Shortly after having the transmission fluid replaced in my 2000 Ford F-150 at 155,000 miles, it began to shake. I had the wheels balanced – twice - but it made no difference. The frequency doesn’t change with speed, but the amplitude does, with the highest amplitude going downhill with my foot off the accelerator. I’ve put it in neutral and let the engine idle at speed, as well as downshifted, but it makes no difference. My shop says the front end is good and says it’s tire cupping. Neither my tire vendor nor I see any cupping, and the symptoms don’t match it anyway. Any ideas?
Check the rear end for a loose pinion and the driveshaft for loose U-joints, center bearing and mount (if it has one) and look for evidence of a lost weight on the driveshaft.
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Thank you, Mustangman. I’ll check all those that I can and have my shop do the rest. I appreciate it.
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Double check trans fluid level.
Unlikely for a 2000 w/155k miles, but fyiI had a shaking problem develop on a much older Ford sedan, turned out to be caused by rear differential problem.
I presume your F150 has an automatic trans. What does the shop that replaced the trans fluid think? How many miles elapsed between fluid change and symptom?
I did check the trans fluid right away and it seemed okay, but I also had the shop check it, which said it was correct.
Yes, it’s an automatic. The shop told me it was due to tire cupping, which it is not: neither my tire vendor nor I can see any cupping on any tire.
I estimate that I drove perhaps 200 miles or less between the fluid change and the shaking.
Thanks for your answer.
hmmm … seems unlikely transmission fluid replacement would cause this symptom. I’m guessing that’s probably a coincidence, unrelated. Ask your shop if trying some experiments driving in D, vs in N & coasting would be helpful. Could trying driving in 2 or 3 vs coasting too I suppose. Are you able to determine which direction vibration is coming from?
The frequency of the vibration is unrelated to vehicle speed? But the amplitude is? That’s a puzzle. I can’t think of anything in a truck that might cause shaking that would be totally unrelated to vehicle speed or at least engine speed, which seems unrelated by your downhill with foot off the pedal experiment.
hmm … I’m guessing your shop may well be on the right track. Not tire cupping, but something wrong w/one of the tires. You might try swapping tires around, see if that makes any difference. Gives an opportunity to verify the tires are properly attached to the wheels as well. And to check wheel bearing play. Asking a helper to drive along-side and watching the wheels for anything weird-looking might be helpful too. Might be something in suspension system has failed.
Common tire/wheel problems that can cause shaking:
- not balanced
- tread wear pattern problem (I’ve had that one)
- internal tire defect
- out of round, flat spots
- lateral (side to side) wobbling
MM’s ideas above definitely should be on the list. If any of those are the problem, or rear diff, symptoms will likely get noticeably worse w/ more miles driven. Esp consider center driveshaft support bearing if anything in that area has been disturbed or adjusted.
I’m presuming your F150 is 2WD. There are other things to check if 4WD.
Thinking back, these are the things that have caused vibrations for me
- Rear differential went kaput
- Wheel lug nuts worked loose
- Tire tread pattern
Thank you for the ideas. It is 4-wheel drive, which I use a lot in winter due to driving on muddy or snowy dirt roads. I’ve had no problems with it, either in 4-wheel high or low.
That pretty much tells me it’s not the transmission.
Like @Mustangman said, I’m thinking driveshaft problems, possibly transmission mount.
Thanks, that’s what I thought about it not being the transmission. Hadn’t thought about transmission mounts.
have you had the tires balanced? or checked for caked on mud inside the wheels? (Example: My Cousin Vinny)
Maybe rotate the tires and see if the vibration changes?
All ready done, when balanced, likely would have seen any mud.
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thanks. I musta missed that. 
Thanks again for the advice (and from everyone who responded). It was the rear u-joint that caused the vibration, as you suggested.
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Did you not see the post where Mr. Knuckles says the problem has been solved ?
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Suggest every once in a while to find a quiet place you can drive safely about 30 mph, with a cement wall located parallel to your drive, roll down windows, and listen for squeaking sounds from u-joints reflecting off that wall. That’s how my Ford truck exhibits early signs of rear driveshaft u-joint problem. Usually if I catch it early, all it needs is a lube. Lubing u-joints may not be possible on your truck however, but at least you’ll know you’ve got a problem developing.
I got a ford f150 lariat 5.3l lariat that started making a shaking noise after I braked too hard and I don’t know what it is for right now, because all the suspect things I had in mind were in their respective places and conditions, so if anybody has any idea; it would be appreciated
Seems like your brake rotors are warped.
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Sometimes its relatively easy to check if a rotor a warped. Remove wheel. Figure out a way to hold a sharpt object (pencil) very close to the rotor surface, but not quite touching. Hand spin the wheel to determine if the distance from the object to the rotor is changing as the wheel spins. Some is ok. Most rotor-run-out specs are in the 2 mil max range. 0.002 inch.