Could it be rubber schmutz?
Oxidation from dissimilar metals?
Now that you mention it, i did use aluminum foil to clean the axle the last couple of times… might be the problem
This. I just wipe down the axle with WD-40 when I store it and clean the oxidation off with brake clean or starting fluid and a rag. Not a big deal either way, but if you let it build up enough, you might find your hubs seizing onto the axle a little more.
I clean it till the hubs glide with no effort after each training session, so its a little wierd with that much buildup
The hubs are likely aluminum or a form of magnesium alloy.
Cleaning my kart today, and see this insane buildup.
Could it be because of extensive play between the hub and axle that creates friction and heat between them?
It would make sense, scince the hub is magnesium and the axle is steel…
that would be my guess, you’re seeing friction abrasion from the way the axle and hub contact each other.
Are the clearances between the key and keyway of the hub correct? Or, when you tighten the hub onto the axle is the cut/split parts of hub the touching?