LSD. Road driving effect?
Discussion
The drivetrain version, not the psychedelic unicorns dancing with bigfoot type.
Would there be a noticeable difference in a mk1 1.6 mx5 (114 bhp) with an open diff as opposed to one with a limited slip one? Normal day to day I'd assume there wouldn't be much in it, but how about when pressing on?
As a matter of completeness, how about on track? More sideways more of the time when you feel like it? Better traction out of corners?
Would there be a noticeable difference in a mk1 1.6 mx5 (114 bhp) with an open diff as opposed to one with a limited slip one? Normal day to day I'd assume there wouldn't be much in it, but how about when pressing on?
As a matter of completeness, how about on track? More sideways more of the time when you feel like it? Better traction out of corners?
Its kind of like the steering wheel isn't solid any more its all melty and rubbery and the road kind of rolls toward you and things just kind of come up at you really quickly but also slow and like the clouds are just whoa, you know like what the f
k was i just talking about? Oh were here. Have you ever wondered how we get here, like you know journeys and clouds and strawberries and that?
k was i just talking about? Oh were here. Have you ever wondered how we get here, like you know journeys and clouds and strawberries and that? WetPaint said:
The drivetrain version, not the psychedelic unicorns dancing with bigfoot type.
Would there be a noticeable difference in a mk1 1.6 mx5 (114 bhp) with an open diff as opposed to one with a limited slip one? Normal day to day I'd assume there wouldn't be much in it, but how about when pressing on?
As a matter of completeness, how about on track? More sideways more of the time when you feel like it? Better traction out of corners?
Mainly the only time you'd feel it is in a car park, when there'd be strange grinding/clonking noises at full lock.Would there be a noticeable difference in a mk1 1.6 mx5 (114 bhp) with an open diff as opposed to one with a limited slip one? Normal day to day I'd assume there wouldn't be much in it, but how about when pressing on?
As a matter of completeness, how about on track? More sideways more of the time when you feel like it? Better traction out of corners?
On the road you'd probably notice it pulling out of junctions and on roundabouts, but depending on how much locking there is (and I doubt there'd be too much on a road-biased diff) you wouldn't notice it on most "fast" roads.
On track and using grippy tyres, especially with a low powered car like a 1.6 MX-5 you'll really need to provoke it to get both wheels unstuck at the back. You'll avoid the "one tyre fire" and get much better traction out of slower corners though.
I have a 1.6 Mazda Eunos which is used as a roadgoing track day car. It has an LSD fitted, but as previously mentioned, it's fairly mild and I had the car for years before I actually realised it was an LSD - it was only when carrying out some work with the back end jacked up when I turned one of the wheels and the opposite wheel turned in the same direction, that I was 100% sure it was a limit slip diff.
On the road, there's no real issues. Because it's a fairly mild diff, it doesn't cause any noticable understeer, but there is a slight advantage when emerging quickly from tight junctions, as there is less tendency for the unloaded wheel to spin up, so traction is a little better.
1.6 MX5s (bless 'em) aren't exactly overendowed with power and torque, so don't expect a particularly lively rear end - you have to try very hard to induce even a small amount of oversteer. On track, the advantages of the LSD are, again, only noticable in very tight corners and chicanes, where the power is better directed to the loaded wheel. In anything faster than a second-gear corner, there's no real difference.
I've done a couple of wet track days and if you fail to carefully match engine speed to road speed when changing down, it does have a strong tendency to snap into oversteer on turn-in. I'm not sure if this tendency would be reduced if it had an open diff, but it's only really a problem in the wet and can be overcome by improving your technique and learning to heel/toe correctly.
I also remember reading that the locking element of MX5 LSDs wears over time and the diff becomes less effective the older it gets. I'm not very technically minded really, so I've no idea if this is true or not, but if it is, there may be more noticable differences with a new or freshly rebuilt diff than there is with my pensionable example.
On the road, there's no real issues. Because it's a fairly mild diff, it doesn't cause any noticable understeer, but there is a slight advantage when emerging quickly from tight junctions, as there is less tendency for the unloaded wheel to spin up, so traction is a little better.
1.6 MX5s (bless 'em) aren't exactly overendowed with power and torque, so don't expect a particularly lively rear end - you have to try very hard to induce even a small amount of oversteer. On track, the advantages of the LSD are, again, only noticable in very tight corners and chicanes, where the power is better directed to the loaded wheel. In anything faster than a second-gear corner, there's no real difference.
