[Edslittleworld]

I'm wondering if a limited slip differential actually needs wheelspin to work. I'm asking because my non-LSD M240i can get a bit squirrelly under hard acceleration...even without any detectable wheelspin. Would an LSD make for more predictable hard acceleration...wheelspin or not?

[TemjinX2]

lsd just splits the power evenly between the two wheels. It could reduce wheel spin not necessarily eliminate it.

I would recommend going with wider, gripper tires first before investing in a lsd.

[Shovelman]

Master those squirrels, they are not dangerous then.

[wt888]

Yes but as someone else said, tires are another major factor in how a car feels.

Better tires will raise your overall grip and can change breakaway characteristics dramatically.

I put in a LSD and the car is much less squirrely in straight lines. 100% stock suspension. It feels like I added 200 lbs in the trunk. In curves its much more controllable, even with stability control off (or reduced, whatever the off mode is) I found the car had a jerky character mid corner and was hard to balance. Some of that is the non-linear torquey turbo power delivery, but with the LSD it's much easier to balance.

[ggggbmw]

Just because you aren't hearing the tires squeal doesn't mean they aren't spinning. Or, not spinning hard enough. With the stock open diff only one wheel can receive maximum torque. The other is just sort-of along for the ride. If you are cornering, the unweighted wheel may be spinning, but not fast enough that you can hear it. But you feel it since it isn't really sticking to the ground, and it's certainly not contributing to forward thrust. You effectively only have one wheel pushing you.

In a straight line, the unweighted/spinning/loose wheel will flip sides as the pavement changes under the tires and the car weight shifts. Again, only one wheel at a time is pushing you, and which one can flip sides back and forth. This is likely the 'squirreliness' you are feeling.

The LSD equalizes the torque across both rear wheels. They both are doing the same thing. So, as the car accelerates, you are getting equal thrust from both wheels. No skipping around as the pavement and weighting on the tire changes, and the loose wheel changes. This stabilizes everything.

[Moflow]

I'd bet you're getting small amounts of wheelspin in one tire. An LSD would fix that right up until the point you're putting enough torque to the pavement to make both tires break loose. And honestly, it'll be a way easier to control once you reach that point if you do have an LSD.

[Poochie]

Originally Posted by Moflow

I'd bet you're getting small amounts of wheelspin in one tire. An LSD would fix that right up until the point you're putting enough torque to the pavement to make both tires break loose. And honestly, it'll be a way easier to control once you reach that point if you do have an LSD.

That and also, the e-LSD (brake based) is still active, so a combination of a mechanical LSD and the pseudo brake modulation adds to the scavenging of traction.

[RoundelM3]

According to Timothy Leary, LSD works quite well when you're "tripping"...

[babaikram]

Getting a pair of wider rear tyres like Michelin Pilot Sport 4 255/35/18 on the stock 18 inch wheels would make more difference to the car stability and traction at a cheaper price than the LSD

[XutvJet]

Originally Posted by babaikram

Getting a pair of wider rear tyres like Michelin Pilot Sport 4 255/35/18 on the stock 18 inch wheels would make more difference to the car stability and traction at a cheaper price than the LSD

Totally disagree. My car had all sorts of traction issues with the stock MPSS 245 width rear tires with even stock power and no LSD. With the LSD, traction isn't an issue with MP4S 245 and 70whp/wtq over stock. Wider tires aren't the answer and will only add a marginal improvement in traction.

[dradernh]

Originally Posted by babaikram

Getting a pair of wider rear tyres like Michelin Pilot Sport 4 255/35/18 on the stock 18 inch wheels would make more difference to the car stability and traction at a cheaper price than the LSD

A 255 tire requires a wheel width in the range of 8.5-10.0".

[babaikram]

As I have been previously discussed, you could easily fit 255 tyres on the stock 18'' rim. I have been doing this for almost 2 years on both winter and MPS 4 on the rear wheels, no adjustments needed and no rubbing. The difference it makes to stability and composure of the car when accelerating and cornering is very noticeable.

LSD increases the speed before reaching the limit of traction just as wider tyres do. Maybe reaching the limit is earlier with wider tyre than the LSD is for a debate. You would still have an accident if you exceed the traction limit without being able to quickly correct it or unable to do especially in bends. A rear wheeled car must be driven progressively.

