Why are exhausts hung instead of solidly attached?

"Jake - Has Bad Luck So You Don't Have To" (murdersofa)
06/09/2014 at 19:13 • Filed to: questionlopnik

When racing the Road Sofa, I looked back after a run and noticed that my muffer was hanging a lot lower than usual. It turns out that the hard braking and cornering of the autocross was enough to make the exhaust slip off of the rearmost hanger hook. I laid down on the ground and put it back on with my shoes, since I had no gloves and it was ludicrously hot, but it begs the question:

Why are exhaust systems attached with flimsy hangers instead of something more robust? Why not have flanges welded onto the pipe that bolt right to the bottom of the car?

DISCUSSION (8)

Arch Duke Maxyenko, Shit Talk Extraordinaire > Jake - Has Bad Luck So You Don't Have To
06/09/2014 at 19:26

Because your car would vibrate, the noises would be intensely harsh, and you would hate life.

Xander, Proud of BOXER > Jake - Has Bad Luck So You Don't Have To
06/09/2014 at 19:36

There are better/stiffer urethane hangers available.

themanwithsauce - has as many vehicles as job titles > Jake - Has Bad Luck So You Don't Have To
06/09/2014 at 19:46

Physics. If your exhaust was a rigid part of the chassis all the welds woult break very shortly because of vibrations the car makes, let alone bumps/imperfections. Remember that the engine has its own suspension of sorts thanks to engine mounts. So if the engine is vibrating or shaking and the rest of the chassis doesnt move with it, the manifold-exhaust pipe connection will break.

nFamousCJ - Keeper of Stringbean, Gengars and a Deezul > Jake - Has Bad Luck So You Don't Have To
06/09/2014 at 20:01

but the coolest look is muffler tip shake when it first starts. Benefit of autostart and a good aftermarket muffler

samssun > Jake - Has Bad Luck So You Don't Have To
06/09/2014 at 20:56

The exhaust is solidly mounted to the engine, which is suspended from the car. You could probably solidly mount the exhaust to the car if you used solid (aluminum) engine mounts.

gmporschenut also a fan of hondas > Jake - Has Bad Luck So You Don't Have To
06/09/2014 at 21:03

Also the heat would bake any coating on the metal off. So you would have a steel bracket under vibration and rusting.

You can tell a Finn but you can't tell him much > Jake - Has Bad Luck So You Don't Have To
06/10/2014 at 14:23

What everyone else is saying about NVH issues and heat transfer to the body. The only thing I haven't seen mentioned is heat expansion of the exhaust. The exhaust piping actually needs to be allowed to expand and contract as it heats up while the car is running. If you had it rigidly fixed to the car at certain points it would end up buckling between the mounting points, or it would tear the mounting flanges off the car body.

MEESTALUBBA > Jake - Has Bad Luck So You Don't Have To
06/11/2014 at 16:19

your engine moves somewhat compared to the rest of the car, and the exhaust is attached to the engine. also the frame flexes, sometimes alarmingly so. any rigid attachment points would break eventually.