Kraton Diff oils

[Lingerfelter6]

A heavier center diif oil won't load up the rear more. It just wont unload to the front as quickly, kerping power in the rear. Weight gets transferred to the back, the front lifts and sufficient traction will cause a wheelie. A heavier front diff affects off power steering into a corner

 

[bicketybam]

Great post guys.

I have a Kraton and 2.0. Both are fitted with vented Talons. The Revo is standard, the Kraton now has 500k in the centre diff.

On heavy acceleration the Kraton will still balloon the front wheels and i have been considering 1 million in the centre. I also wondered if a thicker front would push more power to the rear (that appears not to be the case though).

The Revo appear to be more balanced upon heavy straight line acceleration (on grass at least).

I have wondered if i have inadvertently made it worse with the thicker centre though? By this I mean a heaver centre will load up the rear, this will cause a wheelie and lose of traction due to unloading as the car lifts.

It makes you wonder if its a situation that you can actually win? Or whether everything is a compromise due to having so much power on hand.....

Front and rear diff oil weights have no bearing on the front to rear power distribution. As far as the heavier center oil and wheelies, this is the way I understand it. These differentials will send the power to the half that has the *least* resistance. Under hard acceleration, the weight of the vehicle transfers to the rear and the front will lighten up. Traction will be strongest in the rear tires and the diff will want to send the power to the front, which now has the least traction. I’m not 100% certain but I think this unloading to the front will facilitate a wheelie (makes it worse). At the end of the day I believe it comes down to heavier center diff fluid and throttle control when it comes to reducing wheelies.

 

[olds97_lss]

im surprised you run 500k in center... im at 150k in center.. i trust your knowledge for sure though... im gonna step it up slow though...

Probably depends on where/how you drive quite a bit.

I run 100/500/100 in my outcast because it suits how I drive. My outcast will never see a track, so I don't really care if the front tires pull the truck through a turn or not. I'm on concrete or grass pretty much always, so I have to let off the throttle when turning anyway or I flip due to traction rolling. I don't turn the wheel and punch it to pull itself through a turn as I'm basically turning around to hit a jump again, not carving up the infield of a track. But I do care that there's some give between front/rear so when I land, the energy is absorbed/dissipated to the end that touches last if I'm on the throttle a bit. I also don't want the front tires ballooning all the time and losing a lot of my power to the front tires spinning when I'm powering up the face of a jump.

I also only run 4S. My bashing buddy with his talion runs the same oil as me but he runs 6S (also running the proline trencher 3.8's I run). It still unloads to the front when he leans on the throttle too hard, but it doesn't do it all the time like it did when he had 100K or 200K in the center.

I probably could have run thinner oil in the front/rear, but after having savage's with 50K in the front/rear, I kind of knew I wanted more resistance so when I'm on two wheels, it's not unloading like mad to the tires in the air if I'm on the throttle a bit. Also, 100k leaks out less. Granted, 50K doesn't leak much as it is, but I did want the positraction type effect more and I'll likely change my savage's to have 100k as well. Especially my savage flux.

Comparing the arrma trucks to an erevo 2.0 may not be the best comparison. Looking at the diffs in the ERBEv2, it appears traxxas finally went with a 4 spider diff, thank god. However, the diff cups do look pretty big in the parts explosions, so there may be more free standing fluid in those diffs which is why they run higher weight oil in general. The fluid is able to get out of the way easier than in our arrma diffs.

All that said, I did try my outcast in stock form at first and I just didn't care for how "loose" the diffs felt. Too much diffing out for where and how I drive.

 

[Lazy Bushman]

I saw women guy on YouTube do you 1M oil in the centre diff and it was his view that it improved performance considerably and the video showed better 4wd a ability and less front wheel ballooning. If I come across it again I will post the link but it was in a comparison between the Kraton and the erevo (spoiler alert Kraton won). He talked about the Kraton when stock, bleeds too much power through the front

 

[Necroscope]

I brought the Revo initially as i couldn't get a Kraton at the time. I still love both. If i had to pick one, id pick the Kraton every time.

 

[FishV12]

I just picked up a Notorious over the holidays and I thought they came factory filled with 7k front and rear and 10k center. Now I read that for 2018 that wasn't no longer the case but came with 10k front and rear and 100k center is that correct? That would mean I just picked up 125k fluid for no reason but whatever still good news

 

[razorrc]

Power gets transferred to the wheel of least resistance, thicker center diff reduces this effect, thinner increases it. Under power, the rear end squats and unloads the front wheels (somewhat), and power will tend to go to the front wheels since there is less resistance there. Thicker fluid reduces this effect.

