Kraton V4 center diff build

[BashingBrian]

Hi everybody,

First up, Big thanks to @Thomas P and @Rich Duperbash for their excellent videos on diffs..???

I thought I would post my findings from my diff rebuild on my V4 Kraton, its only had roughly 5 runs or so, so I thought I would open it up..? so here goes.
I've seen much talk about the shims inside the diff so off I went and watched some vids, the first one I watched @Thomas P and the second was @Rich Duperbash..
They both recommend adding an extra shim on one side of the small gears, so you end up with 1-2 shims.

So here is my diff with pictures and some explanation of what I found and what I decided to do..
This is when I first opened it, bit confused as it seemed to have a very sticky silvery greasy substance, not silicone oil as I was expecting..?

After removing the inner gears

All the parts layed out in a gooey sticky mess..? looks like only one shim per side..?

After cleaning the parts...
Started to measure things and this is where it got interesting...
After watching @Thomas P and @Rich Duperbash videos they note add one extra shim, added screenshot from Thomas P vid..??

My shims look concave and convex..? although its quite hard to see in my bad photos..?
I'm also quite amazed at how much wear is on the inner plates, considering as I said before this is less than 5-6 runs..!!

I measured my shims and they are between 0.40mm-0.45mm thick..!!
Compare that with @Thomas P 0.15mm thick, so if I had used his method I would be under shimmed by quite a large amount..!!

His video is great at showing you how to rebuild the diffs, this post is not to complain about his setup, far from it.. It's to show how important it is to measure your own stuff..!! and just use youtube for advice, tips and help..!!??

This is the first Arrma diff I've worked on, not my first ever diff...
All cleaned and ready to put back together?

I didn't fit the big 8x15mm shim under the planet gear as I forgot to buy them..? this just shows what was inside as standard..
As you can see I used Green Slime to lube the o-ring and the outdrive cup shaft also some extra under the shim..?

All test fitted dry with a Tekjo gasket ( Thx Steph ?? ), will be filled with 500k...

At this stage I'm wondering how much has changed in the manufacturing of these diff houses as my shims are huge thickness compared to others I've seen on here..!!

Are these concave/convex shims normal or have I just got a duff batch or a totally new design..?

What amount of play is allowed..???

Everything seems nice and snug fitting at this stage in its dry state..

I will put it all back together and test it before I do the front and rear, because if this one goes wrong at least its the easiest to remove and start again..??

So there you go, I hope this helps people out...??

 

[martysmith223]

I had some do the same thing some worse than others if you don't replace the worn out pieces your diff wont last to long and it will actually eat itself idk if this is heat related or fluid related or both but it's not a good sign either way I'm waiting for my next diff rebuild to see if I find anymore ... I had one factory diff out of countless diffs do this and I didnt swap for new parts it only got worse so be warned

 

[Primarrma]

Somewhat typical wear, many of my shims have come out looking similar, put new ones in if you can. Make sure you put it together dry first and test the feel, I over did my front diff the other day and it wouldn't turn once all done up all I could add was one large shim if I added any small shims or the second large shim it would start to bind.

 

[Rich Duperbash]

I'm a little perplexed by the pictures ?. The V4 diffs come with 4 additional shims, 1 behind each planetary gear, and 1 on each outdrive/bearing. This looks like a normal V1-V3 diff with normal use wear. The new Arrma planetary shims are a smaller OD than the Mugen seiki ones, but I've chosen to just run them as is for experimentation. Just changed the fluids and added 2 TKR1222 shims to the crown gear side bearing front and rear.

 

[bicketybam]

I would not shim the new diffs like those videos. I didn't internally shim any of the diffs in my new Talion.

 

[Rich Duperbash]

I would not shim the new diffs like those videos. I didn't internally shim any of the diffs in my new Talion.

Yeah I'm still on the fence about it?. Sticking with stock shims for now anyways.

 

[bicketybam]

Yeah I'm still on the fence about it?. Sticking with stock shims for now anyways.

I run my trucks a lot....almost daily weather permitting. And I'm not gentle, lol. It will be a good test to see how the diffs hold up.

 

[Mr.Duke]

I've noted the same with regards to wear on the smaller satellite shims and have made a change to running just the 4 smalls behind the satellite gears (the way it comes from Arrma), but still keeping the 2 larger mugen shims under the pins for the sun gears on each end.

