09 ford escape 4wd driveshaft reinstall after driving without it for the summer. experiment to see if fuel efficiency would improve...it did not. i already replaced the u-joints the year b4 and as i was doing that i could still drive the suv without the driveshaft. i thought i was using less gas for the short time the shaft was off so i drove this past summer without it to see if it would be more efficient, it was not or was not noticeable enough to bother doing the job twice a year, once to take and then reinstall.

 

Folks that do this work all the time are aware to mark the position of the driveshaft in relation to the flange on the differential. WHY ?
When originally assembled ,balance is a consideration and reinstalling the shaft if nothing is changed, hopefully does not invite vibration problems.

 

the shaft is not balanced on the vehicle so why would the differential need to be referenced to the flange, even though i did do it i would see no need to do it. if i ordered a new complete drive shaft assembly how would one reference it to the diff.

 

When a vehicle is on a lift and the differential is running ,just because a driveshaft is balanced to itself does not mean it is balanced with the differential..

This is one of the checks done on an assembly line.