Kraton Arrma Kraton EXB (Blown Rear Differential)

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Kraton Arrma Kraton EXB (Blown Rear Differential)

Viking

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I'm aware there are other threads for people who have noted blown rear diffs on their Kraton EXB. I'll share my experience, what caused it to happen and note the potential fix based on what Horizon Hobby told me, as well as the other gracious forum members who have shared their experiences and findings.

Motor: Castle 1717 1650kv
ESC: Mamba Monster X 8S
Pinion: Tekno 23t
Spur Gear: Factory
Battery: 2x Spektrum 3s 100c
Voltage: 7.5V
Tires: Pro-line Bandlands MX38 3.8 (Belted)

Before I ever ran the car I took apart the front, center, and rear diffs to add in Hudy Ultimate Silicone and inspect everything. Thanks to all the forum members who have created threads on the issues with the EXB; it helped me prepare for what could happen with the rear diff.

My Diff Fluid Setup
Front: 50,000cst
Center: 300,000cst (200k wasn't in stock)
Rear: 30,000cst (20k wasn't in stock)

Conditions When The Diff Was Blown
Temperature: 74 degrees fahrenheit
Weather: Clear
Riding surface: Wet grass and Pavement
Riding style: Non-aggressive (feathering the throttle)

As I was riding, I started to hear a clanking noise and so I immediately drove the car into the garage and took apart the diff. Once again, thanks to everyone on this forum posting about their EXB issues, I was able to quickly identify the problem area. As you'll see in the images below, the sun gears cracked and some have also worn down.

I have reached out to Horizon and they are sending me all new diff parts including the LSD plates (ARA310984) that are in the front and center diffs. They said that these plates will resolve the issue. (TBD)

In the meantime, I have won an auction on eBay for a brand new EXB diff. With shipping the grand total was $89.99. To note - I'm super thankful my wife doesn't ask too many questions so long as I'm happy :LOL:. I realized I was raped for paying that much... but I want to get back to bashing and enjoying my car. If it's only $89.99 between me enjoying my car or sitting it on a self, I'd rather shell out the dough.

There isn't a price for the kool-aid smile this car gives me when I'm bashing it. ?

Arrma EXB Diff 1.jpg
Arrma EXB Diff 2.jpg
Arrma EXB Diff 4.jpg
Arrma EXB Diff 3.jpg

Screen Shot 2020-09-04 at 4.29.33 PM.png

**UPDATED September 9th, 2020**

So good news - I dissembled the center diff I purchased at a ridiculous price on eBay ?. What I took from it to rebuild my rear diff was the LSD plates, sun gears, planet gears, and one shim. I took one of the thinner (thinest one) shims from that donor diff and put it on the ring gear side of my rear diff; I tried to add one to the diff cup side as well, but it was extremely tight. (that's what he said) ?

Lastly, I filled the diff back up with Hudy 30,000cst Ultimate Silicone Oil.

I did a "light" bashing session last night and it everything was running well. I was using two 3s 100c Spektrum batteries at 7.5V. I'm hoping this can be consider a chalked up issue, but only time will tell. Hopefully, this information helps someone dealing with similar issues. ?
 
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jondilly1974

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Damn you could have grabbed that diff from JRC for $50

E0795ADE-1540-41DE-9187-7CB483E7DB83.png
 

bicketybam

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I'm aware there are other threads for people who have noted blown rear diffs on their Kraton EXB. I'll share my experience, what caused it to happen and note the potential fix based on what Horizon Hobby told me, as well as the other gracious forum members who have shared their experiences and findings.

Motor: Castle 1717 1650kv
ESC: Mamba Monster X 8S
Pinion: Tekno 23t
Spur Gear: Factory
Tires: Pro-line Bandlands MX38 3.8 (Belted)

Before I ever ran the car I took apart the front, center, and rear diffs to add in Hudy Ultimate Silicone and inspect everything. Thanks to all the forum members who have created threads on the issues with the EXB; it helped me prepare for what could happen with the rear diff.

