Kraton I’m over my exb, won’t last a full pack.

jkflow

TB RC Bashers
Premium Member
Excellence Award
Build Thread Contributor
Messages
3,553
Reaction score
4,259
Location
Tampa, FL
Arrma RC's
  1. Infraction
  2. Kraton 6s
  3. Talion
Blip on the throttle with tires in the air is no issue, if they hit the pavement though stuff must break, that is just physics. Rule #1 for jumping is hands of the throttle when landing, no matter what extend that to tires in air and hitting high friction ground.

The sway bar supports are a pain, totally agree. Mine break all the time and running without swaybars most of the time.
 

Rainger40

Well-Known Member
Messages
613
Reaction score
602
Arrma RC's
  1. Granite
  2. Senton 6s
Well good news bad news. Diff out drives stayed in tact, but I don’t like the ease at which the chassis slaps now. It hits hard, so hard in fact it loosened the motor mount and ended my run a few mins before lvc. So I’ll probably be thickening up the front shock oil to start and see where that takes me. Thanks for the help!
 
Last edited:
Messages
218
Reaction score
231
Location
Bozeman, MT
Arrma RC's
  1. Felony
  2. Limitless
  3. Kraton 8S
  4. Kraton 6s
  5. Kraton EXB
  6. Nero
  7. Raider
  8. Senton 3s
  9. Typhon 6s
Well good news bad news. Diff out drives stayed in tact, but I don’t like the ease at which the chassis slaps now. It hits hard, so hard in fact it loosened the motor mount and ended my run a few mins before lvc. So I’ll probably be thickening up the front shock oil to start and see where that takes me. Thanks for the help!
Tune oil to rebound, preload to compression.

Drop your Kraton from about waist high and stack preload until chassis slap is at an acceptable level. You will always have chassis slap, and it'll always sound much worse than it actually is, but you can reduce it.

Once you get your preload dialed bit, watch how it rebounds, then change your oil to tune it to your liking. Heavier to get rid of bounce past resting position, but be careful not to overdue it and slow rebound so much your shocks can't respond fast enough.

When I get home tonight I will check my preload settings, I think I am somewhere in the ballpark of 80wt oil.
 

ozzynichols

Active Member
Messages
1
Reaction score
2
This guy did a mod to narrow the front arms by 1mm each side to stop the dogbone end of the front shafts up from popping out of the cups under hard turning and compression. Even if they're not popping out getting them to sit deeper will put let stress on the outer ends of the drive cups where they are the weakest. I did the mod with a sand paper and block. took less than an hour but I haven't run it yet. Good luck. Scroll down to step 5 in his write-up. It's a long write-up but very thorough.

https://www.rctech.net/forum/electr...raton-exb-stage-1-build-guide-essentials.html
 

jkflow

TB RC Bashers
Premium Member
Excellence Award
Build Thread Contributor
Messages
3,553
Reaction score
4,259
Location
Tampa, FL
Arrma RC's
  1. Infraction
  2. Kraton 6s
  3. Talion
Yes, one of the standard mods to make your life a little easier.
Never heard about the 'heat-shrink on dogbone pins'. With all the force and sharp edges I doubt it will last one session but I'll give it a try just for the heck of it.
Very long writeup at that link, nothing new though. There are good videos on the diffs, that are better than just words.
 

razorrc

Well-Known Member
Messages
1,436
Reaction score
2,416
Arrma RC's
  1. Granite
  2. Kraton 6s
A couple things I disagree with, that are mentioned in this thread:

1. You can definitely land on throttle, ideally you actually match tire speed to ground speed. If your truck is moving 30 mph and your tires are stopped, that puts as much stress on the drivetrain as your truck going 0 mph and the tires spinning at 30 mph (say you just mashed the throttle and dropped it onto the ground). It's the difference in speed that hurts the drivetrain, whether it's + or -.

2. It's more important to use shock oils to tune compression damping, than rebound damping. The drop test chassis slap will be affected by both the spring tension (preload and spring rate) and the damping (shock oil and piston choice). Springs provide a counter force as they are compressed, damping provides a conversion of that energy into heat. Both will affect how much the truck slaps.
 

jkflow

TB RC Bashers
Premium Member
Excellence Award
Build Thread Contributor
Messages
3,553
Reaction score
4,259
Location
Tampa, FL
Arrma RC's
  1. Infraction
  2. Kraton 6s
  3. Talion
A couple things I disagree with, that are mentioned in this thread:

1. You can definitely land on throttle, ideally you actually match tire speed to ground speed. If your truck is moving 30 mph and your tires are stopped, that puts as much stress on the drivetrain as your truck going 0 mph and the tires spinning at 30 mph (say you just mashed the throttle and dropped it onto the ground). It's the difference in speed that hurts the drivetrain, whether it's + or -.

