[Outlaw 06]

Please note that my 2021 F22 M240i is equipped with a manual gearbox (and rear wheel drive). Additionally, the first thing I do after starting my M240i is toggle the Driving Dynamic Control switch to “Sport +” mode, so the intrusiveness of the car’s electronic nannies may vary if you’re routinely driving in different modes.

In January 2021, I had my local BMW dealer install an M Performance LSD in my M240i to replace the abysmal stock open diff in the car. During the winter, I drove my car on a square set-up of 17” Pirelli Winter Sottozero tires. The LSD provided an immediate and noticeable improvement in the performance of the car on the softer snow tires.

With the coming of spring, I put the stock, staggered, 18” Michelin Pilot Super Sport max performance summer tires back on the car. As expected, the LSD has also greatly improved the power delivery to the rear wheels on the stickier summer tires in wet and dry conditions. The car’s handling and traction with the LSD are now predictable and far superior to the way it was with the stock open diff. It’s literally a night and day difference during both acceleration and throttle lifts or braking (decelerating) for turn-in. The adverse yaw that was induced by the car’s stock open diff under hard acceleration has also been eliminated by the LSD. The car’s electronic nannies are also significantly less intrusive with the LSD (specifically, the computer-induced engine power reduction and intermittent braking action on the slipping wheels with the old open diff).

Regarding clutch-type verses helical-type LSDs. I have clutch-type, LSDs in my E46 M3, my Porsche 718 Spyder and my M240i now too. I have helical LSDs in my Honda Civic SI and my NB Spec Miata race car. I’m used to driving cars with LSDs, so I might have a better “feel” for the shortcomings of cars without LSDs compared to people who only drive open diff cars.

When both drive wheels are on the ground, I can’t perceive any difference between helical and clutch-type LSDs. However, whenever I find myself in a situation where one of the drive wheels momentarily lifts off the ground (perhaps when taking too much curbing on a track), the helical LSD’s power delivery/traction is less predictable and inferior to a clutch-type LSD. That’s the only (slight) performance “con” of helical LSDs in my experience. I’m mentioning this subtle performance difference just in case you’re considering installing a helical vs. clutch-type LSD for occasional track duty. Both types of LSDs provide impressive performance though.

There are a lot of posts about horsepower mods on this forum, and I understand that engine tunes are cheap, but it’s my experience that the stock open differential (lack of traction) is limiting the M240i’s overall performance the most, not the stock engine. Simply put, the stock open diff in these cars can’t adequately handle a stock B58’s rated horsepower and torque, so more horsepower alone won’t improve the car’s overall performance (and more horsepower will probably degrade the traction proportionally in cars equipped with the stock open diff).

Even though BMW hasn’t offered LSDs as factory options in non-M cars for over 25 years, it’s still very disappointing to me that performance cars like the M240i are only equipped with open diffs from the factory. It’s quite unsatisfactory that BMW only provides open diffs in “ultimate driving machines” like the M240i, especially when considering the fact that Honda offers enthusiasts helical LSDs as standard equipment on the $25k Honda Civic SI, while BMW doesn’t even offer an LSD as an option on a $50k M240i…

IMO, a LSD is a “must have” option in order to put down a B58’s significant power to the rear wheels properly and improve the M240i’s overall performance.

Fortunately for enthusiasts, there are several brands and types of LSD’s available to replace the M240i’s stock open diff (I HIGHLY recommend replacing the stock open diff with a LSD as soon as possible after you buy the car).

If you haven’t installed a LSD in your M240i yet, then you should seriously consider doing so, because it will transform your car’s performance.