XRAY - Model racing cars

What is the most commen part that wears or brakes? I was thing of buying upgrades or even getting extras in my box for when something happens & other or I would not be down to long if we had this info.

My common & thinking are wrong. So before I get told or picked at I decided to say something. LOL

well it´s not compleatly wrong ! After 35 hours of ontrack time I have found wear on several parts. here goes. center shaft both ends are worn pretty much and it needs to be replaced, brake pads(frodos only) piston,conrod and sleve(the engine part are only replaced because of the very hard way I race the car, the track I race at are designed to the 1/18 size cars and the low speed, are not good for the cooling of the engine)
clutch shoes and clutch springs are worn down too.

Have to agree with Kant, Tires, Brakes, and clutch springs. Engine parts I've been lucky with no problems. Have 29 hours on mine, runnin' on 10th tracks, 8th track at least once a week. The 18th track here are small and i c kants dilemna, they're too short, terrible with cooling. Guess we would have to change the driving styles lol!!. From a Paul Tracy to Michael Schumacher. lol!!
Other parts CV's, just upgrade them to aluminum. Uprights if you like a stiffer ride.