What is a Limited-slip Differential? (LSD)
Last updated September 23, 2022
You may have observed (or experienced) the phenomenon where a single tyre spins rapidly as it grips the road, while the opposite side tyre rotates at a slower pace. This usually occurs due to a corner being taken too aggressively - and may also result in a trail being left by the frenetic tyre.
Such a marked difference in speed between tyres can compromise a vehicle’s handling and performance. This can be a problem for vehicles with open differentials (the standard type across most car makes and models).
Luckily, there’s another type of differential that can provide smoother handling and greater control for drivers facing these tricky scenarios.
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What is an LSD (Limited-slip Differential) in a car?
Limited-slip Differentials (LSDs) work by limiting the disparity in rotation speed between drive wheels, to provide superior grip and traction. With an LSD fitted, although there may still be some variation in wheel speed, this would not be enough to cause a single-wheel burnout.
In simple terms, a limited-slip diff reduces wheelspin whenever the driven wheels start to lose their grip. The LSD then redistributes engine power to the wheel with the most grip, utilising a system that is mechanical, electronic or a hybrid of the two.
Why do I need an LSD for my car?
Limited-slip Differentials will help provide the grip you need as you navigate tight bends. LSDs are effective for off-roading, but even more so on paved surfaces. Other benefits include a reduction in axle shaft and tyre wear, thanks to smoother handling.
Everyone from rally and racing enthusiasts, through to police drivers and everyday motorists can potentially benefit from having an LSD fitted to their vehicle.
The price range for a typical Limited-slip Differential is between £600 and £1900. Many drivers consider this to be a worthwhile investment, thanks to the enhancement in performance and reduction in wear and tear.
Bear in mind that adding aftermarket parts may adversely affect your car’s trade in value. However, in certain cases, especially if you’re marketing towards buyers in the motorsports community, this could actually be a good selling point!
And, if you’re curious about how much your vehicle is worth, you can get a free car valuation from webuyanycar.
How do the different types of Limited-slip Differentials work?
Now that we’re familiar with how LSDs work, let’s explore some of the different varieties available and the benefits they can provide to drivers:
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Mechanical Limited-slip Differential
Mechanical Limited-slip Differentials are the most common variety and operate by shifting torque to the wheel with the most traction, whilst also limiting slippage for the wheel with the least. They can provide a good level of traction and control at a reasonable price.
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eLSDs
An eLSD (electronic Limited-slip Differential) performs a similar function to its mechanical counterpart, delivering enough torque to wheels - only this time through an electronic control unit. This allows eLSDs to work faster and with greater handling precision than equivalent mechanical systems.
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Clutch pack style LSDs
‘Clutch pack style’ LSDs are designed to prevent wheel slippage before it begins. The carbon disc clutch packs are placed behind each differential side gear. When a wheel slips, the clamping load on the clutch packs increases, so that power is transferred to the wheel with the least traction for greater control.
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Helical gear style LSDs
‘Helical gear style’ LSDs work similarly to open (standard) differentials in regular driving conditions. However, when the terrain changes or traction is lost, the helical-shaped gears mesh with greater force, transferring torque to the higher-traction wheel, until wheel spin is slowed or stopped.
Origins of the Limited-slip Differential
The Limited-slip Differential was developed in the 1930s by German engineering firm ZG, after Ferdinand Porsche requested a new kind of differential to reduce wheelspin in grand prix cars – a frequent problem at the time, given how easily they overpowered the narrow tyres’ grip.
Which cars feature an LSD system?
Car models with LSDs are available from a wide array of manufacturers, including BMW, Ford, Chevrolet and Hyundai. While LSDs are well suited for everyday driving, they are popular among racing and motorsports enthusiasts, for whom precise control over wheel spin is more a necessity than a luxury.
Popular cars with LSD
Popular cars that feature LSD systems include BMW M models, the Ford Mustang, Chevrolet Camaro and Ford Focus. Bear in mind that not all models and trim levels have this feature, so be sure to take a good look at the specs before committing.
Cheap cars with LSD
Surprisingly, the wallet-friendly Nissan Juke Nismo RS (2015-19) has mechanical LSD in front-wheel drive form. The Hyundai Genesis Coupe (2010-16) is available with a Torsen LSD. Both are great options for drivers seeking reliable traction and control without breaking the bank.
What are the disadvantages of Limited-slip Differentials?
Firstly, cars with LSD cannot deliver full power to any wheel, even when it is beneficial. Traction can also be difficult to control. Finally, as there is no singular standardised LSD system, quality, functionality and control vary between models.
What are the other types of differentials on the market?
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Open differential
Open differentials use gears to ensure the wheels rotate at differing speeds when cornering. However, when navigating corners at speed, or in slippery conditions, open diffs can deliver too much power to the wheel with the least grip, leaving it spinning furiously, as the other one turns slowly.
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Locking differential
As the name suggests, locking differentials lock the gear, so that torque can be delivered to both the drive wheels. This is an ideal setup for drag racing, but less so for rally or street driving, where you may encounter sharp turns.
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Automatic locking differentials
Automatic locking differentials lock the axles together when torque is applied, without driver input. Some models, such as the Eaton M Locker, lock automatically when traction is lost and unlock when conditions improve. Others, like Eaton’s Detroit Locker are usually locked – and unlock while turning.
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On-command lockers
On-command lockers aim to provide the best features of locking and open differentials. When engaged, the differential locks the axle shafts together, so that there is no difference in speed between the axle’s wheels. When not engaged, it simply acts as an open differential.
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Spool
A spool is a simple, single-piece unit that is cheaper to produce than any limited-slip or locker differential. However, a spool technically isn’t a type of differential. A variation in wheel speed (from side to side) when turning with spools can cause problems for drivers.
