Servicing Mini-Z MR-03

In this video, let's service this 1:28 RWD ball differential. This is the GLR. It uses the same type of differential as many other chassis such as MR-03, GLR-GT, Reflex, Atomic, etc. Ball diffs are quite common as they perform well and are easy to adjust on the fly.
Ball diffs can wear down over time, specifically the balls themselves and pressure plates. I picked up some generic 2.381mm bearing balls recently. Let's try them out. First, let's disassemble this GLR diff.
The ball diff is constructed like a sandwich. Unscrew the adjustor hub, then the o-ring and the first pressure plate. Within the spur gear are 10 bearing balls. These stainless steel balls can last a while. If the diff was set too loose though and slip excessively, flat spots can develop. Confirming they are 2.38mm in diameter.
With the pressure plates detached, let's examine the condition of the surfaces. They still seem okay here. With this diff, the spur gear is supported by a central bearing so it can be removed without undoing the e-clip. That's convenient since I don't want to mess with the e-clip.
Here's 100 generic stainless steel 440C balls I bought from aliexpress for less than $5. They are likely not better than the stock GL balls, but they are cheap. These balls are measured at 2.39mm, larger than spec. Will they fit the holes on the spur gear? Fortunately they fit through the holes just fine. As usual, apply some ball diff grease to smoothen the diff action.
Reassembling the ball diff is quite straightforward. The mechanical simplicity is one of its selling points. With fresh round balls, clean pressure plates, and new grease, the diff action is very smooth! The friction on these 440C balls seems very close to the stock ones. That's good for running the ball diff relatively loose.
Like cleaning and greasing shock pistons, ball diffs require some TLC just the same. Sometimes sanding down the pressure plates becomes necessary.
This is Sammy and thanks for watching!
440c Bearing Balls (select 2.381mm): www.aliexpress...
Music: "Instructions for Living a Life", Savfk ( • Instructions for Livin... )

[@gotmesom]

gotta clean those dampers homeboy, get a mini blower from silver horse RC

[@popitn2nd]

When you close the spur gear, how tight it supposed to be? I have a RX28 diff and i set it tight because if i don’t it will get loose and the shaft will spin

[@sammybaka]

I try to run my diff as loose as possible but without slipping (e.g: as not to damage the balls or pressure plates). For larger tracks with large flowing corners, I might stiffen the ball diff.

[@QUIET100]

Do you have to do this?

[@sammybaka]

After a few sessions on a track, I'd consider serving a ball diff like this because dust and stuff start getting in between the plates. Balls should last pretty long unless the diff ran too loosely.

[@paolotramonte3528]

Ciao, dove la posso acquistare?

[@sammybaka]

I bought the generic diff balls here: www.aliexpress.us/item/3256805105303049.html (I picked the 2.381mm)