Many motorhomes, both Class A and C require chassis/wheelbases different than the standard lengths that Ford or Workhorse produce. This is accomplished by the process of frame stretching.
Stretching is accomplished by cutting and splicing the frame in several locations. Typically on a class C, there will be two frame modivications. The first is in the rear where the overhand is extended by adding length to the rear of the frame behind the rear axle. The other, more difficult stretch is in lengthening in the wheelbase. Lengthening the wheelbase is more than just cutting the frame, but all items running from the front to the rear of the frame must be lengthend as well.
Many of the manufacturers know the frames will be lengthened, and so leave some excess length in wire harnesses, fuel lines, etc. but at a minimum, the drive shaft needs lengthed, usually brake lines and exhaust.
The actual frame cutting and lengthening if done properly should be as strong or stronger than the original frame.
Years ago, when I installed a MorRyde suspension on our Class C, I spent some time on the phone with a MorRyde engineer about their systems. I also found out they did frame stretches for many RV manufactures in Elkhart. The process they use actually doubles up the frame members for a distance about 1 and 1/2 times the length of the stretch.
Check our the MorRyde Frame Services Webpage
for more information. They have a interactive graphic showing a typical stretching on a Class A chassis.
Joe & Shelly, Justin, Tyler, Alyssa | Butler PA
2008 Tiffin Allegro Bus 43QRP|Cummins 425|Honda CRV