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View Full Version : Ball diff a worthy upgrade over the stock gear diff?


Bung-drew
2011.09.04, 07:53 PM
What are the advantages I would get in terms of handling? Any maintenance measures/tuning I need to do when using it?

unearthed name
2011.09.04, 08:03 PM
when you go into a hotter motor, a ball diff is a must as you can tune the amount of power transferred to your wheels using the diff.

when you use it, the only maintenance to do is to clean the gear and the ball inside the diff so it run smoothly. in order to tune the diff, just follow the instruction manual.

for ball diff upgrade, i recommend to change the ball inside the diff to ceramic ball. but this upgrade is not mandatory.

for more info, you can go here (http://www.reflexracing.net/MR02_build_part_1.asp)

or here (http://www.atomicmods.com/Categories/Tutorial-1-28-Mini-Z-Building-the-Ultimate-Differential.aspx)

color01
2011.09.05, 02:53 AM
Ball diffs (generally) are smoother and more consistent, and in extreme cases you can loosen it to act as a slipper clutch to reduce the power going to the wheels (this is BAD form! But it's OK to use if you have no other choice, such as racing on waxed floors, etc.).

For maximum power transfer, however, the gear diff is king. Gear diffs also have a locking action on-power due to the angles that the gear teeth mesh at. Most ball diffs do not have this locking action except for diffs modified with a PN LSD spur gear.

For most 2WD cars with a ball diff, you run the diff as loose as possible without slipping, this setting gives you the highest mid-corner speed and mild, predictable corner exit behaior. Some people like to drive out of the corner more aggressively, and set the diff tighter -- however, you will lose turn-in steering with a tighter diff unless you let the rear tires slip (which is hard to control on RCP).


Sorry if this is confusing, the basics of ball diff tuning are pretty simple but the finer points can pile up really quickly. :o

Bung-drew
2011.09.05, 03:20 AM
Hmm...I see:) another question if I were to get a motor with ball bearing instead of the bushings in my stock kyosho motor, will it cause it to run quieter on track?

tastetickles
2011.09.05, 06:52 AM
Another advantage of ball-diff over gear diff is the ball diff doesn't diff out (lose forward propulsion) when the inner tires lifted off mid corner.

unearthed name
2011.09.05, 08:08 AM
@drew

AFAIK no. the one that affect the noise of the car is the mesh of the gear, and the pitch of the gears

hrdrvr
2011.09.05, 08:22 AM
^ And the gears within the gear diff.

Bung-drew
2011.09.06, 12:47 AM
I'm also aware that the ball diff is much heavier than a gear diff, will it make a difference if so is it a good idea to upgrade the stock kyosho motor?

unearthed name
2011.09.06, 01:20 AM
it's a very good idea. sooner or later you have to change the motor anyway. due to the brush being worn down.

LED
2011.09.06, 02:00 AM
^ And the gears within the gear diff.

Not true. The gears dont turn in the diff except when the car turns. And even then with low speeds compared to spur.

Bung-drew
2011.09.06, 03:19 AM
Alrighti have set my eyes on the atomic BB standard motor,though quite pricey it offers a good upgrade in terms of torque and speed. Will the motor run well with my Orion 900s without blowing the FETs on my MR-02 EX? I heard the FETs on the ex are different from the older MR-02...

unearthed name
2011.09.06, 03:36 AM
should be fine. get a kyosho x-speed if you want a plug and play motor.

Bung-drew
2011.09.06, 05:36 AM
What about a PN 70T/80T stock motor? Which one will offer more speed if I were to setup a 9T/54T gear ratio?

unearthed name
2011.09.06, 05:58 AM
look at the number of the turn of the motor drew. a 70/80t will be the same as your current motor afaik. x-speed has 50 turn. therefore more rpm.

hrdrvr
2011.09.06, 07:49 AM
Not true. The gears dont turn in the diff except when the car turns. And even then with low speeds compared to spur.

What is it in the gear diff that gives it its "whine" then? When some one puts a gear diff on the track you can hear the difference immediately. I always assumed it was the gears inside.....I know, I know...assumptions :D

color01
2011.09.06, 06:40 PM
The gears inside click around unless you have heavy grease in the case. :) That, and a lot of ball diffs are 64-pitch nowadays and gear diffs are still on Kyosho's 0.5M gear pitch.

LED
2011.09.07, 03:14 AM
Like color said, its simply the pitch of the gears creating the noise.
A new diff and gear make alot of difference in noise level next to a worn one.
Also I noticed the bigger the gear, the more noise. But this could be a coincidence :)

hrdrvr
2011.09.07, 07:43 AM
Even before the switch to 64/126p I always though gear diffs were louder. Maybe its just a difference of mesh between people still using them vs people running ball diffs. Maybe its just a different sound, and therefore it stands out to me, not necessarily because its louder, but I perceive it as such.

unearthed name
2011.09.13, 02:10 AM
Anyone know why some brand of ball diff spur gear has different numberof balls?

Pn and atomic has 10. Reflex has 6. 3 racing has 5 big ones. How does the numbr of balls inside the ball diff affect the characteristic of the car?


Thanks

LED
2011.09.13, 02:15 AM
I'm not sure what the ffect is, but I most people run the 10 ball diffs with only 5 balls in it (I do).
So I wouldnt worry to much about that :)

color01
2011.09.13, 02:50 AM
The higher the track grip, the more balls you need to run to have enough friction inside the ball diff to drive your wheels. :) So on a low-grip track run well with 5 or 6 balls, higher-grip tracks might call for 6 to 8, and only the most insane tracks or the most insane drivers will ever really need the full 10 balls inside. I ran at Kenon -- a grippy track -- for the longest time with only 5 balls, there's absolutely no problem with it slipping so long as the diff is maintained. Rather, if I ran with 10 balls the diff would be a little too tight and the car just wouldn't carve the corners smoothly.

unearthed name
2011.09.13, 04:47 AM
so in conclusion i don't have to run the exact number of balls in my ball diff. and i can run less. thank you guys.

color01
2011.09.13, 02:15 PM
Exactly. :) I exclusively run 6 balls in the PN 126p spur, 12 would just be way too much.

unearthed name
2011.09.15, 01:32 AM
Brian, if you can help me with 1 more thing. Sorry drew for hijacking your thread.

I juwt bought the on 64 pitch delrin gear set for my mr. I sand my kyosho diff, and put 6 balls in it. The problem is. They're not as smooth as my old spur gear. Do you think i need to do anything else with my diff?

color01
2011.09.15, 03:35 AM
... Do you have diff grease in there? Without at least a little quality diff grease, any diff will feel pretty crappy after a rebuild.

unearthed name
2011.09.15, 03:46 AM
i put in silicone oil there. i'm thinking i might need to break in the diff first. the spur is brand new.