Kraton Building a stronger 29mm diff

[HZRDOS]

So, after shearing the tabs on the back of my sun gear, on two different EXB diffs, was time to try some things different.

First diff was on the Outcast and a front still in LSD configuration. After giving it some thought, when in maximum diff effect the round LSD plate is applying direct diff action pressure on the tabs located on back of sun gear as the stationary star plates apply friction to the round plate. Don't like this design that much. Yes, I was hard on the diff... but found this to be the weak point.
Switched the diff to full open with the Arrma shim kit. Only have one pack in it, so no issues with it yet.

Second diff was on the Kraton, and the rear. This one was already converted to full open with the Arrma shim kit using the large 1.8mm thick shim. Sheared the sun gear tabs and then the pin on the outdrive sheared due to the sudden impact and not having the tabs to help support it.

So. After some thought and seeing what @Engineer did, I think it is best to not use just a large or stack of shims with full open, but to use (2) of the round LSD plates on the back of the sun gear, then add a round 12 x 17.5mm shim to the back of that to create a total shim thickness of 1.8mm. With just the large Arrma shim, 1/2 of the outdrive pin is bearing pressure on just the sun gear tabs. Using the round LSD plates gives these tabs support, and should help them not shear.

Test run will be in the morning, but have to say...this diff feels perfect!

 

[SrC]

Not sure if you seen this video.

 

[HZRDOS]

Not sure if you seen this video.

Just watched it, all it does it tell you how to assemble the diff the typical way with the LSD plates?

 

[SrC]

It didn't mention setting up an EXB open diff??? Sorry. I think I have the wrong video maybe?

 

[Rcproponent]

So, after shearing the tabs on the back of my sun gear, on two different EXB diffs, was time to try some things different.

First diff was on the Outcast and a front still in LSD configuration. After giving it some thought, when in maximum diff effect the round LSD plate is applying direct diff action pressure on the tabs located on back of sun gear as the stationary star plates apply friction to the round plate. Don't like this design that much. Yes, I was hard on the diff... but found this to be the weak point.
Switched the diff to full open with the Arrma shim kit. Only have one pack in it, so no issues with it yet.

Second diff was on the Kraton, and the rear. This one was already converted to full open with the Arrma shim kit using the large 1.8mm thick shim. Sheared the sun gear tabs and then the pin on the outdrive sheared due to the sudden impact and not having the tabs to help support it.

So. After some thought and seeing what @Engineer did, I think it is best to not use just a large or stack of shims with full open, but to use (2) of the round LSD plates on the back of the sun gear, then add a round 12 x 17.5mm shim to the back of that to create a total shim thickness of 1.8mm. With just the large Arrma shim, 1/2 of the outdrive pin is bearing pressure on just the sun gear tabs. Using the round LSD plates gives these tabs support, and should help them not shear.

Test run will be in the morning, but have to say...this diff feels perfect!

View attachment 169675View attachment 169676View attachment 169677View attachment 169678View attachment 169679View attachment 169680View attachment 169681View attachment 169682

Interested to see how that beefs it up. looks like a solid plan bud.

 

[HZRDOS]

So first test runs went well. Feels great. Was really wondering since I upped the rear to 50k this time. Didn't notice a difference in steering/cornering. I typically let off when turning anyways, then power through with some slide...so maybe my driving style?

Didn't do any hard jumps yet. Will continue to report back. Ordered a bunch of packs of the LSD plates so I can do front of Kraton, and rear and front of Outcast the same. Sucks it takes 2 packs of plates to get the (4) round plates per diff. I will have A LOT of star plates if anyone needs them. Lol.

 

[jondilly1974]

So first test runs went well. Feels great. Was really wondering since I upped the rear to 50k this time. Didn't notice a difference in steering/cornering. I typically let off when turning anyways, then power through with some slide...so maybe my driving style?

Didn't do any hard jumps yet. Will continue to report back. Ordered a bunch of packs of the LSD plates so I can do front of Kraton, and rear and front of Outcast the same. Sucks it takes 2 packs of plates to get the (4) round plates per diff. I will have A LOT of star plates if anyone needs them. Lol.

So you’re using 4 x round plus 2 x star?

 

[HZRDOS]

So you’re using 4 x round plus 2 x star?

No. Full open, so no star plates. Just (2) round plates that act as a shim with the tab supports just behind the sun gear, and one regular 12x17.5x0.7mm shim.

In the pics above, you will see the 2 round plates and one shim laid out. That makes a total of 1.8mm thickness, just like when I measured the thick arrma shim used for full open conversion.

 

[Engineer]

Looks good! So far mine are holding up but in all honestly I haven’t run mine in quite awhile due to life being busy.

 

[theekorr]

Could probably grind the tabs of the star shims to make them round also. Not sure if it would be worth the time though

 

[HZRDOS]

Looks good! So far mine are holding up but in all honestly I haven’t run mine in quite awhile due to life being busy.

My other thought is a very small shim behind each planetary gear. Like a 0.2mm. This would keep more pressure pushing the sun gears down so they can't raise up any and have less outdrive pin contact area.

I did shove 2 small shims on top of the large shim on each outdrive below the pin. This may also help some. Still spins free, just with no play at all on the outdrives.

 

[HZRDOS]

2 month check in. Many packs through the Outcast and Kraton, both with all diffs converted this way. No issues at all with any of them. Driving the same as before, where I killed (3) of the stock EXB diffs. I feel that is a success so far.

