Riding lawnmower spindle bearings

[Oil pan 4]

3 or 4 bolt, 3/8 or 7/16 threaded bolt, looks like they take the same bearings.
One mower a nearly 20 year old 42 inch uses 3 bolt spindles with 3/8 fine thread bolt to hold the blades on, the other mower from about 2015 uses 4 spinde to deck bolts with 7/16 fine thread blade bolt. Both have the same bearings inside.
The small one up top by the pulley is a 6203 and the larger one by the blades is a 6204.

For a long time I have used SKF 6204-zz "explorer" bearings in generators I work on, they typically last around 300 to 400 hours at 3,600rpm.

A new made in china spindle was $43 yesterday at the mower shop. Higher end made in usa, Japan or taiwan bearings should be less than $25 off ebay. Cheap bearings are more like $15.
So I'm going to be replacing bearings when possible.

I'm sure cub, deere and other higher end and commercial mowers use a completely different design. I say take it apart and check before you order bearings.

 

[North Idaho Wolfman]

I just got all my bearings to do this, 6203 for the top and 6204 for the bottom.
I got what I hope to be good bearings, they have a high rating.
I'm also doing the 3 idler pullies as you can't easily replace the bearings in those.
I'm tired of the mower sounding like it's got gravel stuck in it!

 

[Torinodan]

Unless I bust a spendle I'll always just replace bearings without removing them from the deck. Cheap or expensive you can't really grease them unless you remove the inboard dust seals on the top and bottom bearings. The cheap bearings all have life time grease cause the bearing will fail first.
I discovered some pump bearings on the helicopters I work on are the same size as the ones in my Kubota decks. They are lubed with Mobile 28 and are ran for 3000 hours or 5 years. These are getting harder to find due to being phased out.

 

[Oil pan 4]

I use majestic jt6 or something like that. Only because I found a busted case of it on the side of the road with most of the tubes still useable, even the crushed tubes were salvageable, they got squeezed into an empty bucket and used. Took me about 5 years to use it all and I was not stingy with that free grease.