Saturday, June 1, 2013

PD-M959 Pedal Rebuild and Frozen Knee Saver Removal

I have a set of Shimano PD-M959 (Before XTR) pedals that I put a set of KneeSavers on that got frozen on the spindle. I put the kneesavers on to give myself ankle clearance for when I wore my winter shoes or shoe covers. I discovered this winter I really don't need to be spaced out that much, so I decided to remove them. What I discovered was they were frozen to the pedal spindle.
The problem is this model of pedal does not have the usual 15mm flats on the spindle to tighten the pedal to the crank arm. Instead the pedal can only be tightened using a 10mm allen wrench on the back side of the spindle. However the backside of the KneeSaver / extensions is solid and covers the allen wrench access. So the question is, how do I get it tight? A strap Wrench and as you can see the KneeSavers have 22mm flats.

The first thing I did was drill a small 3/32" hole through the backside of the extension to allow a penetrant like PB Blaster, WD-40, or Liquid Wrench access to the blind side of the threads. After a week of soaking it didn't budge. Time for the frozen bolt torch technique.

I had to remove the spindle from the pedal body and disassemble it. First you need a 17mm wrench and since this is the right/drive pedal the threads are left hand thread. Why left hand thread? If they were right hand thread and through a process of "mechanical precession" they would loosen up over time. So it's Righty Loosey.

Unassembled and ready for the torch. Those are 3/32" bearings, even with a magnetic bowl one managed to escape me. No big deal since 12 fill the whole bearing race.

The idea with the torch is, you want to heat the extension so it expands breaking the bond between the two. You want to heat the extension, not the spindle as best you can, so keep the heat on the extension. Yu want to heat the extension so you get a little discoloration. Too hot or you will be deforming the threads and possibly welding the threads don't want that. Once you start getting some discoloration you might hear a popping sound of the two becoming unbounded.

Let it cool, but while it's still a little hot, see if you can work it loose. I was able to get about 1/16 of a turn, and that was just enough to get some momentum. Be careful here, the vice grips are clamped on the flat part, not the bearing races.

1/16th of a turn became 1/8th, became 1/4 turn and so on. After about 15minutes of work the kneesavers/extensions are off.

You have to put those 12 bearings on the bearing race in that barrel looking thing, then slide the barrel thing over the spindle. Use a fair amount of grease, this will allow the bearings to stick and not fall out. Remember to put the plastic bearing retainer back in with the beveled side up. Then just put in the last set of 12 bearings.

Remember it's Left hand thread. So it's Lefty Tighty! There you have it. I used PhilWood grease so it's buttery smooth.

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