 

[BashingBrian]

I'm a little perplexed by the pictures ?. The V4 diffs come with 4 additional shims, 1 behind each planetary gear, and 1 on each outdrive/bearing. This looks like a normal V1-V3 diff with normal use wear. The new Arrma planetary shims are a smaller OD than the Mugen seiki ones, but I've chosen to just run them as is for experimentation. Just changed the fluids and added 2 TKR1222 shims to the crown gear side bearing front and rear.

@Rich Duperbash
This one is the centre diff, the pics above are from a V4 Kraton..!!
I haven't done the front and rear yet maybe they will have the extra shims..?
From the pictures above would you replace those shims..??

I know you have the new Kraton maybe you could pull your centre diff apart and see what's inside..?

I would not shim the new diffs like those videos. I didn't internally shim any of the diffs in my new Talion.

@bicketybam did you do the centre, did it look like mine above..??

 

[martysmith223]

I would not shim the new diffs like those videos. I didn't internally shim any of the diffs in my new Talion.

the new diffs normally wont allow you to shim them like the video it will bind up iv had to add extra gaskets just cause I didnt want to drain them again now i use hr diffs and they get shims like they come from the factory for now I'm sure I could do the 1-2 but I havnt tried it yet

 

[Wmorgan]

Hi everybody,

First up, Big thanks to @Thomas P and @Rich Duperbash for their excellent videos on diffs..???

I thought I would post my findings from my diff rebuild on my V4 Kraton, its only had roughly 5 runs or so, so I thought I would open it up..? so here goes.
I've seen much talk about the shims inside the diff so off I went and watched some vids, the first one I watched @Thomas P and the second was @Rich Duperbash..
They both recommend adding an extra shim on one side of the small gears, so you end up with 1-2 shims.

So here is my diff with pictures and some explanation of what I found and what I decided to do..
This is when I first opened it, bit confused as it seemed to have a very sticky silvery greasy substance, not silicone oil as I was expecting..?

View attachment 38719

After removing the inner gears

View attachment 38720

All the parts layed out in a gooey sticky mess..? looks like only one shim per side..?

View attachment 38721

After cleaning the parts...
Started to measure things and this is where it got interesting...
After watching @Thomas P and @Rich Duperbash videos they note add one extra shim, added screenshot from Thomas P vid..??

View attachment 38734

My shims look concave and convex..? although its quite hard to see in my bad photos..?
I'm also quite amazed at how much wear is on the inner plates, considering as I said before this is less than 5-6 runs..!!

View attachment 38726

View attachment 38724

I measured my shims and they are between 0.40mm-0.45mm thick..!!
Compare that with @Thomas P 0.15mm thick, so if I had used his method I would be under shimmed by quite a large amount..!!

His video is great at showing you how to rebuild the diffs, this post is not to complain about his setup, far from it.. It's to show how important it is to measure your own stuff..!! and just use youtube for advice, tips and help..!!??

This is the first Arrma diff I've worked on, not my first ever diff...
All cleaned and ready to put back together?

View attachment 38731

I didn't fit the big 8x15mm shim under the planet gear as I forgot to buy them..? this just shows what was inside as standard..
As you can see I used Green Slime to lube the o-ring and the outdrive cup shaft also some extra under the shim..?

View attachment 38732

All test fitted dry with a Tekjo gasket ( Thx Steph ?? ), will be filled with 500k...

View attachment 38733

At this stage I'm wondering how much has changed in the manufacturing of these diff houses as my shims are huge thickness compared to others I've seen on here..!!

Are these concave/convex shims normal or have I just got a duff batch or a totally new design..?

What amount of play is allowed..???

Everything seems nice and snug fitting at this stage in its dry state..

I will put it all back together and test it before I do the front and rear, because if this one goes wrong at least its the easiest to remove and start again..??

So there you go, I hope this helps people out...??

I've been tinkering around on my Kraton the last few days with help from @Primarrma. I've learned quite a bit and less intimidated by the design as it's fairly straightforward. I'm still working on the solution to the cracking sound and I think I'm on the path to a solution. My reply is regarding the "gray grease" comment. I noticed the same when I disassembled diffs on Kraton for the first time. Then I had to do it again after only 3 Batts and found the same gray grease as a result after I put silicone in. They were also at a much lower level. This tells me that the factory level is the same as mine as in they don't wait for ALL of the air to escape and that there is wear on the gears which causes the "metallic gray grease" affect to the silicone.

 

[Rich Duperbash]

@Rich Duperbash
This one is the centre diff, the pics above are from a V4 Kraton..!!
I haven't done the front and rear yet maybe they will have the extra shims..?
From the pictures above would you replace those shims..??

