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Old 02-06-2014, 07:32 AM   #13636
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When gear diffs first came out in rc, they weren't fluid filled. They were always unlimited slip. While this was easier to drive than no diff at all, it created some problems on certain surfaces but was inherently reliable. Sometime around 1980, Cecil Schumacher adapted an old go-cart style diff to an rc car. This was the first ball diff in rc. He tried to patent it but the idea wasn't original. The ball diff was superior to the non fluid filled gear diff. Towards the end of the 80's we started filling in the Kyosho style gear diffs with grease. This was a great setup on dirt ovals but the grease would still leak from the outdrives over time. It got messy. I still have an RC10 belt drive that has this very setup, grease and all.

Keep in mind that up until slippers became widely used, we ran the ball diff loose on purpose to double as a slipper. Yes we rebuilt them quite often! It was that technique that ultimately led to the creation of the dedicated slipper. The nice thing about a ball diff was that it could be quite loose and still send more power to the wheel with lower grip than a gear diff could. It could have much less resistance and still not diff out as badly. Tracks were much looser then too. A downside to the ball diff however was that how loose we could run it was affected by how powerful of a motor we ran. A mod motor needed to run a tighter diff so it wouldn't slip. As grip came up this problem became more apparent. It's an issue we still have with them and is a current downside. You don't have that problem with a gear diff. The difference between the 80's and now is that we don't want a ball diff to slip. With the advent of the fluid filled gear diff, we could run a looser diff and not have it slip. The roles reversed. However we can still get a diffing out situation.

As a general guideline I'd say to run a ball diff in lower grip and a gear diff on higher grip. I do hate adjusting ball diffs though. As they wear they change and it is nearly impossible to set them up the same way twice. Removing a ball cup and adjusting them through an outdrive is also a pain. In 4wd setting up ball diffs well can be a nightmare. I personally would prefer gear diffs only in 4wd but my B44.1 is stuck with only a ball diff right now. Removing and taking apart a gear diff to change fluid isn't fun either but once you get it where you want it, you can repeat it with another one and for the most part it doesn't change much. Temperature will affect it but the main concern is from outside temperature changes between winter and summer and this is fairly easy to account for.

Neither system is perfect but neither is always better than the other. I wish they'd go back to the JRX2 LRM gearbox style. The diff was in the middle. You removed a dust cap to insert the allen wrench to adjust the diff. It was simple. No removing axles.
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Old 02-06-2014, 07:58 AM   #13637
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Quote:
Originally Posted by Slash and Burn View Post
I know a lot of the guys running buggy are successfully using the 2 and 3 hole pistons with the larger holes, like the new pistons TD has come out with. You might try those. My son is using them on his DEX410 and likes them vs. the 4 hole tapered pistons we were using.
Thanks. I will look into those. Its been the most frustrating thing about this car for me. No real universal setups like Associated and Losi have.
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Old 02-06-2014, 09:27 AM   #13638
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Originally Posted by fredswain View Post
When gear diffs first came out in rc, they weren't fluid filled. They were always unlimited slip. While this was easier to drive than no diff at all, it created some problems on certain surfaces but was inherently reliable. Sometime around 1980, Cecil Schumacher adapted an old go-cart style diff to an rc car. This was the first ball diff in rc. He tried to patent it but the idea wasn't original. The ball diff was superior to the non fluid filled gear diff. Towards the end of the 80's we started filling in the Kyosho style gear diffs with grease. This was a great setup on dirt ovals but the grease would still leak from the outdrives over time. It got messy. I still have an RC10 belt drive that has this very setup, grease and all.

Keep in mind that up until slippers became widely used, we ran the ball diff loose on purpose to double as a slipper. Yes we rebuilt them quite often! It was that technique that ultimately led to the creation of the dedicated slipper. The nice thing about a ball diff was that it could be quite loose and still send more power to the wheel with lower grip than a gear diff could. It could have much less resistance and still not diff out as badly. Tracks were much looser then too. A downside to the ball diff however was that how loose we could run it was affected by how powerful of a motor we ran. A mod motor needed to run a tighter diff so it wouldn't slip. As grip came up this problem became more apparent. It's an issue we still have with them and is a current downside. You don't have that problem with a gear diff. The difference between the 80's and now is that we don't want a ball diff to slip. With the advent of the fluid filled gear diff, we could run a looser diff and not have it slip. The roles reversed. However we can still get a diffing out situation.

