Modding Mini-Z MR-03 Ball Differential (More and Faster Gear Ratios)

This is the GL spur gear displaced from the previous video. I have a plan for it. This is my MR-03EVO chassis with a bunch of R246 parts, including the blue Kyosho Ball Differential. This is also a good diff. However, it uses 0.5 mod gear which is the standard Mini-Z spec, but all third party diffs use 64p gears. Let's convert it to 64p too.

This Kyosho diff is constructed with alloy parts (likely Aluminum). It's quite well made and sturdy. The pressure plates are parallel. The hub securely holds the tune. Making the gear pitch to 64p will let me drop it into my Reflex or GL chassis. Another advantage of 64p is a wider range of useful gear ratio options. It's the way to go.

The stock Kyosho spur gear uses just six 2.381mm bearing balls. You know the drill. That e-clip needs to be unclipped.

The GL spur gear is not an easy drop in replacement. Kyosho didn't make one of the pressure plates completely flat. The central hub sticks out by 0.4mm. We will need to trim some material on the GL spur gear. On the left is the Kyosho 44T gear, and the other is the GL 53T. Note the GL gear is even considered for this install because it doesn't use any central bearing, which would get in the way. To determine where the binding is, I test for freedom of movement with and without the hubs, on both sides. In the end, I trimmed the raised inner edge on the outer side of the gear. And sanded down the excess plastic from the injection mold on the inner side. It took me a long time to figure this out.

With the spur gear cleaned up, it's time to grease and put it all back together. With the Kyosho diff converted to 64p gears, it's going to be more useful for me. I really like the robustness of this diff.

It's time to change out the pinion gear as well to match the 64p pitch. My MR-03EVO was running an 8T. I put in a 10T GL pinion on the motor. This motor mount should be able to accommodate a 12T or perhaps 13T too. The diff action is just as smooth as with the stock spur gear. After some trials and errors, I was able to find all the pressure plate binding issues.

This is Sammy and thanks for watching!

GL 64p 53t spur gear (GLR-007-53): https://www.microrcsyndicate.com/prod...

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