Why don't most performance cars have a LSD?
Discussion
blade7 said:
cologne2792 said:
The Escort S1 RS Turbo was the first ever production FWD car to have an LSD as standard. It tended to make it feel like a RWD car which was a bit odd to say the least. More power in the corners tucked the nose in and continued to do so well past the physical limits of grip..
I don't recall my S1 RS Turbo feeling like a RWD car, I had to physically unwind the steering coming out of roundabouts though, and if the rear came unstuck it went sideways quite suddenly.I can’t comment for an S1 RS. But a DC2 ITR or Rover 200 BRM both have front LSD’s (Rover is a TorSen not sure in the Honda). It’s not that they feel rwd exactly. But under hard cornering such as a medium sized roundabout. If you apply throttle instead of the nose pushing wide, they tend to “dig in” and tuck the nose of the car tighter into the corner. This is while under traction. Obviously if you push to wheelspin, then they can massively under steer still. But they are a lot harder to do this in due to the extra traction they have.
SuperchargedVR6 said:
The only people who care about the demise of the LSD are the people who like leaving 11s everywhere, or being drifting throbbers on public roads. Electronic trickery is perfectly adequate for road cars. Even self assured road captains f'ck up when their confidence exceeds their ability......and that's why electronics are replacing mechanical locking.
Sorry but I'll have to disagree with you. I am always trying to stay within the limits of the traction circle and a LSD does help (at least in the longitudinal axis) in a way no pseudo electronics can IME. I actually think mechanical LSDs are making a (timid) come back for that very reason, think CTR, FRS, GT86, Megane, Hunday N30, KIA, Alfa Guilia etc... Nanook said:
Nonsense.
Most electronic trickery is utter gash at getting you going when it's snowy/icy outside. I don't want you to cut the power to one wheel, or brake one wheel, to slow it down to the speed of the other. Using brakes on an open diff to try and imitate a locking or limited slip diff isn't as good as the real thing.
That's not how it works, only traction control limits power when both wheels are overpowered and spinning. Nothing to do with the diff issue.Most electronic trickery is utter gash at getting you going when it's snowy/icy outside. I don't want you to cut the power to one wheel, or brake one wheel, to slow it down to the speed of the other. Using brakes on an open diff to try and imitate a locking or limited slip diff isn't as good as the real thing.
Braking a uselessly spinning wheel ensures that torque goes to the wheel with grip, and the spinning wheel can be accurately slowed to the speed of the non spinning one which is a good thing, not a bad one, as any excess speed means slip.
A mechanical LSD is very crude by comparison, as it is "dumb" always allowing a degree of slip, sometimes against resistance - otherwise cars would not go round corners - which means that the inside wheel can be rotating faster than ground speed, so cornering forces are resisted by the outside wheel.
The "electronic trickery" and ice again relates only to traction control - yes left to its own devices TC will cut power when both wheels are spinning, not ideal on very low friction surfaces where the only way to make forward progress involves some inevitable wheelspin.
Which is why you can normally turn TC off either directly or by selecting "snow" mode on some moderns.
SuperchargedVR6 said:
The only people who care about the demise of the LSD are the people who like leaving 11s everywhere, or being drifting throbbers on public roads. Electronic trickery is perfectly adequate for road cars. Even self assured road captains f'ck up when their confidence exceeds their ability......and that's why electronics are replacing mechanical locking.
Electronic diffs are very rare & are just as able spear you off as a mechanical LSD, most electronic systems cut the power rather than adding drive which is the opposite of what the LSD does.If you ever get the chance try a C63 without a LSD & then one with it, without having to do 11's you will see the benefits especially on a wet greasy road.
ZX10R NIN said:
If you ever get the chance try a C63 without a LSD & then one with it, without having to do 11's you will see the benefits especially on a wet greasy road.
Having done exactly this in the interests of curiosity and wondering if the premium was worthwhile, it very much is on those. In the dry I didn't notice any significantly increased tendency to understeer with the LSD equipped car. In poorer conditions however, it was night and day.
E39 540i Sport (open diff) and M5 (25% locking LSD) provide a similar comparison. Even with a decent wedge more torque at low rpm, the M5 feels a bit more sure footed in less than ideal conditions. It'll also lay down a tidy, straight number 11 rather than a wiggly 1 if you're so inclined, away from public roads. If it does inadvertently step out a tad as you leave a roundabout, it gathers things up more tidily too and makes for less of a 5p/50p *moment*
300bhp/ton said:
So was that lift off oversteer or did it over steer under power?
