The issue is a pronounced vibration coming from the drivetrain, evident at certain cruising speeds. The issue has been reported by numerous owners who have 2016 Ford E-450 model year chassis, but the issue is not isolated to Jayco products. It has been reported to be an issue for several manufacturers who build Class C units on these chassis.
Something many Class C motorhome owners are not aware of is that in order to build some of the larger Class C units the chassis has to be "stretched" to provide the needed long wheelbase. The bare chassis are sent to a third-party manufacturer who actually cuts the frame in two, affixes frame spacer sections, extends the wiring, exhaust, fuel lines, brake lines, etc. They also have to install a new driveline to connect the transmission and rear axle, which are now further apart than they were originally. Some Class C units now have 3 separate sections to the driveshaft. Even the slightest misalignment or problems with driveline balance and phasing can introduce vibration issues. Sometime certain harmonics develop at certain driveline speeds that have to be "dampened". If a change is made to any of the driveline components it can introduce new variables that may cause a vibration even though the other factors remained constant.
While Ford doesn't actually do the work to "stretch" the chassis, they are intimately involved in the process, supplying many of the pieces (and frequently the engineering) needed to make this possible. They require the bodybuilders to adhere to certain standards and guidelines in order for them to be QVM (Qualified Vehicle Modifier)-certified. Since the motorhome manufacturers all are supposed to adhere to the QVM standards regarding "finishing" the incomplete vehicle, that is why Ford then provides the chassis warranty that they do. And why they now have worked hard to come up with solutions to this issue. If you bought a new chassis yourself and cut and extended it, they wouldn't even give you the time of day if you claimed a problem!
2014 Seneca 37TS
Toads: 2014 Ford Explorer Sport or 2013 Ford Focus ST