I wonder if this is common on the nitros?

Ive had every electric and never had more than 2 or 3 broken stub axles. We are talking over 20 redcat electric models in years, and only a hand full of broken stubs.

The hub on the S30 is very different than the electric models tho. Much larger really. Not sure why that would (or could) contribute to broken stubs.

Do you have alloy suspension arms? If so, Id ditch them. The arm is the best part to flex IMO. Remove that flex, and now the other parts have to give. The smaller the part is, the less flex it can give before it breaks!