There are various different types of drivechain upgrades which will not only increase traction, they will increase the ability to put down the power to the driven wheels. Ranging from lightened flywheels, clutches, driveshaft/ propshafts, through to limited slip differentials.

Drivechains in high powered race and road cars, under go extreme stress and strains, especially when they are modified from standard form. It is essential to try and build a firm and stable platform to maximise engine power.

The Propshaft/Driveline is under constant stresses and loads during everyday use and when you drive hard or are on the track, even more strain is put on the Propshaft/Driveline. By upgrading this device with more exotic materials like Carbon Fibre you can not only help transmit more power to the driven wheels but also reduce weight and increase strength. 

 Reducing transitional rotational loses and normally with big weight loses due to the construction with specialise materials. A more efficient and more durable set up, with help maximise any additional power in the Engine reaching the wheels.

Carbon fibre can offers you more strength to resist extreme torque than steel with about half the weight. Just like the common use of lightweight materials for clutch and flywheel units, a lightweight driveshaft allows more of you engine's power to be applied to the wheels. Carbon fiber's unique vibration dampening characteristics also help improve power output. 

All driveshafts twist to some degree when torque is applied through them and by upgrading the materials used, you get a more performance focused design.The advantage of a lower spring rate is less Propshaft/Driveline shock throughout the Rev range and a reduction of stress on other drivetrain components. Also increased traction of the components.

Continual twist occurs when torque is applied to the device and this eventually causes metal construction shafts to set in a twisted position. Consequently the shaft ends become permanently out of line by several degrees and vibration begins to break components, due to the misalignment and high loads the components undergo. Carbon fibre, whoever has a near perfect "elastic memory" and resets itself after the twisting motion, which minimise the chance of failure.

Also another advantage is that if or when the unit is damaged, in normal metal construction. The metal broken end of the driveshaft essentially turns into a flailing ball and chain. Which will continue to cause damage to the underbody and other components. With Carbon fibre, the driveline will shatter into small piece, reducing further damage and potential injury.

This is designed to match a OEM  standard clutch in terms of performance and driveability. Intended for standard performance vehicles with little or no performance gains or increased torque levels. Considered a like for like part exchange will little to small performance gains. 

Improvements over worn out or damaged Clutches can be made, especially if the current unit is slipping under loads. Viewed more as maintenance then purely a performance gain.

With increases clamping and torque capability and normally a mild decrease in driveability respectively for everyday use in traffic. Intended for cars with basic to moderate engine tuning upgrades, these clutches will help maximise any power or performance increases.

As standard equipment may not be up to the job due to the manufacture designing the original kit to meet a certain performance criteria and the increase in Torque and BHP will need to be balanced. Fitting these device will make sure the transfer of power from the engine is fully realised and efficiencies kept to a minimum.

Engineered to provide higher levels of clamping force and torque handling capabilities. Without a uprated clutch with high horsepower engines,all the power increases will not be able to be directly connected via the road driven wheels and create poor drivechain efficiencies. Also the possibility of sub standard parts braking or wearing out too quickly is more likely. Creating a weak link in the performance package.

Created typically for auto racing and Motorsport applications, where extreme heat conditions are generated due to the constant gear changes and huge forces/ loads being applied through the systems. A range of exotic material are used and a F1 clutch can be the size of your fists put together, but having the strength to with stand these huge forces.

Due to the specialist application of Motorsport products, just like tyres/tires and sometimes brakes; these devices may need to reach optimum temperatures to get the best results. Ideally suited for the Race tracks only due to the compromise in driveability. In everyday use these devices will not be a very smooth and gentle application, as they are designed for maximum performance with rapid shifting at high Rpm's. Smoothness and driveability are not top of the agenda, so careful application consideration needs to be in mind.

While standard flywheels have driveability and smoothness in mind, depending on your required goals. It is possible to fit lightweight units which will help the engine in the higher Rmp's. Depending on the exact application, this could result in reduced torque or the engine dropping Revs during gear change. But get it right and you can gain harder and faster acceleration due to the reduction in the units mass inertia. Resulting in a more rev hungry responsive engine, with quicker throttle response and sharper engine pick up.

We have discussed the Differential on the Drivechain sections and mentioned the "Open" Differential and "Locked" Differential. Essentially we mentioned the Open differential was fitted to most Road Cars and that a Locked Differential acted like if one was not fitted. We described how a Differential allowed the inside wheel when cornering to rotate at a different speed then the outside wheel, while allowing equal torque to be transmitted to both wheels. As the outside wheel will be on a larger radius path then inside wheel and a Differential aided cornering performance.

 You may ask yourself why would I want to upgrade my differential if I have one already fitted. Well like most components in a car, they are a compromise especially in run of the mill production specifications. Imagine this situation for a moment, we have a road car with a Open Differential fitted and one wheel is not in contact with the ground (not common in everyday situations) or stuck in mud and the other on solid ground for example. This could allow one wheel to rotate freely (the airborne wheel) and the other to remain stationary as it could lack enough torque to gain traction. Remember the Open Differential is designed to split Torque equally between the two wheels.

In  Motorsport, Rally, driving off road or even for High performance Car applications; this is highly undesirable and this is why the Differential over time has evolved to cope with these situations. By fitting a Limited Slip Differential it can limited the "angular velocity" of the driven wheels and provide more Torque to a driven wheel ( as long as there is traction available).

There are 3 types of Torque inputs states during the LSD functioning: 

Load: coupling proportionate to torque input.

No Load: reduced to Static Coupling.

