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Gear diff Vs. Ball diff

Gear diff Vs. Ball diff

Old 12-08-2011, 10:26 AM
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Originally Posted by Dave H View Post
The friction between the diff gear and the diff balls. No throttle, say mid corner, the balls turn fairly easy in the gear, letting the diff act much like a ball bearing, helping with speed and stability. Give it throttle (or brake) and the gear puts a lot of pressure on the balls, which tends to lock it up some.

I believe it is exactly the opposite. While it is true that the load point is between the balls and the diff gear, it is the only true load point. Other than this one load point, the ball diff is under about the same load when under power as it is sitting on the table. With a gear diff, the gears try to separate under load causing bind gear to gear and against all sides of the housing, not to mention dealing with the primary load of the diff gear itself (unless it is a fully "cased" diff, like a 1/8th scale).

This is why I think ball diffs have historically worked better.
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Old 09-17-2012, 12:25 AM
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Old 10-12-2012, 04:12 PM
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wondering if anyone makes a gear diff for AE B44.1
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Old 10-12-2012, 04:27 PM
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Originally Posted by Davidka View Post
I believe it is exactly the opposite. While it is true that the load point is between the balls and the diff gear, it is the only true load point. Other than this one load point, the ball diff is under about the same load when under power as it is sitting on the table. With a gear diff, the gears try to separate under load causing bind gear to gear and against all sides of the housing, not to mention dealing with the primary load of the diff gear itself (unless it is a fully "cased" diff, like a 1/8th scale).

This is why I think ball diffs have historically worked better.
Oh, forgot all about this thread, sorry for not responding in a more timely fashion. Please allow me to take a different approach, devilís advocate if I may. If a gear diff was binding up and thus locking under power, then why is the fairly thick fluid needed to prevent diffing out?
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Old 10-12-2012, 05:58 PM
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This is an awesome topic! As simple as the theories are on diffs....you can get way deeper on the pros and cons...construction,designs,materials used. Also on how any diff effects vehicle dynamics. There is a ton of info out there. The best places to look are Diff manufacters (1:1) stuff. Strange Engineering...Detroit Locker...Auburn Gear...Dana Spicer just to name a few. It applies to us..believe it or not. One thing i will throw in... a ball diff is more precise...its action very good. And yep...its like a detroit locker. Dont get me wrong....im used to spider gears...aka gear diff. The gear diffs are one tough muthas! In my 22sct i have a ball diff...but bought everything to convert to gear diff. Man ,this is a tough one to say one is better than the other. Im staying neutral on this one! I think its more of a personal preference! Have at it! Jimmy
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Old 10-12-2012, 07:56 PM
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Originally Posted by Dave H View Post
Oh, forgot all about this thread, sorry for not responding in a more timely fashion. Please allow me to take a different approach, devilís advocate if I may. If a gear diff was binding up and thus locking under power, then why is the fairly thick fluid needed to prevent diffing out?
Diffing out is an unloaded condition. It happens when one wheel is unloaded enough to allow free spinning. The heavier oil allows the loaded wheel to continue driving. All I really know about diff oil is that all 1/8 buggies run best with 5kf/7km/2-3kr (tongue in cheek here..). 3k in the rear of my MBX6 was nearly trans-formative from 2k.
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Old 10-13-2012, 11:21 AM
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Originally Posted by Davidka View Post
Diffing out is an unloaded condition. It happens when one wheel is unloaded enough to allow free spinning. The heavier oil allows the loaded wheel to continue driving. All I really know about diff oil is that all 1/8 buggies run best with 5kf/7km/2-3kr (tongue in cheek here..). 3k in the rear of my MBX6 was nearly trans-formative from 2k.
Ah, I understand what you were saying better now, thanks. I was referring just to 2wd, 4wd drive is significantly different, but diff action still applies obviously. What conditions were you seeing a difference, what part of the corner, how much throttle, when switching from 2k to 3 in the rear?
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Old 10-13-2012, 11:27 AM
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Originally Posted by Jimmy Lauri View Post
This is an awesome topic! As simple as the theories are on diffs....you can get way deeper on the pros and cons...construction,designs,materials used. Also on how any diff effects vehicle dynamics. There is a ton of info out there. The best places to look are Diff manufacters (1:1) stuff. Strange Engineering...Detroit Locker...Auburn Gear...Dana Spicer just to name a few. It applies to us..believe it or not. One thing i will throw in... a ball diff is more precise...its action very good. And yep...its like a detroit locker. Dont get me wrong....im used to spider gears...aka gear diff. The gear diffs are one tough muthas! In my 22sct i have a ball diff...but bought everything to convert to gear diff. Man ,this is a tough one to say one is better than the other. Im staying neutral on this one! I think its more of a personal preference! Have at it! Jimmy
Agree, certainly an intriguing topic for me too. Itís a huge area of development both for race cars like F1 and many higher performance road cars, especially front wheel drive and the all wheel drive rally type cars.

