Recently, I noticed there was very minor play on the axle of my XTR PD-M9100 (drive side) pedal.
It also looks like there is a small rubber that is loose or stretched at the point where the axle leaves the pedal body.
I have opened the pedal and adjusted the tension on the bearings numerous times now, but I just can’t seem to get it exactly right. The tension on the axle bearing seems to build up during riding, resulting in a pedal axle that is a little bit too tight.
Strange thing is also that I can really fine-tune it to perfection when the pedal is open, but once on the bike it doesn’t stay the same. Yesterday I really had the perfect tension, but once I fastened the pedal on the crank I again had very minor play on the bearing. I left it like that and cycled for an hour this morning, and now the tension has increased. There is no more play on the bearing, but when I spin the pedal by hand I can feel it is too tight and I can feel a small click for each ball bearing.
What am I doing wrong? I adjust the tension nut so the bearing runs smoothly without any play and then I tighten the lock nut just enough so the tension nut cannot move any more. But somehow it still seems to change position while pedalling.
I would try to tighten the fixing nut more. The rubber thing can be pushed back inside with a poke tool but eventually it will come out again, it’s just a bad design on shimano side.
I don’t know if the fixing nut is also effective against tightening the tension on the bearing. I think the purpose of this fixing nut is avoiding that the tension nut can unwind and in this way develop play on the bearing.
But in the other direction this nut doesn’t really do anything?
I think you are overtighting. It’s an easy fix I’ve done numerous times. To do it right you need the right tools and a bench vice. The one tool you really need is a very thin open-end wrench to hold the adjustable cone as you snug down the locknut. Without it things will loosen up and go wonky on you. The other thing is adjust the bearings to where there is just a tiny tiny bit of play. Barely perceptible. It will be unnoticeable when riding and enables the bearings to work properly.
As for the rubber seal, its easy to pus back in. But I’m wondering; Did you repack the bearings? If so, perhaps you used too much grease? Doing so can force seals out.
It’s a basic cup and cone assembly, so the fixing nut’s primary goal is fixing but if you apply proper torque, it will affect the preload just a tiny bit as well.
If the preload changes during riding, it’s not tight enough. Unless the thread or axle is failing (which is improbable but not impossible) you just need to tighten the fixing nut more. No loctite is needed.
It still took a couple of attempts (bearing felt fine when I adjusted it but was too loose once I installed the pedal body again), but now it is perfect again.
This might be poor advice but maybe putting an o-ring on the crank side of the spindle would keep the seal from coming out. I remember seeing this somewhere but can’t remember where.
There was a “rolling change” (Shimano-speak for we F’d up, but don’t want to admit that publicly) that solved the floating o-ring issue a few years back. My wife had these and I had same generation XT; her seal always migrated and mine didn’t. Solution is a) keeping tucking it back into its spot or b) buy a new spindle (I think they made a small indentation in the spindle so it would sit in one spot).
