Hub bearings are becoming more and more unitized, with the number of parts decreasing from the first-generation to the third (GEN3), and evolving into lightweight, compact products. NTN now mass-produces GEN3 hub bearings on a global scale to deliver diverse generations of hub bearings to automobile manufacturers worldwide. We also offer a full lineup of GEN3 hub bearings with built-in active ABS sensors that respond to the safety demands of the automotive world.

Our hub bearings incorporate a sealed-type construction to deliver a sensor-integrated hub bearing. This design helps to prevent damage, corrosion, and adhesion of iron powders to the internal magnetizing encoder and the sensor probe–and makes our ABS sensors all the more reliable.

A hub bearing on a car servers two primary purposes, including allowing the hub and attached components to rotate freely, and also to keep the wheel tire and rotating mass attached to the car. Learn about the two types of hub bearings, including unit fag bearings and wheel bearings, with help from an auto mechanic in this free video on auto parts.

What is a hub bearing on a car? A hub bearing serves two primary purposes. The first is to allow the hub and attached components -- the brake disc and the tire and the wheel -- to rotate freely, and also to keep the said wheel tire and rotating mass attached to the car. There are two primary types of hub bearings. The more common on modern cars is a unit bearing, where the inner and outer bearing, seals and grease are all in a single unit, and it's installed as one piece. And if it fails, for any reason, it's not serviceable, so it has to be replaced altogether. 

Another style of wheel bearing would be a separate bearing for the inner and outer side of the hub that ride on a spindle, and these bearings are removable and serviceable individually as are the seals, and they do need to be greased on a regular basis to make sure that they spin freely and don't wear. Typically, if a hub bearing fails, you will notice a grinding or a...other noticeable sound going in a certain direction. Usually if you're turning to the right and you hear a grinding noise on the left, that means that your left hub bearing is worn out. And likewise, if you're turning to the left and you hear a noise coming from the right wheel timken bearing -- a grinding noise or the like -- the most likely symptom or cause is the wheel bearing on the right hand side.

The front hub/bearing assembly on an NA model Miata is a one-piece unit consisting of the hub/lugs with the bearings pre-installed and greased. The assembly is typically considered non-serviceable, and you replace the unit when the bearings fail.

In my case, my 1990 Miata developed a thunk-thunk-thunk type sound on the front right wheel while driving. It sounded very similar to driving over a concrete highway with the relief cuts in the road - just a repetitive thunking sound. The sound got louder when making left hand turns, and pretty much disappeared when making right hand turns. Based on forum searches, I determined it must be a failing nachi bearing causing the issue. I had about 118,000 miles on the odometer when I did this service.

I'd like to add the dust cap to the list of the parts needed for the change. It's a part that can be difficult to remove without warping it.The caps aren't available at places like Autozone, Advance, or O'Reilly's, so it's better to have a spare than have to go looking on Sunday afternoon.

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