steppetoes

Boomtubes went on my '08 GT convertible today. Loud, deep, has that old time boat sound at idle, amazing at high rpms. They drone a bit, but not too bad, easy to live with. Better than Macs.

Here is my issue (aside from the absolutely worthless clamps and an alignment issue, replaced the clamps already);

when the exhaust has heated up, there is a god awful rattle coming from somewhere. Sometimes a banging sound, other times a metal on metal buzz, other times a "marbles in a can" rattle. But I have no clue from where. Everything is tightened down, nothing appears to be touching, but I cannot live with this. I drove the car tonight, got it warmed up again, checked everything while hot, and still see nothing that looks like it could be causing this issue.

Oh, and weirdly, with the top down you can barely hear the rattling.

Has anybody experienced a similar problem? If so, how did you remedy it?

shanec

I had a similar issue with Bassani Race axelbacks and I got it fixed this morning. I had about 1/8" of clearance between the front (closest to the axel) muffler hangers and the brackets they hang into.

When the exhaust heats up, metal expands and my mufflers move 1/8" closer to the rear of the car. This surprised me. But I verified this by looking under the car when everything was cold and again after I'd been driving a while.

So when the car was warm, the hangers were up against the bracket rattling and squeaking. When the car was cold, it looked like I had plenty of clearance.

A muffler shop put the car on lift and tapped the tips of my hangers a few times with a 5 lb sledge hammer. This gave me another 1/4" of clearance and I have no more noises.

bbacon05

I also had a similar problem with my slp loud mouths, on mine the pipe that went up over the axle had shifted slightly and was rattling on the spare tire wheel well, maybe check to see if that pipe is touching anthing

JDWalton

Same thing Shanec said. My pypes had the same exavt issue, took a while to nail down what it was. On the drivers side, the farthest back hanger, take a look at the frame, gonna have to lay on the ground to look up at it, but I bet there is a rub spot. I took a sawsall with a metal blade, took off about 1/2 inch, still plenty left past the hanger, and no more noise.

SirKnightTG

I had the same issue when my headers went on. Before that my boomtubes were perfect. It only happened pretty much when things got hot.

I saw how in the same spot as shanec said how the hanger was real close to the bracket. I pulled the boomtube off and bent it back and so far it's be fine. I also noticed rub spots on my over-axle pipe and rear-end. I'm pretty sure some of my noise was from that b/c it sure as heck looked like it. I also rotated that pipe to be farther away from the rear-end.

After all that, it's been quiet (as far as metal banging and squeaking noises go) ever since and it's been several months already.

steppetoes

Thanks for the replies. Still no progress though. Only thing that looks like a possibility is that the passenger side over axle goes pretty close to the floorpan.

But I stripped one of the bolt holes tonight so I have a new issue. Thinking of going to an exhaust shop to have them try and figure it out. This sucks.

JDWalton

on the driver side, even cold, how close is ther rear most hanger to the frame for the bumper.

steppetoes

ABout 1.5 inches. I am leaning towards the over axle pipe's proximity to the floorpan being the most likely cause. Taking the car to an exhaust place and putting it on the lift tomorrow.

JDWalton

Its pretty easy to fix then. Losen the clamp that is at the back of the H pipe, losen the muffler clamp, and then you spin that tube, position it howerver you want, tighten the H, then position your muffler how you want, tighten the calmp, and take it for a spin.

steppetoes

Bingo! This is it. Found it tonight when the exhaust was good and hot. Just wasn't looking in the right place before. Will get this fixed tomorrow