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Old 03-16-2014, 10:12 AM
Chilly807 Chilly807 is offline
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Join Date: Aug 2013
Location: Nova Scotia, Canada
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Vehicle: 2013 Dodge Ram SXT
Trim Level: SXT
Color: Blue
Engine: 2009-20?? 345ci (5.7L) Hemi V8 390hp 407lb/ft
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This reminds me of the 2000 Silverado I had with the 4.3 V6 and auto trans.. it had a persistent exhaust vibration at about 80 km/h (50 mph) under light throttle. Wasn't there when new, it took about 3 months of driving and hot/cold cycles to start doing it.

GM had no fix for it for almost a year, then they added some ballast weights to the exhaust system to reduce resonance, and cured about 80% of the noise and vibration. It turned out that the thinner stainless exhaust was more prone to vibration issues than the older heavier plain steel ones.

The weights looked like the engine pods on the starship Enterprise, one on each side in front of the muffler.

It seems like this is something similar, just the right combination of rpm, rear end ratio, and transmission gearing and it's there.. Aside from the change of TC and flex plates in Canada, it has all the characteristics of sympathetic resonance.

Next time I drive mine I'll see if it does it too. I think it has a faint vibration at around 1800 rpm in high gear.

I usually cruise at about 63-64 mph on the highway, which translates to 1600 rpm with the 6-speed and 3.55 rear end. I was in a hurry a couple days ago and pushed it up to roughly 66-67 mph, noticeably more noise at that speed. Dropped back down to 64 and back to quiet running.

This seems more common with the guys who have the 8-speed and 3.92 rear ends. I was talking with the shop foreman at my dealer a few weeks ago and he mentioned that Chrysler was having some issues with the 8-speed, although he didn't elaborate and I didn't press for details.

Sean
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