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Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 23001
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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Ford F-150 XLT: When I drive my 2010 F-150 XLT to between 30

Customer Question

When I drive my 2010 F-150 XLT to between 30 -40 mph and ease off the gas pedal to barely a load on the drive line I often get a chatter or heavy vibration, like a bumpy road. I replaced the tires thinking they were old and out of round. I put on new front KYB struts and shocks in the back. Still vibrates after a mechanic checked lower ball joints as OK. I replaced upper control arms as well. I questioned the U-joints and the carrier bearing. The mechanic found a minor 6 to 12 o'clock movement in the driver side rear axle. The shop wanted to sell me a $4000 rear end or rebuild one for $2500.
The mechanic never felt the vibration on a test drive he said as it doesn't do it except at 30-40 with minimal load on drive train. Are the U-joints or carrier bearing a possibility?
Submitted: 9 months ago.
Category: Ford
Expert:  roy replied 9 months ago.
good evening my name is ***** ***** I will assist from your description, it sounds like the torque converter in the transmission. it is common for them to shutter or vibrate under light load. the clutches slip inside the converter. when I find this as a symptom, I suggest changing the oil/filter in the trans and add an additive for the shuttering. if it is the issue, it should subside in about 20 miles of driving to coat the clutches. this would be a lot cheaper than a guess at the rear differential. I do not believe the differential is the issue Roy