R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric Off-Road

Reply
 
Thread Tools Search this Thread
Old 01-23-2008, 10:52 AM   #1
Tech Legend
 
Cain's Avatar
 
Join Date: May 2002
Location: West Fargo, North Dakota
Posts: 29,555
Trader Rating: 240 (100%+)
Default Gear vs Ball Diff, a discussion

Currently I am looking at a variety of 2wd stadium trucks, and since I have been acustomed to ball diffs for 1/10 scale, I wanted to get some opinions on how using a Gear diff that can be filled differs performance wise from a ball diffs. Advantages to each, etc.

this discussion doesn't concern gear diffs that cannot be filled.
__________________
Member - Red River Radio/Control Car Club
< Tekno EB48SL / SCT410.3 | Tekno EB410 x 2 | Yokomo YZ-2 DTM x 2 | LC Racing EMB-1 Buggies and Truggies >
Cain is offline   Reply With Quote
Old 01-23-2008, 11:33 AM   #2
Tech Elite
 
sosidge's Avatar
 
Join Date: Dec 2001
Location: Bristol, UK
Posts: 3,865
Default

Unfortunately I have not had the opportunity to test a sealed gear diff in an electric car, they just aren't available!

The only modern example I can think of is the Serpent S400 tourer which has a gear diff as an option and from reading the comments on the web it seems to work really well.

With the power available in modern electric cars I do think the ball diff is starting to struggle to cope. Some are better than others, the new 12 ball Tamiya diffs run better than the 8 and 10 ball diffs from before.

The advantage of the gear diff is zero slip, almost no wear and consistency of setting.

The advantage of the ball diff is lower weight, not really an issue in mod in my opinion though.

I'd like to see more sealed gear diffs available for electric cars!
sosidge is offline   Reply With Quote
Old 01-23-2008, 11:34 AM   #3
Tech Master
 
rockstar81's Avatar
 
Join Date: Sep 2007
Posts: 1,029
Trader Rating: 5 (100%+)
Default

In my opinion ball diffs are the way to go. I have had gear (planetary) and in my cases the ball diff has better action, truer braking and takeoff and I think a quality one like in a T4 will hold up better. Just my opinion.
rockstar81 is offline   Reply With Quote
Old 01-23-2008, 11:34 AM   #4
Tech Master
 
rockstar81's Avatar
 
Join Date: Sep 2007
Posts: 1,029
Trader Rating: 5 (100%+)
Default

In my opinion ball diffs are the way to go. I have had gear (planetary) and in my cases the ball diff has better action, truer braking and takeoff and I think a quality one like in a T4 will hold up better. Just my opinion.
rockstar81 is offline   Reply With Quote
Old 01-23-2008, 02:20 PM   #5
Tech Regular
 
NJA82's Avatar
 
Join Date: Apr 2007
Location: Cairns, QLD
Posts: 430
Trader Rating: 33 (100%+)
Send a message via MSN to NJA82
Default

The main reason i think ball diffs are used in electric and 1/10 scale in general is for precision, you cant beat the no backlash instant response of a belt drive/ball diff drive train. Compare that to a 1/8 nitro buggy driveline and see what i mean.... because in nitro you run a centrifugal clutch it doesnt show the backlash and the car is still as precise as it is ever going to be running a clutch, in electric because the power is instant and very hard hitting from so low in the rev range the less backlash helps protect the driveline ( its like preloading the driveline in a car before doing a launch at the drags, it will take up the backlash and protect the driveline from the SHOCK of the launch, ball diff/belt drive is constantly preloaded IMO ) and make the car a lot more precise.

Only downfall to ball diffs, rebuilding, wear fast and pain in the arse in general.
NJA82 is offline   Reply With Quote
Old 01-23-2008, 02:26 PM   #6
Tech Regular
 
NJA82's Avatar
 
Join Date: Apr 2007
Location: Cairns, QLD
Posts: 430
Trader Rating: 33 (100%+)
Send a message via MSN to NJA82
Default

Just to add to that as SOSIDGE mentioned, i would also like to see more gear diffs in electric, there is no reason a company cant make a graphite composite internally geared diff, this would be still light, very smooth and have not much backlash, would be virtually maintanance free and quiet. There is no need for metal gears in electric 1/10 scale as the weight isnt there and the use of slipper clutches prevents breakage. This would allow a lot more tunability with diff fluids etc. Over the very narrow range we have with ball diffs.
NJA82 is offline   Reply With Quote
Old 01-23-2008, 03:20 PM   #7
Tech Champion
 
Davidka's Avatar
 
Join Date: Oct 2004
Posts: 9,937
Trader Rating: 77 (100%+)
Default

There is one very important difference between gear and ball diffs that continue to give ball diffs viability. A gear diff under load is "trying to come apart". The internal gears are pushing away from each other and binding. With a ball diff all of those forces are non existent. So while a gear diff seems like it would be stronger (it can be) it takes haevy metal parts and strong housings to counter the opposing forces of the gears against each other. They are also more bulky which would be a challenge with current 1/10th designs. A ball diff by comparison can be extremely lightweight because aside from the main diff gear and outdrives, all of the working parts are under relatively low mechanical load.

