axel tramp is your wheels jumping up and down when you lanch of the line . i dont know if its true but i heard it can mean your rubbers are worn ( the ones on all the springs /shocks at the rear )
but yea when your at the drags you will see a few guys with tramp bars

my 180sx neva had any axel tramp but after 6 months it started get it every now and agen . so thats why i think the rubbers had worn out