fifty wrote:I ruled them out based on this: the need for periodic maintenance. There are no wear parts in a helical LSD, but the clutch packs are a wear item.
This is true - but the periods are pretty long from my admittedly very limited sample. I have been running ZF clutch diffs (BMW OE) for a while and they take multiple seasons of racetrack abuse. I run approx. 30 track days and a few races every season. 100% track, no street driving at all. The diff in my car is still holding strong on it's third year and I do make it squawk often because I am very stiffly sprung so any time a ponk a curb, drop a wheel or exit a slow corner with too much throttle I make it work. The last one made it 3.5 years but it had 80k on it when it went into my race car. This one was fresh 3 years ago and is showng no signs of weakness. Still holds 90 ft/lbs at the hub with a torque wrench.
I figure 3-5 years is pretty good for the advantage over the free-wheelspin stuff on a race car. If I raced a rear or mid engined car I would probably agree on the helical as they rarely lift rear wheels and when they do... you are already in a lot of trouble.
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