Kraton How to tell which one of the three diffs is bad

[soko]

Hey guys,

I'm having a blast with my Kraton lately and have also done a couple of replacements on it. But whats still puzzles me are the 3 differentials on the thing...
Since last run it makes same cracking sounds, doesn't accelerate that good anymore and breaking doesn't stop the weels...
So I searched and read a lot and I'm sure its the diffs as I've never opened them since I've got my Kraton.

Now I don't know how to find out which of the three needs replacement gears. Is there a check method without dismanteling the Kraton?

I've read about: lifting it at the back/front, holding the tires which are in the air firmly and rolling it forward on the other tires. It should not roll if the diffs are OK? Is this correct?
But how do I know if the middle diff needs replacement?

Thanks heaps for helping a diff-newbie out

Soko

PS: If you have any good advice or links for the correct way to replace the gears (first time ever for me) its highly appreciated as well

 

[Nucear]

You can put your ear next to each diff when you roll it you should hear wich diff is bad.

 

[Paultro84]

Hey guys,

I'm having a blast with my Kraton lately and have also done a couple of replacements on it. But whats still puzzles me are the 3 differentials on the thing...
Since last run it makes same cracking sounds, doesn't accelerate that good anymore and breaking doesn't stop the weels...
So I searched and read a lot and I'm sure its the diffs as I've never opened them since I've got my Kraton.

Now I don't know how to find out which of the three needs replacement gears. Is there a check method without dismanteling the Kraton?

I've read about: lifting it at the back/front, holding the tires which are in the air firmly and rolling it forward on the other tires. It should not roll if the diffs are OK? Is this correct?
But how do I know if the middle diff needs replacement?

Thanks heaps for helping a diff-newbie out

Soko

PS: If you have any good advice or links for the correct way to replace the gears (first time ever for me) its highly appreciated as well

You are correct, if your holding the front wheels and trying to roll the rear tires, they shouldn't move. If enough force is applied they will turn. That is normal. When buying a new RC that is prebuilt, you really should take all 3 diffs apart and inspect them. Making sure there is enough oil in them. With my Outcast, the rear diff had an ok amount of fluid, my center diff was extremely low, and the front diff only had enough to coat the gears. I noticed the front diff was extremely hot when I touched one of the drive cups and jumped on here to ask if it was normal for it to be hot. Everyone said to take all 3 apart and inspect them. Glad I did. Also the screws on my center diff were not tight. Not falling out lose, but it was starting to leak past the gasket. Taking the diffs out isn't to big of a chore and I highly recommend inspecting all 3 of them.

 

[soko]

@Nucear So when everything is OK no sound/clacking/crunshing sound should come when I roll the Kraton

If enough force is applied they will turn. That is normal.

Thanks, that what I was wondering about. Still difficult to tell then if the front diff or the mid diff is bad (when I hold the rear tires)...

I've just ordered 3 diff-gear-sets and I will replace all of them.

So how much fluid do I put in then? Anything else to be aware about?

thx guys
Soko

 

[Gloggen]

When I had the cracking sound at acceleration and braking, I just pressed down a bit on the car, holding it to the ground while quickly tapping the throttle a few times. Listening to it, I clearly heard that it was the front diff.

Maybe that’s a really bad way of doing it but it worked

Switching out all the diffs just in case sounds like a little waste

 

[WTF MIKE]

I would take them all apart and shim them while they are apart. You will then know which of the diffs is bad. Might as well put heavier diff fluid in them. I’m running 60/200/30 front/centre/rear in my outcast.

 

[Mr.Duke]

You'll probably want to replace the bearings while the diffs are apart

 

[soko]

I would take them all apart and shim them while they are apart. You will then know which of the diffs is bad. Might as well put heavier diff fluid in them. I’m running 60/200/30 front/centre/rear in my outcast.

I'm not quite sure... but "heavier"... According to the manual of the Kraton I should use 10000/7000cps diff fluid and 800/600 for the shocks. So 60/200/30 sounds veeeery heavy to me. Did you miss a 0s in your numbers?

 

[soko]

You'll probably want to replace the bearings while the diffs are apart

Thanks for that! Which bearings do you mean exactly though? Do you have a Arrma part number by any chance...

 

[bicketybam]

Thanks for that! Which bearings do you mean exactly though? Do you have a Arrma part number by any chance...

