Chipmunk Physics

i create a car with the code in post
http://www.cocos2d-iphone.org/forum/topic/11047

but, when run the code in simulator,after the car fall down to ground, the car will keep shaking, what 's the problem?

anyone help? thanks very much.

Try following the advice in this post first: http://chipmunk-physics.net/forum/viewt ... f=1&t=1741