LSD Comparison

All of the limited-slip differentials we sell are exceptionally well designed and provide a huge traction upgrade, however some are better suited for certain applications than others. In this guide we hope to give you an overview of the different LSDs we sell, and their suitability to your use. Comparing LSDs isn’t quite as simple as plated LSD vs ATB. Amongst plated LSDs there are differences in design which makes certain LSDs more suitable than others for a particular type of use. The torque biasing ATBs we sell also differ in design, and one might suit your vehicle better than the other.

The most important thing is to find out which differentials are available for your vehicle, only then can you decide which one will suit you better. You can do this by using our list here.

LSD vs ATB

If you want increased traction, and you never want to worry about maintenance or breakages an ATB is the clear choice. Both the Quaife & Wavetrac come with unlimited lifetime warranties when fitted and supplied by an authorised dealer. They are also very smooth and silent when in use, which results in no additional noise when compared to a standard open differential. Apart from the increased traction they are undetectable and don’t require the use of any different oils, for these reasons they are highly popular with road cars.

For a more aggressive differential that provides a full lock, a plated LSD is the only option. When set up correctly they can give the driver precise control of lock on acceleration and braking. Some maintenance and servicing is required as they have wearable parts. Turning at lower speeds will cause some noise, slight wheel hopping, and a general lack of smoothness from the differential. This is normal, the friction plates slip and bind causing the noise. LSD oils reduce this effect without having an effect on the locking capability of the differential. Because of the need for maintenance and the noise issues, they are less suitable as a ‘fit and forget’ solution.

Both types of differential are suitable for race cars and road cars, with the suitability determined by the type of vehicle and type of use. For example if we compare two of the most popular lotus 7 style cars, the Caterham and the Westfield you will find that they work better with different types of LSD. Both are roughly the same weight (600ish Kg), both have a similar weight distribution (50-50), and can be spec’ed to similar power levels. However the rear suspension is where a major difference lies. A Caterham has a De Dion style of suspension whereas a Westfield has fully independent suspension. This difference makes the Wesfield more suited to an ATB, and the Caterham much more suited to a LSD. The Westfields’ fully independent suspension allows both wheels to remain firmly on the ground under hard cornering, meaning an ATB can torque bias very effectively. A Caterham will experience some wheel lift when cornering due to the De Dion tube acting in a similar way to a live axle, this means a fully locking Plate LSD is necessary to provide drive when one wheel has lifted. We are keen to stress that one suspension type is not better than the other, they just work in different ways, and require different traction solutions.

Another example is in front wheel drive hot hatches, manufacturers of both the 2012 Vauxhall Astra VXR and the 2009 Ford Focus RS both used different types of differential. The Astra VXR opted for a Drexler LSD, and the Focus RS used a Quaife ATB. Both manufacturers clearly felt that due to their traction requirements and their front suspension setups, a different LSD suited their vehicle. Without some form of LSD both of these cars would have struggled to put power down in lower gears, hindering their 0-60 times and cornering. A front wheel drive has less natural traction than the equivalent rear wheel drive due to the power being shifted rearwards on acceleration, reducing grip at the front of the car. It is for this reason a limited slip differential is crucial in a high performance front wheel drive. Both manufacturers would have been concerned about torque steer, and this would have played a large part in the decision making process. Front wheel drive cars with any type of limited slip differential will experience torque steer, and different cars will be affected more by different types of LSD. Both Vauxhall and Ford have developed sophisticated suspension setups to try and reduce this, and would have chosen their differentials appropriately. The end result is a different feel from the differential. Vauxhall have opted for a locking differential to pull the car through the corner by locking when needed. Ford have gone for a smoother differential that torque biases to provide continuous drive whilst allowing both wheels to turn at different speeds. Just like the previous example there is no simple right answer, when choosing an LSD there are multiple factors to take into consideration.

