Kraton Lost Drive But Diffs Look OK?

[CrayZee_One]

Hi all,

Kraton with stock diff oils lost drive after a bash around and a few jumps. Motor revved but Kraton barely moved.
Pulled all 3 diffs down in the end (I expected to find the rear or centre blown) and they look ok, no breakages. All diffs didn't have much fluid and the fluids were dark grey, full of metal fleck.
Motor pinion is tight, diff pinions seem tight although I only had enough time to check by hand. All other gears and shafts intact.
Bearings were gritty (will replace with rubber sealed) but none seized.
Could it be the old fluid causing an instant lack of drive?
I won't have time until later to investigate further.

Any thoughts on this one?

 

[2015GTRBE]

Check your center drive line cups, make sure the set screw didn’t back out.

 

[cootertwo]

Or the pin under the bevel gear

 

[CrayZee_One]

Check your center drive line cups, make sure the set screw didn’t back out.

And, we have a winner!
First time I checked the grub screw on the rear cup, it was tight. I checked it again, it had backed out but was tight against the rounded part of the shaft. Lesson learnt!
I did end up rebuilding all 3 diffs, and with new fluid 20k/100k/10k this kraton has a new life to it indeed! It's punchy and powerful as all get out.