I've done a couple of wet track days and if you fail to carefully match engine speed to road speed when changing down, it does have a strong tendency to snap into oversteer on turn-in. I'm not sure if this tendency would be reduced if it had an open diff, but it's only really a problem in the wet and can be overcome by improving your technique and learning to heel/toe correctly.
I also remember reading that the locking element of MX5 LSDs wears over time and the diff becomes less effective the older it gets. I'm not very technically minded really, so I've no idea if this is true or not, but if it is, there may be more noticable differences with a new or freshly rebuilt diff than there is with my pensionable example.
Edited by R_U_LOCAL on Monday 2nd February 08:20
Best way to experience an lsd is on track, where the back always feels like it's pushing you forwards. especially in hairpins, when a drift is more easily enjoyed. Once you've felt the difference then you'll be more aware of it on the road in a spirited drive. trying to learn about lsds on a public road is not a good idea tho.
i also have a eunos 1.6 with an old viscous lsd (ie, it not very 'limited'), but it still works and is much better on track for having it. On the road i only ever feel it if deliberately provoking the car. My eunos is not over-tyred either, which helps the fun.
i also have a eunos 1.6 with an old viscous lsd (ie, it not very 'limited'), but it still works and is much better on track for having it. On the road i only ever feel it if deliberately provoking the car. My eunos is not over-tyred either, which helps the fun.
davepoth said:
Mainly the only time you'd feel it is in a car park, when there'd be strange grinding/clonking noises at full lock.
On the road you'd probably notice it pulling out of junctions and on roundabouts, but depending on how much locking there is (and I doubt there'd be too much on a road-biased diff) you wouldn't notice it on most "fast" roads.
I can only assume you are referring to LSD designed for racing. There are plenty of cars that come out of the factory with LSD, and I doubt the buyer of many a BWM, Porsche etc would expect "strange grinding/clonking" in every car parkOn the road you'd probably notice it pulling out of junctions and on roundabouts, but depending on how much locking there is (and I doubt there'd be too much on a road-biased diff) you wouldn't notice it on most "fast" roads.
It's not really a like-for-like comparison, being mid engine, but all the other rear drive cars we've owned (MX-5, 350Z, RX-8) have had an LSD and the Elise doesn't. (I'm excluding the Ital I had when I was a kid from this). In extremis, under power, the Elise will spin up a rear wheel. It's got a lot of traction, so that doesn't happen much. It won't oversteer without weight transfer unless on a very slippery surface - ice or snow. The LSD equipped cars didn't do this, and would oversteer under power without a big lift to start them off. I think the main difference in the front engined cars, had they not had LSDs, would be that they would have lost the ability to put any more power down at some point before they would otherwise have started to slide at the back (in a "not arsing around" scenario, perhaps accelerating hard out of a junction).
otolith said:
It's not really a like-for-like comparison, being mid engine, but all the other rear drive cars we've owned (MX-5, 350Z, RX-8) have had an LSD and the Elise doesn't. (I'm excluding the Ital I had when I was a kid from this). In extremis, under power, the Elise will spin up a rear wheel. It's got a lot of traction, so that doesn't happen much. It won't oversteer without weight transfer unless on a very slippery surface - ice or snow. The LSD equipped cars didn't do this, and would oversteer under power without a big lift to start them off. I think the main difference in the front engined cars, had they not had LSDs, would be that they would have lost the ability to put any more power down at some point before they would otherwise have started to slide at the back (in a "not arsing around" scenario, perhaps accelerating hard out of a junction).
yes.the elise has a lot of weight over driven wheels, wide tyres, and normally soft tyres too. Anyone saying an Elise 'lacked' an LSD on public roads would probably be a very qualified driver or pub bore.
For anyone interested in really feeling the difference i highly recommend the drift and slalom days with Caterham Experience. Pure car park hoonery.
balls-out said:
I can only assume you are referring to LSD designed for racing. There are plenty of cars that come out of the factory with LSD, and I doubt the buyer of many a BWM, Porsche etc would expect "strange grinding/clonking" in every car park
But then a 25 year old Mazda is not a brand new BMW. "Old School" LSDs are quite noisy in comparison to an open differential or indeed a modern electronically controlled LSD, especially when making sharp turns when the engine isn't being revved (such as in a car park) and especially in an open-topped car. I've owned two MX5s (Eunos) and currently have a Honda S2000, all with LSDs. The first MX5 was a 1.6 with the viscous diff while the second one was a 1.8 and both it and the Honda have Torsen diffs.