A ball diff only locks up some, it can still provide diff action under load. A fully locked diff on power, the extreme being the Detroit Locker, generally only works in smooth high traction conditions, otherwise they tend to completely lose the rear if one wheel breaks loose.
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Old 11-14-2012, 10:41 PM
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Hey been running a b4.1 ft for about seven months now. I run at a high traction clay track. Just went from 17.5 to 7.5 and noticed I was going through my ball diff a lot quicker now so I decided to build a gear diff for it. I put 3k in it just finished up gonna run it tomorrow see how it goes I will report back if anyone is intrested.
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Old 11-16-2012, 02:03 AM
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Just got back from the track. I gotta say ball diff is more consistent. I had to change my driving style quite a bit but the gear diff wasn't all that bad. I was still keeping up with the guys that are on my level. It did give me a ton of steering which I like but just a little to much so I'm gonna make some tweaks. The reason I ran it is cuz a guy there runs a durango buggy 2wd with a gear diff and he is super fast. I think with some set adjustments it should be great for endless fun with the boys at the track. I wanna build a sc10 4x4 and I know those are a lot of work so I need to cut corners somewhere as I don't have much time to wrench my RC s.but overall it did very well takes a little more effort to drive it but I think with some set up changes it should get better.
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Old 11-16-2012, 06:40 AM
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Originally Posted by johnny ray View Post
Just got back from the track. I gotta say ball diff is more consistent. I had to change my driving style quite a bit but the gear diff wasn't all that bad. I was still keeping up with the guys that are on my level. It did give me a ton of steering which I like but just a little to much so I'm gonna make some tweaks. The reason I ran it is cuz a guy there runs a durango buggy 2wd with a gear diff and he is super fast. I think with some set adjustments it should be great for endless fun with the boys at the track. I wanna build a sc10 4x4 and I know those are a lot of work so I need to cut corners somewhere as I don't have much time to wrench my RC s.but overall it did very well takes a little more effort to drive it but I think with some set up changes it should get better.
Do you think increasing the viscosity of oil would help make it feel closer to a ball diff?
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Old 11-16-2012, 11:35 AM
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Yeah I was thinking of trying 4k next time. Probably go back to the track Saturday and try it. But like I said not bad at all just wasn't use to it. I feel like its more aggressive so you have to watch your throttle control more plus tons of steering in the corners. I just need some more track time with it to get it dialed in but I saw a lot of potential for a high traction track but I would defenetly use a ball diff on a medium to low bite track. I have raced on one before and a ball diff is king there. But then I saw a 4wd durango with gear diffs take second in that class against a bunch of b44s
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Old 11-16-2012, 11:42 AM
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you want to go thinner on the oil. The thicker oil makes it more like a solid axle making it slide more. Try in empty with some black grease, then add more and more until you're happy, and it doesn't really leak out like oil will.
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Old 11-16-2012, 11:52 AM
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Originally Posted by rcjunky1 View Post
you want to go thinner on the oil. The thicker oil makes it more like a solid axle making it slide more. Try in empty with some black grease, then add more and more until you're happy, and it doesn't really leak out like oil will.
Plus 1
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Old 11-16-2012, 11:59 AM
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I ran my 22 back to back with a fresh ball diff and a geardiff with 1k oil in it. Running on a medium bite track I couldn't really feel the difference, maybe just a little more hooked off power.. Last week I raced on a low bite track and the car felt very good again so I'll stick with my gear diff and 1K for now.

Going back to carpet for the winter so will be more on the 5k range as it worked very well last year.
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