Kraton (Outdrives) First time fixing differential

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.

lokii2

Member
Military Veteran
Messages
8
Reaction score
13
Points
93
Location
Sac, CA
All, I broke my Kraton 6S BLX FRONT differential out drive (right) pretty quickly into owning this RC. This is my fault and I have M2C out drives in the mail..

I have never worked on a full RC differential before. In this repair, I am just installing the m2c outdrives, my goal is to make this "as easy as possible" without having to rebuild the differentials.

Can I quickly take apart the diff, install the new bits, and rely on the existing grease to get the whole diff back into the car? I don't want to rebuild if I don't have to with grease. Heck, maybe it's easy and stress free for some of you but I don't want to have to worry

Thank you!
 
It’s not grease, it’s silicon fluid. The grease goes on the outside of the diff on the input/pinion and crown gear. And if you take your diff apart it would be really silly not to shim it (if necessary) and put back the correct amount of fluid.
You’re going to have it all apart to fix the outdrive anyway, you might as well just do it. The BLX diffs are pretty easy, just pay attention when disassembling them. Watch a YT video, there’s a million of them. Here’s one. There are other more comprehensive ones out there, too. Let us know if you have questions or there’s something you can’t figure out.
 
You have more travel than your drive cups can handle. If you limit your travel a little bit you'll stop breaking drive cups. I use the spacers that come with the shock parts kit AR330339. Damaging drive cups has become very rare for me.
 
You have more travel than your drive cups can handle. If you limit your travel a little bit you'll stop breaking drive cups. I use the spacers that come with the shock parts kit AR330339. Damaging drive cups has become very rare for me.
I watched the above video man. You just throw a shim on the inside of the out drive cup when before you put it onto the diff case?
 
I watched the above video man. You just throw a shim on the inside of the out drive cup when before you put it onto the diff case?
Maybe. The whole thing about shimming is that every diff can be a little different. Pay attention to see where the shims are from the factory when you pull the diff out. That orientation may be ok. When you get it all put back together, the diff should turn smoothly all the way around without a slight bind at some point in the rotation. If it does bind up, or is too tight, pull the diff out of the bulkhead again and shim as necessary. I have five 6s Arrmas and I think only two have been ok as delivered. That’s why there is so much discussion here and many threads on this issue. If you just bite the bullet and do it properly, you’re going to greatly extend the life of your diffs, as well as your input and crown gears. And, like @RC Steve said, proper setup will also stop frequent failures like you’ve been experiencing with your drive cups.
Also, the video I linked probably wasn’t the best choice, as it was for the center diff. The diffs are the same, but it obviously doesn’t cover how to properly shim a front or rear bulkhead. Try checking out the very comprehensive thread we have here on AF. There is everything you need to know here.
https://www.arrmaforum.com/threads/how-to-shim-your-arrma-diff.5396/
And I have to mention (no offense) that you’re very new to this and immediately set your priority as big jumps/big air, backflips, etc. No matter how perfectly your rig is set up, this leads to frequent breakages until you get really, really good at your landings. If you land a big air jump on the throttle or on the brake, you will break things. Period. Mic drop. Your plastic parts will suffer as well. Rear wing mount, a-arms, etc. So bear that in mind.
These trucks are great, and for bashing it’s really hard to beat an Arrma 6s. That said, there is maintenance involved and that will be a big part of ownership. And as you learn how to do it, the apprehension goes away and you might even enjoy it. And even if you continue to hate the prospect, you’re still going to have to do it or you will end up with an expensive Arrma paperweight. The silver lining is here, where you’re reading this. This forum will help you. Don’t get discouraged. It’s easier than you think.
 
