They're practically non-existent, yet we see so few pedal problems with water and dirt intrusion. Some of the pedals like eggbeaters and some of the Wellgo ones, have flimsy little contact seals that press laterally against the collar that you machined. These are of course very quickly overwhelmed by dirt and grit and grind away in no time. I would have liked to see a nice contact seal inside - even if it is an O-ring and a labyrinth seal on the outer (crank) side. But none are designed that way. You have some challenges with that O-ring design I so flippantly suggested. You may not have enough meat in the nylon insert for such a groove. I think a 1mm O-ring should be thick enough, which will require a 0.5mm groove. Ideally you'd want two O-rings in there 5mm apart, with a grease chamber between the two. I'd like to see if this makes a difference in the long run.
brussel Posted August 31, 2009 Author Posted August 31, 2009 I think with a 1mm o-ring I could easily machine the groove...getting two grooves would be more difficult, but doable I think...5mm apart would be impossible, the new surface is only 5mm wide...so one might have to do! as for the seals, I was amazed that one little flimsy seal was all there was, and there seemed to have been fairly little ingress even with the amount of wear.
Cassie Posted August 31, 2009 Posted August 31, 2009 I just love these "boer maak 'n plan" tricks...well done - when are you going commercial?
brussel Posted August 31, 2009 Author Posted August 31, 2009 Cassie the problem is that to do this for others, the time would cost you as much as a new set of 520's. For myself though I can justify the time brussel2009-08-31 01:13:02
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