Kraton diff gears breaking. Help!

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Dman0712

Dman0712

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Arrma RC's
V3 kraton with leopard 1480kv motor. I keep breaking front and rear diff main gears. I have my diffs shimmed. They are shimmed internally and i have 2 shims on outside next to bearing. I have even tried 3 shims. I have tried just the one shim! I have gone through 3 main gears in 4 batt packs. Two front diff gears and one rear. Running 100k 500k 100k. I recently added a couple blobs of 500 to the 100k diff fluid to try and take some power off the front diff being that one is breaking more often. (I didnt have any other diff fluid on hand so i just wanted to try it as i was replacing ANOTHER main gear on front diff) The input gears have no slop. I tightened the cup against them so there is no play. I just keep chipping teeth on the big gear! Is there any other better gear out there that i can run? Is this motor just too damn harsh for this truck? With the arrma political garbage are the replacement gears made of trash? This is getting pricey and not fun when i cant get though one battery pack. Im not even jumping this thing yet. Im driving it across my lawn! Really like the power of this motor but if this truck cant handle it forget it. Il get the tekno mt. I always run 6s. Any ideas? Thanks, Dave
 
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Hmmmm......... to see if it's simply too much power, run that pig on 4s. Like Kevbar40 said, that motor has serious torque.
 
I have lowered the punch from 9 down to 5. I really liked it at 9 haha. I have 3 tekno shims outside of diffs next to bearing.I didnt takeout all the play but just about! Its holding up so far. I left the brakes at factory setting as i havnt messed with that. Ran 5 packs through it being hard on it as I want it to handle abuse. I didnt buy this truck to pussy foot it but i also understand it wasnt meant to handle this motor. But I want it to! No abnormal gear noise so far. Now the only thing breaking is my wing mounts from wheelie impact. 3rd wing mount. Cracks them in half. Rpm install tomorrow. Im also running outcast wing with wheelie bar. I prefer the look and I need the wheels to keep it from cartwheeling forward. Currently running 15 pinion. I have 18 on the way. (Robinson racing) Loved the 20t in it but too much heat. Tried a 22 thinking i was undergeared but got hotter quicker so figured i must being gearing the wrong way. I was confused because motor was hot but esc and battery were both not over 90 degrees. Thought that meant undergeared. I don't want a pinion that i cant run a full 4500mah pack of offroad 6s through. Also have dboot backflip tires on it now. Hoping 18t is sweet spot for tad more speed. With 15t right after lvc my motor temp was 165 degrees with batt and esc at 95 and that was running pretty hard. Thanks for the advice guys. I wouldnt call it a success yet but id say a step in the right direction. Time will tell.
 
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Dman0712 said:
I have lowered the punch from 9 down to 5. I really liked it at 9 haha. I have 3 tekno shims outside of diffs next to bearing.I didnt takeout all the play but just about! Its holding up so far. I left the brakes at factory setting as i havnt messed with that. Ran 5 packs through it being hard on it as I want it to handle abuse. I didnt buy this truck to pussy foot it but i also understand it wasnt meant to handle this motor. But I want it to! No abnormal gear noise so far. Now the only thing breaking is my wing mounts from wheelie impact. 3rd wing mount. Cracks them in half. Rpm install tomorrow. Im also running outcast wing with wheelie bar. I prefer the look and I need the wheels to keep it from cartwheeling forward. Currently running 15 pinion. I have 18 on the way. (Robinson racing) Loved the 20t in it but too much heat. Tried a 22 thinking i was undergeared but got hotter quicker so figured i must being gearing the wrong way. I was confused because motor was hot but esc and battery were both not over 90 degrees. Thought that meant undergeared. I don't want a pinion that i cant run a full 4500mah pack of offroad 6s through. Also have dboot backflip tires on it now. Hoping 18t is sweet spot for tad more speed. With 15t right after lvc my motor temp was 165 degrees with batt and esc at 95 and that was running pretty hard. Thanks for the advice guys. I wouldnt call it a success yet but id say a step in the right direction. Time will tell.
Click to expand...

I highly recommend that you remove your wing. I would snap my wing mount EVERY time I used it. After studying it and looking at it for a while I realized when you crash it's the wing that catches the ground and twist the wing mount till it snaps. I put a TBR wing mount and wheelie bar on, leaving the stock wheelie bar on as well, and removed my wing and now she handles cartwheels like a beast!!!!
 
Well big gear in front diff went again. Lasted a little longer. I heard in grinding and got mad and just drive the poop out of it for the rest of the pack. Well the motor got hot. Real hot. 250 degrees. Esc 115 and battery 110. So motor still seems to work but i don't trust it anymore. I have esc and motor tore out. Time to upgrade. Any opinions on motor/esc upgrade. Like i said i kinda only want to run 6s because i don't want to buy additional batteries but I will if i have to. I want a torquey combo that will allow me to run 50mph offroad for a full pack. 30 min. I have a heavy finger. This front diff situation is annoying. Apparently im still bleeding waay to much power to front diff
 
Well i bought a nero motor with blx200 esc. I also bought acer ceramic bearings kit as i have everything torn out now anyway. All the bearings feel pretty sloppy on this truck and im hoping these tighten things up. Especially the front support bearings the pinion goes through in diff. I think this contributes to my constant gear breakage. I have hardly any play in and out but there is and uncomfortable amount up and down. Anyway, I Hope the nero combo works. I hear its a beast and most importantly it runs cool. I also have a heat sink and fan i will install.
 
