Replaced the DPF/NOX with a straight pipe several weeks ago along with EGR/Cooler/Throttle valve deletes and Smarty install. Everything works great - except, when the transmission is placed in reverse, the exhaust pipe shakes like the dickens. I added a clamp (right next to the factory clamp) in front of the muffler, and it seemed to help a bit, but it still shakes like crazy. The straight pipe is from FloPro and is aluminized. I know the DPF and NOX canisters were considerably heavier, but find it hard to believe they would abosorb as much vibration as the exhuast pipe now displays. Any ideas/recommendations?

 

I had a similar experience and my understanding is that in reverse, the RPM as dropped a bit lower than in drive and this makes more vibration which evidenced in the lighter weight exhaust as compared to the stock heavy cans.

Considered normal I believe.

 

Yup. I noticed that the RPM in reverse drops to near 500 rpm where in drive it stays around the 700 mark. The lower rpm seems to cause the pipe to resonate. With the other 50lbs of DPF etc on it before this wasn't an issue.

 

Mine even shakes in park, so bad i can feel it in the truck. It also makes quite a loud noise with the shaking.People at intersections even look over to see what the loud noise is. my rear tailpipe rubber hanger is worn out from all the shaking. I ordered 2 new ones that I should have tomorrow.I am going to put on both of them at the same time and clamp a big heavy iron something to the tailpipe & see what that dose.

 

Mine didn't show up until it got below freezing in November, In gear at idle it resonated bad. Anything off idle was fine. I kept moving the rubber hangers on the brackets until I found a sweet spot, made spacers and tied in place. Also when I switched from BlackMaxx to Smarty it changed in loudness.FWIW

 

I was thinking of doing some Mechanical Natural Frequency testing on the piping just to see how close it is to idle speed. You may need to just clamp some weight to the pipe mid section to change the resonant frequency. The worn rubbers are just a result of the pipe resonating, need to fix the source of the vibration.

 

Just did the same thing. The delete pipe is slightly smaller in diameter than the stock pipe. The clamp does not hold it tight enough.

Looses the clamp and insert some thin metal strips under it so it cinches up tight, or, buy a 4" clamp at the parts store and add it next to the factory clamp.

The noise goes away.

 

I just installed 2 factory rubbers on the tailpipe. I had to loosen up the muffler & slid it on further to line up the tailpipe rods so 2 rubbers would fit.The steel rods are long enough for almost 3. Started it up no more rattle or noise!