CranMaro99

iTrader: (10)

So I picked up my girlfriend when getting off work just now, and something weird happened.

Long story short I was slowing down to a stop (for a stop light) and was pressing the brakes at about 30 mph, slowing down.

At that moment I heard a weird "vibration sound" that was more mechanical sounding (not a rattle). My girlfriend goes "what is that?"

Weird thing is, is that my g/f could FEEL the vibration right under her seat. I could not feel it, but only hear it (my g/f could hear it too, and also feel it.

It sounded like it was coming right under the passenger seat, hence why her seat was "vibrating" and mine was not.

Here is why I can't figure out what is making the noise: it happened when the car was moving, and when it was also parked. I then pulled over when the vibration/noise occurred when slowing down, and the noise was still there. She then got out of the car and it went away. Weird.

I asked her what it felt like and she said "it didnt feel like the seat itself was vibrating, more like something rotating or mechanical underneath the car was vibrating it.

So then when we get out of the car the noise stops... Then when driving home again I try and re-create the noise driving in all ways possible. Then I got the noise to occur (for only a few seconds) when I hit the brakes firmly going down a hill (with the car in 3rd gear). Then after that, nothing.

What could it be or what should I look for? I have no idea. It's dark outside and I'm going on a short vacation this weekend and I looked under the seat and under the car etc to see if there was anything obvious and no luck.

Ideas? It's not my engine, its not the tranny as the sound occurred with the car moving, stopped, clutch engaged and non-engaged, (aka it was very intermediate), it sure doesnt sound like a suspension piece as it was going on with the car not moving (and all parts looked legit when looking under the car) etc.

The only thing that pops into my head is my true dual exhaust (even though it has been on my car for 3 years with nothing like this happening.) It would make sense and sounded as if the passenger side pipe was gently rubbing against the passenger seat undercarriage. But then again the pipes never have (and still dont) bang against my floorboards at WOT. I drove around after the noise/vibration occurred shifting at WOT to see if the pipes would bang against the floorboard and they did not. So how could the exhaust be hitting them while the car isnt moving (and when I looked under the car there was decent amount of clearance between the floorboards and the pipes anyways.)

This problem seems abstract and I'm trying to troubleshoot.


Ideas fellas? Last thing I want to happen is something bad when I'm traveling at 70mph on the highway.

CranMaro99

iTrader: (10)

Seems like nobody else has any ideas, either. lol

91RS383

Do you have cats on the true duals. Is the passenger cat right under the seat. I don't know why you would feel that though.

98pontiac

First thought in my head was "does this guy have aftermarket exhaust"? And sure enough, maybe a hanger broke, or somthing got tweeked and is hitting the floorboards. get under and hit your exhausrt upward with your palm a few times and see if something hits.

vikingramair

start to examine your exhaust. Vibration and rotation under your GF.............. ;-)

CranMaro99

iTrader: (10)

I do not.

Yeah after all consideration I'm thinking it has to be the true duals. I just got home from a plane flight and it is still daylight out so I'm going to check it out more in depth. It's the only thing I can think of. (And I kind of hope it is the issue.)

I know, right? Let's just say she didn't complain as much as I did

CranMaro99

iTrader: (10)

Did a bunch of random work to the car today including the suspension so I took a look at the exhaust since I had way better view and what do ya know?



The bolts from the clamps were touching the passenger side of the floorboards.

Problem now solved unless the vibration occurs again, which I doubt, and hope doesn't happen. I took it for a short spin and nothing happened.