M140i LSD necessity?
Discussion
Evening all,
Some of you might have seen my readers ride topic on my M140i, I have had it 4 years and its been modified to make it a bit better to drive and to sort out the (imo) terrible stock suspension. I have it booked in for an M Performance LSD in a couple of weeks but I'm starting to second guess if its really something worth getting fitted or not? I have coped fine with it over the past few years in all weathers but rather than getting rid of the car for something else when there isn't really anything suitable to replace it with I thought it would be better to spend the money to improve the car instead and take it on some track days.
As I haven't had an LSD fitted car before, I am hoping that those of you with some experience could explain how it improves the car? I know it should give better mechanical grip and better control if the rear of the car loses grip? Is that right?
Some of you might have seen my readers ride topic on my M140i, I have had it 4 years and its been modified to make it a bit better to drive and to sort out the (imo) terrible stock suspension. I have it booked in for an M Performance LSD in a couple of weeks but I'm starting to second guess if its really something worth getting fitted or not? I have coped fine with it over the past few years in all weathers but rather than getting rid of the car for something else when there isn't really anything suitable to replace it with I thought it would be better to spend the money to improve the car instead and take it on some track days.
As I haven't had an LSD fitted car before, I am hoping that those of you with some experience could explain how it improves the car? I know it should give better mechanical grip and better control if the rear of the car loses grip? Is that right?
I didn't fit an LSD to my 140, but I did trade it for an M4 and noticed a huge difference to the controllability of the rear with it's LSD.
Initially it felt more susceptible to breaking traction at the rear when cornering, but you get used to loading it up - once you've 'settled into' the corner it feels more planted. However if you're harsh with your inputs it will break away more freely.
Once you've lost grip its infinitely more controllable than the open diff. My 140 felt unpredictable in that situation as you could feel the power shuffling side to side which affected the angle of the slide. With an LSD that's locked up the angle of the slide is down to your inputs rather than what the car decides to do...
I would say it grips better from a standing start too but that could be down to the other differences between the 140 and the M4.
If the M perf LSD still runs about 2k supply and fit I'd be tempted to just trade the 140 for an M2 or M4 then you get all of the other changes included for not a lot more money.
Initially it felt more susceptible to breaking traction at the rear when cornering, but you get used to loading it up - once you've 'settled into' the corner it feels more planted. However if you're harsh with your inputs it will break away more freely.
Once you've lost grip its infinitely more controllable than the open diff. My 140 felt unpredictable in that situation as you could feel the power shuffling side to side which affected the angle of the slide. With an LSD that's locked up the angle of the slide is down to your inputs rather than what the car decides to do...
I would say it grips better from a standing start too but that could be down to the other differences between the 140 and the M4.
If the M perf LSD still runs about 2k supply and fit I'd be tempted to just trade the 140 for an M2 or M4 then you get all of the other changes included for not a lot more money.
Thanks for the reply, I have been trying to get my head around it and your explanation makes much more sense in the context of the back being a bit unpredictable when losing traction.
I have considered a full fat M car but I need the hatchback to fit my dog, as we use my car for most of our longer journeys and an F-chassis M3 is a bit out of budget for me and the running costs of an E90 M3 jump significantly over the M140i so I'm making the best of the situation!
I have considered a full fat M car but I need the hatchback to fit my dog, as we use my car for most of our longer journeys and an F-chassis M3 is a bit out of budget for me and the running costs of an E90 M3 jump significantly over the M140i so I'm making the best of the situation!
Depends how hard you push the car tbh. I added an LSD to mine and it certainly made a noticeable difference although mine is running rather more power and I track it.
Before it was unpredictable, sometimes grip, sometimes one wheel spinning, sometimes a nice slide, sometimes a combination of all of it. If it’s mainly a road car driving half sensibly then you won’t ‘need’ one.
Before it was unpredictable, sometimes grip, sometimes one wheel spinning, sometimes a nice slide, sometimes a combination of all of it. If it’s mainly a road car driving half sensibly then you won’t ‘need’ one.
I was at a similar crossroads with my 340i, loved the car but really felt with a map it was at the limit without adding an LSD. It was on my to do list for a while when I had a proper think and decided to flog it for a E90 M3. If I wasn't doing so few miles then I'd have stuck the diff on and probably loved it but it wouldn't have filled the V8 hole in my life. 
Glenn63 said:
Depends how hard you push the car tbh. I added an LSD to mine and it certainly made a noticeable difference although mine is running rather more power and I track it.
Before it was unpredictable, sometimes grip, sometimes one wheel spinning, sometimes a nice slide, sometimes a combination of all of it. If it s mainly a road car driving half sensibly then you won t need one.
^^^Before it was unpredictable, sometimes grip, sometimes one wheel spinning, sometimes a nice slide, sometimes a combination of all of it. If it s mainly a road car driving half sensibly then you won t need one.
That's the key IMO; track the car = diff - daily drive the car/road going car = diff not needed (unless you're a Mansell in disguise)
I don't think you need to be driving they hard. I love the throttle adjustability at low speed to be honest. The back axle is directly connected to my right foot.
I have a few RWD cars and all have LSDs - I personally wouldn't contemplate one without one.
M cars are fine but I find they are often a fair chunk heavier so I tend to prefer a skinny tyred "standard" car which flies under the radar.
I am far more a chassis and steering man than an engine man though.
I have a few RWD cars and all have LSDs - I personally wouldn't contemplate one without one.
M cars are fine but I find they are often a fair chunk heavier so I tend to prefer a skinny tyred "standard" car which flies under the radar.
I am far more a chassis and steering man than an engine man though.
I think I said this on your other thread; my experience is that people that have fitted an LSD think they are great, people that haven t often say you don t need one.
For an F20/21 M1xxi, I would say the most important change is to fit upgraded rear subframe bushes or inserts. The second most important is to fit an LSD. Mapped cars in particular and an open diff don’t make sense to me. I think even stock cars need an LSD.
You will notice having an LSD every time you drive even moderately quickly. You don t need to be on track to feel the benefit.
Don t forget that you can remove the M Perf diff and sell it when you sell your car. They hold their money really well.
For an F20/21 M1xxi, I would say the most important change is to fit upgraded rear subframe bushes or inserts. The second most important is to fit an LSD. Mapped cars in particular and an open diff don’t make sense to me. I think even stock cars need an LSD.
You will notice having an LSD every time you drive even moderately quickly. You don t need to be on track to feel the benefit.
Don t forget that you can remove the M Perf diff and sell it when you sell your car. They hold their money really well.
Edited by Tommie38 on Saturday 5th July 07:34
danb79 said:
As above - I know I'm selling my 130i now; but the c£2k cost for an LSD (even at mates rates etc) - put me off and it's not going to drastically change the drive of the car for me...
130i has a lot less torque than an M1xxi, particularly a mapped one. It will break traction a lot less frequently.Gassing Station | BMW General | Top of Page | What's New | My Stuff