F350 Vibration

Boss just had me go bring his truck in, 09 F350 Super Duty 4x4 diesel.

It started making a slight vibration last week, but I never got a chance to look at it.

This morning coming in it got drastically worse, so he left it on the side of the road. We went and got it, sure enough, horrible, violent mechanical vibration at drive line speed.

I looked the U joints over, didn't see anything wrong, jacked the rear wheels up, ran it at various speeds, NOTHING... Tried loading it with the brake, nothing.

It is in rear wheel drive, so nothing forward is turning. Lock out hubs are disengaged.

The vibration is not effected by throttle or coasting, anytime rolling over about 10 mph and up it vibrates, over 30 is scary.

I've looked at the tires, felt the bearings, nothing loose or heating up. Vibration too fast for wheel speed.

Unbelievable something this bad can hide so well!

Any ideas what I've missed?

Thanks!

I had bad vibration on mine.. was tire.. couldnt tell until I took each tire off and rolled it down the drive..

Missing any weights on wheel?

steve.. one more thing ..rotate tires see if it changes

You only looked at it in rear wheel drive and you found nothing. I"d suspect something in the front end. Wheel bearings front drive joints, steering rod ends, delaminated tire etc

It was on a smaller rig, but look for a bent or twisted drive shaft tube, or worn splines where the shaft slides. Only one guess why I would think of these items.

U-joints can get nearly seized and make the driveline jerk and shake.

If there's nothing else obviously wrong, it mite be worth dropping the driveshaft and checking to see if the U-joints are free to move normally.

Also, since it does not do it on rack, only under load, check wheel bearings, and carrier bearings of differential.

so it is a 4X4 , did you check the pinion for slop . if it is that stupid 10 1/4 sterling then check the pinion for up and down movement as they have had problems with the crush spacer collapsing , next look at the C V joints . Then i would check the transfer case for oil and see if you have any extra pieces and parts falling out of it . Now you did say that the ft. hubs were locked out but even so i would look at the ft. end . Now i know everything i know about a Ford is almost prehistoric and not surre what they are usen on the ft. end now i had a problem back in 78 almost the same . Where the ft axle stubs came thru the knuckle they used needle bearings inside the axle spindle to support the axle stub on the u/ joint end and the only way they got grease was for you to tear into the ft end and use your FINGER and pac those bearings once or twice a year if you used that ft. end for such things as SNOW PLOWING , getting OFF ROAD in the MUD and WATER and the ceap seal did NOT do it's job of keeping things out . In the end you would get to BY new axle stubs seal and new needle bearings . So looks like you have some wrench twisten to do . Even though you THINK all the U / Joints are good drop the shafts and check and replace ALL with new Danna Spicer joints with that OLD forgotten thing called a GREASE FITTING ., Also check the slip yoke as the PLASTIC may be coming off on both shafts.

Steve, many years ago while working the line in Ford dealership, I came upon a
similar problem. It turned out to be the shaft itself. Something inside of it
came loose and caused the vibration. Not common but could be.

Thanks, I found it!

It was the front drive shaft. Evidently, even though it is disengaged, it still turns by frictional drag through the transfer case and hubs.

The rear CV joint alignment ball failed, letting the shaft offset, causing the vibration.

You sure one of the u joints isn?t froze up

Did you try running it while on a rack
lift it up and run it .
how many miles on It

Had a similar thing happen on a '78 Ford. It had a 2-piece drive shaft with a carrier bearing. Carrier bearing mount was apparently not tight from the factory. Driveshaft got loose and shook the whole truck.

I just had a similar problem with my '95 Ram. All the way back to my '69 K20 Chevy to engage the transfer case I've always had it rolling backwards a good 10' when I've engaged it before moving forward. I still do that. This past winter I got caught a couple of times where I've engaged from a standing start, disengaged while rolling backwards. But I noticed something was grabbing and jerking while turning at low speeds, vibrating at higher speeds. I thought I hosed something, so engaged and disengaged as normally do and didn't resolve it. Last Friday after driving it I walked around and felt the wheels and the passenger front was pretty warm. The caliper piston is hanging. My guess is that while replacing all of the brake lines because one rotted and blew and others looked like were bloated as were going to blow, I probably got a piece of dirt or rust into the line that made its way into the caliper while bleeding it. Never had a caliper wit it until then, so...most obvious is that I caused it and fixed it. Smooth sailing now.

Mark

It wasn't the Ford death wobble was it? If it is a 4x4 that may have been it. It is a very violent front end vibration that has several causes. Here is a link to the problem. Good news, there is a fix. It can be as simple as correct tire pressure.
Death Wobble