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.
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.
@@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 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.
Hi Tjay, how often do you replace the balls and pressure plates? how do you check their wear? do you have a guide about how to choose diff ball material? Thanks
Hi, I haven't replace any pressure plates. Two of my ball diffs have plates from over 10 years ago and I still use them. For shaft, I only use Kyosho Steel or Titanium. For hardware, I can use both Kyosho or Reflex Racing: hubs and plates. For Spur, I only use PN Racing. For diff balls, I am using Carbide lately to get traction. I put down 45,000k+ laps in 1.5 years. I had only replaced 1 set of ceramic bearings because they looked dull (not shiny). I haven't replaced any Carbide. I also don't inspect it, I just replace when I feel they're old. I haven't seen any carbide of ceramic balls get flat spots. They stay consistent from my experience. I don't have a guide but I did updated the description above where I linked all the parts that I use. Please note that you will need to modify the Kyosho ball diff to fit the PN Spur. I don't have a video or guide for that mod. Why Kyosho steel/ti shaft - Because they're reliable. It always stay true and you can play around with the weight (adding or removing) in the rear.
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.
@@NOTREALLYHANKAARON 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. th-cam.com/video/4Ydob5UOiv8/w-d-xo.html
Thanks again for another very informative video!
Thanks Jose!
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.
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.
@@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.
@@EMU1 Diff rings are glued to the plates. I don't think the grease will hold that. Always glued since back in the days.😉
@@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.
Hi Tjay, how often do you replace the balls and pressure plates? how do you check their wear? do you have a guide about how to choose diff ball material? Thanks
Hi, I haven't replace any pressure plates. Two of my ball diffs have plates from over 10 years ago and I still use them. For shaft, I only use Kyosho Steel or Titanium. For hardware, I can use both Kyosho or Reflex Racing: hubs and plates. For Spur, I only use PN Racing. For diff balls, I am using Carbide lately to get traction.
I put down 45,000k+ laps in 1.5 years. I had only replaced 1 set of ceramic bearings because they looked dull (not shiny). I haven't replaced any Carbide. I also don't inspect it, I just replace when I feel they're old. I haven't seen any carbide of ceramic balls get flat spots. They stay consistent from my experience.
I don't have a guide but I did updated the description above where I linked all the parts that I use. Please note that you will need to modify the Kyosho ball diff to fit the PN Spur. I don't have a video or guide for that mod.
Why Kyosho steel/ti shaft - Because they're reliable. It always stay true and you can play around with the weight (adding or removing) in the rear.
@@tjaymacRC amazing answer thanks so much =)
Every week?!!!
Yessir! I put 500+ laps per visit in 1 car. When I come back the following week, I want my car/s in tip top shape.
Is the yellow spur gear and blue parts modifications to a stock Kyosho ball diff? Is the spur gear a more durable Delrin material?
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.
@@tjaymacRC Thank you. I did some research before asking you the expert.
@@tjaymacRC why is 5 better than 6? what mods needed?
@@NOTREALLYHANKAARON
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.
th-cam.com/video/4Ydob5UOiv8/w-d-xo.html
@tjaymacRC very cool. Thank you.
Do you run this diff in the RX28?
Yes I do. I only use Kyosho Ball Diffs in my RX28’s.
@@tjaymacRCThank you. 🙂