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Old 12-26-05, 10:19 PM   #1
PoorBehavior
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I thought I would post these pictures for those who have not opened one up.
I pulled my Shimano Pedals, 520's I think, and was going to transfer them to my new bike. One of the pedals would not spin freely so I figured I had nothing to lose by taking it apart to see if I could figure out what was wrong or maybe fix it. I was very suprised to find a large part of the pedal to be a plastic/rubber shell. The problem turned out to be that the top two nuts had tightened somehow and were putting too much pressure on the bearings. I regreased the whole thing and used some blue locktight on both bolts hopefully to keep them in place. Right now it spins free and has no free play.
Weird thing is, I never noticed anything when they were on my other bike.

Someone tell me what I missed if you would. I have never opened one of these up before.
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Last edited by PoorBehavior; 12-26-05 at 11:04 PM.
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Old 12-26-05, 10:35 PM   #2
neil0502
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Two other links to help others on this:

Exploded Diagram
http://www.shimano.com.au/publish/co...-M520-2235.pdf

Service Instructions
http://www.shimano.com.au/publish/co...PD-M959-EN.pdf
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Old 12-27-05, 12:55 AM   #3
cascade168
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Quote:
Originally Posted by PoorBehavior
I thought I would post these pictures for those who have not opened one up.
I pulled my Shimano Pedals, 520's I think, and was going to transfer them to my new bike. One of the pedals would not spin freely so I figured I had nothing to lose by taking it apart to see if I could figure out what was wrong or maybe fix it. I was very suprised to find a large part of the pedal to be a plastic/rubber shell. The problem turned out to be that the top two nuts had tightened somehow and were putting too much pressure on the bearings. I regreased the whole thing and used some blue locktight on both bolts hopefully to keep them in place. Right now it spins free and has no free play.
Weird thing is, I never noticed anything when they were on my other bike.

Someone tell me what I missed if you would. I have never opened one of these up before.
Maybe I'm missing it, but it's not clear what your question is. Are you trying to figure out why the pedal stopped spinning freely? I kind of doubt that the lock nut and the cone nut "re-adjusted" themselves and got tighter. It's much more likely that some little bit of crud worked it's way in and wedged something. The fact that you serviced it and it now works fine tells me you got the bad bit removed and you're back in business. One thing that is pretty important is that the little grease seal that goes on the widest part of the axle gets pushed down in to the plastic shell. That seal is what keeps crud out of the pedal. When you put it all back together, spin the axle and push that seal in with a fingernail. When you clean your bike you should take a look and see if that seal has worked it's way out. Push it back in if it has. SPD-SL type pedals use the same design. All that plastic sleeve is really doing is holding the grease in. The weight bearing parts are where the axle screws into the crank and where the pedal housing contacts the barrel that contains the ball bearings.

Here is an article from Cyclingnews about servicing these pedals. I don't use it myself as I like to take the whole thing apart and clean everything. As you now know, complete disassembly and service takes a LOT of patience and a steady hand. A good pair of tweezers to handle those tiny little ball bearings helps a lot. They do get cruddy. I service mine about twice a year and they stay silky smooth. Ok, here's that article. Maybe it will help you or someone else out:

http://www.cyclingnews.com/tech/fix/?id=shimano_pedals

This method does not require disassembly. It just tells you how to pack new grease in and adjust the bearings. I don't like it because you don't clean out the parts, which I think is the right way to do it.
But, that's just my opinion. The downside of disassembly and cleaning is that it is very time consuming. I'd be surprised if you could get a shop to do this. They'd probably tell you new pedals are cheaper. It takes me about an hour per pedal and I have done this many times.
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