As has been said, the effect of the viscous diff was pretty marginal, possibly because it was quite high mileage and worn but never having driven an MX5 with an open diff it's hard to be sure. In the 1.8 with the Torsen diff, however, I felt it played quite a big part in the way the car handled. If you were driving briskly you could really adjust the cornering line through the throttle. I'm not talking about big power slides out of roundabouts, just a sense that as you applied power, so you could pay off steering lock. The car had quite a stiff suspension set up which probably increased this characteristic but was otherwise standard. I really enjoyed that adjustability though and would therefore recommend a Torsen diff on a road car.
In the case of the Honda there is just so much more grip and therefore speed that looking for slip angles on the road is altogether less of a good idea! On track, however, I found the traction (wet and dry) quite astonishing so I guess the LSD is doing its thing. When I could get the back end to break away under 2nd gear power there was still no spinning from the inside wheel.
Many years ago I owned a rally prepared Mini Cooper S with a Salisbury LSD. That was hilarious. Under power it pulled the nose tight in to the apex, rather as if it was rear wheel drive but then if you broke traction on mud or gravel, both wheels spun up and you had total understeer. On snow the front hunted from side to side as first one wheel and then the other found traction. The secret was to relax your grip and let it sort itself out.
Incidentally, none of the cars I've had with LSDs made undue noises on full lock. I think this is dependent on the type of diff and how tight it's set.
As has been said, the effect of the viscous diff was pretty marginal, possibly because it was quite high mileage and worn but never having driven an MX5 with an open diff it's hard to be sure. In the 1.8 with the Torsen diff, however, I felt it played quite a big part in the way the car handled. If you were driving briskly you could really adjust the cornering line through the throttle. I'm not talking about big power slides out of roundabouts, just a sense that as you applied power, so you could pay off steering lock. The car had quite a stiff suspension set up which probably increased this characteristic but was otherwise standard. I really enjoyed that adjustability though and would therefore recommend a Torsen diff on a road car.
In the case of the Honda there is just so much more grip and therefore speed that looking for slip angles on the road is altogether less of a good idea! On track, however, I found the traction (wet and dry) quite astonishing so I guess the LSD is doing its thing. When I could get the back end to break away under 2nd gear power there was still no spinning from the inside wheel.
Many years ago I owned a rally prepared Mini Cooper S with a Salisbury LSD. That was hilarious. Under power it pulled the nose tight in to the apex, rather as if it was rear wheel drive but then if you broke traction on mud or gravel, both wheels spun up and you had total understeer. On snow the front hunted from side to side as first one wheel and then the other found traction. The secret was to relax your grip and let it sort itself out.
Incidentally, none of the cars I've had with LSDs made undue noises on full lock. I think this is dependent on the type of diff and how tight it's set.
It was interesting in a 911 GT3 RS I test drove which has a fairly severe LSD setup as it was used primarily on track.
I was pushing accelerating round a LH bend thinking that the steering was fairly heavy. I lifted off and shot sideways at the hedge. The weight in the steering was understeer from the locking of the diff. The one I eventually bought was a standard road setup and had the same but much milder effect. It chuntered a lot in car parks especially when reversing.
On an MX5, I doubt you'd notice it much on the road.
Bert
I was pushing accelerating round a LH bend thinking that the steering was fairly heavy. I lifted off and shot sideways at the hedge. The weight in the steering was understeer from the locking of the diff. The one I eventually bought was a standard road setup and had the same but much milder effect. It chuntered a lot in car parks especially when reversing.
On an MX5, I doubt you'd notice it much on the road.
Bert
WetPaint said:
The drivetrain version, not the psychedelic unicorns dancing with bigfoot type.
Would there be a noticeable difference in a mk1 1.6 mx5 (114 bhp) with an open diff as opposed to one with a limited slip one? Normal day to day I'd assume there wouldn't be much in it, but how about when pressing on?
As a matter of completeness, how about on track? More sideways more of the time when you feel like it? Better traction out of corners?
Depends on the the type; plate diff or quaife ATB and the "lock up"...Would there be a noticeable difference in a mk1 1.6 mx5 (114 bhp) with an open diff as opposed to one with a limited slip one? Normal day to day I'd assume there wouldn't be much in it, but how about when pressing on?
