Kraton Kraton 4s v2.5 center diff. I've cut it, so you don't have to. Speechless.

[Barmaleus]

Hey all.

So after just several months of owning the K4s v2.5 the threads (2 of 4) inside the center diff were gone.
https://www.arrmaforum.com/threads/...done-looking-for-a-quality-replacement.70639/

I thought it does not make sense, because I tightened these 4 bolts only once (because I discovered that the spur gear was loose).
Went to the local shop where I bought the car. Together with the shop owner we examined the aluminum center diff case and came to a conclusion that:
1. The specific unit I have is defective.
or
2. If it's not just this specific unit, then the hardware design of the aluminum center diff case is absolutely nuts.

Because the case was already of no use, I decided to cut it and look inside.

...what I saw left me absolutely speechless. The threads for bolts that hold the spur gear (that handles all this mad power) are around... 1.80mm deep. The rest is a bunch of empty space.

Can you believe it? No? Then I welcome you to check the pictures. I don't know what to say and what to do next.

 

[Glitch]

No responses so I just wanted to thank you for looking into this

 

[Barmaleus]

@Glitch Thank you! Latest news is that I sent photos and description to Horizon (Europe). They replied that "it's first time they see such thing" and are sending free replacement (ARA311166). Once I get it, I will surely examine the unit. Hopefully the one I had was a dud. Because if not...

 

[Glitch]

@Glitch Thank you! Latest news is that I sent photos and description to Horizon (Europe). They replied that "it's first time they see such thing" and are sending free replacement (ARA311166). Once I get it, I will surely examine the unit. Hopefully the one I had was a dud. Because if not...

Hopefully! I hope you don’t end up cutting this one too, lol

 

[Just a hobby]

Funkie

 

[Dales396lt4]

I was wondering if I was to run into this problem what would be the disadvantage of just drilling out the hole the same size as the threads that are already there and putting a nut and bolt. Possibly can be continued the threads of the bigger hole all the way out and just run one screw, instead of one from each side

 

[Just a hobby]

I was wondering if I was to run into this problem what would be the disadvantage of just drilling out the hole the same size as the threads that are already there and putting a nut and bolt. Possibly can be continued the threads of the bigger hole all the way out and just run one screw, instead of one from each side

Will the nut clear the plastic case? If should work. I was thinking the same thing just don't have it to try.

 

[Dales396lt4]

I think you could still run two screws. It’s just the one that you’re replacing. It’ll be a little bigger. I like the idea of having one on each side. I will have to check but 3mm to 4mm or something like that.

Now that I think about it, the screws don’t really hold any torque from the motor. The spines on the aluminum case correspond with the spines on the gear and that’s what transfers all the power.

 

[Barmaleus]

I was wondering if I was to run into this problem what would be the disadvantage of just drilling out the hole the same size as the threads that are already there and putting a nut and bolt. Possibly can be continued the threads of the bigger hole all the way out and just run one screw, instead of one from each side

In fact, the hole already goes through the whole case. Strangely enough, on the other end it's 3mm, rather than 2.5mm (at the spur gear).
If all fits, a long bolt and a nut should work, theoretically.
I'd rather use 4 on both ends though. So that each part is held in place independently.

Still waiting for the replacement.

But IF the new case is the same, I will fill that empty space with something (liquid metal?), put in the screw and let it dry.
There is really zero sense in having that empty space.

 

[Just a hobby]

I think you could still run two screws. It’s just the one that you’re replacing. It’ll be a little bigger. I like the idea of having one on each side. I will have to check but 3mm to 4mm or something like that.

Now that I think about it, the screws don’t really hold any torque from the motor. The spines on the aluminum case correspond with the spines on the gear and that’s what transfers all the power.

Just doing one side might throw it off balance. Do two opposite sides for balance. Just a observation.

 

[Barmaleus]

Just doing one side might throw it off balance. Do two opposite sides for balance. Just a observation.

Yeah, absolutely. If I were to do it, then all 4. My hope is the new case will be properly made.

 

[Just a hobby]

Yeah, absolutely. If I were to do it, then all 4. My hope is the new case will be properly made.

Hopefully it is personally inspected. All four sounds best.