How To Video: Kyosho Mini-Z | Ball Differential Rebuild/Service

I made this video on 1/30/2024.
Also applies to most ball diffs since most brands are quite similar.
Tools I used:
1.5mm Hex
Bearing removal tool
Flat head screw driver
Tweezer
Electric motor cleaner
Small tip plier
Differential grease (Team Associated or Kyosho)
Bearing oil (ACER Racing SIN lube)
Please comment if you have any questions. Thanks!
For photos, please check my KZread Community page: www.youtube.com/@tjaymacRC/co...

Пікірлер: 16

  • @MrJoseJasso
    @MrJoseJasso4 ай бұрын

    Thanks again for another very informative video!

  • @tjaymacRC

    @tjaymacRC

    4 ай бұрын

    Thanks Jose!

  • @EMU1
    @EMU14 ай бұрын

    I usually do a short break in with a dremel on the lowest speed. I start with the adjustment nut LOOSE, chuck the long end of the shaft in the dremel, then hold spur and turn on for 2-3s, then off. Then I slightly tighten the diff and turn on again for 2s while holding the spur. I feel that this helps set a little bit of a groove on the plate, and seats the o-ring for better pressure distribution. Usually after 3-4 iterations, the diff is up to tension and track ready. Kyosho diffs I feel have some of the best diff rings, they are very hard and very flat. So, with the Kyosho diff it may not really be needed. But, with diffs that have softer pressure plates, I find that when I dont break in they feel like the loosen during the first pack and need to be tightened a bit. I dont think its necessary unless you need the diff to be race ready on the first pack. If you have open practice, then just put it on track and adjust the diff as needed. One thing that is very important is for users to know that tightening the diff too much can damage the rings and/or balls (depending what king of balls are used). Ceramic balls are very hard, and with some diff rings which are soft, tensioning too much will dig grooves on the rings that take a long time to sand out. The sanding does 2 things, it flattens the surface, but it also increases grip with the balls. Using too fine grit (1000-2000) can make them too smooth that there are no pockets on the rings for the grease to squish into and the diff slips at a higher tension. With 400-500 like recommended, the diff is smooth, but not too smooth and allows good contact with the balls but also good grip. This is important for use with ceramic/carbon balls that are harder than the diff rings. With steel balls, they tend to have better grip with the rings, but will deform over time and be replaced after 3-4 services in my opinion. I change the outer pressure plate bearing before every big event, or every 3-4 services when I change the steel balls. The bearing is by far the highest cause for a rough action in the diff and can be damaged easily with impact on the wheel. Since the bearing is the same size as all of the bearings used on most of the cars today, its always good to have at least one spare set of bearings and if the diff is rough after a collision, you can usually just replace that bearing and get the diff action smooth again if there is no time to rebuild.

  • @tjaymacRC

    @tjaymacRC

    4 ай бұрын

    Thank you Eugene for posting this. This is good addition to the video. I don't really use any other ball diffs other than Kyosho because of 3 things: 1) I have not bent any of the steel or Ti Kysho shaft. 2) The pressure plates are consistent (hardness and flat surface) and easy to remove grooves. 3) I haven't had the adjuster nut back out. When I get a new car and it comes with ball differential, I keep the diff and donate it to whoever needs it locally. The only back up ball diff I use is the PN v2 ball diff. The v3 with gold plates are way too hard. The v2 plates are soft but its still better than the v3 in my experience. For Mod, I use carbide diff balls. For 2500 and 3500, I use ceramic diff balls.

  • @EMU1

    @EMU1

    4 ай бұрын

    @@tjaymacRC Many of my old Kyosho diffs I updated with other adjustment nuts to reduce mass. I had built many with the Qteq or Reflex assembly kits which cut pressure plate, adjustment nut and wheel adapter mass down considerably from the Kyosho without negatively effecting what makes the Kyosho diff a really good diff (pressure plate and shaft). I often prefer good steel shafts because they dont bend. I have bent too many lightweight shafts using a lexan body that I just dont run them in lexan classes anymore. The shaft mass being at the center of the axle reduces the inertia compared to mass which is further away from the axis. I prefer to finish all races than have a diff that is a gram or two lighter. Carbide for mod and ceramic for 2500 is what I run. 6 balls in round, none in the elliptical holes. Do you glue your diff rings to the pressure plates, or just use grease to hold in place? I have always glued my rings in the Kyosho/Reflex/Qteq diffs which do not use a D cut ring.

  • @tjaymacRC

    @tjaymacRC

    4 ай бұрын

    @@EMU1 Diff rings are glued to the plates. I don't think the grease will hold that. Always glued since back in the days.😉

  • @EMU1

    @EMU1

    4 ай бұрын

    @@tjaymacRC I assumed that you did glue them, but always better to ask then just assume. On the D cut rings, I always put a little grease between the ring and the plate. This makes assembly much easier as the ring will cling to the plate.

  • @user-ix9mr1qr3t
    @user-ix9mr1qr3t4 ай бұрын

    Is the yellow spur gear and blue parts modifications to a stock Kyosho ball diff? Is the spur gear a more durable Delrin material?

  • @tjaymacRC

    @tjaymacRC

    4 ай бұрын

    This is the Yellow Spur: www.kenonhobby.com/PN-Racing-Mini-Z-2WD-Machine-Cut-Delrin-Limited-Slip-64P-PNWC-Spec-Spur-Gear-53T_p_46199.html The blue parts in the Kyosho ball diff are all stock Kyosho parts. This blue ball diff is very old and if I'm mistaken, its from MR02 Mini-Z ball diff. The Yellow Spur is PN Racing Spur. This is the PNWC Spec Spur Gear 53T that I ran in a race. I prefer the black PN Spur Gear because its half the price and 1 less diff ball to use (5 balls vs 6). www.kenonhobby.com/PN-Racing-64-Pitch-Delrin-Spur-Gear-53T_p_42260.html You will have to modify the Kyosho ball diff (old or new model) to fit these 64 pitch Spur Gears.

  • @user-ix9mr1qr3t

    @user-ix9mr1qr3t

    4 ай бұрын

    @@tjaymacRC Thank you. I did some research before asking you the expert.

  • @user-ix9mr1qr3t

    @user-ix9mr1qr3t

    4 ай бұрын

    @@tjaymacRC why is 5 better than 6? what mods needed?

  • @tjaymacRC

    @tjaymacRC

    4 ай бұрын

    @@user-ix9mr1qr3t I don’t know if 5 balls are “better” than 6. I was just thinking that 5 would be easier to spin up with 2500KV motor vs 6. I want the most advantage I can get out of my 2500KV car in a legal way. The pressure plate holders will need to be shaved and glued. Its an oldschool mod we used to do back in the days. I made this video 6 months ago for someone. I don't have Kyosho diff at the time but I used the PN to give the viewer an idea. kzread.info/dash/bejne/Zo2Y0cRuhbLPpps.html

  • @user-ix9mr1qr3t

    @user-ix9mr1qr3t

    4 ай бұрын

    @tjaymacRC very cool. Thank you.

  • @user-ix9mr1qr3t
    @user-ix9mr1qr3t4 ай бұрын

    Do you run this diff in the RX28?

  • @tjaymacRC

    @tjaymacRC

    4 ай бұрын

    Yes I do. I only use Kyosho Ball Diffs in my RX28’s.

  • @user-ix9mr1qr3t

    @user-ix9mr1qr3t

    4 ай бұрын

    ​@@tjaymacRCThank you. 🙂