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How to replace your Cartridge Bearings

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(This post was originally published on Projekt-B, and does not deal with Vallie Components Hubs)

In this post I'm going to detail the steps necessary to replace the cartridge bearings in your sealed hub. If you don't have sealed bearings, this doesn't apply to you.

How do you know if your cartridge bearings need replacement?

Well, for one, they will not spin as well and you will hear them. Secondly, they may develop side to side play even with the lock nuts tight. Thirdly, the seal may be wrecked, and they might be dribbling rust down your pretty high flange hub.


Supplies needed:

  • 2x new bearings (I'm using Nachi 6000RS2)
  • Soft faced mallet
  • Block of wood with 11mm hole drilled in it
  • Cone nut wrenches (My hubs take 14mm and 17mm, yours may differ)
  • Paper towel or rag
  • 500 grit sandpaper or emery cloth
  • Grease


Procedure:

1) Using the cone nut wrenches, undo the two lock nuts on each side of the hub. I hesitate to say 'cone nuts' here because the inner one is NOT cone shaped like on a loose ball hub. It simply shoulders up to the inner race of the cartridge bearing, stopping it from moving laterally.


2) Once all four lock nuts have been removed from the hub, there is nothing holding the axle and bearings in place other than friction. You may now strike the end of the axle with the soft faced mallet in order to coax it out the other side. Be sure to strike the axle dead on the end, so that the force pushes the bearing straight out. What should happen, is that the shoulder on the axle should push the inner race of one bearing outwards. If the bearings are not COMPLETELY destroyed, the rest of the bearing will come out along with it.
(If this blows the bearing apart, don't worry we'll cover that scenario in a second)

3) At this point you should have the axle separated from the hub shell, with one bearing on it. You SHOULD be able to pull the bearing off the axle at this point.
(If not, insert the axle into the block of wood, and tap the bearing off)

4) Reinsert the axle and flip the hub over. Now use the mallet to strike the end of the axle and tap out the cartridge bearing on the other side.

5) If any of your bearings have blown apart, you will have a serious mess on your hands. Skip this step if your bearing came out in tact. You then need to use a flathead screwdriver from inside the hub shell, to get the outer race out. This may be difficult, but try to catch the screwdriver tip on the inner edge of the outer bearing race before tapping. Then work your way around the circumference of the outer race, coaxing it from the hub shell.

6) You should now be left with these unhappy little fellows:

Look at how gross that one on the left is!

7) It's time to clean things up. I was able to just wipe the rust off my axle with a rag, but the hub shell wasn't so easy. You wouldn't think that rust would adhere to aluminum that well, but mine was pretty stuck on.

8) I've used some 600-grit sandpaper to clean the outer race shoulder of the hub shell. This is a step that not a lot of bike shops will spend time on, but I like to know that my bearing is not butted up against rust.

 

 

 

 

 

 

 

9) Lets take a closer look at the axle:

This is a thing of beauty.

What's so interesting about it you ask?

 

It's made of hollow hardened stainless steel, with shoulders to hold the bearings the correct distance apart. Also, it's machined to a very precise tolerance. The bearing seat is exactly 9.96 mm in diameter.

The inner race of the bearing is exactly 10.00 mm in diameter. This is on purpose, and is the reason why you were able to pull the bearings from the axle. If this tolerance was any tighter than 4 one hundredths of a millimeter, you would have had a much tougher time removing that bearing in step 3.