98 Expedition 5.4, 4x4. Noticing a vibration coming from rear of vehicle starting around 50mph. Also happens when letting off gas. Could be tires need balancing, or something transmission or rear end related? It is the deceleration vibration that makes me think it might not be balancing
Rear Vibration At Highway Speeds
- Thread starter Fitz98
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An out of balance wheel will still cause a vibration upon deceleration within a certain range of speed as much as it will upon acceleration. Either way it is still spinning and wobbling until it reaches a speed where it's not noticeable. We need a little more info as to exactly what it is doing and when. Is it only within a certain MPH range?
Everything feels toght and "normal" until around 50 mph and then start to feel a slight vibration in seat and pedal. As speed increases, vibration increases and deceleration vibration becomes more pronounced. Can't describe frequency...sort of tickles foot on pedal and bottom of leg. I could look at u-joint. That seems like a good fit for diagnostics. Also tires are getting old and looks like lead may have fallen off mounting clamp.
Often new tires takes care of the issue.
How old tires? Thinking tread separation. If you're sure it's the rear. Swap tires front to back and see what happens.
Nick1994
$100 site donor 2024
Rotate the tires and see if it changes.
Likely a U-Joint or a bad motor/transmission mount.
Likely a U-Joint or a bad motor/transmission mount.
Right on man.. Tires (rotate), U-joints (just do both), and then trans mount (least likely). Good luck and post results.
FYI: I had the same symptoms. I just pulled the driveshaft and took it to a local drive line shop. They put on new joints and rebalanced it. They changed the weight just a small amount. Truck was smooth as butter after. I am going to do that with my crown vic soon. Same symptoms.
SammyChevelleTypeS3
$50 site donor 2023
Its always cheaper and easier to start making sure all tires are ok and balanced. After that it is "troubleshooting time." The next thing I would do is to make certain you do not have any bad struts. If struts need changing you also must have a four wheel alignment done after. Tires and or struts could hopefully solve your troubles. If not , then its on to brake issues? etc.... Take care of those tire inspections and balances to start. Hope u know a good mechanic you trust either at dealership or another shop. Good luck. Look at your tires. Rub your hand lightly over the treads and see if you can detect any uneven surfaces. Sometimes with a slightly bad strut your tire can develope what is called cupping. Its like high and low points on the treads that will make noise when you get moving. Usually u can hear it at low speeds too. I am thinking strut or struts are worn.
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Oh holy crap I just noticed that its a 1998 vehicle... How many miles does it have?????
SammyChevelleTypeS3
$50 site donor 2023
The one I was looking at last night was a 2000 Grand Prix GTP 2 door Supercharged Coupe with 70,000 miles they are asking about $13,000 for.
I was referring to the op's expedition. I'm almost sure the vibe is going to turn out to be a u-joint.
Replace your Ujoints first, before one quits on you.
Right? My guess is he has 188k on the original joints. I consider u-joints to be a maintenance item at 100k, or when you get driveline vibes.
SammyChevelleTypeS3
$50 site donor 2023
You know that actually was a pretty common "thing" with FORD back in the late 90s. I recall having to replace at least 2 back them. One on my full size Bronco and one on another FORD for my brother. They did not completely fail but you had no doubt they were going to. I BET you on to something with that idea.
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