Helical Differentials - Quaife or Wavetrac

Wavetrac Wave Centre- standard position

Wavetrac Wave Centre- standard position

Both of these ATBs share the same basic design, a series of helical gears meshed together allow each wheel to turn independently. Torque is biased by the angle of the gears meshing with each other providing friction. The level of torque biasing is dependant on the number on gears meshing, and the helix angle, the tighter the angle the more aggressive the torque biasing. As this relies on a level of internal friction any friction modifying oils (LS oils) will reduce the effectiveness, and are not recommended.

Wavetrac Wave Centre - locked position

Wavetrac Wave Centre - locked position

They do have some differences, Quaife differentials tend to cost less than the equivalent Wavetrac, however this isn’t indicative of quality. Both are manufactured to an exceptional standard using high grade steel and rigorous quality control. Quaife do quote a torque bias ratio for all of their differentials, the ratio varies on application as some require a more aggressive bias. Wavetrac give all their differentials a bias ratio of 2.5 : 1, which is quite mild. This mild bias ratio is coupled with an internal ‘wave’ device that stops one wheel from spinning. When a wheel starts spinning this ‘wave’ device engages, slows the wheel, and then disengages when it reaches a speed close to the other wheel so normal torque biasing can occur. This gives Wavetrac the ability to provide drive when one wheel has lifted, or on higher powered vehicles where wheel spin still occurs in spite of the torque biasing.

We would recommend Quaife ATBs for those looking for a traction upgrade for road cars, and for race cars, where both wheels are firmly planted and you don’t need the locking capability. For vehicles looking for maximum strength they are excellent, with the design tested to withstand 13,000 FtLb of torque.

Wavetrac ATBs are recommended for situations where a wheel is more likely to lift, or when the vehicle is so high powered one wheel will spin despite the torque biasing effect. It is for these reasons we tend to recommend Wavetrac differentials for higher powered vehicles such as the BMW M3 & M5, & Mercedes AMGs.

Plated Differentials - Cusco, Drexler, Kaaz, Titan or Tran-X

All of our plated differentials work in a conventional fashion, ramps control the aggressiveness of the lock. Preload controls the static load, and also acts to reduce the aggressiveness of the lock. Their main differences lie in the details of their design, and the clutch plate material. These design differences are what sets one apart from the other, and explains the variation in price. Starting at the more affordable end of the scale is Tran-X, then Kaaz, Titan, Cusco and most expensive is Drexler. This does not hold true in every case however.

Tran-X LSD Showing Internals. The bottom ramp block is not active, and is used to support the cross pins. The top ramp block is angled in a traditional way.

Tran-X LSD Showing Internals. The bottom ramp block is not active, and is used to support the cross pins. The top ramp block is angled in a traditional way.

Tran-X were bought by Quaife in the mid 2010’s, and since then the differentials have been updated, strengthened, and modernised. Using the huge resources and expertise Quaife has they have undergone a transformation, to further improve the existing design. Their main differences compared to a conventional LSD is the use asymmetrical ramp blocks, and high friction sintered clutch plates. One ramp block is not ‘active’ it is just used to hold the carrier pins for the planetary gears. The other ramp block has the working ramps on it, under load the carrier pin rides up these ramps. This forces pressure on both ramp blocks, which locks the clutch plates in the conventional way. The clutch plates themselves are made of a sintered brass material that provides excellent lockup characteristics, and increased longevity. Tran-X offer a range of ramp angle options and different preloads so the differential can be easily tailored to your use. Their range is limited and their LSDs are available for classic vehicles such as the Lotus Elan, or modern classics such as the Toyota GT86 / Subaru BRZ.

Kaaz uses a very traditional LSD design, with symmetrical ramps and multiple metal on metal clutch plates. By using only high strength steel instead of unconventional materials they can keep the costs low and still maintain high product quality. Full lock is still given by using multiple clutch plates. They are all designed and manufactured in Japan, and cater to mainly Japanese manufacturers, and some European ones. They are popular with both drifters and circuit racers due to their value for money and durability. With offerings for a variety of vehicles such as the Fiat 500 / 595 Abarth, the Mazda MX5, and the Porsche 991, LSDs are available for most popular vehicles.

