KTM 450EXC wheel bearings

[warewolf]

Good thought but no, just ordinary deep-groove ball bearings. The 640A sprocket carrier has a double-row angular contact bearing... fcuk is it expensive... $125 direct from SKF. In the last year or so they changed to a pair of deep-groove jobbies... cheapo solution.

[pete.ktm]

so had to make my ali spacer by hand. Bit of a hassle but worth the effort imo.

hmmm a spacer there, thats not a bad idea. BUT theres gotta be a reason, maybe it's to make sure there is a tight fit between the spacer and the inner bearing to keep water/dirt out? hope so coz the ones i took out were dry and rusty.

is it just a ktm thing, a vid i was watching was doing a yammie and he just bashed the bearings till they wern't going any further.

anyway i heated my hub enough so i could gently tap the bearing in little by little and got it just nicely seated against the end of the spacer. wheel spins just like a new one.

tomorrow it's valve adjustment time! anybody got any good tips on that, the vid on youtube makes it look pretty easy.

[warewolf]

is it just a ktm thing, a vid i was watching was doing a yammie and he just bashed the bearings till they wern't going any further.

Nope; feel free to bash away until the bearing hits the inner spacer, which it should do before it hits the hub's shoulder.

[kezzafish]

all ktms i've done bearings on were as you describe pete. I've always figured the reason was to make it possible to bash the bearing out (hitting the outer race so that you don't root it) wouldn't bother with a spacer to compensate for the difference... i've always just done as you have done making sure i don't drive the bearing in too hard putting outward force on the inner race. I leave the spacer able to move freely and figure the outter spacers will move the bearings to where they are most comfortable (when you do the axel up)

[camchain]

Been thinking about this some more. Maybe they made it this way to allow for manufacturing differences. When cranking out thousands of them you'd eventually get a tolerance/binding problem if hole even fractionally not deep enough.

Making it (effectively) a blind hole means you can always guarantee a perfect bearing position - but ONLY if you install the bearing 'properly.' Still think it's a bit daft and too easy to get it wrong given that 'proper' way to drive bearing is via outer race. By the time you feel it contact the spacer tube, bearing races not perfectly aligned and stuck in this position. (Spacer tube has to be there for whole assembly to have something to tighten up to)

I've tweaked my previous post. Making a spacer washer suited me so I could easily get exactly same bearing position every time, but you'd need to be sure of dimensions (on each individual bike). Using a vernier, measuring the spacer tube is easy, but measuring hub accurately is trickier. Spacer trick probably not for everyone.

OK yeah, you can get a result just by tapping bearing in with a socket and wheel goes round and round, but I'd rather be sure bearing position is accurate every time and job simple to do.

Think maybe best solution is to just drive the bearing in with something that contacts inner and outer race.



BTW, with wheel lying flat, I pour some boiling water in the concave/cup part of hub to heat it for easy bearing extract/install.

[warewolf]

Nice trick with the water. I've bought a $20 hair drier/heat gun from the hardware shop.

I dunno that leaving the spacer loose is a good idea. That means the axle clamp load will push the inner race inboard of the outer race. If you drive the bearing via the outer race until the inner race just contacts the spacer, then the outer race could be ever so slightly inboard of the inner race. The axle clamp load will tend to bring the inner race in-line with the outer.