The one reason that they thought it might be the flange was that they also service large trucks and they see issues with DSes and pinion flanges all the time. They said they talked with one of their heavy truck specialists and he told them to check it. I suspect that these vibrations are a bit more rough on a large truck than a car. Once they inspected it further, they noticed the issue.
The new DS is in and they say it is much better but not gone. That means it will come back, from everything I've read so far. At any rate, the field service engineer is supposed to be back tomorrow morning to look at it again. I asked them to call me when he is there so I can go and talk with him. I bet they don't... They said everything measures in spec now and they don't know what else to do. I'll let you know what the Ford engineer says. Hopefully, he actually drives it.
Anticipation is the best part!
A "pinion angle spec" was mentioned in this post. If the angle is supposed to be within some specification, then what caused it to be out of spec?
That's the million dollar question... Hopefully the Ford engineer can answer that.
Maybe it's the way the whole rear suspension & differential assembly bolts into the car, and if it's off so then the pinion angle is wrong? :shrug:
Unfortunately I am not a Heavy truck specialist so I was repeating what the one guy at the shop said. All I know is that replacing that flange fixed my issue.
