Have a 2010 F250 CC FX4 4x4 with 20" rims and think the 3.55 rear end. Been having a rear end hop at a given speed of 50-52 MPH. This hop is different than what others are experiencing based on symptoms so not sure if it is a drive shaft related issue in regards to balance or angle, not saying it's not though.

My issue is when the motor and tranny are both cold, so in the first 10-20 miles of driving after sitting through the night I will get a rear end hop/bounce at a steady speed of 50-52 mph. If I come off the trottle at all or even accelerate slightly past 52 mph it will go away completely. The truck seems to shift fine in all gears and hit OD at appox. 45 mph. So when slowly accelerationg to the speed of 50-52 mph and holding it there produces this hop. What makes it even harder to diagnosis is that when the truck is warmed to normal operating temps it is not noticable unless you are highly tuned into it. This hop also seems to be more obvious when ambient temperatures outside are cold, though it will also do it on random occasions, but easily repetable when cold. Not sure if it is a driveline issue because when not under throttle and just coasting is dose not produce the hop. No vibration or hop at higher speed, tows just fine with no axle wrap felt.

Have had the tranny and drive line looked at multiple times with dealership unable to duplicate event and tell me all is good, but when i drive it it hops and I drive like grandpa going to church on sunday, trying to save fuel $4.25 a gal in CA. They have dropped the tranny out twice and replaced the front internal pump and seal along with a rear main oil seal. I have had the PCM flashed per the recall, unfortunatley it was done in that time period when it had the bug in it and will be getting it reflashed on Wednesday.

Anyone else have this issue? Was thinking maybe the tourque converter as that is the speed I believe it locks up. Don't have much working knowledge of how the torque converter works or locks up. Any help would be greatly appreciated as I am new to Fords, FTE and diesels. Truck is all stock with only 13,000 miles on it and this all started about 7,000 miles ago. Did put airbags on over the weekend and no change.

 

Tires? Balanced?

 

Balanced and road force tested

 

My friend had a chevy s10 that did almost what you describe.

It was the drive shaft. Although perfectly balanced, under torque it was deforming causing vibrations.

The only way we figured it out is that I was riding in the box, and when he stomped on the gas you would see the drive shaft start to wobble. I was looking through the crack in between the box and cab.

 

How do I get the tech's at the dealership to do that kind of diagnosis???? I have seen it done in commercials. LOL Maybe they can hold on to the frame as we test drive

Thanks I'll have them look it over again.

 

You said you can easily reproduce it, but that the dealership can't. I suggest you go along with the tech with you driving it and reproduce it for him. That way he can feel it and will be able to better concentrate on a cause without having to worry about driving. Ive done this before when I was told the dealership couldn't reproduce the problem.

 

I see a lot of views but not a lot of input, makes me feel like my experience was unquie. Notice I said "was" beacuse after about 7,000 miles, four dealerships, multiple calls to Ford corperate customer serrvice and the transmission removed three times I think, hope and pray that it is finnally fixed. Thought I would update what my lastest fix was incase anyone else had similar issues. They ended up with the tech completely trearing down the tranny and checking all clutches, which were fine. They ended up replacing the tourque converter and two shift solenoids, I believe related to 5th gear. Truck runs and shifts better than it did brand new right off the lot. It even feels more responsive and has less turbo lag. Also had them re-flash the PCM due to the recall to the recall. Hope this helps anyone else in a similar situation. Thanks to those for their input. Can hopefully enjoy the truck once again.