xDezor

You must flip the front differential gear over and then all XL motors will rotate together. See the photo below: I have taken apart my 42070 and I am currently rebuilding it similar to Jim's. :-) After this mod I may take it apart once again to include a working center differential and 2 speed transmission. I'd like to be able to disengage the XL motors from the drivetrain to play with unpowered. I'd also like to avoid the need for replacing the 8/24 tooth gears with 12/12. I think the 8/24 gear combination is good for the portal axles since the front has universal joints. The universal joints are currently the weakest link, and I'd like to avoid breaking them in the future.