AR610016, but don't use those. Get a kit from Fast Eddy: http://www.fasteddybearings.com/ The Arrma bearings are not sealed.

 

[soko]

Anything else I should get from FastEddy once I'm there?

 

[bicketybam]

I'm not quite sure... but "heavier"... According to the manual of the Kraton I should use 10000/7000cps diff fluid and 800/600 for the shocks. So 60/200/30 sounds veeeery heavy to me. Did you miss a 0s in your numbers?

My manual shows 10,000 for all 3 diffs. Mike is running 60,000 up front, 200,000in the center and 30,000 in the rear. There is no right or wrong weight for the diff lube. A lighter weight will allow the diffs to transfer power to the side with the least traction more easily. A heavier diff lube will make it more difficult for that to happen. The reason many people go heavy in the center is because under heavy acceleration the front end become lighter and has less grip. The center diff will want to send more power to the front wheel and that causes them to spin faster, which in turn make them balloon up. A heavier center diff lube will help prevent that. It's really a personal preference as to how you want the truck to run. I've heard of people running 500k or 1,000,000 in the center. One thing I can say is that I do not like to go too heavy in the front because one wheel needs to turn faster than the other when you are turning. A real heavy front diff lube makes it hard to turn.

Anyway, if you tear down all three diffs you are going to need to replace the oil. If anything I would suggest going heavier in the center. 10K is just too light.

 

[bicketybam]

Anything else I should get from FastEddy once I'm there?

I don't think so. Just get the sealed (not ceramic) bearings for the Kraton. Be prepared to disassemble a good portion of your truck when you go to put them on.The most challenging are the two bearings that sit on the differential input gear. The set on the rear aren't too bad, but the set up front requires a lot of disassembly. Make sure you use a heat gun to loosen up any tight screws (you don't want to strip the hex or break a tool). Take your time. If you have to, take pictures as you go. And be organized. It's a great learning experience and the bearings are definitely an upgrade.

 

[WTF MIKE]

I'm not quite sure... but "heavier"... According to the manual of the Kraton I should use 10000/7000cps diff fluid and 800/600 for the shocks. So 60/200/30 sounds veeeery heavy to me. Did you miss a 0s in your numbers?

It is much heavier than stock. Lots of people use 500k in the centre or 1 million

 

[WTF MIKE]

It handles a lot better and helps the front wheels from ballooning

 

[soko]

...Anyway, if you tear down all three diffs you are going to need to replace the oil. If anything I would suggest going heavier in the center. 10K is just too light.

See, this is how much I know. Thought the heavier the smaller the number
Perfect explanation, thx heaps!

Sooooo... I ended up with:
1x sealed bearings kit
3x AR310436 (Diff Gear Set)
1x Team Corally Diff 75000 for my middle

So I will go with 10k/75k/10k if thats is not completely wrong in your eyes.
Ohhh bdw: I have 50ml bottle. How many fillings is this roughly?

thx Soko

 

[bicketybam]

See, this is how much I know. Thought the heavier the smaller the number
Perfect explanation, thx heaps!

Sooooo... I ended up with:
1x sealed bearings kit
3x AR310436 (Diff Gear Set)
1x Team Corally Diff 75000 for my middle

So I will go with 10k/75k/10k if thats is not completely wrong in your eyes.
Ohhh bdw: I have 50ml bottle. How many fillings is this roughly?

thx Soko

Like 4 or so. Maybe more. I've never counted. 10/75/10 isn't unheard of. See how it goes. If the fronts still balloon a lot, you can always go heavier.

 

[paul_pl]

10/75/10 isn't unheard of. See how it goes. If the fronts still balloon a lot, you can always go heavier.

I wouldn't risk it. Just go with 200k or 500k like me in the middle diff. Most people who are 'in businnes' recommend it so don't hesitate. Check this video where guys try to make perfect Kraton getting 1000k (1 million) in iddle diff oil

 

[Mr.Duke]

started with 100k in the center diff and then put 200k which made a big improvement.
I've since switched to 500k and love the way it distributes power now.

 

[soko]

Thanks guys. I'll try the already ordered 100k and will switch to 200k on the next chance (when I have to order spare parts )
The video is great. I will also try to remove those "sway bars" the guy is talking about