Kraton EXB LSD to Open differential solution

[GRIFFINJ]

I feel like there are 100 or more ongoing discussions about this topic. Maybe this can be a reference to those looking for the parts needed to make the diffs open.

To convert the Arrma EXB LSD (Limited Slip Diff) into an open diff, you need part number ARA311094 - the kit comes with enough parts for 3 diffs

 

[Partypeople]

Open diff? What does that mean?

 

[RCBro80]

Standard diff... Not limited slip

 

[GRIFFINJ]

The EXB models are designed with limited slip differential (LSD) and the internal plates that make that possible can be removed using this kit and a single shim used in its place.

removal of the plates and putting in a shim = open diff

 

[FatCatRC]

Open diff? What does that mean?

open diffs allow one wheel to spin faster then the other. LSD or limited slip diff has plates that control wheel spin and lock the diff up a bit or "limit the slip". Open diffs are stock fr/cnt/rr on kratons but exb came with lsd rears I think and they had lots of issues in the begining of their release. Open diffs allow the outside wheel to spin at a different rate then the inside, in your car you have open diffs so you can turn without taking a mile or wheel cupping. If both wheels spin at the same rate or locked diffs you can't turn as sharp and you will get wheel cupping or hopping.

 

[RCBro80]

I'm out of the loop... I don't have an EXB diff... are the LSD's still problematic? I would have though it would have been an improvement over the standard fluid diffs.

 

[Engineer]

I'm out of the loop... I don't have an EXB diff... are the LSD's still problematic? I would have though it would have been an improvement over the standard fluid diffs.

The problematic EXB diffs were the open rear diffs in the first batch of Kraton EXB's released. These were just open diffs with nothing behind the sun gear. Arrma remedied this in the second/current batch by add the diff plates to the rear, but placing them in a configuration that provided less limited slip than the configurations in the middle and front diffs. They also created an open diff configuration using a large 12x18x1.9 mm shim that goes behind the sun gear. You can either buy a replacement diff as an open diff (with this new shim) or by buying the shim kit shown above, which allows you to configure (up to) all three of your EXB diffs to an open configuration.

 

[Woodley99]

My EXB is the newest batch Jan 2021 that came with 2 star plates each side in rear diff, I bought the recommended ARA311094 kit and installed shims as directed but my diff is completely locked when reassembled. I took it apart and put back together 3 times and it's still locked.
I removed 2 star plates and put the super thick shim in to replace the 2 star plates and its locked. I eneded up doing 1 wide thin shim and 2 narrow thicker on one side and 2 wide thin and one narrow shim on other to remove play and didn't put the super thick
Shim in. Haven't ran it yet but am I missing something?

 

[GRIFFINJ]

The thick shim replaces 2 star plates AND the 1 round plate.

sounds like you aren’t removing all the plates

 

[Woodley99]

The thick shim replaces 2 star plates AND the 1 round plate.

sounds like you aren’t removing all the plates

Your right haha, I'm a dummy I took it back apart and realized the circle shim was stuck to the sun gear and I missed it. Put it back together it it seems perfect! I'm gonna test it this weekend and see how the open diff compares to "minimum" effect on lsd compared to open diff. I'll post the outcome for anyone curious on newest batch of exbs with lsd in rear diffs

 

[SrC]

I think this says it all conclusively.

 

[Woodley99]

Update on open rear diff in the EXB.. handled soooo much better! But still a little squirrely in the rear. Currently I have 20k front/100k center/ 10k rear diff fluid. Front and center LSDs set for max effect. What do you guys recommend for fluid weight and LSD effect for front diff? I'm trying to get this thing to handle better, I'm usually spinning out exiting a corner and hard to keep her straight. much Better with the rear open diff tho but still think it could be improved

 

[JayP.]

