I've got that can or worms picture, but can't find it!! Since it's open anyway...
I'll try again with the diff check. You hold the right wheel and the spur in your right hand so neither can move. Then try to turn the left wheel. It should not slip - at all, ever.
Chris, I have absolutely no doubt that what you are saying about a Centrax clutch is true, but we're dealing with polar opposites here! A decent 8th engine is popping out 1500 watts-ish, we're struggling to find 200 in 12th. An IC engine outputs maximum torque well up it's rev band, and our DC electric motors output maximum torque at zero revs. Add to that you are talking about a clutch, not a diff, and it seems to me to be a completely different application requiring, without any doubt, a different lube compound.
The other thing not yet mentioned is that our 12th tracks are not flat, and the suspension cannot keep up with the little bumps and unevenness in the track (Look for that wafffleboard effect on many main straights, where the additive goes down in strips). Under acceleration and speed, the rear is hopping up and down, and the throttle is open. The shock load on the diff when a wheel touches down again is much greater than the rising, or constant load if the track was absolutely flat. Add to that the slight eccentricity of most wheels, and you have a situation where the balls in the spur gear are constantly slipping and grabbing. Unless the diff is absolutely tight - no slip at all when tested by hand - you will be wearing the balls or the races.
Whether you know what I do for a living or not (thanks, Jason!) I can assure you that if your collective knowledge of mechanics was applied to the products we design and build, I wouldn't travel in the products we make!!
I type all this with a smile and a pleasant demeanour, and no concern at all about your posts. You can believe me or not, you can act on the advice or not - but I'm glad you lot don't design my diffs, and Dave Irrgang does!! The can of worms is firmly shut here - and I hope you will all be as smiley and content as I am, and enjoyed our little conversation.
