You should also verify that the center mount is good and the rubber
hanger is in good shape. On the W124, this is a three-hole affair that
supports the pipe just behind the center muffler. If it is bad
(stretched rubber), it won't hold the pipe up against the center body
bumper and the whole pipe will vibrate too much.
Verify the condition of the transmission rear mount (not the pipe
hanger, the on the tranny sits on) and both engine mounts as well --
collapsed or broken mounts will allow excessive engine vibration that
will get transmitted to the exhaust. I dont' remember if you are
discussing a W123 or W124 chassis, but the W124 engine mounts are gel
filled with a suspending spring inside -- when they rupture (as they
eventually will), the engine will bounce terribly on that spring, much
much worse than collapsed mounts on the W123 chassis. On the W123,
usually excessive vibration is a result of dead engine shocks or a
separated mount allowing the engine to "fly free" on one side.
That "flex pipe" is more for shaping the pipe that for flexibility,
it's about as flexible as "flex" water pipes. Easily bent, but not
like hose!
Peter