Paultro84 said:
I highly recommend that you remove your wing. I would snap my wing mount EVERY time I used it. After studying it and looking at it for a while I realized when you crash it's the wing that catches the ground and twist the wing mount till it snaps. I put a TBR wing mount and wheelie bar on, leaving the stock wheelie bar on as well, and removed my wing and now she handles cartwheels like a beast!!!!
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Yeah i might do this as i bent the rpm mount so bad it mine as well be broke. My wing now sits with the top part of wing facing front of truck. Ha
 
I cant believe there aren't more people with this same issue! I'm having a hell of a hard time trying to get these diffs to last, currently on the stock motor, punch set to 1!
 
Pfaulk54271 said:
I cant believe there aren't more people with this same issue! I'm having a hell of a hard time trying to get these diffs to last, currently on the stock motor, punch set to 1!
Click to expand...
Are you jumping a lot and, if so, are you landing while on the throttle?
 
KevBar40 said:
Are you jumping a lot and, if so, are you landing while on the throttle?
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Nope, normally I do jump but on this last rebuild I have taken it super easy. No good excuse or reason for it this time. I'm so pissed/frustrated I feel like selling all of them. I'm supposed to be installing my TP 4070 this weekend but I'm not doing it, I'm thinking about asking them for an exchange or a refund. Super disappointed with these gears. I've had to replace atleast one diff on every single arrma I own except my notorious which I'm sure is next to fail. I NEVER land on power, I always try to tap my brakes and let off before landing. Ive had better luck on my stock untouched diffs with no shims! I don't get it!??
 
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I agree, the diff ring and pinion gears are not heavy enough. The spiral is almost straight so it might as well be. I have learned to live with it. It least the diffs are easy to get out...
 
This. I knew it. Arrma diffs aren’t big enough for their larger Kraton talion and notorious. I made a thread about it a little while ago and got hate, but this just shows it’s not ok. If you need to drive like a (you know what) for the diffs to last, that’s not how it should be. Redesign the damn diffs. They should be able to handle a 4582 motor on 6s with the punch setting not reducing anything. Not being able to handle a 4092 (and in some cases a 4074) is unacceptable, and it’s one thing arrma is definitely not arrma tough in!!!

And for the luckier guys who go through a diff every 50 or so runs, it’s still not acceptable. Diffs shouldn’t be wear items. The only time a diff should blow is if something happens, like a bearing blows out or the bulkhead gets cracked. Not just “after a few runs on 6s”. No. The truck is rated for 6s, the drivetrain should be able to take 6s. Makes me very angry with all the people I’ve messaged who’ve resorted to 4s lipo because “they break less diffs that way”.

(Not angry at them, I’m angry at the diff designer)
 
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Really the only way to fix this is to put thin fluid into the center diff. The diffs are too small for 500k diff fluid in the center. It makes the truck really grip and smashes those poor gears. If you keep it thin, it’ll all diff out to the front and won’t break anything. It won’t wear out the front diff, it’ll preserve both. It’ll put more rotating motion to the front but it won’t put torque onto the front, and the rear won’t be getting much torque because the front would be receiving the most power. Torque is what breaks the gears. Rotating speed doesn’t do any damage. I mean it may heat the center diff up but it won’t really cause problems.

I have a sneaking suspicion that’s why they put these trucks out of the factory with such thin fluid..
 
I had that issue. I learned that you have to make sure you are not on the throttle when landing a jump. It will break it every time with that high torque motor.
 
Jimbobjr said:
I agree, the diff ring and pinion gears are not heavy enough. The spiral is almost straight so it might as well be. I have learned to live with it. It least the diffs are easy to get out...
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I'm really surprised no one has made a superior, aftermarket gear set for them. How in the heck is anyone running 8s on these!? I'm really confused how there are so many 100+mph 6s blx builds but I'm destroying diffs left and right on the stock motor. Definitely can not blast, more like light bash!
 
Pfaulk54271 said:
I'm really surprised no one has made a superior, aftermarket gear set for them. How in the heck is anyone running 8s on these!? I'm really confused how there are so many 100+mph 6s blx builds but I'm destroying diffs left and right on the stock motor. Definitely can not blast, more like light bash!
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To be fair speed runners put a lot less stress on the diffs than a basher. Your 50mph setup is probably on 5 to 10 times as much stress as their 100-120mph setup because you’re bashing. They’re just doing a slow acceleration to top speed, very little torque actually on those diffs.
 
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