LSDs in slippery conditions?
Discussion
At some stage, I will buy an M135i. Negotiations with the missus have been slow and torturous but I think we should get on in the Spring.
While I'm unlikely to do much track work (there aren't any down here), I've heard that a decent LSD also works very well in slippery conditions, partly proven by a few vids of M3s doing very well up snowy slopes. This benefit appeals to me more than flinging it around a track with DCT off.
Mr Bird has told me his LSD works as well as, if not better than the M Diff in slippery stuff but can anyone else confirm (or not) whether this is true?
It would be very handy on our rural roads! And I don't want AWD - we have it in our camper and that's enough.
While I'm unlikely to do much track work (there aren't any down here), I've heard that a decent LSD also works very well in slippery conditions, partly proven by a few vids of M3s doing very well up snowy slopes. This benefit appeals to me more than flinging it around a track with DCT off.
Mr Bird has told me his LSD works as well as, if not better than the M Diff in slippery stuff but can anyone else confirm (or not) whether this is true?
It would be very handy on our rural roads! And I don't want AWD - we have it in our camper and that's enough.
Vladimir said:
At some stage, I will buy an M135i. Negotiations with the missus have been slow and torturous but I think we should get on in the Spring.
While I'm unlikely to do much track work (there aren't any down here), I've heard that a decent LSD also works very well in slippery conditions, partly proven by a few vids of M3s doing very well up snowy slopes. This benefit appeals to me more than flinging it around a track with DCT off.
Mr Bird has told me his LSD works as well as, if not better than the M Diff in slippery stuff but can anyone else confirm (or not) whether this is true?
It would be very handy on our rural roads! And I don't want AWD - we have it in our camper and that's enough.
An LSD can promote more intial understeer under some conditions and of course more sideways action too.While I'm unlikely to do much track work (there aren't any down here), I've heard that a decent LSD also works very well in slippery conditions, partly proven by a few vids of M3s doing very well up snowy slopes. This benefit appeals to me more than flinging it around a track with DCT off.
Mr Bird has told me his LSD works as well as, if not better than the M Diff in slippery stuff but can anyone else confirm (or not) whether this is true?
It would be very handy on our rural roads! And I don't want AWD - we have it in our camper and that's enough.
For aggressive driving it really depends on the car in question, some modern cars and with modern TCS and stability systems actually manage ok without, although others can be screaming out for an LSD. If you drive hard, then I'd say an LSD is likely to make the car slightly more extreme at times, but with higher levels of control once you go past normal levels of traction.
In terms off slippery surfaces like snow. Open diffs will go 1wd, while an LSD will retain 2wd ability. That's a 100% improvement.
Modern e-diffs are very good and largely due to being progressive and often allowing almost full lock up.
Old fashioned mechanical diffs can't do this, although I suspect it would take a fairly skilled driver to really sense the differences. I would expect an e-diff'd car to be slightly less snappy and more tame.
Had an Alpina B10 (e39) retro fitted with the Quaife diff from Birds.
I was travelling on a lot of muddy B roads and I found the traction control to be more of a hindrance than a help; the diff worked brilliantly with the traction control and certainly I never got stuck in mud/snow/ice with it fitted (I was running Avon winter tyres too mind).
After the initial euphoria of going sideways wears off I never really gave it any further thought - which I think is recommendation enough.
Edited to add:
I was travelling on a lot of muddy B roads and I found the traction control to be more of a hindrance than a help; the diff worked brilliantly with the traction control and certainly I never got stuck in mud/snow/ice with it fitted (I was running Avon winter tyres too mind).
After the initial euphoria of going sideways wears off I never really gave it any further thought - which I think is recommendation enough.
Edited to add:
Mr2Mike said:
A torque biasing diff is very unlikely to promote understeer on a RWD car, they are rarely intrusive like a plate diff.
Certainly, I never felt the B10 under-steered more with the Quaife unit fitted.Edited by TurboBlue on Wednesday 6th November 16:25
300bhp/ton said:
An LSD can promote more intial understeer under some conditions and of course more sideways action too.
For aggressive driving it really depends on the car in question, some modern cars and with modern TCS and stability systems actually manage ok without, although others can be screaming out for an LSD. If you drive hard, then I'd say an LSD is likely to make the car slightly more extreme at times,
A torque biasing diff is very unlikely to promote understeer on a RWD car, they are rarely intrusive like a plate diff.For aggressive driving it really depends on the car in question, some modern cars and with modern TCS and stability systems actually manage ok without, although others can be screaming out for an LSD. If you drive hard, then I'd say an LSD is likely to make the car slightly more extreme at times,
Is the M135 available with a LSD?
My experience of an LSD, pulling out of a road end at work that's very slippy in the wet, is cars like my S2000 and M3 just grip and go. Cars like the Boxster S, z4 and 335d scrabble for grip, and cut power and have flashing lights on the dash.
Defo worth it.
My experience of an LSD, pulling out of a road end at work that's very slippy in the wet, is cars like my S2000 and M3 just grip and go. Cars like the Boxster S, z4 and 335d scrabble for grip, and cut power and have flashing lights on the dash.
Defo worth it.
In theory, an LSD can introduce more understeer in certain conditions, the term "in theory" being the key phrase. If a corner is tight enough to introduce enough of a torque difference between the wheels, then it will lock and introduce a level of understeer. However, you will rarely ever get a factory LSD with more than 30/40% lock, let alone the 60/70% required to create such events. But then, if you are driving hard enough to illicit such symptoms, then you will be in the situation to be able to apply a bit of power and remedy it, making it a non issue.
