M Performance LSD in the M240

[equ]

I actually don't love the braking aspect (pointing in) of PTV. I do like LSD compared to my previous mid-engined porsches. Still squirms a bit under power but puts it down better (when you're really going for it). Oh yeah, our GTI has one as well. So we are 3 for 4.

The brake-derived DTC (on rwd bmw's) does a decent job in snow actually, much better than expected.

[John V]

I still want one for the Boxster. I just don't think it's super necessary as it doesn't have enough power to overwhelm the rear tires in the dry. And having an open diff makes the turn-in much better than with an LSD.

[rumatt]

Originally Posted by wdc330i

I'd be interested to hear Rumatt's thoughts about the E46 now-equipped with an LSD...

I love it. I wish I had gotten it sooner.

The majority of the time it makes absolutely no difference though. The 330i isn't that powerful, so most of the time the open diff was fine. But when it wasn't fine, it was annoying as fuck. Accelerating on gravel, or from a stop around a corner with a little dirt in it - it was infuriating.

The diff fixes all that. It's a torsen, so if you lift a wheel it becomes an open diff. I did manage to get one-tire-fire from it once. But it was in the rain, doing a 90 degree turn, in first gear, full throttle.... So I can't hold that against it.

In more sane conditions, I occasionally notice some wheel chirp. For instance when pulling out of my driveway - which is angled so it's like a mini diagonal test with significantly different weights on the various wheels. Even in the dry the the inside wheel will chirp, but it doesn't spin. The car still zooms forward.

One thing I noticed that was frigging awesome. I was driving on a long gravel road. I accelerated around a corner and got some rear wheel spin, and the back end went into a controlled drift. I was giddy. With the open diff you have this bizarre phenomenon where one wheel is spinning, but the other still has full side-to-side traction. So you've lost traction and are spinning a wheel, but not drifting. This is what you want if you're my mother and want the car to point forward, and for the mass market is a benefit of open diffs. But it's not what you want when trying to have fun around a corner.

Bottom line. Worth every penny and more.

So does anyone know what your OEM diff is? Clutch type, but somehow quiet and non-clunky?

[John V]

The M performance diffs are a clutch style diff. I recall seeing a picture of one a few years ago and you could see the cross-ramps on it. It looked like it was a 1.5-way which slightly more lockup on accel than decel. I'm guessing they run very low preload so it doesn't bang around.

I'm glad you like the torsen. I was a little worried about making that decision until I drove it. It's really quite trans-formative.

[wdc330i]

The M Performance LSD:

The mechanical Limited Slip Differential provides the extra performance advantage that true performance drivers desire. This differential utilizes 3 clutch plates for a total of 30% lockup on acceleration and 9% lockup on deceleration. This lockup provides instant power to the wheel that has the greatest amount of grip to gain better traction out of tight corners. An additional benefit in low-grip situations is that both wheels get equal power, meaning more forward driving force on roads with reduced traction.

Supposedly made by Drexler.

Mine is not noisy at all.

[John V]

Yeah, so pretty sloppy. Won't be good for track work but will be nice on the street

[wdc330i]

Yep. Perfect for my dilettante needs

Edit: Re: the gravel traction. We rented a lake house last weekend with a pea gravel driveway. To exit the driveway, I had to turn and go uphill on wet gravel. One of the rear wheels began to spin, and then BAM I had enough grip to move forward. Thank you, LSD!

[wdc330i]

Nice love for the 240 in Autoweek--they parse how it might be a better all around car than the M2

: http://autoweek.com/article/car-revi...n=awdailydrive

[Theo]

That’s a great read. Wish they gave the standard 2 just a litttttle more rear hip. Not M2 size but maybe big enough for a 265. The 245’s look so tiny. Otherwise I’m sold.

[wdc330i]

Originally Posted by Theo

That’s a great read. Wish they gave the standard 2 just a litttttle more rear hip. Not M2 size but maybe big enough for a 265. The 245’s look so tiny. Otherwise I’m sold.

Agreed. I'm sure that was strategic to get people to move up to the M2--if just for looks alone.