Kraton Destroyed planetary gears. But why???

[aidas]

So, had some horrible noises coming from my kraton. Assumed I had stripped the input gear, nope, slipper was fine. With dread in my heart I opened the diff and saw the carnage.

so, am wondering why this happened...
60k and just rebuilt it a few days ago. What could have I done that caused this???

 

[bicketybam]

So, had some horrible noises coming from my kraton. Assumed I had stripped the input gear, nope, slipper was fine. With dread in my heart I opened the diff and saw the carnage.

so, am wondering why this happened...
60k and just rebuilt it a few days ago. What could have I done that caused this???

View attachment 94788

How was the little bearing that sits between the two outdrives? If that failed, it would cause that. If you didn't put it in, that would cause this as well.

 

[aidas]

Bearing seems totally fine. I thought maybe fluid leaked out but seems extreme that this would result...

 

[Surchaufeur]

I abuse my trucks and i never had those fail on me even after a year of use something moght have went wrong check the center bearing i might need to change that when i think about it

Bearing seems totally fine. I thought maybe fluid leaked out but seems extreme that this would result...

Was the diff full of fluid or not?

 

[aidas]

Yep 60k in there. Thinking it may have leaked out.

 

[Camaroboy383]

What does the cap and cup look like where the pins enter the bores? Usually these only die if the pins were not in the bores..

 

[aidas]

What does the cap and cup look like where the pins enter the bores? Usually these only die if the pins were not in the bores..

Bingo. Just compared to a spare I had, the cup where the posts sit in was ripped open.... one side of the cup is gone. Could that have been caused by it just not being seated properly during assembly???

 

[Camaroboy383]

Yes 100% the pins were not seated in the bores when it was tightened..?

 

[aidas]

Okay cool. Glad its an easy thing to fix and parts were available.
Thanks for the help!

 

[Camaroboy383]

Okay cool. Glad its an easy thing to fix and parts were available.
Thanks for the help!

No problem at all, now at least you know what to pay attention to.. what happens is the pins are pulled from the deeper bores, those bores fill with fluid.. the pin now hydraulics itself out when its inserted.. it's best to clean the cup and cap completely with alcohol or brake clean.. make sure the pin bores are clean and empty before inserting the pins..

 

[Surchaufeur]

Maybe diff was not tigt enough

 

[Camaroboy383]

Maybe diff was not tigt enough

Plenty tight, the pins pressed the edge of the plastic bore to almost nothing.. the pins were not in the bores.. the bore sides aren't broken out they are smashed upright.. the picture tells all..?

 

[jondilly1974]

Here’s a tip when building any of the 3S or 4S diffs. Make sure you assemble all the gears dry. Get all of the diff fluid out of the cup. Be careful to take out the orings and the gasket before cleaning too. They get eaten by some solvents.

Now with it clean and dry, get the gears and pins in the cup. Place the gear side output shaft in place too. Now fill the diff and let it settle for 10 mins. Keep topping it off until full. Put the cap on and make sure all the pins line up before putting the screws in. Snug the screws, but don’t over tighten them.

The reason you assemble dry is because diff fluid will get into the cup holes where the pins go and will hydro lock the pins out of the hole. They will push back and won’t stay in. They will act like a shock with rebound.

I also wanted to add that 60k shouldn’t have been a factor, other than the ticker the fluid you use, the harder it will be to get the pins into a hole filled with fluid. I’ve ran 500k in my Typhon diffs and they didn’t have these issues.