Here's some notes I made from changing the bearings. Might be helpful for some. Unfortunately I couldn't take pictures as I was on a deadline by the missus (had to go to a wedding). When I get the chance, will do one with pics,
Note that a bearing has two metal rings visible: the outer ring is known as the outer race, and the inner ring is the inner race. You should only be putting force on the outer race. Never put force on the inner race
1. Get it into your head now - don't forget the spacer, don't forget the spacer, don't forget the spacer
2. Get it into your head now - don't lean on the rotors at all (assuming you don't remove the rotors first). DO NOT REST THE WHEEL ON THE ROTORS AT ALL.
3. Grab a drift and a decent hammer. Ideally a hammer with a large surface area. If you don't have a drift, grab one of those screwdrivers with a metal head. You'll also need a socket. I think its 33mm for the front and 35mm for the rear. I will check and update the post with the correct info so don't take that as gospel
4. Remove the dust seals carefully. They are hard to get out and you will ruin them if you get them out with a screwdriver. Use something with a larger contact surface area, like a chisel. Insert chisel in the gap between the bearing and seal. They require some force to get out by pushing down towards the rotors, and the last thing you want to do is end up putting stress on the rotors (see point 2 above). On the front wheel repeat for both sides. On the rear, dust seal is on one wheel only
5. See point 2 again
6. And again see point 2
6a. Once the seals are removed, clean the recess. There will be dirt and grime stuck between the outer race and recess. Grab a flat blade screwdriver and gently loosen it by going around the circumference of the bearing.
7. With the drift, insert it into the spacer and attempt to move the spacer to the side. Depending on how snug it is against the bearing, it may require a little force. Which is fine, as long as you observe point 2 above. Imagine looking down at the wheel while its flat on one side. What you're trying to do it move the spacer so you can look through the hollow spacer and see the inner race bearing at the other side of the wheel
8. Once the spacer has moved (and it will only be slight), one portion the inner race of the bearing should be visible. And its a very small portion. If the brace just about catches it, then that is about right. As soon as you hit the inner race, that's it. The bearings integrity is gone and you must replace it. No going back now.
9. So start at 12 o'clock, put the drift on the inner race, refer to point 2, and give the brace a good whack. Then repeat for 6 o'clock, 3 o'clock and 9 o'clock. Each time refer to point 2.
10. It might be a bit stubborn at first, and you may have to do a few hard whacks. You'll know its started to move once the spacer moves about more freely. Refer to point 2.
11. Once the bearing falls out, the spacer will follow it. Refer to point 1
12. Again refer to point 1
13. Turn the wheel around
14. Refer to point 2
15. The second bearing should be easier to remove as there is no spacer in the way. Repeat from point 9
16. You could use heat to help remove the bearings if they are really stubborn. I haven't come across a really stubborn one on the GTR yet
17. With the bearings out, give the recess a good clean
18. Get some grease and apply to both recess liberally. I put loads on
19. Refer to point 1
20. Refer to point 2
21. To make things easier, leave the bearings in a freezer overnight and warm up the area around the recess (although its not necessary)
22. Get the first new bearing. Put it over the recess. Note how it is an extremely tight fit
23. Grab yourself the correct socket. With the bearing on the recess, put the socket on the bearing. Note the socket covers the outer race, but is just small enough not to get stuck in the recess. Tip: for the front bearing, you can use the socket for the rear wheel bearing as it fits the outer race perfectly. Only until its flush with the recess when you will need to move to the smaller socket
24. Don't screw this next part up. If you do, you'll have to remove the bearing by hammering on the inner race which will render the bearing useless. You don't want the bearing to go in at an angle. It must go in cleanly.
25. Refer to point 2. It is so easy to lean on the rotors at this point.
26. With the hammer, gently tap the socket at the following positions 12, 6, 3 and 9. Remove socket, and look at bearing to see if it looks consistent at all sides of the recess. With the socket on the bearing, repeat until bearing is flush to the recess. If it looks like one side is in slightly more than the other, just hammer the socket gently on the other side.
27. Refer to point 2.
28. The bearing should now be flush to the recess. It needs to go in further, but do not be tempted to drive it in all the way. If you do, you'll find that the spacer on the other side protrudes significantly from the recess. I don't know if that would cause an issue, but I like to have my bearings located at the same distance in each recess
29. Refer to point 2
30. Start to tap in the bearing into the recess more, until its in by about 5mm. Remember to use the correct socket size
31. Turn the wheel over. Time to do the second bearing
32. Refer to point 1
33. Grab the spacer, give it a good clean. I like to grease mine lightly from the outside and liberally from the inside. Greasing from the inside helps the wheel spindle when you put the wheel back on the bike.
34. Insert the spacer. Notice how it goes below the recess area presently. That's because the first bearing isn't yet correctly located in the recess.
35. Refer to point 2
36. Repeat from step 23 and refer to step 2 every time you're about to tap with the hammer
37. Again refer to point 2
38. If you've got this far, congrats.
39. Both the bearings should now be in by 5mm. The spacer should be rattling loose. Now its time to get the spacer snug with the bearings
40. By turning the wheel over alternatively, start to drive in each bearing a little more using the socket. Ensure that both bearings are located about the same in the recess. Keep checking the spacer, ensuring that it is resting on the inner race
41. Eventually you'll see that the gap between the inner race and spacer is becoming smaller. Once the spacer just starts to catch the inner race, progresses slowly so that the spacer and inner race are just touching and no more. The bearings should be located about the same distance in the recess
42. Grease over the bearings. I put a load of grease on
43. Grease the bearing dust seals and insert by pushing fully in. I like to get more grease and shove it in the gap between the bearing and seal. On the top part of the seal there is a light smudge only. That's because you don't want it flung off onto the brakes or anything
44. Give yourself a pat on the back
There's typos and grammatical errors in the points above which I'll amend later. But its enough to give the gist of what to do. I don't think its any harder than doing brake pads.
Remember when putting the wheel back on to clean the rotors with brake cleaner
