Ford shimmy troubles

[dobienut]

Hey Guys....my friend has a 2009 Ford F450 dually with the powerstroke automatic and is having some issues, or should I say , an issue. He tows a 45 or 47 ft (can't remember for sure) fifth wheel horse trailer and when on the highway coming into a hill the truck will shift down to a lower gear and sometimes the truck will start what he calls jumping, I guess i would call it a vibration, for about 10-12 times and then stop, or stops when it shifts back into high gear. He had it to the dealer this week and they first tried telling him it was because the fifth wheel hitch was 2 inches ahead of the rear housing, throwing the truck off. He basically told them BS because he had it installed at a dealer and he knew it was right.He also let them know it does it with his 2 horse bumper pull trailer also, so how can they blame it on the hitch! The Ford dealer ended up calling the trailer dealer and they also said it was in the right spot. Then they tried telling him the trailer is to much weight for a F350, he looked at them like a bunch of idiots and said that's why it's a F450!:banghead: They said he needed airbags or something to help out and he said the F450 is what they told him would tow what he wanted and that's why he gave them $80k for a truck! Then they said maybe axles...and so on and so on. So, I know it's hard to diagnose a vehicle you can't drive, but anyone have any ideas what he maybe looking at for a cause , I said maybe torque converter? He ended up hauling his truck out of there, i told him just to run it until it busts then make them fix it under warranty, but knowing them they'll try to weasle out of it saying he had something done wrong

[Mopar1973Man]

Just the fact that it comes and goes with gear change makes me think it going to be transmission related. Being when it kicks down it starts to act out and then shift to high gear and lose the problem. other things to look at is the u-joint or any carrier bearing it might have.

[ISX]

Only thing I can think of is just an issue with the 1997+ F150's. They would vibrate when going into O/D, not sure what it was doing but every single f150 auto of that style does it. I think we need more details on this jumping though. I could say my dodge is jumping and diagnose it as a death wobble..