I have experienced something strange over the last couple drives. After coming to a stop after exiting the free way, I let the clutch out, put it in neutral, and waited for the light to change. After about 5 seconds I heard and felt a fairly faint, but definitely perceptible "clunk" coming from the rear of the car. It was very strange since the was stationary at the time. It was almost as though someone was walking behind the car and lighly tapped the bumper with a fist.

It has happend 3 times now, doesn't happen everytime I come to a stop, and has only happened after coming to a stop immediately after driving at freeway speeds.

Anyone ever experience this sound? Any guesses? No codes, car runs fine, new plugs, new maf, new o2 sensors, no obvious problems, etc.... Thanks guys!

EDIT/UPDATE: I figured it out! one of my spoiler rams was hanging up a little bit when the spoiler was going back down. This caused one ram so slow down because of the discrepancy and added pressure from one ram being fully in the down position, and the other not. THen, after coming to a stop, the ram that was hanging up would slowly work its way down and then suddenly release with a thud. I lubed up both rams with wd-40 and now both rams are going up and down at the same rate and the thud is gone! That explains why it only happened after slowing down from speeds over 75! Thanks for the input guys.

 

Was it a constant "clunk" until you engaged the clutch again and drove off, or how long does the noise happen for? Any work done recently, ie) loose line or bracket moving around?

 

Only recent work (a few months ago) was gt2 slave and new stage 3 clutch at evo (which I love). Its only a single clunk. Only happens once per deceleration from highway speeds (the first time I come to a stop...it won't happen again until I slow down from the freeway the next time. Its almost as though the exhaust or a heat sheild has expanded and is "popping" back into shape. very strange.

 

Have you looked at the brakes? It could be either air in the system or the guide pins need to be lubed, essentially the brakes are binding for a split second then engage.

 

I'll try that...thanks for the advice. The pins you refer to are the pins that you tap out when doing a pad change, right?

 

This is exactly what I thought.

 

Ok, I'm stumped. I've tightened every nut and bolt in the exhuast/header/turbos/heat sheild system that I could get wrench on, and the problem persists. The other night I was stopped (on the freeway offramp light) for about 45 seconds before the "clunk" occurred. So freaking strange that it happens when the car is not moving. It has been suggested that I check my motor mounts, but I'm at a loss to figure out how a worn/blown mount can cause a sound like this when the car is stationary. Also, I'm sure its not the brakes as the sound occurs when the brake pedal is still being depressed (and the clutch pedal is pushed in as well). Any other suggestions? Frustrated!

 

I figured it out! one of my spoiler rams was hanging up a little bit when the spoiler was going back down. This caused one ram so slow down because of the discrepancy and added pressure from one ram being fully in the down position, and the other not. THen, after coming to a stop, the ram that was hanging up would slowly work its way down and then suddenly release with a thud. I lubed up both rams with wd-40 and now both rams are going up and down at the same rate and the thud is gone! That explains why it only happened after slowing down from speeds over 75! Thanks for the input guys.