Why don't most performance cars have a LSD?
Discussion
ZX10R NIN said:
I feel your pain but luckily there's Quaife who make some great LSD's I've bought a few & also benefitted from a final drive change to get them just the way I wanted so not having one fitted has never me buying a car, but I get where you're coming from.
Not usually a cheap option sadly. Not so bad if you are looking at used cars of a certain higher price. But at the low to mid end of the used market, an LSD retrofit might be a high proportion of the vehciles value with next to no return on investment when you want to sell the car. cerb4.5lee said:
That's a fair point and a good way for manufacturers to make more money, the problem is hardly anyone ticks the box, so if you're in the second hand market you can never find one with one fitted.
It's not really a box to tick as it's a dealer fit upgrade that can be added to a second hand car too. I think for road use / intended use the M140i are fine without one, what with the soft rear kinematics. It does improve the car but at quite a disproportionate cost IMO.Loyly said:
dme123 said:
The X300 XJR had an LSD as standard, it was an optional extra on the regular cars but unavailable on the XJ12 as you say. The traction control system on these cars was dire, it was a vacuum servo tugging at the throttle cable!
Really? How did that work?From the Jaguar service book:
"Throttle control is achieved by using a small motor and pulley arrangement, located in the throttle cable assembly. This adjust the relative position of the throttle cable during TC. Using the rear speed sensor inputs the ABS/TC CM regulates the throttle valve position independent of the accelerator position to prevent wheel spin. Along with throttle control braking ressure is applied through the ABS modulator's motor/pump unit to the spinning wheel.
During traction control activation the driver may notice a very slight fluctuation on the accelerator pedal"
The 2wd Nissan Skyline R34 has an electronically operated throttle in the intake that is operated by the ECU , it has a cable throttle so whilst your foot might be to the floor the throttle will be closed if you have no traction , its very annoying and like hitting a brick wall
But they also have a viscous lsd
But they also have a viscous lsd
cerb4.5lee said:
I will admit I was pretty shocked that the early C63's didn't get one, because that's just the type of car to really benefit from one for me, I didn't realise it was made standard on the later models thanks.
Standard on 205 series C63s (2015-present), optional on 204s (2008-15) as part of Performance Pack Plus (extra power and upgraded floating brakes with red calipers and bucket seats) or latterly as a standalone option - code 603 if my Mercbeard doesn't need trimming. Added a couple of grand, but worth every bit of it, particularly when temperatures drop and it gets wet/slippy out. Without it, it just spends a lot of time spinning up the inside rear, a waste of all that lovely torque of the 6.2 motor. I *think* the run-out 507 Editions had an LSD as standard too. Ditto the Black Series.
4941cc said:
cerb4.5lee said:
I will admit I was pretty shocked that the early C63's didn't get one, because that's just the type of car to really benefit from one for me, I didn't realise it was made standard on the later models thanks.
Standard on 205 series C63s (2015-present), optional on 204s (2008-15) as part of Performance Pack Plus (extra power and upgraded floating brakes with red calipers and bucket seats) or latterly as a standalone option - code 603 if my Mercbeard doesn't need trimming. Added a couple of grand, but worth every bit of it, particularly when temperatures drop and it gets wet/slippy out. Without it, it just spends a lot of time spinning up the inside rear, a waste of all that lovely torque of the 6.2 motor. I *think* the run-out 507 Editions had an LSD as standard too. Ditto the Black Series.
Up until traction is lost LSDs actually have a negative affect on the drive. Given that most cars are designed for use on the road where breaking traction is rare and mostly illegal there isn't much of a use case for specifying their inclusion.
In my personal experience their positive contribution to road driving is limited to traction when pulling away quickly (out of junctions etc), I prefer their tractive effect to that of electronic TCS but honestly unless you drive a lot on gravel, snow or drift tracks they aren't really needed.
In my personal experience their positive contribution to road driving is limited to traction when pulling away quickly (out of junctions etc), I prefer their tractive effect to that of electronic TCS but honestly unless you drive a lot on gravel, snow or drift tracks they aren't really needed.
TurboHatchback said:
Up until traction is lost LSDs actually have a negative affect on the drive. Given that most cars are designed for use on the road where breaking traction is rare and mostly illegal there isn't much of a use case for specifying their inclusion.
In my personal experience their positive contribution to road driving is limited to traction when pulling away quickly (out of junctions etc), I prefer their tractive effect to that of electronic TCS but honestly unless you drive a lot on gravel, snow or drift tracks they aren't really needed.
Depends on the car. A V8 TVR would be pretty naff without one. As would most Yank performance cars with big V8 engines. In my personal experience their positive contribution to road driving is limited to traction when pulling away quickly (out of junctions etc), I prefer their tractive effect to that of electronic TCS but honestly unless you drive a lot on gravel, snow or drift tracks they aren't really needed.
I have RWD and LSD in my daily driver - a 2002 Ford Ranger pickup.
The LSD and half a tonne in the back is far more beneficial in daily use than an empty truck with 4wd.
The LSD has got me moving many times,
The Rangers have it as standard equipment from 99-12 whereupon it's replaced by traction control - which owners tell me is hopeless off road.
The LSD and half a tonne in the back is far more beneficial in daily use than an empty truck with 4wd.
The LSD has got me moving many times,
The Rangers have it as standard equipment from 99-12 whereupon it's replaced by traction control - which owners tell me is hopeless off road.
cologne2792 said:
I have RWD and LSD in my daily driver - a 2002 Ford Ranger pickup.
