Banging noise from under the passenger side of the car?

[Chris B.]

On Friday, I was pulling out of the parking lot of a local auto parts store. Their exit has a bit of a rise and a drop off that I forgot about. I heard a scrape and clunk when I was pulling out of the parking lot. Even when my car was the stock height, I use to sometimes scrape the bottom of the car on the concrete when pulling out.

On the way home, I noticed a new rattle that started to turn into a bang and clunk. Its not a really loud bang, but its noticeable. After letting the car cool down, I got underneath the car and found the passenger side of my H pipe was pushed up higher than the driver's side. So I loosened the bolts for the H pipe and repositioned everything. I have at least 1" of clearance between the H pipe, cats, and O2 sensors and the bottom of the car. Yet I still hear a banging noise when I go over bumps. I tried getting under the car and grabbing the H pipe and shaking it hard, putting my weight into it and also pushing it up against the car. Nothing seems to be hitting the car. I also checked the pupes near the rear axle and mufflers and can't see or hear them hit anything when I shake the pipes.

Today, I tried loosening all the bolts and repositioning everything again and I still have the same noise. I still have at least 1" of clearance between the exhaust pipes, cats, and O2 sensors and any other part of the car. Yet, I still have the same banging noise. I can't see any marks or dents to indicate what's making contact and causing the noise.

I also checked the bolts for the sway bars and shocks both front and rear just in case it was a part of the suspension causing the noise and everything is still tight and nothing moves around that shouldn't. Nothing changed about the handling of the car.

Any idea if 1" of clearance around all parts of the exhaust is enough and if there could be anything else that could be causing the noise?

 

[808muscle]

Well I had a banging going on and after a week I found it. My ota pipe was pushed up just high enough to when I drove over a bump the pipe would vibrate and hit the bottom corner of the trunk. I could yank on the muffler and nothing but when I push the pipe up I can see and hear it hit the trunk floorboard. Might want to check the clearance there. My passanger side has two fingers, drivers side less than a finger.

 

[Chris B.]

I rechecked all the exhaust pipes, mufflers and took extra time to check the OTA pipes. With very vigorous pushing and shaking, I was able to make one the Driver's side OTA pipe barely touch the bottom of the trunk. So I adjusted it by loosening the clamp further up the exhaust pipe and twisting the pipe a little to get more clearance.

After re-tightening the bolts, and shaking and pushing it again, the pipe didn't make contact anywhere and had plenty of clearance. I thought that would solve the problem, but apparently it wasn't it. I still have the same knocking/banging noise from under the passenger side of the car.

I've been working on this for two days and can't find any other part of the exhaust that comes anywhere close to making contact with anything even when I push and pull hard on the pipes. I even tried checking around the headers and nothing seems to be making contact there.

I'm beginning to wonder if it isn't the exhaust and its something else. I checked the suspension, and the spare tire to make sure they weren't rattling. I also checked under the seats and I checked the folding rear seats to make sure they were up all the way and locked in place.

At this point, I have no idea what it could be, but the noise definitely seems to be coming from the passenger side of the car.