Titan currently offer a very limited range for only 3 differentials, Ford Sierra 7 Inch, BMW 168 and Ford English. They were designed from the ground up specifically for the Caterham & other ultra lightweight kit cars. Starting from a blank slate they focused on optimising performance for these types of vehicles. This was achieved by thorough real world testing on a variety of circuits to select the best ramp angles and preloads. Preloads are also adjustable to tailor the amount of oversteer to suit a specific handling set-up or driver. The rest of the design was focused on reducing rotating mass, and reducing manufacturing costs. By reducing manufacturing costs they are able to pass on the cost savings to the end user, whilst also incorporating high friction Sintrak clutch plates. These clutch plates are highly durable and last for years of hard use without needing to be replaced. They also have a high coefficient of friction which allows less plates to be used, and for the clutch plates to be smaller. This also contributes to reducing rotating mass. Titan LSDs are used in the factory & kit built Caterhams as they offer the best performance when compared to other competing LSDs.

Cusco RS showing internal coil springs

Cusco RS showing internal coil springs

Cusco RS differentials have a unique design, normally preload opposes the action of the ramps, with the Cusco RS preload assists the ramp action. Instead of traditional belleville washers on the outside of the clutch plates, they used small coil springs between both ramp blocks to provide preload. In doing this the coil springs don’t get fatigued as they are not compressing past the idle position, only extending under lock. This means the preload remains constant, unlike belleville washers which lose their preload from being compressed. Apart from the means of generating preload, the rest of the design is fairly traditional. They utilise multiple metal on metal clutch plates to provide a high level of lock that is easily controllable. Cusco have a huge range of differentials, catering to mainly the Japanese vehicles, with a few other marques. Their Japanese differentials are for the export market, JDM vehicles, and Kei cars, meaning you will find an LSD for your vehicle even if it is an unusual import. They have a large ramp angle offering suiting a variety of uses, from road, race, rally, and drag use. Cusco limited slip differentials are popular with Mitsubishi Evo’s (1-10), Nissan Skyline, Nissan Silvia, and Lotus Elise / Exige / Evora.

Drexler have focused on outright strength and performance. They utilise a standard design with high friction & low wear molybdenum clutch plates. It is their strength and performance that has made them popular with some of the top tiers of racing, and with very high powered vehicles. During designing they have reinforced any potential weak spots, and used high strength belleville washers to reduce wear as much as possible. They are able to withstand constant hard use during endurance racing without losing preload, allowing for repeatable lap times. When used in road vehicles this means longer service intervals without having to inspect the differential. All Drexler differentials are made to order, and have a huge range of preload & ramp angle options to precisely suit the vehicle, type of use, and driver. The robustness of a quality German engineered, race proven differential explains the higher cost. However they still represent excellent value for money as they are worth the investment. Their performance makes them very popular with track based BMW M-series cars, Mercedes AMGs, and also Supercars such as McLaren, Ferraris, Lamborghinis, & the Audi R8. They also produce LSDs for more common vehicles, covering a wide range of marques.

Conclusion

To summarise, first work out which LSD manufacturers produce a differential for your vehicle, if there is only one option the decision making process is made very easy. If there are multiple options, you have to decide if a helical differential will suit your vehicle, or if you want a more aggressive, locking plate differential. Deciding between differentials is not too difficult, you have to weigh up different features of each brand and find whatever suits your vehicle. For example if you are constantly lifting wheels, a plate differential would be a clear choice, and if you want to extend service life as long as possible then a Cusco or Drexler would be our recommendation. If you have a road car and wanted a more mild upgrade to improve safety and increase traction in poor weather, then a Quaife or Wavetrac would be the obvious choice.

To remove the decision making progress feel free to contact us, we will provide recommendations and discuss your various options.