Going around a corner, each wheel will travel at a different speed and line. Inner wheels spin slower, outer wheels spin faster. Front wheels travel a longer difference than rear wheels. If your center diff fluid is too thick, it won't allow the front and rear wheels to spin at different speeds.

Center diffs explained. Example is a Slash 4x4, but it's the same for any RC car.

http://razorrcblog.blogspot.com/2015/09/center-differentials-explained.html

 

[FishV12]

Well just to answer my own question my manual states that there is 100k in the center already for the Outcast/Notorious but Kratons come with 10k. I'm going to trade my recently purchased 125k to something like 200k or 500k so I can give that a try if I find the front balloons too much. As well front and rear are factory filled with 10k. I am going to go straight to what has been recommended to me and change the front to 50k and rear to 20k. I already have some 65k would that work for the front? 65/100/20 front to rear?

 

[The bashist]

I run 80k front, 20k rear, and 200k center on all my Arrma rigs (6s) great power distribution and almost no bleeding power to front. I still want the front to pull the rig, but want most of it going to the rear differential. Works for me and how I bash, not saying its the right way, just my settling point I've come too. I also ditch the standard pinion and install the optional at least for a starting point. My 2 cents.

 

[Notorious J]

Well just to answer my own question my manual states that there is 100k in the center already for the Outcast/Notorious but Kratons come with 10k. I'm going to trade my recently purchased 125k to something like 200k or 500k so I can give that a try if I find the front balloons too much. As well front and rear are factory filled with 10k. I am going to go straight to what has been recommended to me and change the front to 50k and rear to 20k. I already have some 65k would that work for the front? 65/100/20 front to rear?

Keep this in mind though, if you like how it handles stock, the 125 is good to have around when it's time to clean and service your difs. Shimming is considered a must when servicing, so you should start your search (so many threads) for those shims now. No sense getting rid of the 125 until you've had some real time behind the wheel, so to speak. Jmo. Hope your having fun with your new Notorious.

 

[olds97_lss]

I run 80k front, 20k rear, and 200k center on all my Arrma rigs (6s) great power distribution and almost no bleeding power to front. I still want the front to pull the rig, but want most of it going to the rear differential. Works for me and how I bash, not saying its the right way, just my settling point I've come too. I also ditch the standard pinion and install the optional at least for a starting point. My 2 cents.

I'm surprised you get away with 200k in the center with 6S. What tires do you run and what surfaces do you run on?

With 500K and trencher 3.8's, my buddies talion would still unload to the front a lot on any surface the rear tires got grip. He runs 6S.

On my outcast, it unloaded too much for my liking with stock oil and I followed what he did with 500K (same tires as well) and it really helped the ballooning. Since I run 4S only, probably could have gotten away with 300-400k. But it does a good job with 500.

 

[The bashist]

I'm surprised you get away with 200k in the center with 6S. What tires do you run and what surfaces do you run on?

With 500K and trencher 3.8's, my buddies talion would still unload to the front a lot on any surface the rear tires got grip. He runs 6S.

On my outcast, it unloaded too much for my liking with stock oil and I followed what he did with 500K (same tires as well) and it really helped the ballooning. Since I run 4S only, probably could have gotten away with 300-400k. But it does a good job with 500.

I run on a variety of surfaces, mostly loose topped hard pack. Some skatepark action, some short grass. Run the backflips on the outcast, the trencher x on one kraton, 3.8 badlands on the other one, mx28 on the talion, mx28 on the trugified. They still balloon a little but its reduced enough so I have np getting top speed out all of them even on asfalt. All rigs are currently running the optional pinion. Don't have to lower my dualrate at all. I tried 500k c, 100 f, 50 r, but my run times were reduced and the motor got to where I didn't like it 178-190 degrees.
In 50 degree weather, that's ? hot.

 

[bicketybam]

I really don’t think that 500k vs 200k center diff oil will cause heat issues. People lock the center diff with foam earplugs or silly putty with no adverse heat effects.

 

[olds97_lss]

I could see heavier oil causing things to heat up a bit just because it's forcing more current flow due to the power transfer to the rear wheels when the fronts lose grip. With thinner oil, the esc/motor doesn't have to work as hard to just spin the front tires freely. The diff itself would probably heat up more with lighter oil though due to all the extra spinning of the internals and friction of the oil.

I know my center diff in my stampede got pretty warm this weekend when I was trying 200k. It was unloading the front tires pretty bad constantly. I've increased the weight some to see how it does with power transfer. It was "warm", not hot. I just never thought of diffs getting hot. The only reason I noticed is because my center axle cup on the diff came loose, so I had the diff out in my hand. Not sure what the esc/motor were doing as I didn't have my temp gun with me.