Kraton Arrmas fix for exb rear diff?

[bicketybam]

Are we talking about this piece? That looks like more than a shim.

 

[Surchaufeur]

Took apart the spare diff I picked up at lhs. Found out that these are now built with large shim under the sun gear.
View attachment 102529

Thats amazing!

Are we talking about this piece? That looks like more than a shim.

View attachment 102587

Its a thick boi shim I want these if its real

 

[TooTall]

You don't need this to have a solid solution, weeks ago someone here posted to take a front diff setup, take out the round plate and replace with a 3rd star plate. Basically same as that spacer.
The 3 star plates work great.

 

[Surchaufeur]

You don't need this to have a solid solution, weeks ago someone here posted to take a front diff setup, take out the round plate and replace with a 3rd star plate. Basically same as that spacer.
The 3 star plates work great.

Yeah but people are bending the LSD in some cases leading to diff failure

 

[TooTall]

Yeah but people are bending the LSD in some cases leading to diff failure

Likely due to shimming too much under the pin on the cup side, it then will wear the cup under the pin, or even push it out making it concave, my first one i did too tight regular open style and it wore under the pin till the plastic holding the metal insert the shaft goes thru wore away, then the metal insert started to spin, i have seen pics of ones where the insert pushed right out also, then ether way it gets loose and stripps the gears. I set my last one up just like Arrma did in the front from the factory, except I removed the round plate and added another star and it has been good for 15+ 6s runs.


Shimming too much under the pin on the crown side will put pressure on the cup side and bend the plates also.

you have to make sure there is a tiny amount of in/out play on both sides when you done.

 

[Surchaufeur]

Likely due to shimming too much under the pin on the cup side, it then will wear the cup under the pin, or even push it out making it concave, my first one i did too tight regular open style and it wore under the pin till the plastic holding the metal insert the shaft goes thru wore away, then the metal insert started to spin, i have seen pics of ones where the insert pushed right out also, then ether way it gets loose and stripps the gears. I set my last one up just like Arrma did in the front from the factory, except I removed the round plate and added another star and it has been good for 15+ 6s runs.


Shimming too much under the pin on the crown side will put pressure on the cup side and bend the plates also.

you have to make sure there is a tiny amount of in/out play on both sides when you done.

Good point?

 

[Ju0n1]

Likely due to shimming too much under the pin on the cup side, it then will wear the cup under the pin, or even push it out making it concave, my first one i did too tight regular open style and it wore under the pin till the plastic holding the metal insert the shaft goes thru wore away, then the metal insert started to spin, i have seen pics of ones where the insert pushed right out also, then ether way it gets loose and stripps the gears. I set my last one up just like Arrma did in the front from the factory, except I removed the round plate and added another star and it has been good for 15+ 6s runs.


Shimming too much under the pin on the crown side will put pressure on the cup side and bend the plates also.

you have to make sure there is a tiny amount of in/out play on both sides when you done.

Yeah, the pin is not tightly shimmed in this one. Also with the new larger od shim under the pin the new thick shim/washer is supported almost to the edge. With the old design shims the starplates are supported only little in the middle which might also lead them to bend.

 

[Rcproponent]

Are we talking about this piece? That looks like more than a shim.

View attachment 102587

Yes sir, that’s what some of us have done with stack up of spring steel shims... we’ve had luck with it not breaking after that. I first saw the idea on @BashingBrian build thread and tried it. ??‍

looks like arrma just made a solid spacer. (this is what I would have done if I had the right equipment.

I keep checking the exb manual to see if they’ve revised it yet... nothing..

 

[dk3000]

Interesting as they sure as poop haven't been sending these out for the warranty parts in the UK, just sending out gears an LSD plates with 30k oil.

Wow they are sending you 30k fluid under warranty? To confirm I've got only lsd plates and gear sets also.

 

[bicketybam]

When you look at the sun gear and the new spacer together, that's how they should have made the sun gear to begin with. I'm sure they didn't in order to save money but I bet they wish they did now. Or at least have this new spacer in there from the get go.

 

[Engineer]

When you look at the sun gear and the new spacer together, that's how they should have made the sun gear to begin with. I'm sure they didn't in order to save money but I bet they wish they did now. Or at least have this new spacer in there from the get go.

If they're doing a re-design, I hope they remove the cross-slot and replace it with a single slot for the cross pin as that seems to be another point of failure on some sun gears I've seen.

 

[JMS RC]

@Ju0n1
Nice find You don't happen to have a partnumber for this diff, did it come in a bag with a header ?
It seems like this is Arrma's official solution then, i was really expecting something else though, then only difference i see in this
solution apart from the other mods where 12x18 shims are stacked on the sun is that Arrma's solution is a single shim.

 

[Ju0n1]

ARA311066 is the part number

 

[Engineer]

Jason will give his answer tomorrow morning (EU time).

View attachment 102555

Did we ever get an official response from Jason or Arrma? I didn't see anything in the EXB forum, but wondering if @jym73 heard anything.

