i don't see any problem with repairing the car, for example, if the wheels need straightening, body needs popping or batteries need reconnecting, its not a problem. At the end of the day its just practise and if your worried about tenths of a second, then your probbly in a heat where there's driver ability similar to your own and there won't be many crashes as your opposition are more consistent and if they do have a crash it's normally a good one and they come off good and proper. If you had a crash and all it was, was a balljoint popping, would you want the chance to get back the 20 seconds you lost?