Kraton Odd way for a diff to fail? Twice...

[Jerry-rigged]

Howdy gang -

I'd though I'd share a pic of my dead Kraton diff. This is the second time this has happened. The first time, I figured it was a "one in a million" failure, now I am not so sure. First failure was the Center diff, this is the rear diff. I went thru the front diff about a month ago (ring gear failure) and it did not have this issue.

Anyway on to the picture -

So here we have my dead diff, and a new diff case. If you look at the diff, under the bearing, you can see the metal sleeve that the bearing rides on has separated from the case. Yeah, that bearing is in nasty shape - it was packed with dirt, locked up. Once the case failed, the diff could move in the case, and the ring gear promptly lost a few teeth.

I am guessing (in this case) the dead bearing caused the metal sleeve to heat and melt the plastic case. Sounds good in my head, anyway. The first time this happened, though on my CD, the bearings were good.

Anyway, I have the pars now, so it will be back together as soon as my son gets around to it (his truck, I make him work on it... )

Oh, and this is a V1 Kraton, bought used, this diff is probably +2 years old. never shimmed, but oil changed a few times. The last year as been on a Nero 4075 motor, almost all 4s running by me, but I think the PO use 6s some (he gave me a 4s and 6s pack with the truck)

 

[Vanning]

Simple answer. The plastics, bearings and metal used in these RC's are sometimes hit or miss. . They are decent but not the best and will fail every so often. I've noticed that I had some out drive cups that wore out very fast and others lasted a long time. I'm sure it's true for the plastics etc. I've compared 1/8 race kits to RTR kits. The extra cost is obviously from the attention to quality control, better steel and plastics. Upgrades are key !!!

 

[ParkRacing]

Like Vanning said , every thing is hit or miss on these ready to run rc's.
Gonna try the Durango cups all around.

Here is the input gear on the rear after a bearing failure causing it make contact at a weird angle

 

[Vanning]

Some rtr's hold up a little better but the price is up there. They are a good 300-400 dollars more. The Kraton has available upgrades from HR and RPM etc. The diffs and shocks always needed attention. Got to upgrade where needed. My Slash and Kraton had a bunch of work done just to get them close to very reliable as bashers. If you don't run hard and fast.... most stuff holds up well. As soon as you start catching some bad jolts and landings from jumping ....higher dollar RC's will hold up much much better. The tolerances, the plastic formula, heat treating, research and development....it totally shows up. If you spend time on the Kraton and get the diffs shimmed up well and address a few parts...they do well also. I mostly busted shock shafts with mine....the diffs held up decent but I did shim them internally and also did the external shims. But then there is the infomous hit or miss factor from Arrma. Sometimes a part will suck and other times it never gives up. Overall...they are very good for the money in my opinion. Not bad for a RTR. They take some good 6S abuse out of the box. Upgrades are fun to do also if you are into it.

 

[Jerry-rigged]

My son finally got around to tearing the diff down.

 

[ParkRacing]

My son finally got around to tearing the diff down.

View attachment 12101

Toast

 

[Vanning]

It's funny how that sheers open with a clean circle. A shim behind the pin might help. Fill around the O-ring with grease, put the outdrive and o-ring in, squash down the shim, put the pin in etc.

 

[Jerry-rigged]

Oh, and the bearing that rides on that side was lock solid. I am about 98% sure heat from the sliding bearing killed this diff case.

 

[ParkRacing]

Oh, and the bearing that rides on that side was lock solid. I am about 98% sure heat from the sliding bearing killed this diff case.

That woild make sense, it looks melted.

That woild make sense, it looks melted.

Would lol

 

[Camo]

Oh, and the bearing that rides on that side was lock solid. I am about 98% sure heat from the sliding bearing killed this diff case.

I've got 3 of them all the same. The stainless insert broken out. The HR one is mad haven't had a problem since I changed it out. Hasn't leaked one drop

 

[Vanning]

Locked bearing...try a Boca bearing in problem areas. Ceramic hybrid. They don't rely too much on lubercation and seem to take much more abuse. The stock bearings are horrible....they keep out zero grit.

 

[dpricenator]

View attachment 12057

Here is the input gear on the rear after a bearing failure causing it make contact at a weird angle

The Kraton input gears, on the front and rear diffs, have a spiral cut to the teeth and all look just like that one.

MAIN INPUT GEAR 10T SPIRAL (1pc)
#AR310498

https://www.arrma-rc.com/part/AR310498