First, I know this has been addressed in several threads already. But, after searching and doing a lot of reading, I'm still not sure what's really going on with my truck. Just looking for some clarification.

TRUCK: 2003 F250, extended cab, long bed, 4x4, XLT, V10, auto, FX4 package with 122K miles. I don't have any previous history, since I just bought it a couple of weeks ago.

So, here's what's going on. When towing my boat (scaled at 3700# on the trailer when loaded for a weekend trip... so call it 3500# max since it was empty), there is a pretty violent shudder coming from the rear end when accelerating from a stop. It's more pronounced in 2wd, but it doesn't go away entirely when trying it in 4wd. Without the trailer, acceleration is smooth. But I haven't had a chance to load the bed yet.

From what I read, this is due to poor driveline angles when loaded, and may be fixed with some shims. But, it's not like I'm dealing with a lot of tongue weight here, only about 300-350 pounds... maybe. I actually think it's closer to 275. And there's no other load in the truck, besides me and a quarter tank of gas. I can't imagine that loading the hitch this lightly would cause the rear end to squat any. Certainly not enough to change those angles much. I suppose it's possible. But I've been driving a lifted Jeep Wrangler since '97 (and towing the same boat), and I know what happens when driveline angles get bad. Believe me, with or without the trailer, the DL on this truck seems lazer straight compared to the Jeep.

So, do you guys think this is really a DL angle issue from adding such little tongue weight? Or maybe u-joints (they seem solid). Tranny problem? Rear end? Something else? Please. I'm looking for anything here. I'm taking the boat out for the Memorial Day weekend, and if the wife feels that shudder she'll hassle me about getting rid of the Jeep for the whole 250 mile round trip.

 

OK. I just went out and took some measurements. There's only 1/4" of sag at the ball with the trailer hooked up. And I'd say that there's maybe only about 150# of tongue weight. I can easily lift the tongue as it's currently sitting. And when I stand on the bumper, my 250 pounds sags the ball 1/2". So I really don't think my problem is the driveline geometry changing. Could it be an axle wrap issue?

 

As long as you don't have any suspension lift, I'd guess your driveshaft ujoints are suspect.

 

I guess you could leave her home.......The shudder seems to be more pronounced due to pulling more weight which could be u-joints, center shaft bearing (if you have one), or the bushing where the shaft goes into the tranny. Possibly loose nuts/bolts, bent driveshaft.. Check under there.

 

Take it to a dealer and ask if the TSB for drive-line shudder applies to your truck and whether it's already been done. There has been a problem in the past with this even though the truck wasn't under load. The TSB requires installation of shims in the suspension.

 

Alright, I'll give everything the once-over again, paying particular attention to u-joints, bearings, and hardware. As far as the TSB goes, the only thing I know at this point is that there aren't any shims installed now. If I can't find anything wrong today, I'll look at shims next week.