Mr. Kilmer, I have a 2006 Ford F-150 4wd. I have always had my truck serviced at the Ford…
I have a 2006 Ford F-150 4wd. I have always had my truck serviced at the Ford dealership. I had a 150,000 mile service performed last week, which included having the rear differential fluid changed. After picking the truck up, I noticed a shudder/vibration in the rear end only when moving forward from a stop. Since I have never experienced this particular problem before, I returned to the service department. It was explained to me that a new friction modifier was used when the rear differential was serviced. They, too, noticed the shudder/vibration and decided to drain the fluid and replace with the "Ford" modifier. They also inspected the clutches and said that everything appeared to be fine.
The Ford dealership has asked that I continue driving the truck for a week or so to see if it smooths out. They seem to think that it could be "the clutches breaking in with the newer fluid." I still have a slight shudder/vibration but it is not near as bad as it was. Does the information they are providing me with sound logical, in your opinion?
Thank you for your input.