[Bigun426]

On my 08 Charger Daytona I have for quit some time now a shudder or a hard thump in the drive line when decelerating. While moving above 25 mph and taking my foot off the gas the engine drops to idle rpm but the drive train produces a heavy thump as if I downshifted to low. This was an intermittent problem but now it is common. After 40000 miles this is the only drive train problem that has occurred. The 5-speed gets a lot of knocks but the one in my car is set up perfect for performance and economy. The shifts are quick and keep the engine in its power band. The slap stick shifter(old school) is a blast to use because it lets the engine work up to its red line. Since the mechanical condition of the transmission seems to be 4.0 makes me think it needs a little tweaking with the programing. Hasn't set a code so the dealership doesn't have a starting point.

 

[valiant67]

Even without a code there may be a revised "flash" available for the transmission controller. I had a problem with the slow updating of the outside temp display on the 2005 300C I owned which was a required a reflash of the cluster node computer. While the car was hooked up, they upgraded every module including the one for the transmission. When I got the car back, I really was impressed. before the trnasmission flet like the worst part of the drivetrain. Afterwards it felt like a totally different animal.

 

[ImperialCrown]

It does not need a fault code to go to the dealer. It may never generate a fault code for what ails it. There are several other diagnostic methods for the NAG1. If it is acting up consistently, it should be easy to demonstrate to the dealer and fairly easy to find.
Any filter and fluid change history?

 

[Bigun426]

The transmission still has the factory fill of fluid. It also has the tamper-proof dipstick so I don't know how the fluid looks,smells or if it is full. My wife has put al least 39 of the 40K miles on it which in my case the brakes are the only thing that comes close to getting abused and I think the Daytona has cop brakes because the sticker list peformance brakes.