Kraton Kraton EXB rear diff blown again

[Sirkensirlot]

Yes these are different gears. The spur gear, ring gears and diff pinion gears are all specifically for the 29mm LSD diff cup

The motor pinion is a mod 1 so any mod 1 pinon with the correct size motor spline ( 5 mm most of the time) will work. I try to use arrma safe d pinions

 

[PaPa Thorn]

Thank you

 

[eezzzee_rc]

Here's my diff build as promised ?? click here.... #13

I'm running Castle 1717/MMx8s so there is plenty of power going through this setup..

I anxiously waited for your comeback on this subject Brian before initially running my new EXB. I'm very happy to report that after four battery packs of hard running and burnouts on 6s.....she's running butter smooth!

Shims used to support both rear diff sun gears:
12x18mm (0.3mm, 0.5mm & 1.0mm - in that order on both the sun gears) oddly they totalled 1.77mm...ish on both sides.

Shims used behind pins:
The original Arrma 6x12mm (2 x large [0.2mm] & 1 x small [0.3mm]) on both sides. Mine came with these.

Thanks again Brian and to all of you contributing to this fix....I really enjoyed this one and learned a lot!

It will be interesting to see what the final official Arrma update for this will be.

 

[BashingBrian]

I anxiously waited for your comeback on this subject Brian before initially running my new EXB. I'm very happy to report that after four battery packs of hard running and burnouts on 6s.....she's running butter smooth!

Shims used to support both rear diff sun gears:
12x18mm (0.3mm, 0.5mm & 1.0mm - in that order on both the sun gears) oddly they totalled 1.77mm...ish on both sides.

Shims used behind pins:
The original Arrma 6x12mm (2 x large [0.2mm] & 1 x small [0.3mm]) on both sides. Mine came with these.

Thanks again Brian and to all of you contributing to this fix....I really enjoyed this one and learned a lot!

It will be interesting to see what the final official Arrma update for this will be.

Glad to have helped..???

 

[jondilly1974]

So I got some shims today from @Rcproponent and built up an open EXB diff. I used the following:

6 x 12x18x0.5 mm shims (3 per side)
4 x 12x18x0.1 mm shims (2 per side)
2 x Arrma 0.3 shims
2 x Arrma 0.2 shims
15k cst fluid

This thing is buttery smooth and zero slop or binding. Most amazing feeing diff I’ve ever built. Not that I’m some diff guru, but this feels way smoother than the LSD diff.

I first measured the LSD plates and they came up as 1.74mm by my calipers. The shims above came out to 1.75mm, even tho their rated sum would be 1.70mm. I tried a third 0.1mm shim per side and it was too tight. 1.75mm per side was a perfect fit for this cup.

Here is a pic of the shims from McMaster Carr

Now the other thing I realized was I had a bad cup too. The cup I first tried was the original open EXB diff from the factory. I had blown the sun gear on the cup side in that diff. When that happened, it scuffed up the inside of that cup to the point where it isn’t visible but you can feel it if you run your fingers in there.

This ended up making the planetary gears not seat right, leading to them locking up. I thought that I had too many shims in there and that was the cause. Ended up taking all shims out and it was still notchy. Changed to a new cup and used the above shims and it was so nice.

TL/DR Use a good cup when building a diff ??

 

[chrisexv6]

I sure wish we could get the normal sized shims from McMaster....that place makes tinkering so much more affordable.

 

[Rcproponent]

I still haven’t even gotten to test mine out yet ??‍ Lol.

But like you, when I built the diff up it felt SOLID. Super smooth, no glitching or notching. Just felt super ?? Only way to describe it. So I have a good feeling it’s going to be a slam dunk for the true open diff. Fingers crossed bud ??

 

[jondilly1974]

I still haven’t even gotten to test mine out yet ??‍ Lol.

But like you, when I built the diff up it felt SOLID. Super smooth, no glitching or notching. Just felt super ?? Only way to describe it. So I have a good feeling it’s going to be a slam dunk for the true open diff. Fingers crossed bud ??

As soon as I get my rear arm I will give it a hard bash. Post office is playing ping pong with my package. No, not that package.

 

[Rcproponent]

As soon as I get my rear arm I will give it a hard bash. Post office is playing ping pong with my package. No, not that package.

After you added that last part at the end. It makes the part at the beginning sound like a reach around.... ?

 

[jondilly1974]

After you added that last part at the end. It makes the part at the beginning sound like a reach around.... ?

Seriously tho...

 

[Rcproponent]

Seriously tho...