 

[JMS RC]

Did we ever get an official response from Jason or Arrma? I didn't see anything in the EXB forum, but wondering if @jym73 heard anything.

Well i guess it's kinda official although i haven't seen any statement made, i just opened up my Open Diff that i bought this Tuesday and it does have the thick sungear shims, Diff partnumber ARA311066

 

[jym73]

 

[Hammer Down]

Here’s the vid

 

[Jason_D (Mr ARRMA)]

FULL DISCLOSURE on the ARRMA 29mm diffs as used on the 6S EXB line.
As many know, we had some mass production quality control issues that caused some problems on the open specification diffs. A detailed investigation into this whole issue revealed that factory production tolerances on several parts (not just shims) were combining to affect the user experience on some open spec diffs. This variability and interaction of the different parts is the reason why some people had no problems; some were OK with just shimming and others needed LSD plates.

Warranty - The fastest, cleanest, and most reliable support solution was switching to use LSD plates in the rear diff. Genuine diff issues are, as always, covered under our warranty via local channels.


BUILDING the LSD Diff – (ARA310990)
We have seen users struggle to build the LSD diffs correctly and in some cases damage or bend the plates trying to close the diff. Following the steps in this video will make for correct build.

The perfect build, please see this video –

FUTURE VEHICLE Spec’s -
The second batch of the Kraton EXB 1/8th scale and the Mojave EXB 1/7th (when it releases) will sell with the LSD (x1) spec diff in the rear and LSD (x3) in the front/centre.



OPEN 29mm Diff – (ARA311066)
Adding a large spacer 12 x 18 x 1.9mm, that replaces the LSD plates, is the best go forward solution to support the gears at their widest, remove any axal play resulting from a build-up of production tolerances. The sizing of this spacer has been optimised to work with the same thickness shims used behind the LSD plates. So switching between LSD and open spec will now just mean switching plates and spacer.


STRONGER by DESIGN –
Everything about the new 29mm diff is stronger by design than the RTR (31mm) diffs -
- The ring and input gear have much more engagement = stronger
- The drive pins in the out drives are thicker = stronger
- The inner gears have more engagement = stronger.
- Internal gears have more section behind the pin slot = stronger

On top of all that we made space for limited slip plates option, which is another tuning feature, driver add and durability upgrade.

 

[jym73]

"
FUTURE VEHICLE Spec’s -
The second batch of the Kraton EXB 1/8th scale and the Mojave EXB 1/7th (when it releases) will sell with the LSD (x1) spec diff in the rear and LSD (x3) in the front/centre.

Adding a large spacer 12 x 18 x 1.9mm, that replaces the LSD plates, is the best go forward solution to support the gears at their widest, remove any axal play resulting from a build-up of production tolerances. The sizing of this spacer has been optimised to work with the same thickness shims used behind the LSD plates. So switching between LSD and open spec will now just mean switching plates and spacer. "

FULL DISCLOSURE on the ARRMA 29mm diffs as used on the 6S EXB line.
As many know, we had some mass production quality control issues that caused some problems on the open specification diffs. A detailed investigation into this whole issue revealed that factory production tolerances on several parts (not just shims) were combining to affect the user experience on some open spec diffs. This variability and interaction of the different parts is the reason why some people had no problems; some were OK with just shimming and others needed LSD plates.

Warranty - The fastest, cleanest, and most reliable support solution was switching to use LSD plates in the rear diff. Genuine diff issues are, as always, covered under our warranty via local channels.


BUILDING the LSD Diff – (ARA310990)
We have seen users struggle to build the LSD diffs correctly and in some cases damage or bend the plates trying to close the diff. Following the steps in this video will make for correct build.

The perfect build, please see this video –

FUTURE VEHICLE Spec’s -
The second batch of the Kraton EXB 1/8th scale and the Mojave EXB 1/7th (when it releases) will sell with the LSD (x1) spec diff in the rear and LSD (x3) in the front/centre.



OPEN 29mm Diff – (ARA311066)
Adding a large spacer 12 x 18 x 1.9mm, that replaces the LSD plates, is the best go forward solution to support the gears at their widest, remove any axal play resulting from a build-up of production tolerances. The sizing of this spacer has been optimised to work with the same thickness shims used behind the LSD plates. So switching between LSD and open spec will now just mean switching plates and spacer.


STRONGER by DESIGN –
Everything about the new 29mm diff is stronger by design than the RTR (31mm) diffs -
- The ring and input gear have much more engagement = stronger
- The drive pins in the out drives are thicker = stronger
- The inner gears have more engagement = stronger.
- Internal gears have more section behind the pin slot = stronger

On top of all that we made space for limited slip plates option, which is another tuning feature, driver add and durability upgrade.

Welcome here @Jason_D (Mr ARRMA) . SInce the time we wanted to see you coming here

 

[Engineer]

OK, who else read "yadda ... yadda ... yadda ... Hey, we're getting a Mojave EXB ... yadda ... yadda ... yadda."?