I believe having a wider tyre and getting firmer springs would make m240i a better composed car than getting only LSD

[perryair]

Originally Posted by Edslittleworld

I'm wondering if a limited slip differential actually needs wheelspin to work. I'm asking because my non-LSD M240i can get a bit squirrelly under hard acceleration...even without any detectable wheelspin. Would an LSD make for more predictable hard acceleration...wheelspin or not?

an lsd "works" at all time while you're driving. different types apply different amounts of traction to the wheel that wants to spin faster than the other wheel, whether in a turn, or one wheel is on a surface with slightly less traction than the other. technically, with an lsd its easier to put yourself in a spot where both tires are spinning and if you're mid curve will put you in oversteer - which while lots of people (including myself) consider that fun, to the uninitiated can be 'pants staining'. no lsd reduces your chances of that happening. ymmv.

[Heitzer]

Originally Posted by babaikram

As I have been previously discussed, you could easily fit 255 tyres on the stock 18'' rim. I have been doing this for almost 2 years on both winter and MPS 4 on the rear wheels, no adjustments needed and no rubbing. The difference it makes to stability and composure of the car when accelerating and cornering is very noticeable.

LSD increases the speed before reaching the limit of traction just as wider tyres do. Maybe reaching the limit is earlier with wider tyre than the LSD is for a debate. You would still have an accident if you exceed the traction limit without being able to quickly correct it or unable to do especially in bends. A rear wheeled car must be driven progressively.

I believe having a wider tyre and getting firmer springs would make m240i a better composed car than getting only LSD

I tried the 255 on stock rims (Michelin PA4s) for a couple years. It works, but the center of the tire gets eaten quickly while the shoulders are fine. Mine only lasts two seasons anyway with LSD and aggressive driving but its not pretty.

I realized that the 255 tire is a bit bend on an 8 inch wheel. It also means you aren't fully using the 255 thread width. I moved to a 8.5 rear wheel recently and wear looks much better now. It's the better choice if you have the option.

[babaikram]

Originally Posted by Heitzer

I tried the 255 on stock rims (Michelin PA4s) for a couple years. It works, but the center of the tire gets eaten quickly while the shoulders are fine. Mine only lasts two seasons anyway with LSD and aggressive driving but its not pretty.

I realized that the 255 tire is a bit bend on an 8 inch wheel. It also means you aren't fully using the 255 thread width. I moved to a 8.5 rear wheel recently and wear looks much better now. It's the better choice if you have the option.

Good points

[Darcibat81.]

How many different opinions as for such a seemingly simple question. Okay, I knew for sure that I would have to visit the online store to buy toggle clamps anyway, but whether I put on wider rear tires or take advice about LSD ... You all seem to be driving different models here, lol. I know for a fact that I don't want to jerk around in my car the way I do it on a ski lift. On skis, this is at least tolerable, but on the road - no.

[XutvJet]

Originally Posted by Darcibat81.

You all seem to be driving different models here, lol. I know for a fact that I don't want to jerk around in my car the way I do it on a ski lift. On skis, this is at least tolerable, but on the road - no.

This post makes total sense.

[nickgsa60]

Originally Posted by XutvJet

This post makes total sense.

I too drive my car on ski lifts all the time, so yes, totally makes sense

But in all seriousness, I'm surprised that no one brought up drive modes. If you are not driving in at least sport+ the benefit of the LSD is going to be minimal. Even with the LSD, under hard loads in comfort and sport modes I often feel the DSC intervene and cut quite a bit of power (which negates much of the benefit of the b58 and the LSD). But in sport+ with the LSD the car is very predictable AND fun and you can tell it is able to put down much more of the available power vs the lower modes. Personally I appreciate that the nannies will still intervene at the extreme limits in sport+ to keep you out of serious trouble. Without the LSD it felt more squirrely, less fun, and less predictable in sport+ and made me hesitant to use that mode.

Bottom line, if you want to get full performance and fun, I recommend the LSD and sport+ mode. But if you never want to drive in sport+ anyway, don't bother with the LSD.