My Diff Fluid Setup
Front: 50,000cst
Center: 300,000cst (200k wasn't in stock)
Rear: 30,000cst (20k wasn't in stock)

Conditions When The Diff Was Blown
Temperature: 74 degrees fahrenheit
Weather: Clear
Riding surface: Wet grass and Pavement
Riding style: Non-aggressive (feathering the throttle)

As I was riding, I started to hear a clanking noise and so I immediately drove the car into the garage and took apart the diff. Once again, thanks to everyone on this forum posting about their EXB issues, I was able to quickly identify the problem area. As you'll see in the images below, the sun gears cracked and some have also worn down.

I have reached out to Horizon and they are sending me all new diff parts including the LSD plates (ARA310984) that are in the front and center diffs. They said that these plates will resolve the issue. (TBD)

In the meantime, I have won an auction on eBay for a brand new EXB diff. With shipping the grand total was $89.99. To note - I'm super thankful my wife doesn't ask too many questions so long as I'm happy :LOL:. I realized I was raped for paying that much... but I want to get back to bashing and enjoying my car. If it's only $89.99 between me enjoying my car or sitting it on a self, I'd rather shell out the dough.

There isn't a price for the kool-aid smile this car gives me when I'm bashing it. ?

View attachment 98270
View attachment 98271
View attachment 98272
View attachment 98274

View attachment 98275
You said you changed the fluid. While you were in tbe rear diff, did you check the shims? Did you add any?
 

Viking

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  1. Kraton 6s
  2. Typhon 6s
Damn you could have grabbed that diff from JRC for $50

View attachment 98286

I should’ve asked the forum members first. I’ll chalk this up as a learning experience.?

Thanks for sharing! ??
You said you changed the fluid. While you were in tbe rear diff, did you check the shims? Did you add any?

I did check the shims and it didn’t feel like it needed any. I’m not an expert, so I was just looking for any wiggle/play.

Most of my knowledge has come from reading your threads, as well as others. I didn’t add any shims, by the way.

The tolerances seemed tight.
 
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bicketybam

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  2. Granite
  3. Infraction
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  5. Kraton 6s
  6. Kraton 4s
  7. Mojave
  8. Notorious
  9. Talion
  10. Typhon 6s
I should’ve asked the forum members first. I’ll chalk this up as a learning experience.?

Thanks for sharing! ??


I did check the shims and it didn’t feel like it needed any. I’m not an expert, so I was just looking for any wiggle/play.

Most of my knowledge has come from reading your threads, as well as others. I didn’t add any shims, by the way.

The tolerances seemed tight.
So I can assume you didn't measure the shims. Oh well. Not too many people have been able to keep a stock open diff in one piece. I'm one of the few lucky ones. I did re-shim it last week though, so now it runs two of the 0.3mm shims and one of the 0.2mm shims.
 

Viking

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So I can assume you didn't measure the shims. Oh well. Not too many people have been able to keep a stock open diff in one piece. I'm one of the few lucky ones. I did re-shim it last week though, so now it runs two of the 0.3mm shims and one of the 0.2mm shims.

Correct assumption; I didn’t measure the shims. I still have it open though. I could still measure them and let you know.
what voltage did you use?

Just updated the OP. The batteries I was using was 2x Spektrum 3s 100c and the voltage was on 7.5V.
 
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TpPartsRcXtreme

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My tip, since i also read people running it without any problem, but also killed them instant. Keep LSD front and mid, go for a regular V4 diff for example, shim that inside, and external.

Even if there are correct shims in the open rear, imo the planetary gear have little to 0 support due to the x pattern for the crosspin..the LSD plates gives it
 

BashingBrian

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  7. Typhon 6s
Not too many people have been able to keep a stock open diff in one piece. I'm one of the few lucky ones. I did re-shim it last week though, so now it runs two of the 0.3mm shims and one of the 0.2mm shims.
I run fully open too, but with my own recipe of shims, see my EXB build thread..??
 

Viking

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My tip, since i also read people running it without any problem, but also killed them instant. Keep LSD front and mid, go for a regular V4 diff for example, shim that inside, and external.

