Ford 6.7 Transmission

[mlh]

Keith. A lot of torque isn't the problem. I have over 1000 pound feet of torque. Something loose isn't the problem. The transmission isn't the problem. The drive shaft is the problem. You have a 2 piece drive shaft when you put weight on your truck you increase the angle between the 2 parts of your drive shaft and that allows it to chatter. In 2008 Ford went to about an 8 inch longer rear spring for a better ride. This allows the rear to sag more increasing that CRITICAL drive shaft angle. You can get rid of the problem. Put F350 single rear wheel springs on it. That will hold the rear end up and help with spring wrap like Ron said, or you can fix the drive shaft angle. The F350 springs is probably your best solution because it solves 2 problems spring warp and sag. Without checking I think you would need only to put 1 extra leaf in the spring pack.
Lynwood

[Carl n Susan]

I have a 2011 F350 SRW and it chatters too. So changing springs is not the ultimate answer.

[mlh]

Thanks Carl. If F350 springs isn't the answer then changing the drive shaft angle is. I know the problem can be fixed, I did it.
Lynwood

[1retired06]

Air bags might be another option, easily installed. Selected air pressure would maintain desired level, and no sag.

[mlh]

Like Mike said air bags might help. I know the problem can be solved. When I took my truck in for this problem the dealer called Ford and Ford didn't have a fix so I fixed it myself. I saw the service manager at my dealer a few weeks ago and we were laughing about me fixing it myself.
Lynwood

[kab449]

Lynwood:
Couldn't respond to thread cause for the last 3 days I have been alternatively at Hershey Medical Center ER and Physicians Clinic to take care of a retinal tear in my left eye that pretty much wiped out my vision. It is coming back after two days of laser treatments to seal of the tears.
Anyway I have a one piece driveshaft as my truck is 4 wheel drive and a short bed. The pinion angle is pretty much straight unloaded and after hitching, I do have airbags, the truck moves down maybe 2 inches which actually straightens the angle. I have the heavier springs as the truck is a 250 but is the higher (10000 lb gvwr) weight rating.
Still think the shudder is flexing at the driveshaft/pinion connection?