exhaust thrashing

[ivandrocco]

Been having a bizarre problem with my exhaust... initially it was whacking the trailing arm just past the resonator. This would happen after 1 to 1.5 hours of highway driving, and only when hitting the accelerator. You can see where it was hitting, the pipe was halfway crushed in. I assumed this was due to the engine rocking and shaking the exhaust.

I adjusted the valves, replaced engine mounts, checked engine shock, got new injectors, i have the gold IP adjust screw... engine rock is minimal usually, sometimes it acts up especially after highway driving, but the exhaust was still whacking the trailing arm. I think this is either a coupe specific problem, I don't think the sedan has the same overlap of exhaust pipe and trailing arm. Either that, or my muffler was replaced by a PO and didn't quite fit right.

I decided to straight pipe the exhaust and just route it away from the trailing arm. I did this by deleting the muffler and putting the resonator in its place. Sounds great, feels great, but drove to Boston this weekend and sure enough the exhaust is still thrashing around after about an hour on the highway. Now it's hitting the differential due to its positioning.

This has to be abnormal engine shake causing the exhaust to thrash around so much. Any theories?

[SD Blue]

It may be due to the exhaust hanging loose and the wrong exhaust hangers in partigular locations. IIRC, the resonator ends should have a figure 8 type of hanger and the muffler needs round "donuts". The exhaust should be suspended but not "dangling" loose. I had problems of "eating" hangers and banging around until I found the correct hangers and snugged everything up.

[ivandrocco]

Brazed tailpipe to the resonator and a steel bar underneath it. Bent the bar up and around like a mustache. It's hanging from the stock hanger locations with the reinforced hangers, not the donuts. Also this is minus the weight of the muffler, which is at least twice the size (and im assuming weight) of the resonator.