I say this currently having an E36 328 with a welded diff and 215 section tyres on the back. It corners just fine whenever you ask it to; the initial understeer is cured with a dab more power to introduce a slight (slight, not hooligan lockstop type behaviour, though that's not unusual either
) slip angle. If anything I prefer the way it drives.
I say this currently having an E36 328 with a welded diff and 215 section tyres on the back. It corners just fine whenever you ask it to; the initial understeer is cured with a dab more power to introduce a slight (slight, not hooligan lockstop type behaviour, though that's not unusual either
) slip angle. If anything I prefer the way it drives.Are you specifically talking about driving on snow?
My experience of adding an LSD to my 328i is that in the snow you still have bugger all traction, however, as both wheels are spinning the back kept sliding into the kerb due to the camber of the road. Stick on some winter tyres though and it's the most fun you'll ever have.
You defo should spec an LSD though, best thing I ever added to the 328!
My experience of adding an LSD to my 328i is that in the snow you still have bugger all traction, however, as both wheels are spinning the back kept sliding into the kerb due to the camber of the road. Stick on some winter tyres though and it's the most fun you'll ever have.
You defo should spec an LSD though, best thing I ever added to the 328!
Why not buy one (when wife agrees/is replaced with a more amenable model) and see if you feel the need, I do this, I look at a car model and then start planning the modifications before I get it based on other peoples experiences, not my own.
I would love to try and explain a limited slip diff costing a couple of grand to a woman who isn't into cars, two grand extra for something that makes no material difference most of the time to most people, the defense that it allows you to skid the back tyres more easily or go round corners better will not work, you need to subtlety get it in, either by buying one already done or contriving a failure of the existing one some months into ownership, do you know nothing of dealing with females ?
My 350Z, being a proper thoroughbred sports/GT car
, developed as such from the ground up (Using RSJs and Oak beams it would seem), as opposed to a hatch with a very powerful engine, of course has one as standard, my 944 didnt and to be honest I have not noticed much of a difference other than it does seem a little more predictable on wet, low speed turns, to be honest the electronics call time a bit too abruptly, not really had the bottle or space to investigate further, I just drive it so I can hear the nice noise it makes at sensible speeds.
I would love to try and explain a limited slip diff costing a couple of grand to a woman who isn't into cars, two grand extra for something that makes no material difference most of the time to most people, the defense that it allows you to skid the back tyres more easily or go round corners better will not work, you need to subtlety get it in, either by buying one already done or contriving a failure of the existing one some months into ownership, do you know nothing of dealing with females ?
My 350Z, being a proper thoroughbred sports/GT car
, developed as such from the ground up (Using RSJs and Oak beams it would seem), as opposed to a hatch with a very powerful engine, of course has one as standard, my 944 didnt and to be honest I have not noticed much of a difference other than it does seem a little more predictable on wet, low speed turns, to be honest the electronics call time a bit too abruptly, not really had the bottle or space to investigate further, I just drive it so I can hear the nice noise it makes at sensible speeds.Vladimir said:
Mr Bird has told me his LSD works as well as, if not better than the M Diff in slippery stuff but can anyone else confirm (or not) whether this is true?
Mr Bird is telling porkies i'm afraid!(The quaiffe diff requires a cross axle speed differential to be able to create a cross axle torque bias. As such, one wheel must be spinning faster than the other for this to occur. However, in slippy conditions, you are quite likely to already be driving with a lot of longitudinal slip, so the "extra slip" required to provide a torque bias will be less noticable. A modern electronically controlled plate diff (such as the "M" diff) can provide full locking capability at zero differential speed, and as such can act faster in all situations, especially in high dynamic trailing throttle situations where they massively boost yaw stability etc)
But having said all that, will the average driver be able to tell the difference on the road? Unlikely! ;-)
Cheers all- not quite conclusive then!
We very rarely get snow here in Cornwall (none for the last two years) but had to do occasional trips to London and other parts of the SE. This is when something with a wee bit more grip than our comedy (in snow) 335d would be useful.
My wife would buy into it - she's quite a petrol head (learned in a new Scooby Wagon, took her test in a Defender pick up, has driven all sorts) and generally does "understand" stuff - just struggling to persuade her we need a new car now. TBH she's probably being sensible and I'm just being a spoilt kid - again.
We very rarely get snow here in Cornwall (none for the last two years) but had to do occasional trips to London and other parts of the SE. This is when something with a wee bit more grip than our comedy (in snow) 335d would be useful.
My wife would buy into it - she's quite a petrol head (learned in a new Scooby Wagon, took her test in a Defender pick up, has driven all sorts) and generally does "understand" stuff - just struggling to persuade her we need a new car now. TBH she's probably being sensible and I'm just being a spoilt kid - again.
What are you looking for?
Better traction and lower risk of getting stuck in the snow? Winter tyres will be a great help (normal tyre with plenty of tread are a start). An LSD will give minimal help and I'm not at all sure it would be worth the money
Make the car easier to drive sideways (and go sideways more often when pressing on) ? LSD is the answer.
Better traction and lower risk of getting stuck in the snow? Winter tyres will be a great help (normal tyre with plenty of tread are a start). An LSD will give minimal help and I'm not at all sure it would be worth the money
Make the car easier to drive sideways (and go sideways more often when pressing on) ? LSD is the answer.
aeropilot said:
Depending on when you actually get around to buying a M135, you might have the option of a dealer installed retro-fit BMW LSD (as well as the Birds-Quaife diff) as one is being added to the BMW Performance accessories catalogue early next year sometime.
I heard that rumour but don't believe that BMW have confirmed this yet?
Gassing Station | General Gassing | Top of Page | What's New | My Stuff