Planetary grear diffs are another option but I think they have to have bigger housings.

It would be very interesting if someone could compare how effeciently they both operate under load.
__________________
"I have no idea what you're talking about, so here's a bunny with a pancake on it's head."

In mind and body, we're all heading towards old age. It is slower to go by bike.
Davidka is offline   Reply With Quote
Old 01-23-2008, 03:31 PM   #8
Tech Elite
 
Join Date: Jun 2005
Posts: 2,570
Trader Rating: 26 (96%+)
Default

Ball diffs are lighter & better suited for stock aplications where drivetrain weight is a big issue. Gear diffs are better suited for high power aplications where drivetrain weight isn't as big a concern. In classes like li//bl mod you can get gobs of power & run time that will actually take advantage of these.
party_wagon is offline   Reply With Quote
Old 01-24-2008, 10:36 AM   #9
Tech Adept
 
Join Date: Mar 2007
Location: Dalton,Ga
Posts: 151
Default

Am I understanding this right? Are you talking about a trans that is pretty much locked up 1 to 1? Not having any type of slip other than your outside slipper?
Andy Haynes is offline   Reply With Quote
Old 01-24-2008, 11:22 AM   #10
Tech Elite
 
Join Date: Jun 2005
Posts: 2,570
Trader Rating: 26 (96%+)
Default

Yes, I am talking about being able to lock down the slipper. In 2wd this isn't something you want, but in the 4wd classes you are able to acelerate harder out of the corners. It really makes a huge performance difference in classes like mod tc. In off road it will simply help to make the drivetrain more durable.
party_wagon is offline   Reply With Quote
Old 01-25-2008, 09:54 AM   #11
Tech Adept
 
Join Date: Mar 2007
Location: Dalton,Ga
Posts: 151
Default

I was thinking for 2wd there would be no advantage of it. Actually it would hurt you coming out of the corner's. Being that the trans works like a real cars limited slip. In 4wd you could always take a use a drill press and drill through the outdrives and center gear and put a small pin through it. But really I dont see how it would help having your trans lock up 1 to 1 even with a 4wd. I still think you need some slip from side to side with how uneven the tracks are. The slip that the ball diff has helps you with traction. Doing away with it would just have you spinning out every corner.
Andy Haynes is offline   Reply With Quote
Old 01-25-2008, 02:13 PM   #12
Tech Elite
 
Join Date: Jun 2005
Posts: 2,570
Trader Rating: 26 (96%+)
Default

When you run 2wd properly you will learn throtle control. The ball diffs do not always hold up to the rigors of a high power bl motor or nitro engine if you run them in a long main. The gear diffs are simply more durable & better suited for mod li//bl trucks that can run for 30 minutes w/ high power possibilities.
party_wagon is offline   Reply With Quote
Old 01-26-2008, 02:16 AM   #13
Tech Apprentice
 
Join Date: Jan 2006
Posts: 96
Trader Rating: 3 (100%+)
Default

i like my e-firestorm's sealed gear diff. i cleaned out the grease and put oil in it. it's been great so far.
bionictony is offline   Reply With Quote
Old 01-26-2008, 10:02 AM   #14
Tech Adept
 
chrlie sidebite's Avatar
 
Join Date: Dec 2004
Location: phx
Posts: 0
Default

http://www3.towerhobbies.com/cgi-bin...I=DTXC7338&P=X

1/10 scale gear diff
chrlie sidebite is offline   Reply With Quote
Old 01-26-2008, 05:36 PM   #15
Tech Master
 
Join Date: Sep 2007
Posts: 1,644
Trader Rating: 67 (100%+)
Default Ball Diff vs Gear

Here is a different point of view. I run on a high banked carpet oval and we only run 1/18th scale. I bought my new Vendetta Stadium Truck and everyone said I would have to have to pull the gear diffs and switch to ball diffs to be competitive. I never made the change. Currently I hold the track record for this class and was the points champ of the last series. Of 18 races, I won 16. The two I didn't were the result of battery charge error (my mistake) and a snapped front axle. I also run the plastic when everyone said I had to have steel CVDs.

Normally on the start whether I am in the front or back by the time we come out of turn 2, I am in first. Gear diff is immediately pulling. This is just another type of racing and another way to use the diff.
nutz4rcyktw is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Gear Diff VS Ball DIff NOVICE4EVER Singapore R/C Racers 23 08-29-2012 10:03 PM
losi xxxt ball diff change to a 1/10 desert truck diff newbie2 Electric Off-Road 49 12-13-2010 08:49 PM
NTC3 Complete ATD Diff, diff nut, pivot ball socket caps Judge Joe Brown R/C Items: For Sale/Trade 2 05-09-2008 10:18 PM
FS: T1FK'04, '04 Multi-diff, ball diff bbentley40 R/C Items: For Sale/Trade 4 05-17-2005 08:22 PM
WTB: XRay Front Ball Diff with pulley for 1.77 gear ratio bbking9 R/C Items: Wanted to Buy 1 04-04-2005 09:18 PM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 08:52 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net