Maybe. The whole thing about shimming is that every diff can be a little different. Pay attention to see where the shims are from the factory when you pull the diff out. That orientation may be ok. When you get it all put back together, the diff should turn smoothly all the way around without a slight bind at some point in the rotation. If it does bind up, or is too tight, pull the diff out of the bulkhead again and shim as necessary. I have five 6s Arrmas and I think only two have been ok as delivered. That’s why there is so much discussion here and many threads on this issue. If you just bite the bullet and do it properly, you’re going to greatly extend the life of your diffs, as well as your input and crown gears. And, like @RC Steve said, proper setup will also stop frequent failures like you’ve been experiencing with your drive cups.
Also, the video I linked probably wasn’t the best choice, as it was for the center diff. The diffs are the same, but it obviously doesn’t cover how to properly shim a front or rear bulkhead. Try checking out the very comprehensive thread we have here on AF. There is everything you need to know here.
https://www.arrmaforum.com/threads/how-to-shim-your-arrma-diff.5396/
And I have to mention (no offense) that you’re very new to this and immediately set your priority as big jumps/big air, backflips, etc. No matter how perfectly your rig is set up, this leads to frequent breakages until you get really, really good at your landings. If you land a big air jump on the throttle or on the brake, you will break things. Period. Mic drop. Your plastic parts will suffer as well. Rear wing mount, a-arms, etc. So bear that in mind.
These trucks are great, and for bashing it’s really hard to beat an Arrma 6s. That said, there is maintenance involved and that will be a big part of ownership. And as you learn how to do it, the apprehension goes away and you might even enjoy it. And even if you continue to hate the prospect, you’re still going to have to do it or you will end up with an expensive Arrma paperweight. The silver lining is here, where you’re reading this. This forum will help you. Don’t get discouraged. It’s easier than you think.
Dan B, you are a good man... and Thorough!
 
Dan B, you are a good man... and Thorough!
Thank you. And yes, it was kind of wordy. 😂

Glad to help, and most here are. It’s a great forum, man.
 
How do we know when we have spaced the shocks enough? I'm guessing we shouldn't see the diff cup lifting up on full compression. Is there a tried-and-true test? I don't want to go overboard on the spacer.
 
These shims?

Screenshot_20241210_215755_Gallery.webp
 
All, I broke my Kraton 6S BLX FRONT differential out drive (right) pretty quickly into owning this RC. This is my fault and I have M2C out drives in the mail..

I have never worked on a full RC differential before. In this repair, I am just installing the m2c outdrives, my goal is to make this "as easy as possible" without having to rebuild the differentials.

Can I quickly take apart the diff, install the new bits, and rely on the existing grease to get the whole diff back into the car? I don't want to rebuild if I don't have to with grease. Heck, maybe it's easy and stress free for some of you but I don't want to have to worry

Thank you!

Another option is to get a full assembly from Jenny's RC and just bolt it in.
Easy-peasy and some times worth the coin.

https://jennysrc.com/collections/ar...fferential-front-rear-factory-built-ara8608v5
 
Maybe. The whole thing about shimming is that every diff can be a little different. Pay attention to see where the shims are from the factory when you pull the diff out. That orientation may be ok. When you get it all put back together, the diff should turn smoothly all the way around without a slight bind at some point in the rotation. If it does bind up, or is too tight, pull the diff out of the bulkhead again and shim as necessary. I have five 6s Arrmas and I think only two have been ok as delivered. That’s why there is so much discussion here and many threads on this issue. If you just bite the bullet and do it properly, you’re going to greatly extend the life of your diffs, as well as your input and crown gears. And, like @RC Steve said, proper setup will also stop frequent failures like you’ve been experiencing with your drive cups.
Also, the video I linked probably wasn’t the best choice, as it was for the center diff. The diffs are the same, but it obviously doesn’t cover how to properly shim a front or rear bulkhead. Try checking out the very comprehensive thread we have here on AF. There is everything you need to know here.
https://www.arrmaforum.com/threads/how-to-shim-your-arrma-diff.5396/
And I have to mention (no offense) that you’re very new to this and immediately set your priority as big jumps/big air, backflips, etc. No matter how perfectly your rig is set up, this leads to frequent breakages until you get really, really good at your landings. If you land a big air jump on the throttle or on the brake, you will break things. Period. Mic drop. Your plastic parts will suffer as well. Rear wing mount, a-arms, etc. So bear that in mind.
These trucks are great, and for bashing it’s really hard to beat an Arrma 6s. That said, there is maintenance involved and that will be a big part of ownership. And as you learn how to do it, the apprehension goes away and you might even enjoy it. And even if you continue to hate the prospect, you’re still going to have to do it or you will end up with an expensive Arrma paperweight. The silver lining is here, where you’re reading this. This forum will help you. Don’t get discouraged. It’s easier than you think.
Man, that was just poetry. Beautiful and eloquent. Truth.
 
Back
Top