2. It's more important to use shock oils to tune compression damping, than rebound damping. The drop test chassis slap will be affected by both the spring tension (preload and spring rate) and the damping (shock oil and piston choice). Springs provide a counter force as they are compressed, damping provides a conversion of that energy into heat. Both will affect how much the truck slaps.

Agreed on both!
Sounded though like you were gunning it and that delta snapped the cup. No way that can happen with minimal difference in tire speed.
 
Messages
218
Reaction score
231
Location
Bozeman, MT
Arrma RC's
  1. Felony
  2. Limitless
  3. Kraton 8S
  4. Kraton 6s
  5. Kraton EXB
  6. Nero
  7. Raider
  8. Senton 3s
  9. Typhon 6s
A couple things I disagree with, that are mentioned in this thread:

1. You can definitely land on throttle, ideally you actually match tire speed to ground speed. If your truck is moving 30 mph and your tires are stopped, that puts as much stress on the drivetrain as your truck going 0 mph and the tires spinning at 30 mph (say you just mashed the throttle and dropped it onto the ground). It's the difference in speed that hurts the drivetrain, whether it's + or -.

2. It's more important to use shock oils to tune compression damping, than rebound damping. The drop test chassis slap will be affected by both the spring tension (preload and spring rate) and the damping (shock oil and piston choice). Springs provide a counter force as they are compressed, damping provides a conversion of that energy into heat. Both will affect how much the truck slaps.
To clarify when it comes to tuning rebound vs compression with shock oil, yes, damping has a significant effect in both directions. By tuning springs to compression and oil to rebound you don't run excessively thick oil, ruining your rebound and still end up further reducing chassis slap by thickening oil for rebound, just not insanely so. It lines up a good starting point that is good enough for most people. Yes, you can ultimately tune the suspension better by repeatedly tuning back and forth, but constantly altering 2 variables against 2 different results gets tedious, and most bashers don't need race-quality suspension performance.
 

Rainger40

Well-Known Member
Messages
613
Reaction score
602
Arrma RC's
  1. Granite
  2. Senton 6s
Lasted one pack with droop flat with chassis. Don’t know what else to do, but I’m getting real sick of this truck. 1BD9CCA4-040D-4673-AF9E-61BD485319AA.jpeg
 

jondilly1974

Speed running apprentice, motor Slayer 🤘 hoe
Lifetime Premium!
Premium Member
Excellence Award
Build Thread Contributor
Messages
21,184
Solutions
1
Reaction score
26,730
Location
Toledo, OH
Arrma RC's
  1. Granite
  2. Infraction
  3. Kraton 6s
  4. Kraton EXB
  5. Senton 3s
  6. Typhon 6s
  7. Typhon 3s

Rainger40

Well-Known Member
Messages
613
Reaction score
602
Arrma RC's
  1. Granite
  2. Senton 6s

jondilly1974

Speed running apprentice, motor Slayer 🤘 hoe
Lifetime Premium!
Premium Member
Excellence Award
Build Thread Contributor
Messages
21,184
Solutions
1
Reaction score
26,730
Location
Toledo, OH
Arrma RC's
  1. Granite
  2. Infraction
  3. Kraton 6s
  4. Kraton EXB
  5. Senton 3s
  6. Typhon 6s
  7. Typhon 3s
I know M2C makes those, but it sounds like I’m the only one breaking them in this way. I don’t know what else to tweak, check, ect. It’s the same front left out drive too, there’s got to be something I’m missing. It’s taken huge Sends and awkward arm breaking type landings with ease and then breaks these on the small little nothings. Idk what’s up with it.
Mine are chewed up badly but I don’t think mine ever snapped clean off. Is this the front or rear? I ask because I run CVDs both front and rear. I also don’t use those rubber inserts in the cups.
 

