almost every time i take off from a jump i hear a clack;when i land i hear it again. any help would be great

 

It could be a number of things.
1) your axle bearings are shot.
2) your shock is going down to far.
3) your chain is too loose and is getting hung up on something.

Those are just some places to start looking.

 

ill try the shock. i thought it was the chain so i tightened it and it kept doing it. plus we just replaced the axle berings a month ago.