i have a 1996 polaris indy classic 500 and recently a grinding noise or very rappid thumping noise has been coming from what sounds like the track. i cheked the track tention and it was a little loose but not enought to realy need to be tightened but i decided to do it anyways. it still does it. it usualy starts when i accelorate or when i hit bump (woop sized or plow hill sized) when the suspension goes down. it will allways do it if im going under 10mph and i put it to the grip. i dont know what is wrong outher then track tension and it wasnt it.