I have EXB diffs all around in my outcast 6s, built the front to be open, center is stock, and the rear is an LSD set to minimal effect. I've ran it really hard and had no issues until today. My rear diff decided to completely lock itself up. It's basically a spool now... I'm getting so sick of dealing with arrma diffs. I made sure the smooth side of the plates were facing the correct way, and I disassembled it and made sure it wasn't missing anything. It's ran good for a couple of weeks with no signs of any issues. About to take it apart and see what's wrong with it.

 

[Woodley99]

I have EXB diffs all around in my outcast 6s, built the front to be open, center is stock, and the rear is an LSD set to minimal effect. I've ran it really hard and had no issues until today. My rear diff decided to completely lock itself up. It's basically a spool now... I'm getting so sick of dealing with arrma diffs. I made sure the smooth side of the plates were facing the correct way, and I disassembled it and made sure it wasn't missing anything. It's ran good for a couple of weeks with no signs of any issues. About to take it apart and see what's wrong with it.

Your running open diff and front and LSD in rear? What fluids you running? That's kinda backwards, you want the front to grab more than the rear, better handling. Wouldn't effect the lockup you had just an FYI.
Let us know what you find out with the diff when you take it back apart, did it happen randomly or in a wreck or jump?

 

[JayP.]

I don't like the way it handles personally with the LSD in the front, I wanted it open in the front with a little more resistance in the rear, which is why I didn't go completely open. Just my personal preference. I'm running 20k front and rear with 100k in the center. And no it wasn't from a jump or a crash, it just decided to lock up when I was doing wheelies down the street. I honestly can't explain it.

I don't like the way it handles personally with the LSD in the front, I wanted it open in the front with a little more resistance in the rear, which is why I didn't go completely open. Just my personal preference. I'm running 20k front and rear with 100k in the center. And no it wasn't from a jump or a crash, it just decided to lock up when I was doing wheelies down the street. I honestly can't explain it.

I'll make sure to update you when I tear it apart. I'm curious to see what happened to it.

 

[Woodley99]

I don't like the way it handles personally with the LSD in the front, I wanted it open in the front with a little more resistance in the rear, which is why I didn't go completely open. Just my personal preference. I'm running 20k front and rear with 100k in the center.

I hear ya, these LSDs are a pain to dial in. I ended up with open front and rear and max effect center. 30k front, 200k center and 10k rear. Still kinda handles like crap lol super squirrelly, but I have to max6 combo and 18t pinion on 6s so it is alot of power. I keep adjusting settings and got BF MTs and it's getting better and better. Just ordered M2C +5mm hubs to make it a bit wider, that might help a little too

 

[JayP.]

I hear ya, these LSDs are a pain to dial in. I ended up with open front and rear and max effect center. 30k front, 200k center and 10k rear. Still kinda handles like crap lol super squirrelly, but I have to max6 combo and 18t pinion on 6s so it is alot of power. I keep adjusting settings and got BF MTs and it's getting better and better. Just ordered M2C +5mm hubs to make it a bit wider, that might help a little too

I was considering the M2C hubs as well. But honestly the way I have mine, it handled well, wasn't squirrely either, and that's with a castle 1650kv 1520 motor on a 20 tooth pinion, doing over 60mph topped out. But of course after I get it just right, and start enjoying it the rear diff decides to turn into a spool... I'm hoping something just happened with the LSD plates themselves, and not the gears

 

[JayP.]

Found out the issue.... It was the back end of the sungear, where the pin locks it in place... It chunked metal where the pin sits and locked it in place... Very annoyed that this already happened. All the gears are in perfect condition too.

 

[JayP.]

Found out the issue.... It was the back end of the sungear, where the pin locks it in place... It chunked metal where the pin sits and locked it in place... Very annoyed that this already happened. All the gears are in perfect condition too.

This is it

 

[JayP.]

There's play when the pin is sitting inside the sungear... Pretty disappointing. The pins do seem to fit better in the outdrives, but there's still some play with the pins when they locate the sungear. C'mon arrma... They'd probably be bulletproof if it wasn't for that. Looks like I'll have to find some drill blanks to cut to size still after all.