4203 bearing in 2010 M8 update

[rotax]

any more updates from the 4203 guys?

 

[Paul27]

This response is way after the fact. Sorry. Just saw this thread.

Just pulled my diamond drive cover ... The 4203 bearing is smooth as butter. I packed it with Maxima waterproof grease when I installed it. ... The bearing had shifted out 1-2 mm on the transfer gear shaft (now flush with the end of the shaft) ... If I had much of a side load, I don't see how the bearing could have shifted out like that.

Your bearing moves because: 1) Your bearing runs hot (300 to 400 F) due to churning thick grease. 2) Your inner bearing race expands. 3) Your DD transfer shaft stays cool, due to the DD aluminum case and DD Syn-Lube oil-cooling. 4) Your bearing no longer has an interference fit on the shaft and it floats around. 5) Crushes the balls because the outer race can't expand, so you start running metal-to metal. All bad stuff.

Next: The grease continues to heat and turns black (at about 500 F). The steel balls expand, causing the bearing cage to warp and break. The 5203 2RS seals get pushed put. All that crap goes into your DD lube and gears.

Disregard if you are always slow trail riding. Grease will work fine. For deep powder or lake running when you use WFO throttle for several minutes, you will cook the grease.

Why not run a non-sealed bearing? DD syn-lube is a much better lubricant than any grease. And it keeps the 3203 bearing cool and clean. Grease is not meant for high-speed bearings.

Also: SKF bearings use Polyamide nylon cages (or brass in larger sizes), which are way better than steel cages and often better than brass. The proper non-sealed bearing number is SKF 3203 ATN9/C3.

Good Luck!

 

[Paul27]

I pulled the seal on my 5203 in my Diamond Lite and it appeared to not have any grease in it. Everything was just oily inside.

You probably boiled the grease out, during some high-speed runs.

At top end, the track drive shaft turns about 4000 rpm counterclockwise (along with the DD output shaft and 3203 bearing outer race), and the DD transfer shaft turns at about engine speed clockwise (8000 rpm, along with the 3203 bearing inner race). So the little 6203/4203/5203/3203 bearing is spinning at roughly 12,000 rpm! Way too fast for grease.

 

[mrduramax]

subd