my friend just bought a 2001 i think it is RSX-S and almost every time he shifts you can heard and slightly feel a thump. it is more on the passanger side. we can't tell if it is under the seat or under the car.any one have any ideas what thqat might be?

 

maybe 02 then..? no RSX in 01

anyways.... could be a cv half-shaft going out. They can make very strange mysterious noises.

Or it could be the passenger side motor mount gone bad and the engine is moving when shifting

 

02 could be i'm not sure he just got it today type S injen intake DC header and greddy exhaust sounds really nice and really fun to drive!what ever it is, is most likely hitting the bottom of the car cause you can actually feel it a little bit so would you still think possible half shaft.we kinda thought about the motor mounts and trany but it feels and sounds so close to the passanger seat that kinda leads us away from thinking it is a mount...?

 

oh i guess i should be little more specific but it is right under the passanger seat

 

is it a dc race header? if so its probably the header hitting the sway bar! common problem. Inserts or new motor mounts can solve that problem. If its under the car by the passenger side thats all I can think of if a solid hitting sound

 

I got that same problem except mine only knocks when i bit dips, brake a little hard, and when i put it in first gear and start going. Im still trying to figure out what it is too.

 

You guys are hitting alot of squirrels...

 

^ he's right! classic squirrel syndrome.... how could I be so blind rofl

 

Remove the sway bar and see if it still does it. You can check the mounts by parking in gear and rocking the car back and forth, watching mounts for excessive movement.