So I got my car dyno'd this past Saturday (206/138 stock on a dynojet) and the next day I started noticing a clunking noise when I put load on the car or take it off by either hard acceleration, shifting (only in 1st-2nd and 2nd-3rd), hard braking and hard cornering. It seemed like it didn't get any louder until today. I was on an onramp and slalom'd to avoid a knocked over traffic cone and it sounded like someone hit my undercarriage with a hammer. The noise sounds like like a hard knocking noise on hollow metal. Anyone have any clue what it could be?!

I put the car on a lift and all the control arms/sway bar endlinks seem fine. I am thinking maybe my rear diff is going? Car is an 02 with 100k on it and idk if its suppose to do this or not, but the axles move up and down ever so slightly and its not from the joint either, i can visually see the spindle coming off the diff move up and down, but its less then a mm of travel.

 

Can you post a vid so we can hear the sound?

 

I'll see what I can do.

 

When i heard knocking (metal on metal) under hard acceleration/braking and cornering my thought was also that the diff is going out. So i had my car gently towed to the dealer only to find out that all the lugnuts on the back wheels has gone so loose that they almost fell out. I don't remember being that ashamed ever
Also today i started to hear slight knocking and squeaking from the rear, turns out that again the lugnuts started to come loose. So first of all - check them.

 

does it sound liek its coming from the rear of the car? im pretty sure my diff is clunking, if im coasting and then plant my foot i get an audible clunk noise. good excuse for some 4.5/4.77 gears!