Quote:
Originally Posted by mdputnam
First off folks, don't pay over $2,000 for the BMW differential!! There is a BMW dealership in Mechanicsburg, and others, that sell them for less than $2,000.
Second, per BMW, installation should not be more than 2.5 hours of shop time. For those of you who are mathematically challenged just multiply 2.5 by the hourly charge rate at your favorite independent BMW repair shop. If you live in Eufaula, Alabama that's about $56/hour, if you live in San Francisco, California it's about $156/hour. YMMV
Third, if you're not sure you need a limited slip differential you probably can live without one. In regular driving in dry conditions the only advantage is in accelerating hard out of a low speed tight turn, with dynamic traction control on the computer doesn't do a very good job using the brakes to "limit the slip" and the rear end gets skittish. In less than ideal traction conditions this zone of instability is wider. If you drive without any of the nanny controls on (hopefully only on the track) then you really should have a LSD.
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Quote:
Originally Posted by Cyberdemon
The reality is if you are driving on the street in DSC off and breaking traction often enough that an LSD starts to become valuable, you are probably a jerk.
The car with the eLSD or Sport+ is already extremely capable near the limits. For the track, the mechanical LSD is certainly extremely valuable for being able to better control the rear end through the corners and have it more predictable than the electronics.
If you have the cash to burn and feel like you want it, then I wouldn't stop you, but you need to be pushing the car very hard to start gaining the benefit. At that point I would suggest just moving up to a stickier class of tire which would improve traction at all 4 corners when paired with the eLSD.
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Quote:
Originally Posted by Liquidpaper
I've run both. I've had 10+ days on track with the "open" diff, and then several more with a LSD.
On street (I have about 24k miles on the car), there is a difference, but it isn't massive. The car is much more "chuckable" wth the LSD, and traction control doesn't interfere quite as much. I assume if you do power mods, it will become more noticeable (my engine is still stock).
On the track, it's night and day. The back end of this car can get seriously harry on higher speed turns without the LSD, and it is very hard to counter steer the car out of oversteer without it (back end becomes unpredictable).
If you are keeping the engine stock and not tracking, you don't need it. If you are increasing power or plan on tracking, it's a good investment.
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Pretty good advice right here.