I know you have the new Kraton maybe you could pull your centre diff apart and see what's inside..?


@bicketybam did you do the centre, did it look like mine above..??

All 3 diffs should have the same new shimming ?. Same gears and cups in all 3 diffs. That's why I said I was perplexed cuz I didn't see yours in the pictures. If you look at the schematic in your manual you'll see them for all 3 diffs.

 

[bicketybam]

All 3 diffs should have the same new shimming ?. Same gears and cups in all 3 diffs. That's why I said I was perplexed cuz I didn't see yours in the pictures. If you look at the schematic in your manual you'll see them for all 3 diffs.

My V4 Talion came without the new shims. I emailed HH and they sent me two packs of them.

 

[Captain Dirt]

I usually don't follow someone else's shimming setup. Going through the threads, some say they have less shims than the manual, some have the same amount and some have more.

The shims on my V3 satellite gears looked the same as yours @BashingBrian. I just replaced them with Mugen shims.
After my planetary gear broke on the front diff, I went through all of them, put new shims in and fresh silicone fluid.

My rule of thumb is to shim until there's no play but don't over-shim to where it starts binding.
I've got the V4 center mount in my V3 and, when putting in the diff, I noticed a lot of back and forth play. Had to add 2 of the Tekno shims to each side to get rid of the slack.

Ran it yesterday after getting her back together and she sounds smooth as ever. We'll see how long they last this time.

 

[martysmith223]

check the locking blocks or whatever you call them they get damage also

 

[Jimbobjr]

The silvery tone is tiny metal particles in the diff fluid, pretty much normal wear and tear. Next time you replace the fluid it will be the same. I bought a new front/rear v4 diff from jrc, it feels a little notchy like when I shim mine.

 

[BashingBrian]

So I had a look at the manual "page 42" and it shows the diffs, mine are exactly like the manual..?

I missed a couple of photos on my post, maybe that's why there is some confusion..???

 

[olds97_lss]

In the end... it doesn't really matter what everyone does. Shimming is done to take up slop/imperfections in machining or to take up slop caused on purpose by the mold or machining to end up with proper gear lash.

You shim until it feels nice and smooth without any binding when dry. If it binds, remove a shim or use thinner shims. If it doesn't bind, shim until it does, then remove one until it doesn't.

Personally, I try to at the very least use shims under the large sun gears to cover the o-ring on the outputs so the pin itself isn't rubbing on the o-ring. If those are the only 2 shims that fit while still not having binding, then that's all I'd run.

As it was, on my outcast, I ran whatever was in it for 2-3 bash sessions because I was waiting for shims/oil to be delivered. So my gears were "worn in" by the time I pulled them apart. I used the full mugen shim kit on my 2018 outcast and they spun nice and smooth when dry. One under each of the 4 planetary gears and one under each sun gear. I then added 3-4 shims (tamiya I think) on the outside of the ring gear side bearing to set the gear lash on the ring/pinion.

 

[BashingBrian]

I ordered the Mugen shim kit today..?? so hard to find them in the UK..!! also the standard Arrma 3.5x12mm shims as backup ..

Thx @Rich Duperbash for the Mugen part numbers from your vid..??

 

[martysmith223]

mitch at m2c mentioned something awhile back about hooking a drill to your diff ..I did it to my kraton diffs dry only ran it long enough to get the gears hot ... I used a broken dog bone end kinda convenient the process is pretty quick and it seems to make my diff alot smoother... the tool Mark's or tiny imperfections on the factory diffs gears where it's made will wear down really fast and can cause extra slop for example one shim seems just enough but one good run and you could possibly have needed two not on both sides but the 1-2 ... this is a new method to me using the drill so time will tell if it's worth it I guess

mitch at m2c mentioned something awhile back about hooking a drill to your diff ..I did it to my kraton diffs dry only ran it long enough to get the gears hot ... I used a broken dog bone end kinda convenient the process is pretty quick and it seems to make my diff alot smoother... the tool Mark's or tiny imperfections on the factory diffs gears where it's made will wear down really fast and can cause extra slop for example one shim seems just enough but one good run and you could possibly have needed two not on both sides but the 1-2 ... this is a new method to me using the drill so time will tell if it's worth it I guess

I will say every gear and gear case is not the same iv had some that don't need shims yet some that need extra it's crazy... they do the best they can to make it as uniform as possible they just cant be perfect every time