Axle Bearing two questions

Hello all,
I have two questions. We have recently acquired a second additional kart. This new kart has rear 50mm axle bearings that seems to be very spinny and when you turn the axle they spin really well. The bearing has the number 58210ZZC4 on one side and GBI on the other. I’m liking this bearing and was looking to see where I could find them?
second question:
On our other kart we just bought some 50mm bearings from CometKartSales and installed them. They are not very spinny and actually my older bearings seemed to spin better( I have no chain or anything attached. Just the axle inside the bearings and on the frame). Is there a break-in period for axle bearings and what is the best way to break them in?? Just time or is there something magical I should be doing?

Thank you guys so much.

A new bearing is not going to spin as easily as an older one because it’s packed with grease. It will free up on its own with use or you can speed up the process with a spray lubricant such as Tri-flow.

It’s actually a SB210ZZ and C4 is the internal clearance. You will notice that the shield doesn’t contact the inner raceway which makes the bearing free spinning. Give your new ones a good spray between shield and raceway with a good lubricant and they should free up with more use.

One of my rear sealed bearings be making a grinding noise. More than likely some grit In the bearing but when is the right sign to replace the bearing. And what maintenance tips does anyone have specifically for bearing after a race day… personally we spray with brake cleaner to clean and then add bearing lube.

I break the seals off even if they’re brand new. Brake clean, blow with air, add triflow every session.

That’s just what me and a few others here do, though.

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The Bearing Number is SB 210 ZZ Made by GBI

I am pulling up that that thing is a 50x90x18mm bearing which is a bit odd size for a 90mm kart bearing generally I see 20mm width.

I would like to note when it comes to bearing performance on a kart application you really want a C2 Bearing but no one makes them, The next best would be a CN bearing (unmarked clearance is CN) and as clearances get larger for C3/C4. The reason for this is simple, kart bearings are generally 2-4k RPM and are axial loaded. Its far more important that they are not preloaded on the shaft or by the bearing housings. This means a C4 bearings has a higher level of clearance which isn’t idea for a karting application due to dynamic loading that occurs.

I would really suggest if its a 90mm bearing going to as it is the best 90mm bearing on the market (The only good one) other then the BOCA bearing option which is a Hybrid and that can be good or bad depending on a number of factors so I can’t say if its a better or worse bearing to be honest. There is alot of things at play when loaded like hertzian contact stress. This can lead to Ceramics actually wearing out quite fast due to hardness of ceramic vs steel races. The cage quality and material as well as the seals all play major roles in friction.

The RHP bearing usually sells for $100 in Kart Shops! So your welcome, but more importantly the RHP bearing is made to much better standard and its poly cage is to a MUCH MUCH higher standard then any other on the market for 90mmx50mm Karting Axle Bearings. This means the balls track true, less friction loss and much less loss in dynamic situations.

Please keep in mind that free spinning a bearing without load isn’t accurate to loaded friction numbers. The additional clearance of a C4 that will actually add friction on the track might make the free spinning unloaded bearing seem better due to skidding but I can assure you its not.

When it comes to lubricant karts peak 100mph around 1200lbs per ball on the outer race for a 50mm bearing (if my rough math is correct) or significantly less for a ceramic ball due to ball weight add in driver load + cornering load your usually alright to use an oil if you wish to do so. I personally don’t like the maintenance of dealing with oils and I don’t think they do as good of job when it comes to friction when loaded. My personal grease of choice right now is called Archoil 8300, its faster when loaded after break-in, it requires zero maintenance and the bearings get faster with time and will last for years at near or over maximum RPM the kart demands of them.

-Your Pal
Ronald Swift


Ronald Swift,
Thank you so much for that explanation. You know your bearings! I’ll take a look at the RHP bearings. Sounds like they are what I am needing.
Currently I have been going out every night and spinning the new bearings hoping to break them in. So far it doesn’t seem to be working but once it warms up I’ll stick a motor on it and really spin it. Hopefully that helps.

Phillipe Kunos, you do need to be aware that 50mm bearings do come in a few different sizes. The most common are 80 and 90mm O.D. with slightly varying widths of both the bearing and collet width. I suggest measuring the bearing OD and generally the widths will not effect the performance.

Also, the GBI bearing is a decent bearing but I have not seen them since 2011ish but are very common on karts though both the 210 and 210/208 models (90mm and 80mm O.D. respectively)

Here is a picture of the different carriers and how you could at one point get both 80mm or 90mm in the same model year so you got to really just measure.

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Thanks for the info, mate. I have so many questions.

Why does Archoil 8300 grease require zero maintenance and how do you use it on those RHP bearings when they’re “not re-greaseable” according to the website you’ve shared?

Thanks in advance

Don’t know if this helps, but we’ve got an actual rocket scientist at our track who makes it clear that the grease in a bearing quickly moves to either side of the balls and acts as a grit shield. Accordingly, I, for one, NEVER lube my bearings (so as not to disturb this barrier) and my rear tire on the stand spins fast and easily with my chain in place. Part of buying into this approach is to note that the front press-in bearings are never lubed by anyone I know of, and I think they are of a similar design as the larger ones for the rear axle.

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Also remember to point the bearings in the right direction. They can rotate in the house… They need to be aligned proberly. If they are a little off, they dont spin very well. Also the bearing holder needs to be wider than the bearing, so you can adjust.

Is there any goog alternatives to Archoil 8300, since it is discontinued and it is hard to find it now.