As a general guideline I'd say to run a ball diff in lower grip and a gear diff on higher grip. I do hate adjusting ball diffs though. As they wear they change and it is nearly impossible to set them up the same way twice. Removing a ball cup and adjusting them through an outdrive is also a pain. In 4wd setting up ball diffs well can be a nightmare. I personally would prefer gear diffs only in 4wd but my B44.1 is stuck with only a ball diff right now. Removing and taking apart a gear diff to change fluid isn't fun either but once you get it where you want it, you can repeat it with another one and for the most part it doesn't change much. Temperature will affect it but the main concern is from outside temperature changes between winter and summer and this is fairly easy to account for.

Neither system is perfect but neither is always better than the other. I wish they'd go back to the JRX2 LRM gearbox style. The diff was in the middle. You removed a dust cap to insert the allen wrench to adjust the diff. It was simple. No removing axles.
I remember those JRX2 days. Anyhow, speaking of diffs, just watch, sooner or later someone is gonna come up with a limited slip diff, or self-locking diff for the 2WD buggy. Its already out for 2WD 5th scale like FG, and we seen some smaller self-locking versions in 8th scale buggies.
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Old 02-06-2014, 09:47 AM   #13639
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An easy way to do it would be to go to a JRX2 style of gearbox with the diff in the middle with lower gears to the outdrives. The diff itself could be a dry gear diff. The two gears below that go to the output shafts could be connected much like they are in a gear diff. However there'd be no physical connection between them. Just two finned disks. Then it could be filled with oil. Now you've got a loose diff that is free to move and a viscous limited slip that kicks in when a wheel starts to spin faster than the other. It wouldn't be that hard and would be the best of everything.
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Old 02-06-2014, 09:52 AM   #13640
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Originally Posted by RC10Nick View Post
It is my understanding ball diffs are less prone to diffing out by design. The friction between the balls and the main diff gear under heavy acceleration/braking will create a sort of "locking" effect. In gear diff terms, it's like having a thicker fluid under acceleration/braking but a lighter fluid off power.

With that said, I've been running an sc10 gear diff in my buggy for the last 2 years with 2k diff fluid and the car runs just fine on a med bite clay track. I have been thinking about switching back to a ball diff just to try it again. I only switched to the gear because it was cheaper after I chewed up the outdrives on my ball diff.
That is correct, a ball diff is less prone to diffing cause its resistance is the same regardless of rotating speed, while the gear diff is loose until the speed ramps up and is slowed by the viscosity of the oil wt. Keep in mind what may work in a durango diff may be different in another manufacturer due to the capacity of the diff housing and how much oil it can hold, the friction of the gears, or tolerance gap of the gears, and the o-rings used on the outdrives. So 2K in a SCT may feel more like 5k in a durango.
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Old 02-06-2014, 10:02 AM   #13641
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Originally Posted by wyd View Post
Thanks. I will look into those. Its been the most frustrating thing about this car for me. No real universal setups like Associated and Losi have.
Well, i think there is a lot of setups for the car posted not only on the Durango site but on PetiteRC. Its hard to have a universal setup that works on all tracks. The thing is the setups are for the tracks they race at. Its not classified as setup for high bite clay, setup for low bite dusty track. You kinda got to read the track conditions and description and find a track description that is close to the conditions of your track.

But at least with the new DETC410 there are general setups for low bite carpet, high bite carpet, low traction asphalt, and high bite asphalt. So I think they are moving in the right direction. Hopefully we will see new standard setups for the 210 and 410 soon.
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Old 02-06-2014, 11:42 AM   #13642
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Does Durango usually have pretty lengthy customer service responses? It's been a couple days since I e-mailed them regarding an unfinished aluminum pre-load nut that I got from them.
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Old 02-06-2014, 06:52 PM   #13643
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call hobbico they are great and get back very fast...

