Operation " I need to leave crap alone " is underway.
There is a high demand for M916/920 rear axles obviously. So I sold the ones from my 920. Have a few RBUs laying around. Going to mate the RBU to the back of the 920.
Mk17 RBU is around 16ft long front to rear without the crane section.
There is ABSOLUTELY NO WAY that the bolt tp the truck section of the RBU can be removd from the RBU frame. None. I tried every which a way except dropping it from a C130. Cutting it in half doesn't work. Excavator would drag 60k with the RBu and it still wouldn't even shift the bolt holes. I gave up and cut the frame so I lost 2ft of the RBU frame.
RBU is 33 1/4in inside to inside on the frame. 11 5/8" top to bottom inside.
920 is 34 1/4" outside to outside to outside with the double frame. Inside frame itself is 33 1/4* outer side to outside. 920 frame is 11 1/2" tall top to bottom. So....
The plan is to cut the outer frame on the outside part cutting down the top and bottom off the frame to keep its height at 11 1/2" and leave the inside frame at its width.
Then slide the 920 frame into the RBu frame. I have 6ft of RBU frame till I get into the 2 rear air tanks. They aren't really needed so I may yank them anyway.
From the 920 center brace to the rear of the truck without the roller is 108in so basically 9ft.
So it will come into the frame that fat leaving 3 ft from the RBU frame stopping and the center of the cross brace.
I will leave the X brace in the middle of the 920 frame for reinforcement to the frame IF I can
I am going to be adding a 3rd rear drive/lift axle using the Hendrickson long arm air ride from the HET.
Axle will be able to be raised and lowered and allow power thru it when not in use. If it's needed drop it down and engage the power divider or locker.
Mk48 axles are massive Eaton types. 5.43 ratio. They use a parabolic 3 spring 58k rear suspension. They use a 5 ft spread on the axles as well center to center meaning more drive axle weight.
Will be using a front discharge cement mixer front axle to swap in with a 5.54 ratio as it is the same exact axle as the current only a little heavier rated.
Basically adding 5 ft of frame to the 920 is all. Maybe 6 depending on a few other things.
Hoping to bench the inner frame to the RBU so it can just be bolted of the course of that 6ft of overlap. To help it out.