The LSD and half a tonne in the back is far more beneficial in daily use than an empty truck with 4wd.
Although all the 4x4 pickups I've ever had went one better and had a rear axle diff lock.The LSD and half a tonne in the back is far more beneficial in daily use than an empty truck with 4wd.
I'm assuming the OP means rear wheel drive cars. I've only driven one FWD car with an LSD, an Astra GTE, and that was a sod to drive, the diff tended to pull it all over the road. Traction was much improved though.
I'm not convinced most owners need an LSD, although they are the sort of thing that some owner enthusiasts would like, especially for track days. I think the one issue that can't be overstated is that cars do handle and behave differently with a LSD and this could cause problems for an unwary or inexperienced driver in certain situations. Some one has already mentioned an issue with bumpy or uneven road surfaces where the loss and sudden regaining of traction on one or both drive wheels could easily cause a loss of control.
warch said:
Although all the 4x4 pickups I've ever had went one better and had a rear axle diff lock.
I'm assuming the OP means rear wheel drive cars. I've only driven one FWD car with an LSD, an Astra GTE, and that was a sod to drive, the diff tended to pull it all over the road. Traction was much improved though.
I'm not convinced most owners need an LSD, although they are the sort of thing that some owner enthusiasts would like, especially for track days. I think the one issue that can't be overstated is that cars do handle and behave differently with a LSD and this could cause problems for an unwary or inexperienced driver in certain situations. Some one has already mentioned an issue with bumpy or uneven road surfaces where the loss and sudden regaining of traction on one or both drive wheels could easily cause a loss of control.
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'm assuming the OP means rear wheel drive cars. I've only driven one FWD car with an LSD, an Astra GTE, and that was a sod to drive, the diff tended to pull it all over the road. Traction was much improved though.
I'm not convinced most owners need an LSD, although they are the sort of thing that some owner enthusiasts would like, especially for track days. I think the one issue that can't be overstated is that cars do handle and behave differently with a LSD and this could cause problems for an unwary or inexperienced driver in certain situations. Some one has already mentioned an issue with bumpy or uneven road surfaces where the loss and sudden regaining of traction on one or both drive wheels could easily cause a loss of control.
On the pickup front the new Rangers have an optional Off Road Pack which includes an electronic rear diff lock. They're great for very serious use in extreme conditions but not generally as useful on loose road surfaces as an LSD.
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.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.
I think a lot of people don't actually understand what a limited slip diff is doing and hence the effect it has, basing their opinions on watching Clarkson and Harris powersliding round racetracks.
All LSDs regardless of type bias torque attempting to equalise wheel speed, i.e. the slower wheel gets more torque and the faster wheel less. When a car is going round a bend within the limits of traction, the inside wheels are going slower than the outside wheels thus the diff will apply more torque to the inside wheel than the outside. If we then think about weight transfer, the lateral acceleration of the car means there is more vertical force and hence available traction on the outside wheels than the inside wheels, thus the diff is actually aportioning torque the wrong way round and will force the inside wheel to break traction earlier than it would with an open diff.
Only when that inside wheel is spinning faster than the outside will the diff bias the torque in the correct direction, i.e. towards the outside wheel which has more traction available. As someone pointed out earlier this leads to a sharper loss of traction on the outside wheel as it simultaneously has to cope with the increased share of lateral loading from the inside wheel exceeding its traction circle and the increase in torque shifting its own vector away from the lateral within its own traction circle.
The upshot is they are great for powersliding and will get you round a corner quicker if but only if you are spinning tyres and driving in an utterly inappropriate manner for the road. They certainly don't make FWD cars feel anything like RWD cars as someone implied earlier.
As a side note it's interesting to consider the effect on AWD cars which have some form of torque biasing centre diff (audi Torsen, subaru viscous etc). A car following a curve has its front wheels traveling faster than the rears, that difference becomes ratiometrically greater the tighter the curve. The net effect of this is the torque bias actually shifts rearwards as steering angle is applied and the effect is very noticeable on tight radius turns.
All LSDs regardless of type bias torque attempting to equalise wheel speed, i.e. the slower wheel gets more torque and the faster wheel less. When a car is going round a bend within the limits of traction, the inside wheels are going slower than the outside wheels thus the diff will apply more torque to the inside wheel than the outside. If we then think about weight transfer, the lateral acceleration of the car means there is more vertical force and hence available traction on the outside wheels than the inside wheels, thus the diff is actually aportioning torque the wrong way round and will force the inside wheel to break traction earlier than it would with an open diff.
Only when that inside wheel is spinning faster than the outside will the diff bias the torque in the correct direction, i.e. towards the outside wheel which has more traction available. As someone pointed out earlier this leads to a sharper loss of traction on the outside wheel as it simultaneously has to cope with the increased share of lateral loading from the inside wheel exceeding its traction circle and the increase in torque shifting its own vector away from the lateral within its own traction circle.
The upshot is they are great for powersliding and will get you round a corner quicker if but only if you are spinning tyres and driving in an utterly inappropriate manner for the road. They certainly don't make FWD cars feel anything like RWD cars as someone implied earlier.
As a side note it's interesting to consider the effect on AWD cars which have some form of torque biasing centre diff (audi Torsen, subaru viscous etc). A car following a curve has its front wheels traveling faster than the rears, that difference becomes ratiometrically greater the tighter the curve. The net effect of this is the torque bias actually shifts rearwards as steering angle is applied and the effect is very noticeable on tight radius turns.
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