Kraton Kraton 6S Exb diff questions re LSD or open diffs(from a newb)

[Arrma6]

Arrma hasn't filled diffs up properly for as long as I can remember. It could be Arrma just being cheap and saving money on diff fluid, or there not being enough time on the assembly line to let the diff fluid settle into the gears and then refill properly (fluid weight of 100k or more takes a long time to settle in a diff case). Whatever the reason, I always check the diffs when I get a new Arrma vehicle. I can honestly say that all but one diff on my three 6s vehicles was half full or less. The one diff that wasn't filled half full or less, a center diff, was 2/3 full.

As a side note: it's not only Arrma that has issues with diff fluid levels. My three Corally vehicles had diffs that weren't full, but they were close to 2/3 or 3/4 full from the factory.

Ok. I am opening up all of the diffs to check now to be sure. Thanks. Is it ok to just top up with a different cst oil? To mix with existing or I have to remove the one in there?

 

[Johnboy5586]

Yea it won't hurt anything to top them off with a different weight

 

[Arrma6]

Yea it won't hurt anything to top them off with a different weight

Great. That means I don't even have to take out the planetaries. I'm getting to work on it now. Thanks.

 

[Johnboy5586]

Great. That means I don't even have to take out the planetaries. I'm getting to work on it now. Thanks.

Oh yea no problem!

 

[KnowAir]

I think we see diffs less than full from factory is likely due to the time it takes to properly fill them.. I imagine that doing piecework on an assembly line would be a real grind.. also I believe less than full is better than overfilled, not that the assembly workers likely care. Aside from the mess created by overfull that is..
I've literally never paid attention to whatever any rc manual states for recommended services, only for assembly process verification or part numbers, otherwise it might as well be written in braille for all I care, LOL.
Fluid changes, sure when I happen to have it apart for something else maybe. They're just toys to me, not like I'm relying on them getting me to work daily, or the hospital in an emergency..

 

[KnowAir]

Hello there. I am pretty new Kraton Exb owner. Had it for couple months but only drove it once. Didn't use it more because I didn't have time to take apart and check diff fluid levels. I will be only using it on 4S to start with.

Is there anything I should know about diff issues? I've read that the Exb has had issues with the rear diff. I have the newest model. I'm not sure if mine has LSD diffs or open diffs. From what I read on here, it comes with LSD in the front and center, and open in the back. But in the manual it seems like only the center is LSD. I have started taking the front diff apart yesterday. But I'm not seeing the star shims when I open the diff. They should be right there right? As soon as you open it.

So what is the best setup? Leave it as is original or changing something? I mean not regarding tuning but just durability. I don't want to get in to tuning yet as I don't understand it yet but I want to avoid any newbie mistakes before I start using it regularly.

I have already bought 50000 for the front, 20000 for rear and 500000 for the center as I read on here. But I need to know wether to convert any of the diffs(LSD/open), before I put in the oil. Cause I don't want to waste oil and take it apart again.

I'm not a fan of the LSD plates myself. I left mine as is until I had a need to go inside. I have had problems with the "star" washers, or LSD plates taking out the gaskets.. even on diffs that "I " never opened.. honestly, the fact that Arrma is moving away from the LSD diffs tells the story IMO. The 29mm aspect of those diffs is good, LSD, only good for recreational use IMO. And no, I'm still not a fan even then,LOL. Bad dreams are scary enough for me, I don't need that other stuff!!

 

[RyanC1332]

I bought the shim kit to replace the rear diff shims
Because they got damaged and I used the kit to change my center to open and i put 500k in the center with stock 80k front and rear and I love how it runs

 

[Jluther@becoinc]

That's great to hear. It was a reason why I chose Arrma Kraton vs Corally Kagama.

Here's a better picture of the inside of diff. How does that look? It seems like one corner is empty but the rest looks good. Is it ok to just add my 20K oil in there to top up? Or is mixing different cst oils not good?