Could someone explain "diffing out" to me? I don't understand this term.. I only use Gear Diffs as I don't feel comfortable building ball diffs
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Old 02-06-2014, 07:02 PM   #13644
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Originally Posted by Dino_D View Post
Well, i think there is a lot of setups for the car posted not only on the Durango site but on PetiteRC. Its hard to have a universal setup that works on all tracks. The thing is the setups are for the tracks they race at. Its not classified as setup for high bite clay, setup for low bite dusty track. You kinda got to read the track conditions and description and find a track description that is close to the conditions of your track.

But at least with the new DETC410 there are general setups for low bite carpet, high bite carpet, low traction asphalt, and high bite asphalt. So I think they are moving in the right direction. Hopefully we will see new standard setups for the 210 and 410 soon.
(nudging Durango... HINT! HINT!)
+1 on this....I figured out my durango........after experimenting for almost a whole season.
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Old 02-06-2014, 08:37 PM   #13645
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Originally Posted by cripplethreat View Post
call hobbico they are great and get back very fast...

Could someone explain "diffing out" to me? I don't understand this term.. I only use Gear Diffs as I don't feel comfortable building ball diffs
When one wheel loses grip or lifts off the ground (but the other does not), all the power will be sent to that wheel, and you'll lose forward speed.

A tighter ball diff or heavier oil in a gear diff will keep the wheels spinning more closely at the same speed, so it when traction is lost, the car will "diff out" less.
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Old 02-07-2014, 03:12 AM   #13646
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i dont understand, what this guy is talking, but there are some nice closeups....

http://m.youtube.com/watch?v=OYePXcS...atch%3Fv%3DOYe PXcSDmBk
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Old 02-07-2014, 05:15 AM   #13647
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He comments on the new upgrades from the dex210v2 compared to the dex210v1...

New front shock tower, with bigger holes to let more air go through, it said that it now comes with the cab forward body from default, the flat more durable front arms and the better turnbuckes? (sorry i dont know this word) and at last it talks about the +8mm alu standard chassis and that is going to be easier change between rear and mid motor configuration in this car because it simpler now..
And all this upgrades can be used in the original dex210 if you feel like.

Basically almost that, of course everyone imagine what he is saying but just in case..
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Old 02-07-2014, 05:44 AM   #13648
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Originally Posted by micholix View Post
i dont understand, what this guy is talking, but there are some nice closeups....

http://m.youtube.com/watch?v=OYePXcS...atch%3Fv%3DOYe PXcSDmBk
Cool, thanks for posting the clip..
Quote:
Originally Posted by lovethebuggy View Post
He comments on the new upgrades from the dex210v2 compared to the dex210v1...

New front shock tower, with bigger holes to let more air go through, it said that it now comes with the cab forward body from default, the flat more durable front arms and the better turnbuckes? (sorry i dont know this word) and at last it talks about the +8mm alu standard chassis and that is going to be easier change between rear and mid motor configuration in this car because it simpler now..
And all this upgrades can be used in the original dex210 if you feel like.

Basically almost that, of course everyone imagine what he is saying but just in case..
..thanks for translating the clip..
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Old 02-07-2014, 06:21 AM   #13649
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Originally Posted by lovethebuggy View Post
He comments on the new upgrades from the dex210v2 compared to the dex210v1...

New front shock tower, with bigger holes to let more air go through, it said that it now comes with the cab forward body from default, the flat more durable front arms and the better turnbuckes? (sorry i dont know this word) and at last it talks about the +8mm alu standard chassis and that is going to be easier change between rear and mid motor configuration in this car because it simpler now..
And all this upgrades can be used in the original dex210 if you feel like.

Basically almost that, of course everyone imagine what he is saying but just in case..
Yes, thx for translating!
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Old 02-07-2014, 07:01 AM   #13650
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No problem
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