How To: Repack Cartridge Bearings
March 4th, 2008 by JoelGuelphBikes are increasingly coming with more and more sealed cartridge bearings. Most bike shops will tell you they are not serviceable and when you notice a grinding feel or sound, you need to replace them. Technically, that is the right advice. Once a bearing is compromised with grit, it causes small imperfections in the metal that will cause more and more wear with time. But, here at Blue Collar, we aren’t maintaining the space shuttle, we’re just trying to keep riding, with a little cash in our pockets. So, we service our non-serviceable bearings!
Some will also claim that if you are going to service your cartridge bearings, only do the ones that spin 360 degrees (hubs & BB’s) and not the ones which rotate back and forth (headsets & suspension pivots). These naysayers claim that bearings in the headset ovalize and should be replaced every time they are removed from the bike. I’d say that’s excessive. I’ve overhauled bearings on my own rig and have never noticed any deadspots or knocking.
Besides, the worst that can happen is you’ll wreck the bearings and have to replace them, which is where you were at when you started.
How-To Repack Cartridge Bearings
Step 1: Remove the bearings from the bike. You may need to consult the manual for how to. A bearing puller is best, and the flat blade screwdriver or chisel should be your last resort. Wherever possible, try to use the whole 360 degrees of the bearing for contact when pulling or tapping. You can usually find a socket in your socket set that has the same OD as the bearing.
Step 2: Gently pry the the seals with a knife blade, or perhaps an old spoke that has been ground down. It is of the utmost importance to avoid cutting the seals.
Step 3: Clean the bearings out with your favourite degreaser. Noah likes brake cleaner, but I prefer something a bit gentler on my body and the environment, like a citrus based cleaner. That old spoke can come in handy for picking dirt of the bearing. Make sure to flush out all of the grit.
Step 4: Let the bearings dry. I prefer the air-dry and time method. An unlubed bearing spun by an air compressor is impressive, but it creates a lot of friction that at best, causes more damage to the balls and races, and at worst, locks up and explodes in your workshop. You’ve been warned.
Step 5: Repack the bearings with grease. I’d recommend automotive wheel bearing grease. 
Apply a little lube to the seals, and gently press them back into place, making sure the seals engage the lip. If you are having troubles, use an appropriately sized socket to get even pressure all the way around.
Step 6: Re-install the bearings and away you go!
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Once upon a time, there was this little company called Wilderness Trail Bikes. They used to ride their bikes a lot and after probably performing this “how to” came up with an ingenious concept - Grease Guard! After that, hubs, bottom brackets, headsets, and even pedals became easy to service. Ooop, forgot about the Speedmaster rollercam brakes with Grease Guard. Grease Guard bearings were custom made so that as new grease was injected in (without having to remove the bearing), old grease came out. This method ensured that your bearings always had fresh, clean grease in them at all times. Ahh, those were the days.
Here’s one thing to think about when removing the bearing: don’t beat on an unsupported race when removing or installing the bearing. This will do more damage to the bearings ability to spin freely than the grime inside of it. Beating on the race could damage both the bearing and the races then you might as well fall back to the initial thought of just replacing them anyway.
I do the same thing with my non-sealed bearings. Clean up the races with a dremel and wire brush, then follow it with some polishing compound. I can always buy new bearings later. Good call on servicing sealed bearings. I like it.
We used to repack aircraft axle bearings in the same manner as you describe above. Basically just clean ‘em out, dry ‘em and cram some new grease in.
As for the debate about using bicycle grease or general auto grease, I say someone ask the experts at the National Lubricating Grease Institute at http://www.nlgi.com/ask_the_expert/. Serving the grease industry since 1933.
Yea, that’s what I said.
At my shop we use a dental pick to pry the covers off.
That is a seriously handy tool for a lot of things, like cleaning, and opening up the ends of housing after you cut it.
I emailed NLGI. We’ll see what they say.
+1 on the dental pick. I asked my dentist for his old picks and he agreed to give them to me as long as I promised not to do “home dental work” with them. I’ve also seen them at the surplus store for a couple of bucks each.
Bring back grease guard! Just like the grease fittings on a back hoe or a bobcat. It only makes sense. Seems like it might work better on angular contact hubs. How cool would it be to just keep your hubs pumped with fresh grease and properly adjusted? Can you hear me Shimano?!