View attachment 367960

That diff looks good compared to how they were a couple years ago.

 

[parcou]

Ok. I'm pretty sure most of the posts I have seen said they are running either 50/20 or 60/30. That's why I bought those. And 500k in the middle.

I could use these oils and change them more often since I got them. Because I don't want to waste them. I mean only the f/r not the center. I will get 100k for the center.

How often do you think I need to refill the oils?

I am glad you have some great feedback here.

I have the v1 EXB and did the open setup for the rear. The other two are LSD. I am happy they removed the LSD from the F/R, and the 50/20 diff setup is a great place to start. I can deal with the center. As someone said, I went 100-center LSD since the plates will make the resistance like 200. If I were open, I would do 200k over 500k anyway. 500k is great if you want to stand it up and have all that power to the rear...not for me like 200k power sticks and moves bleed off. I like the off-the-line launch better than the wheels up

 

[Arrma6]

I am glad you have some great feedback here.

I have the v1 EXB and did the open setup for the rear. The other two are LSD. I am happy they removed the LSD from the F/R, and the 50/20 diff setup is a great place to start. I can deal with the center. As someone said, I went 100-center LSD since the plates will make the resistance like 200. If I were open, I would do 200k over 500k anyway. 500k is great if you want to stand it up and have all that power to the rear...not for me like 200k power sticks and moves bleed off. I like the off-the-line launch better than the wheels up

Yeah it's a good think I asked here before doing it. I don't even like wheelies really. Arrma is great also for this reason, that it has such a large and good community if you need help with something. This is my first RC over 200 Euros so I'm extra careful with it. It'll be fun to try it on 6S for the first time.

 

[Arrma6]

Does anyone know how I put the diff back in the housing properly with this shim on the left that came with it? When I push the diff in, the shim doesn't want to go in with it. It's very very tight in there with this shim. Is it supposed to be that way?

Why are there 4 different size shims in these two bags? The bag on the right came with the car, those are the ones I was talking about above. And the other bag I bought but I'm not sure why there are 3 different size shims in there and none are the same as the thin one that's on the car.

 

[Tex Koder]

Does anyone know how I put the diff back in the housing properly with this shim on the left that came with it? When I push the diff in, the shim doesn't want to go in with it. It's very very tight in there with this shim. Is it supposed to be that way?

Why are there 4 different size shims in these two bags? The bag on the right came with the car, those are the ones I was talking about above. And the other bag I bought but I'm not sure why there are 3 different size shims in there and none are the same as the thin one that's on the car.

View attachment 368115View attachment 368116

The tolerances of the diffs and its bearings "could" have differences..

Or after awhile the wear on/in the diff housing may change...
Requiring you to re-shim, thus the different sizes of shims..

 

[KnowAir]

There is no predetermined number or thickness of shims needed for these. Each will vary from one example to the next. The reason for shimming is to get as precise a fit as possible for that specific gearbox, and gearset. You need to use whichever quantity or thickness makes the proper fit. Basically you need just a very slight amount of freeplay between the ring and pinion gear. Opinions vary here, some shim them tight, some leave a touch of freeplay.. if you can't fit a shim, it's likely not needed or too thick.
They're not rockets carrying living beings into space, so don't get too carried away with perfection, close counts, too tight makes excess heat and accelerated wear. I feel a touch too loose is better than too tight. I think most would be surprised just how tolerant these things really are to variance..

 

[JT58]

Personally I wouldn't go any higher than 200k in the center if you're running limited slip.

I put 500k/1million in several LSD EXB diffs recently but haven't run those rigs much yet. How big of a mistake did I make?

 

[Johnboy5586]

I put 500k/1million in several LSD EXB diffs recently but haven't run those rigs much yet. How big of a mistake did I make?

It makes all the plates and stuff for the lsd that much stiffer, essentially defeating them all together but I'm sure it'll make them generate more heat than usual

 

[Arrma6]

The tolerances of the diffs and its bearings "could" have differences..

