BT-01 rear-drive layout ball differential

Installation notes

• Use one complete 22046 pack for one rear axle. It supplies 39T ring gear and matched 15T bevel pinion, ball/thrust hardware, two joint cups, two 850 and two 1280 bearings, axle rings/pins and ball-diff grease. Replace the rear differential, not the center drive.
• Match the number on the 15T bevel pinion to the ring gear: 39 with 39. If the rear previously used the optional 40T gear, remove that matched pinion as well. Preserve front/rear ratio intent; an unequal 39/40 setup is a separate tuning choice.
• Apply ball-diff grease to the rings and balls, compress the spring once before fitting and use separately available molybdenum grease on the thrust assembly. Tighten while holding the long joint until the ring rotates with slight resistance, then check that the ring does not slip with both joints held.
• Insert universal swing shafts into the narrow openings of the supplied cups. Fit the 2x9.8 pins and seat axle rings in their grooves. The installed differential faces the same direction as the original; increased adjustment range also adds maintenance.
• Scope is the driven rear axle with the original rear-drive gearbox and suspension retained. This does not itself convert a front-drive layout to rear drive or relocate the motor.
• Build each rear universal using the axles and cross hardware from 53792, replacing its original shafts with 51700 37 mm shafts. Keep the joint cups supplied in 22046. The maker explicitly calls for this shaft substitution; using 53792 unchanged is incomplete.
• The optional oil-sealed gear diff and the stock gear diff have different cup/dependency branches. This route covers only 22046. Inspect the installed drive layout before applying it.

Sources