Wltoys 104001 104002 DIY Center Diff Mod

I designed a spur gear and spacer that converts the stock front or rear diff to center diff. All you need to do this conversion is this kit, buy spare diff and 100mm and 70mm dog bone drive shaft. Needs a bit of grinding to clear the diff, and probably a mini blow torch, sometimes the screws are too stuck. The spur I design directly replaces the ring gear on the diff, it really self-explanatory.

Link to Dog bones:
https://www.aliexpress.us/item/3256806592125334.html?spm=a2g0o.order_list.order_list_main.11.1c911802WtBl0u&gatewayAdapt=glo2usa

You can get the diffs from Banggood or AliExpress or whatever:
104001-1930 is the part number. I reccomend getting your hands on the metal shell versions, less likely to strip and flex.

And any 32p pinion

Look at the pictures on where the parts go.

Optionally you can use some springs or o ring to prevent the dog-bones from shifting around but it really makes no difference other than noise. I like to find a empty pen and cut the spring in half and place it in the drive cups you can see it in the pictures. Again, not necessary.

The picture also have an older version, this version you are printing has 1mm extra clearance.

2/16/25 Added 42T, 44T, 48T, for your convenience
4/21/26 Added 52T, 54T, I use 54t the most.