Rainger40

Well-Known Member
Messages
613
Reaction score
602
Arrma RC's
  1. Granite
  2. Senton 6s
Mine are chewed up badly but I don’t think mine ever snapped clean off. Is this the front or rear? I ask because I run CVDs both front and rear. I also don’t use those rubber inserts in the cups.
Front left, 3 times now.
 

jondilly1974

Speed running apprentice, motor Slayer 🤘 hoe
Lifetime Premium!
Premium Member
Excellence Award
Build Thread Contributor
Messages
21,184
Solutions
1
Reaction score
26,730
Location
Toledo, OH
Arrma RC's
  1. Granite
  2. Infraction
  3. Kraton 6s
  4. Kraton EXB
  5. Senton 3s
  6. Typhon 6s
  7. Typhon 3s
Front left, 3 times now.
Any damage to hinge pins or pin retainers? Arms are free of cracks? Sounds like a pattern and I would suspect something else is wrong.
 

Rainger40

Well-Known Member
Messages
613
Reaction score
602
Arrma RC's
  1. Granite
  2. Senton 6s
Any damage to hinge pins or pin retainers? Arms are free of cracks? Sounds like a pattern and I would suspect something else is wrong.
Not that I’ve seen up to this point, but I’m going to give it a good once over when I’m not disgusted with it. I did notice it was going right off the jumps last time out, but I figured alignment was thrown off by moving droop and adjusted before this run. It broke on first jump so don’t know if it was still doing it or not.
 

jondilly1974

Speed running apprentice, motor Slayer 🤘 hoe
Lifetime Premium!
Premium Member
Excellence Award
Build Thread Contributor
Messages
21,184
Solutions
1
Reaction score
26,730
Location
Toledo, OH
Arrma RC's
  1. Granite
  2. Infraction
  3. Kraton 6s
  4. Kraton EXB
  5. Senton 3s
  6. Typhon 6s
  7. Typhon 3s
Not that I’ve seen up to this point, but I’m going to give it a good once over when I’m not disgusted with it.
I feel that 💯 I get fed up at times too. A little time and a shot/beer/smoke will get you over the sting.
 

Pat_ranch

Well-Known Member
Messages
582
Reaction score
953
Location
Bozeangeles
Arrma RC's
  1. BigRock 4x4
  2. Kraton EXB
  3. Kraton 4s
  4. Notorious
  5. Senton 3s
  6. Typhon 3s
There's got to be something else out of alignment. The same corner every time is a statistical anomaly. Check your a arm pin holders, pin, shock tower bolts, standoffs, pillow balls, arm ends (might need to shorten that side), and I'd even step up the oil weight in the fronts proactively. I'd also put more droop in until you stop popping out. There has to be something you're missing- no offense.
 

jkflow

TB RC Bashers
Premium Member
Excellence Award
Build Thread Contributor
Messages
3,553
Reaction score
4,259
Location
Tampa, FL
Arrma RC's
  1. Infraction
  2. Kraton 6s
  3. Talion
Might be a good idea to video what you are doing. I have yet to break any of my cups. Just got close once on my Infraction, looked like material defect but that is not what is happening in your case.
Considering that this has nothing to do with EXB and nobody else seems to have this issue it is unique to your situation.
Are your arms freely swinging? Nothing over tightened and binding?
Take off shock and tire and it should freely swing under it's own weight.
 

Yas

Well-Known Member
Messages
1,174
Reaction score
1,329
Location
UK
Arrma RC's
  1. Notorious
  2. Outcast 6s
  3. Typhon 3s
I would rebuild the entire front bulkhead and also change the front diff. You never know, it could be a machining issue with the diff cup - maybe the steel insert isn't straight, or maybe there's an issue with the driveshaft - the drive pin may be binding or not centre

Considering you've checked droop... maybe the suspension is over compressing instead. RCDUDE81 aka. Eric on YouTube used fuel tubing or an o-ring on the shock shafts to prevent the driveshafts from popping out - but it could potentially bind the outdrives too

Fault finding can be a ball ache. The problem will be sorted, just don't worry about rushing it. Pull it apart when you can find time for it 👍
 

Rainger40

Well-Known Member
Messages
613
Reaction score
602
Arrma RC's
  1. Granite
  2. Senton 6s
Thanks guys, I feel like this was a productive rc therapy session haha. This issue is really bumming me out. I was out of my mind excited for this truck, my first jump into 6s, and to have these stupid out drives break and force me to rebuild the front diff every time is driving me crazy. For it to be the same breakage, the same way, on the same side there has to be SOMETHING up, I just don’t know what that something is.......yet. See you’ve already got me looking on the bright side again haha. These stupid breakages are going to force me to buy a batt discharger though. Coming home with full packs and the passport 2 takes FOREVER to discharge them.
 
Top