Even if there are correct shims in the open rear, imo the planetary gear have little to 0 support due to the x pattern for the crosspin..the LSD plates gives it

This is good advice. I’ll head to pick one up today. Thanks for sharing! ?
 

Th3pwn3r

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It's crazy to think that diffs have been a problem with these Kratons since the original.
 

DoNoHarm

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It's crazy to think that diffs have been a problem with these Kratons since the original.
Don’t worry there are tons of rcs that have had diff issues since conception man. It’s just the fact that these cars have drivetrains that absorb so much trauma and stuff.
 

Th3pwn3r

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Don’t worry there are tons of rcs that have had diff issues since conception man. It’s just the fact that these cars have drivetrains that absorb so much trauma and stuff.
I'm not worried. I've had my Kraton a long time with modded diffs and I've only broken a wing mount on a huge jump :)

The fact is that they advertise these things as being able to handle 6S INSANE POWER BULLETPROOF DRIVETRAIN and all that crap and yet the products aren't tested enough and still fail.
 

DoNoHarm

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I'm not worried. I've had my Kraton a long time with modded diffs and I've only broken a wing mount on a huge jump :)

The fact is that they advertise these things as being able to handle 6S INSANE POWER BULLETPROOF DRIVETRAIN and all that crap and yet the products aren't tested enough and still fail.
Yeah it is a little misleading but they’re good trucks ya know. Great to see yours treats you well! It is a shame they didn’t test the EXB diffs nearly enough I agree.
 

Th3pwn3r

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My Kraton is a first edition ? It's amazing how durable it is and I've bashed it harder than most would. It's almost like I try to break it ha.
 

Viking

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**UPDATED THE OP**

So good news - I dissembled the center diff I purchased at a ridiculous price on eBay ?. What I took from it to rebuild my rear diff was the LSD plates, sun gears, planet gears, and one shim. I took one of the thinner (thinest one) shims from that donor diff and put it on the ring gear side of my rear diff; I tried to add one to the diff cup side as well, but it was extremely tight. (that's what he said) ?

Lastly, I filled the diff back up with Hudy 30,000cst Ultimate Silicone Oil.

I did a "light" bashing session last night and it everything was running well. I was using two 3s 100c Spektrum batteries at 7.5V. I'm hoping this can be consider a chalked up issue, but only time will tell. Hopefully, this information helps someone dealing with similar issues. ?
 
Last edited:

jondilly1974

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  2. Infraction
  3. Kraton 6s
  4. Kraton EXB
  5. Senton 3s
  6. Typhon 6s
  7. Typhon 3s
**UPDATED THE OP**

So good news - I dissembled the center diff I purchased at a ridiculous price on eBay ?. What I took from it to rebuild my rear diff was the LSD plates, sun gears, planet gears, and one shim. I took one of the thinner (thinest one) shims from that donor diff and put it on the ring gear side of my rear diff; I tried to add one to the diff cup side as well, but it was extremely tight. (that's what he said) ?

Lastly, I filled the diff back up with Hudy 30,000cst Ultimate Silicone Oil.

I did a "light" bashing session last night and it everything was running well. I was using two 3s 100c Spektrum batteries at 7.5V. I'm hoping this can be consider a chalked up issue, but only time will tell. Hopefully, this information helps someone dealing with similar issues. ?
Did you like the 30k fluid? I ran mine with the three star plates and 10k and it still felt too locked for me. I’m going to shoot for 5k with the three star plates next run.
 

Viking

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  1. Kraton 6s
  2. Typhon 6s
Did you like the 30k fluid? I ran mine with the three star plates and 10k and it still felt too locked for me. I’m going to shoot for 5k with the three star plates next run.

I'm undecided. I'm running the 30k because I've seen a lot of guys recommending 20k in the rear, and 30k was the closest I could find. I'm not that experienced of a driver yet to know the difference. Maybe if I switched it out to the 5k I could report back more accurately. It does "hook up" pretty hard, but I'm not sure if that's because of my motor and tire combo or because of the diff fluid. Thoughts?
 
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