Or after awhile the wear on/in the diff housing may change...
Requiring you to re-shim, thus the different sizes of shims..

Thanks. I see that I was not clear there with my question. I was talking more about the diamater than the thickness. There are three different type of shims in the bag. Are there more spots where shiming needs to be done? Like maybe the small gear that connects to the diff? Or maybe for the open diffs on the inside that go there instead of the lsd star and round plates. Also the biggest diameter shims in the bag are much thicker than the one on the car.

 

[Tex Koder]

Thanks. I see that I was not clear there with my question. I was talking more about the diamater than the thickness. There are three different type of shims in the bag. Are there more spots where shiming needs to be done? Like maybe the small gear that connects to the diff? Or maybe for the open diffs on the inside that go there instead of the lsd star and round plates. Also the biggest diameter shims in the bag are much thicker than the one on the car.

Yes.
There will be shims for going behind the input gear and any other areas that "may" be a little loose. So just depends on where in your drivetrain you're finding slop..

But, it's not a necessity to use all the shims up at once.
Just wherever it's needed.

 

[Arrma6]

There is no predetermined number or thickness of shims needed for these. Each will vary from one example to the next. The reason for shimming is to get as precise a fit as possible for that specific gearbox, and gearset. You need to use whichever quantity or thickness makes the proper fit. Basically you need just a very slight amount of freeplay between the ring and pinion gear. Opinions vary here, some shim them tight, some leave a touch of freeplay.. if you can't fit a shim, it's likely not needed or too thick.
They're not rockets carrying living beings into space, so don't get too carried away with perfection, close counts, too tight makes excess heat and accelerated wear. I feel a touch too loose is better than too tight. I think most would be surprised just how tolerant these things really are to variance..

Ok I will have that in mind when I take the gearbox apart, to check the mesh between the gears. But I just opened it from the front to put oil in this time. The shim I was talking about that I couldn't get in there, was there from the factory. The truck has only been uses once since new so I thought surely that shim has to be in there.

I saw a video after I asked on here where they say to put in the side with the shim first, and it worked. But I was surprised how tight it was. I didn't notice any play side to side even without the shim.

Yes.
There will be shims for going behind the input gear and another other areas that "may" be a little loose. So just depends on where in your drivetrain you're finding slop..

But, it's not a necessity to use all the shims up at once.
Just wherever it's needed.

Yeah I read somewhere on here a while ago that I should get that bag with extra shims when I buy the car and I did that. But since then I forgot where exactly they go. But now I know. Thanks.

Looking at the picture I posted of the diff I see bits of toilet paper on there. I probably should use a rag to wipe it clean next time.

 

[Jluther@becoinc]

Hello there. I am pretty new Kraton Exb owner. Had it for couple months but only drove it once. Didn't use it more because I didn't have time to take apart and check diff fluid levels. I will be only using it on 4S to start with.

Is there anything I should know about diff issues? I've read that the Exb has had issues with the rear diff. I have the newest model. I'm not sure if mine has LSD diffs or open diffs. From what I read on here, it comes with LSD in the front and center, and open in the back. But in the manual it seems like only the center is LSD. I have started taking the front diff apart yesterday. But I'm not seeing the star shims when I open the diff. They should be right there right? As soon as you open it.

So what is the best setup? Leave it as is original or changing something? I mean not regarding tuning but just durability. I don't want to get in to tuning yet as I don't understand it yet but I want to avoid any newbie mistakes before I start using it regularly.

I have already bought 50000 for the front, 20000 for rear and 500000 for the center as I read on here. But I need to know wether to convert any of the diffs(LSD/open), before I put in the oil. Cause I don't want to waste oil and take it apart again.

Fill it with what you got there 50/500/20 is good. You can make adjustments accordingly. Everyone has different preferences. What you have will make the truck drive better than stock.