I can’t comment for an S1 RS. But a DC2 ITR or Rover 200 BRM both have front LSD’s (Rover is a TorSen not sure in the Honda). It’s not that they feel rwd exactly. But under hard cornering such as a medium sized roundabout. If you apply throttle instead of the nose pushing wide, they tend to “dig in” and tuck the nose of the car tighter into the corner. This is while under traction. Obviously if you push to wheelspin, then they can massively under steer still. But they are a lot harder to do this in due to the extra traction they have.
Indeed, FWD and an LSD is an awesome for tight cornering. An autotest car with a diff will dramatically outperform one without . I can’t comment for an S1 RS. But a DC2 ITR or Rover 200 BRM both have front LSD’s (Rover is a TorSen not sure in the Honda). It’s not that they feel rwd exactly. But under hard cornering such as a medium sized roundabout. If you apply throttle instead of the nose pushing wide, they tend to “dig in” and tuck the nose of the car tighter into the corner. This is while under traction. Obviously if you push to wheelspin, then they can massively under steer still. But they are a lot harder to do this in due to the extra traction they have.
This thread is a nice excuse to post a link to one of my favourite Internet videos - https://www.youtube.com/watch?v=yYAw79386WI&t=... - How a diff works
996TT02 said:
A mechanical LSD is very crude by comparison, as it is "dumb" always allowing a degree of slip, sometimes against resistance - otherwise cars would not go round corners - which means that the inside wheel can be rotating faster than ground speed, so cornering forces are resisted by the outside wheel.
Variable locking diffs e.g. BMW's M-diff go some way to mitigate the on/off characteristics of a simple mechanical diff. I guess as TC gets better and better the more it can do to overcome the effects of a simple mechanical LSD hence it being used in more 'high-end' cars recently.300bhp/ton said:
blade7 said:
cologne2792 said:
The Escort S1 RS Turbo was the first ever production FWD car to have an LSD as standard. It tended to make it feel like a RWD car which was a bit odd to say the least. More power in the corners tucked the nose in and continued to do so well past the physical limits of grip..
I don't recall my S1 RS Turbo feeling like a RWD car, I had to physically unwind the steering coming out of roundabouts though, and if the rear came unstuck it went sideways quite suddenly.I can’t comment for an S1 RS. But a DC2 ITR or Rover 200 BRM both have front LSD’s (Rover is a TorSen not sure in the Honda). It’s not that they feel rwd exactly. But under hard cornering such as a medium sized roundabout. If you apply throttle instead of the nose pushing wide, they tend to “dig in” and tuck the nose of the car tighter into the corner. This is while under traction. Obviously if you push to wheelspin, then they can massively under steer still. But they are a lot harder to do this in due to the extra traction they have.
h, but it was a step in the right direction and reduced understeer in the dry.But, the handling was nothing like a RWD car, with or with a slipper in the rear.
Would it be possible to fit an LSD to a Bedford Rascal?
I tried leaving a set of 11s once in it, but only really managed a 1.1 in the end..
They were an option on the Vauxhall Senator, one that I am glad was ticked on one of the ones I owned many years ago. and had one on the E24 as well... lovely stuff.
I do like mechanical bits, but am aware that even they usually operate best at a level above my own ability!
I tried leaving a set of 11s once in it, but only really managed a 1.1 in the end..
They were an option on the Vauxhall Senator, one that I am glad was ticked on one of the ones I owned many years ago. and had one on the E24 as well... lovely stuff.
I do like mechanical bits, but am aware that even they usually operate best at a level above my own ability!
SuperchargedVR6 said:
The only people who care about the demise of the LSD are the people who like leaving 11s everywhere, or being drifting throbbers on public roads. Electronic trickery is perfectly adequate for road cars. Even self assured road captains f'ck up when their confidence exceeds their ability......and that's why electronics are replacing mechanical locking.
Surely they're mainly aimed at track use, where the electronic trickery tends to be less useful as it just overheats the brakes.Flibble said:
SuperchargedVR6 said:
The only people who care about the demise of the LSD are the people who like leaving 11s everywhere, or being drifting throbbers on public roads. Electronic trickery is perfectly adequate for road cars. Even self assured road captains f'ck up when their confidence exceeds their ability......and that's why electronics are replacing mechanical locking.
Surely they're mainly aimed at track use, where the electronic trickery tends to be less useful as it just overheats the brakes.
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