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Allow me to preface this by saying this is not my truck, it belongs to my father but I use it almost as often as he does, and only I have noticed this problem. It started a few months ago, at around 55 mph it would shudder gently, every few seconds. At 50 it would stop, and at 60 it would stop. The problem gradually worsened and now it does it at 55, 60, 65, and 70. It also will sometimes do it at 45 and 50, but not nearly as often. The shuddering is also becoming stronger. The longer you maintain the speed, the more intensely and the more frequently it shudders, eventually becoming one constant shake. A deviation in speed or revs of even 2 mph or 200 rpm will make it stop. It generally happens when you have maintained one of the above speeds for over a minute, and only once the RPMs have settled to about 1500-1750. This truck runs and drives like brand new in every other way, including when accelerating and decelerating. All of the above leads me to suspect the overdrive. On the other hand, a trusted friend of mine who rode in the truck and experienced the shaking believes that the torque converter is going out. He said that he had to replace one on his old F-150 because it was having similar symptoms of only shaking when the overdrive engaged. I’d like more opinions though, so I thank you for any and all help you can provide.
Some stuff you should probably know:
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+ 1 on the above post. and Welcome to the forums.
I would also look into the following areas as well –
Tires – check for uneven wear , balance issues.
U-joints – a worn u-joint can cause a shudder ( or vibration&I’m honestly not sure if the plugs and wires have ever been changed. Unfortunately I don’t have a scanning tool, either. No, I forgot to mention that, the vibration is completely through the body of the truck. I don’t feel any in the steering wheel or pedals at all. The whole vehicle seems to shudder. The tires are fine, in fact the truck just passed inspection needing absolutely nothing a week ago. I wasn’t there, and my dad forgot to ask the mechanic about the shaking or have him check into the torque converter or transmission for causes. Your comment on plugs and wires interests me because I did wonder if under a very specific load, the engine was misfiring. However that seems unlikely because, even when accelerating to 60 from a dead stop, it doesn’t shake. In fact, no signs of the truck’s advanced age and heavy usage are apparent, and under that kind of load I would expect any issues to make themselves known.
That is about 100 times more severe than my problem… This is a subtle shaking, which is why I first described it as a shudder. Definitely noticeable, and it does FEEL like a misaligned or flattening tire (although all the tires are fine), but compared to that video its nothing. It’s best described in detail as if the power of the engine is coming and going, and this is why the torque converter was suspected. The shaking is forward and back, almost a stop and start jolt. But what really gets me is that any change in speed or RPMs and it goes away. It does NOT happen when using the cruise control either, only when maintaining a speed manually.
It would be interesting to see if you could recreate it while on a lift — if so, it’s not a steering problem. I’ve seen some guys mount a video camera under the front bumper, watching as the car drives down the highway to see the steering components shake, to verify death wobble. I wouldn’t be put off by the more mild symptoms — it’s getting worse and it will be more obvious with time. Also, steering issues may feel more like a power problem, since the front wheels are active participants in the drive train.
briansmobile1 did a video of his frustrating experience (and fix) of death wobble.
Please let us know what it ends up being….
Well, it could be any number of things. If it only happens at higher speeds, then I would suspect the tires might be out of balance. Since you said you only feel it in the seat, and not the steering wheel, then I would check the rear tires. But overall, you need to put the truck on jacks an do a good visual inspection of all the items listed, such as the u-joints, which could also cause your issue. Check for play in the rear wheels, see if you can find noises in the axle bearings, etc. Take a good look at everything, and go from there.
all great posts. the vibration in the seat steers me to look at the trans output shaft
. I would also u joints. check the drive shaft for a missing balance weight. its something
that rotates. next time your up to speed and the vibration is felt try shifting into neutral
and coast to see if the vibration stops or continuesC8-)I just remembered something that is probably crucial… last year, the vehicle lost a wheel. A lug bolt cracked and the driver’s side rear tire removed itself from the truck at almost 70 mph. That was scary. However, the axle itself and all related components weren’t damaged, only the brakes on that wheel needed replaced. The vibrations began a few months after that. I’m still fairly certain that didn’t cause any of these problems though.. and I’ll see about jacking it up ASAP, but if it passed inspection and the mechanic didn’t mention any problems, I don’t expect to find any either. The fact that it only does it when maintaining a high speed still leads me to suspect the O/D. Thanks to everyone for the quick and informative responses, by the way.
What you are describing sounds a lot like what they call “death wobble” on the Dodge Ram discussion forums. If you search that phrase you’ll find all kinds of reference to it with Dodge Rams. There is a video on youtube showing this in a Dodge Ram from the side of the road — simple harmonic motion of the front wheels. I’ve never experienced it, but it is said to be related to a harmonic motion problem in the steering system. If this is death wobble, it might be secondary to a worn track bar, and there is also a steering dampener you could install that seems to settle it down. This week I posted a youtube video showed how I replaced the track bar on my Dodge Ram, though I did it for an unrelated reason (inspection fail).
I would start with an inspection of the tires and steering system, and probably a steering alignment if it all checks out. Dodge dealers have some experience with Death Wobble, if that is what you have.
Wow, thanks for the tip. I’ll look into that. I took the truck for a drive with the O/D off, and it still shook, so I was wrong and I’m capable of admitting that. Putting it in neutral while coasting does stop the shaking, but so does any change in the throttle, up or down. It does seem likely that there is a very specific harmonic range that certain speed + RPM combinations could match. Referencing your video, this truck has that exact same amount of steering play, and has for as long as I’ve been driving it so I didn’t find it unusual.
Is this what you are experiencing?
inspect your harmonic balancer for cracks or deterioration. also check the the wheel
studs themselves on the rear for looseness. I think its transmission related due to
when you took the load off the transmission by shifting into neutral the problem
went away. keep us postedSince you mentioned losing a tire then the prob started I would check the rear end very well. jack the back up and run the truck. watch the rear wheels for any wobble .
The speed the problem happens fits a tire balance problem to a ‘T’, It might be a good start to just have the tire balance checked. Other than that I would be checking the U joints for looseness. I would put the transmission and torque converter at the bottom of the list until you address the simple stuff first. The rule is always to try the easy stuff first before getting into complicated theories.
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