View attachment 100127View attachment 100128

Tell em to lay off your package and let it settle where it’s supposed to go already eh? Lol

 

[jondilly1974]

Tell em to lay off your package and let it settle where it’s supposed to go already eh? Lol

It came within a few miles when it hit Toledo 43614. My zip is 43615. It just got sorted wrong in Detroit and now they sent it to 2-1/2 hours away in Cleveland instead of my post office a few miles away.

 

[Rcproponent]

It came within a few miles when it hit Toledo 43614. My zip is 43615. It just got sorted wrong in Detroit and now they sent it to 2-1/2 hours away in Cleveland instead of my post office a few miles away.

I hate it when that happens... haha. Damn tracking bouncing.

 

[BashingBrian]

So I got some shims today from @Rcproponent and built up an open EXB diff. I used the following:

6 x 12x18x0.5 mm shims (3 per side)
4 x 12x18x0.1 mm shims (2 per side)
2 x Arrma 0.3 shims
2 x Arrma 0.2 shims
15k cst fluid

This thing is buttery smooth and zero slop or binding. Most amazing feeing diff I’ve ever built. Not that I’m some diff guru, but this feels way smoother than the LSD diff.

I first measured the LSD plates and they came up as 1.74mm by my calipers. The shims above came out to 1.75mm, even tho their rated sum would be 1.70mm. I tried a third 0.1mm shim per side and it was too tight. 1.75mm per side was a perfect fit for this cup.

Here is a pic of the shims from McMaster Carr
View attachment 100120

Now the other thing I realized was I had a bad cup too. The cup I first tried was the original open EXB diff from the factory. I had blown the sun gear on the cup side in that diff. When that happened, it scuffed up the inside of that cup to the point where it isn’t visible but you can feel it if you run your fingers in there.

This ended up making the planetary gears not seat right, leading to them locking up. I thought that I had too many shims in there and that was the cause. Ended up taking all shims out and it was still notchy. Changed to a new cup and used the above shims and it was so nice.

TL/DR Use a good cup when building a diff ??

I still haven’t even gotten to test mine out yet ??‍ Lol.

But like you, when I built the diff up it felt SOLID. Super smooth, no glitching or notching. Just felt super ?? Only way to describe it. So I have a good feeling it’s going to be a slam dunk for the true open diff. Fingers crossed bud ??

@jondilly1974 @Rcproponent ...
I told you guys that was the way to go..?? Glad to see you got all the parts to build a proper open diff, now get out their and enjoy it..!!
@jondilly1974 .. that parcel tracking is hilarious, I've never seen such a long tracking history ???

 

[jondilly1974]

@jondilly1974 @Rcproponent ...
I told you guys that was the way to go..?? Glad to see you got all the parts to build a proper open diff, now get out their and enjoy it..!!
@jondilly1974 .. that parcel tracking is hilarious, I've never seen such a long tracking history ???

And it’s still getting bounced around like a beach ball, but it made it to my post office this morning ??

 

[Rcproponent]

And it’s still getting bounced around like a beach ball, but it made it to my post office this morning ??

View attachment 100144

Ha, now your calling your package a ball. ??

 

[Engineer]

Lol - next time I'll just drive down to Aurora and pick them up for you and meet you halfway on the turnpike


Had I looked at your post earlier, I would have just gone there to get some, but I picked up two packs of 13x16x0.2 shims and stuffed 8 each under each of the sun gears on the rear diff. Everything still feels nice and smooth, so we'll see how she holds up ... logically it makes sense to support the outer edge of each gear. Now we'll see if the "L"s that hold the cross pin in place are the next weak link.

 

[jondilly1974]

So to update the thread, the 12x18mm shims I used above have held up well. Here are the internal gears after some hard sets of bashing.

 

[Engineer]

So to update the thread, the 12x18mm shims I used above have held up well. Here are the internal gears after some hard sets of bashing.

View attachment 103064

Looks like just a little bit of wear on the sun gear, but otherwise very good. How does the backside look? Any chipping/wear on the raised surfaces that hold the cross pin in place?

 

[jondilly1974]

Looks like just a little bit of wear on the sun gear, but otherwise very good. How does the backside look? Any chipping/wear on the raised surfaces that hold the cross pin in place?

Looked brand new but I didn’t take any pics. Next time I will try to remember. It’s all back together now and ready to rip again. I replaced the gasket but all the shims have been reused this time. Really want to put some 8S thru it and see what happens. I did notice minor wear on the input gear. The mesh is what I would consider perfect with just the smallest amount of lash. I have two Kyosho 0.2 shims on the ring side bearings.