As a matter of completeness, how about on track? More sideways more of the time when you feel like it? Better traction out of corners?
james_gt3rs said:
Lotus don't fit them to their cars because they say they induce lots of understeer... which goes against the norm for performance cars. I guess the only way to know for sure is drive the same car with and without.
The theory is sound, in a mid engine car they're almost too effective, in that they will produce so much thrust on corner exit that the already lightly loaded front tyres will have even more load shifted off them, resulting understeer. The instinctive reaction is then to lift off, which is generally a terrible idea for that sort of car. In a MR car, you can definitely do without them, but in a performance front engine RWD or FWD, they are an absolute necessity. I wont own another performance car without one!WetPaint said:
The drivetrain version, not the psychedelic unicorns dancing with bigfoot type.
Would there be a noticeable difference in a mk1 1.6 mx5 (114 bhp) with an open diff as opposed to one with a limited slip one? Normal day to day I'd assume there wouldn't be much in it, but how about when pressing on?
As a matter of completeness, how about on track? More sideways more of the time when you feel like it? Better traction out of corners?
In answer to the original questions...Would there be a noticeable difference in a mk1 1.6 mx5 (114 bhp) with an open diff as opposed to one with a limited slip one? Normal day to day I'd assume there wouldn't be much in it, but how about when pressing on?
As a matter of completeness, how about on track? More sideways more of the time when you feel like it? Better traction out of corners?
In my Mk1 1.8, I notice the Torsen working daily, but then I do enjoy getting the back end moving whenever the opportunity arises. Even when you are not trying to provoke power oversteer, the effect is noticeable during hard cornering as there is so much traction, you are never left with the disappointing one wheel tyre fire.
Having competed against a whole bunch of MX5s at my local autotest event, the difference between the ones that have LSDs and those that don't is significant. The ones with can pirouette 360° around a cone beautifully with both wheels spinning, the ones without spin up the inside wheel and then just plough wide. On the occasions they do manage to initiate oversteer with trailing throttle, they never manage to sustain it, it looks more like a FWD doing a handbrake turn.
Honestly, I imagine driving an MX5 without an LSD must be a pretty disappointing experience if you actually enjoy thrashing the b
ks off it.Here's a video of our last event, see if you can figure out which MX5s had LSDs and which didn't...
https://www.youtube.com/watch?v=xmuv9yboIC8#t=206
Kozy said:
The theory is sound, in a mid engine car they're almost too effective, in that they will produce so much thrust on corner exit that the already lightly loaded front tyres will have even more load shifted off them, resulting understeer. The instinctive reaction is then to lift off, which is generally a terrible idea for that sort of car. In a MR car, you can definitely do without them, but in a performance front engine RWD or FWD, they are an absolute necessity. I wont own another performance car without one!
I had a mk3 MR2, it had an LSD and seemed to benefit from it. Under power it would push the tail out a little instead of spinning inside wheel, was fantastic.One theory I heard was that the MR2 has quite soft suspension so the body roll lifts the inside wheel, hence an LSD needed to maximise the traction.
It's quite possible. Lotus set the Elise up so it didn't need it, I guess a lower CG wider track and firmer suspension are enough to keep that inside rear planted. PLenty of people fit aftermarket ones and say they're great, but I bet they also do a lot of other work too.
All I know is it's certainly less of a requirement that in other drivetrain arrangements, I'd rather drive a FWD with an LSD than a RWD without one!
All I know is it's certainly less of a requirement that in other drivetrain arrangements, I'd rather drive a FWD with an LSD than a RWD without one!
But I also heard Lotus (of old at least) does not like anti-roll bar either - similar philosophy as there is no need for a LSD if the chassis has been designed properly in the first place.
Thick anti-roll bar is actually pretty horrible to drive on certain country roads, such as the Cambs fens roads. Tree roots grow under the tarmac on the near side so the thick anti-roll bar transfers the bumps from the near-side to the off-side, where the off-side has no bumps to deal with anyway ...
Thick anti-roll bar is actually pretty horrible to drive on certain country roads, such as the Cambs fens roads. Tree roots grow under the tarmac on the near side so the thick anti-roll bar transfers the bumps from the near-side to the off-side, where the off-side has no bumps to deal with anyway ...
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