This is the rear motor bearing for Kirby upright vacuums, a shielded ball bearing that carries the armature shaft on the commutator end of the motor, opposite the fan. It is a wear part, and on a machine with real hours on it a dry or notchy rear bearing is one of the most common causes of motor whine, vibration and eventually armature damage. Anyone who services Kirbys says the same thing: the bearing costs a few dollars, the armature does not, and the motor does not either. Replace it while the motor is already apart for brushes and you have effectively reset the clock on the machine.
Use Cases
- Replaces a noisy or rough rear bearing during a Kirby motor rebuild or carbon brush change
- Cures motor whine, growl and vibration traced to the commutator end of the motor
- Stocks a shop rebuild kit alongside carbon brushes and a front bearing
- Restores a high-hour Generation-series or Sentria machine before the armature is damaged
Specifications
- Bearing type: 608-ZZ C3 shielded ball bearing
- Tolerance class: ABEC-3
- Dimensions: 8 x 22 x 7 mm
- Bore 8.00 mm, outer diameter 22.00 mm, width 7.00 mm
- Shields: metal on both sides
- Position: commutator end of the motor, opposite the fan
- Replaces Kirby part number 115589
Fits
Published fitment lists for part 115589 cover Kirby Generation 3, Generation 4, Generation 5, Generation 6, Ultimate G and Ultimate G Diamond Edition, Sentria and Sentria II, Avalir and Avalir II. Coverage of earlier Kirby models is not confirmed by the sources reviewed and is not claimed here. Because this is a standard-size bearing, the dimensions above are the reliable check. Confirm fitment against your machine model number before ordering.
Frequently asked questions
How do I know the rear bearing is the problem?
A failing rear bearing usually shows up as a rising whine or growl that changes with motor speed, or as vibration you can feel through the handle. With the machine unplugged and the fan case off, spin the armature by hand: a good bearing turns smoothly and quietly, a bad one feels gritty, notchy or loose on the shaft.
Should I replace the front bearing at the same time?
Not always, but it is the usual practice. Both bearings have seen the same hours and the labor to open the motor is the same either way. If the front bearing feels rough at all, do both while you are in there.
Is a generic 608-ZZ bearing the same thing?
The dimensions are the same, which is why this size is easy to source. What varies is internal clearance and tolerance class. This part is specified as a C3 clearance ABEC-3 bearing, which suits the heat and speed of a vacuum motor; a low-grade skate bearing of the same size is not an equivalent.
Do I need a press to install it?
It should be driven on squarely against the inner race, never the outer race or the shields. A bearing press or arbor press is the right tool; tapping it on with a socket that bears only on the inner race also works. Do not hammer on the outer race and do not drive a bearing through the balls.
Discount Cleaning Products stocks vacuum motor components and service parts for residential and commercial machines, including bearings, carbon brushes and complete motor assemblies. Support is US-based, and we are glad to help you confirm a part against your model number before you buy.