 

[mxfan69]

Very very clever fix and Im assuming you are still driving as “abusive” as before, so this should be a good testimony to your resolve. Like you, I dislike the fact you have to buy so many packs of plates just to get the couple round ones you need, but I do like the end result.

GOOD JOB BRO

 

[HZRDOS]

Very very clever fix and Im assuming you are still driving as “abusive” as before, so this should be a good testimony to your resolve. Like you, I dislike the fact you have to buy so many packs of plates just to get the couple round ones you need, but I do like the end result.

GOOD JOB BRO

Can't take all the credit. Got the idea from @Engineer

 

[milehighspeed]

So just picked myself up a Kraton EXB on that sale recently and these will be my first experience on the LSD diffs. Just curious your thoughts on why you opened up all the diffs. Was it because you were just interested in tuning the car to your liking and getting it to turn in better etc… or is it because the limited slip set up stresses the drive train ( and maybe even the diff itself) in hard bashing? If its the latter, seems odd for ARRMA to add this feature to the diffs on the extreme bash version if it causes advanced wear over open diffs during extreme bashing. I haven’t opened mine up yet to see what’s in there but also sounds like in these newer versions Arrma has possibly opened the back diff already? Seen a few recent posts that say that’s the case for some vehicles?
FYI…as a keep it simple idea guy i think the method here makes tons of sense over all the other things I’ve been reading up on. Thanks for posting the knowledge.

 

[parcou]

So just picked myself up a Kraton EXB on that sale recently and these will be my first experience on the LSD diffs. Just curious your thoughts on why you opened up all the diffs. Was it because you were just interested in tuning the car to your liking and getting it to turn in better etc… or is it because the limited slip set up stresses the drive train ( and maybe even the diff itself) in hard bashing? If its the latter, seems odd for ARRMA to add this feature to the diffs on the extreme bash version if it causes advanced wear over open diffs during extreme bashing. I haven’t opened mine up yet to see what’s in there but also sounds like in these newer versions Arrma has possibly opened the back diff already? Seen a few recent posts that say that’s the case for some vehicles?
FYI…as a keep it simple idea guy i think the method here makes tons of sense over all the other things I’ve been reading up on. Thanks for posting the knowledge.

I would suggest opening the diffs to check fluid levels and see what you have, open or LSD. Then before changing it bash it and see how it feels. I had all LSD diffs but changed the rear to open because it was locking one side under heavy power bashing while LSD. Likewise, others have done the same as me but have no issues with all LSD. I'd say try what you have first to get a baseline and go from there.

 

[HZRDOS]

So just picked myself up a Kraton EXB on that sale recently and these will be my first experience on the LSD diffs. Just curious your thoughts on why you opened up all the diffs. Was it because you were just interested in tuning the car to your liking and getting it to turn in better etc… or is it because the limited slip set up stresses the drive train ( and maybe even the diff itself) in hard bashing? If its the latter, seems odd for ARRMA to add this feature to the diffs on the extreme bash version if it causes advanced wear over open diffs during extreme bashing. I haven’t opened mine up yet to see what’s in there but also sounds like in these newer versions Arrma has possibly opened the back diff already? Seen a few recent posts that say that’s the case for some vehicles?
FYI…as a keep it simple idea guy i think the method here makes tons of sense over all the other things I’ve been reading up on. Thanks for posting the knowledge.

As @parcou said above, I think it all depends on the driving style of each person.

That said, for me:

I like less moving parts.
With the LSD plates, the star plates are stationary, they do not rotate during diff action. They are locked into the tabs on the diff housing. The round plate spins with the sun gear. They are locked into the sun gear tabs. This rotation of the round plates against the star plates creates the additional diff "locking" action by friction. But...when there is "diff action" of the sun gears rotating at a different speed, the plates slipping creates friction...and heat. Lots of heat if they slip a bunch. I don't like this heat. My diff got REALLY hot once, and warped the plastic diff case a bit causing it to sling out a bunch of diff fluid. I don't like that. Also the plates create a wear point.

I feel that a correctly built open diff is much stronger and will last longer.

 

[parcou]

@milehighspeed I did not add that I do have a HW 4985\1650kv motor so my motor setup could have been part of my diff locking situation. Meaning I was putting down a lot of power and stock Kraton RTR setup and some others might not see that like that big can I have.

As my friend said above does depend on your driving style and what you are working with.

 

[Spoc85]

I run 60/500/20 LSD Max all round in a Kraton and Outcast. Bash hard with both cars. Iv had over 1Kg of extra weight thrown onto the OC to stop it back flipping at over 50mph. The car went over 83mph…… 76mph with 6s backflips. Video’s on here.
Iv pulled these diffs apart a few times now and the only problem I have is with the gasket. She seems softer than what’s on the regular diffs.
Compared to the V4 Kraton’s open diffs, LSD’s $hit all over it. 15 packs between both cars without a diff problem.

 

[Spoc85]

I run 60/500/20 LSD Max all round in a Kraton and Outcast. Bash hard with both cars. Iv had over 1Kg of extra weight thrown onto the OC to stop it back flipping at over 50mph. The car went over 83mph…… 76mph with 6s backflips. Video’s on here.
Iv pulled these diffs apart a few times now and the only problem I have is with the gasket. She seems softer than what’s on the regular diffs.
Compared to the V4 Kraton’s open diffs, LSD’s $hit all over it. 15 packs between both cars without a diff problem.

View attachment 181521

This was recorded nearly 2 years ago.
V4 Kraton in the same area half asleep compared to the EXB.
It’s the LSD in the rear which makes that EXB pop like it does. Definitely more fun to operate.