coil over kit

[Norm Peterson]

If a torsen overheats what actually goes bad? Since it is all gears does it just shorten the life of the gears? I would think friction based diffs need better heat management?

My guess would be the fluid. 300°F is hot for lube but well below the annealing temperature of any steel I could find.

I suppose if you let the lube get too hot, it might not retain sufficient film strength to prevent metal-to-metal sliding.


Norm

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[Grintch]

I think the idea is that a Torsen is more complicated and generates some extra heat all the time. While going straight a clutch limited slip is essentially an open diff with nothing extra going on and no extra heat after the initial corner exit.

 

[TeeLew]

If a torsen overheats what actually goes bad? Since it is all gears does it just shorten the life of the gears? I would think friction based diffs need better heat management?

They're all friction based. The Torsen does it through worm gears which are very inefficient (read: create a lot of friction) when being used as drive gears. This is what produces the drive torque (diff bias ratio) shift to the outside rear which keeps the inside rear from spinning.{< last sentence editted}

A stock Traction-Lok creates it's friction with clutch plates pressed together by the spreading load of the side pinion gears. Because Ford intentionally keeps total locking force low, these clutches slip a lot on power, don't produce much overall locking (low bias ratio) and get burnt up quickly, giving the driver effectively an open differential. It works just about well enough to allow you to do a two-wheel straight-line burnout, but if you're turning and have substantially different vertical loads side to side, it's a peg-leg.

A good clutch plate differential (which will produce it's clutch force with ramps as opposed to just side gears) will allow a certain amount of slipping on corner entry to let the car to turn into the corner, but on throttle will lock solid and not allow _any_ speed difference side to side once on power (generally, full lock occurs about 10-20% throttle). By being completely locked, this eliminates the sliding friction on the plates. This is where I think some reduction in operating temperature might be found.

This is all speculation, though. It might very well be that the ring/pinion just isn't a very efficient gear(similar to a 9") and creates too much friction all on it's own.

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