Over Run: when the LSD is on Over Run, this determines (during Trailing Throttle or in Neutral Gear) what type of behaviour the LSD undertakes. 1 Way, 1.5 Way and 2 Way are the options available

1 Way: If there is no additional coupling on over run, the LSD is a 1 way type and essentially controls acceleration. A safer and more predictable LSD selection because as soon as the driver lifts the throttle (trailing throttle), the LSD unlocks and behaves somewhat like a conventional open differential. This is the preferred selection for for FF (front wheel drive cars) due to the fact it allows the car to turn in on throttle release. Especially important due to the fact FF cars are engineered to Understeer and fitting a 1 way LSD can help to combat these negative effects on Turn In.

1.5 Way: Essentially the same as a 1 Way LSD which locks under acceleration, this type of differential also has some Coupling under deceleration. This can help out under hard braking and on corner exits and increases stability. You could view this as a balance between 1 and 2 Way types Limited Slip Differentials.

2 Way:  This type of LSD has increased coupling in relation the Torque Inputs whether the direction is acceleration or deceleration and is classed as a 2 way differential. Drifters normally prefer this type as the LSD behaves the same way regardless of their erratic and aggressive throttle inputs. Also due the nature of the sport it allows the driven wheels to keep  spinning all the way through a corner extending the Drift. An inexperienced driver can easily spin the car when using a 2 way LSD if they lift the throttle suddenly ( trailing throttle Oversteer), expecting the car to react like a conventional open differential set up. Also some chassis and suspension tuning may need to be adapted to this LSD set up to counteract the extreme nature of it's characteristics.

There a commonly two different categories of LSD available Torque Sensitive ( Clutch, Helical based and Cone based) and Speed Sensitive (Viscous,Pump and Clutch Pack).

This type of LSD operates in a mechanical fashion by interaction between two or more moving parts. Under this category you will find Clutch, Geared and Cone type designs. Compared to a traditional Open LSD design, it is possible to transmit up to 80% to one of the wheels in a given situation rather then 50% in Open designs. This can help combat the earlier scenario when one wheel spins and the other is stationary due to lack of Torque being transmitted to it due to the 50-50 split.

Clutch:consisting of thin clutch discs, 50% of which are coupled to one of the drive shafts. The remaining of which are coupled to the spider gear carrier. The clutch stacks may be present on both driveshafts, or just on one. If only present on one then the remaining drive shaft is linked to the clutched drive shaft through the spider gears. If the clutched drive shaft cannot move relative to the spider carrier, then the other drive shaft also cannot move and they are then locked.

When the input Torque of the driveshaft turns the differentials center, internal pressure rings (adjoining the clutch stack) are forced sideways by the pinion cross shaft trying to climb the ramp, which compresses the clutch stack. 

Regular maintenance and inspection must be undertaken especially under hard use. The Clutch system needs to be broken in gently in the beginning and special attention to smooth any manufacturer imperfections are critical. Failure to do so could permanently damage the clutch  materials and cause irregular handling characteristics. 

Unlike the Open LSD design which might need fluid inspection every couple of100 thousand miles. Regular oil changes must be upheld to replace oil which can contain metal particles every 40 thousand miles. Clutch discs and central components might also be subject to strain and need replacing.

Geared:These types of LSD's respond to Propshaft/Driveshaft Torque input by increasing friction and press together mechanical parts as the levels increase.They have the ability to couple the wheels together more with increased Torque levels and sometimes may include spring loading to offset the effect to the driven wheels when trailing throttle, or in neutral with the clutch depressed. The amount of Static Coupling present on this type of system is normally dependant on the condition of the units.

Geared LSDs are more dependent on the torque and not on the speed difference between the output shafts (however the speed difference plays a part). Such differentials may not be up to the job on extreme slippery surfaces such as ice (or thin air, when a driven wheel loses ground contact altogether) and will operate like a Open LSD in these circumstances. Some torque sensitive differentials feature a bias plate, which allows some torque to be transmitted to the wheel in contact even when the opposite wheel has no traction.

Geared LSD can be used to reduce Understeer in FF ( front wheel drive) cars. As a central differential in four wheel drive cars or to help managed Oversteer in Rear wheel drive cars. Although in cases of extreme Oversteer ( like Drifting) the Clutch type design is more suited and this design is not used for Rally for example.

Cone:A cone clutch limited slip differential uses the friction produced by cone-shaped axle gears to provide improved traction levels.These cones fit behind and are splined to the axle shafts, with the axles splined to the cones. The axles tend to rotate with the differential case. Coil springs are situated between the side gears to wedge the clutches into the differential case. 

Under rapid acceleration or when one wheel loses traction. the differential pinion gears, as they drive the cones, push outward on the cone gears. This action increases friction between the cones and case, driving the wheels with even greater torque.

Speed sensitive LSD's consists of Viscous, Pump and Clutch pack designs. The latter is gaining popularity especially in modern all-wheel drive vehicles, and generally requires less maintenance than the mechanical type.

Viscous: Generally simpler in design then other types of LSD's because of the hydrodynamic friction from fluids with high viscosity. Silicone based oils are often used sealed with in a cylindrical chamber of fluid,with a stack of perforated discs that rotates with the normal motion of the output shafts. The inside surface of the chamber is coupled to one of the driveshafts and the outside coupled to the differential carrier. 

Half of the discs are connected to the inner, the other half to the outer, alternating inner/outer in the stack. Differential motion forces the interleaved discs to move through the fluid against each other. In some viscous couplings when speed is maintained the fluid will accumulate heat due to friction. This heat will cause the fluid to expand, and expand the coupler causing the discs to be pulled together resulting in a non-viscous plate to plate friction and a dramatic drop in speed difference. This is known as the hump phenomenon and it allows the side of the coupler to gently lock. In contrast to the mechanical type, the limiting action is much softer and more proportional to the slip, and so is easier to cope with for the average driver.

Generally less effective then other designs, sudden lose of coupling can be experienced when the silicone oil is under constant use and heats up. It is widely known that constant hard use will slowly result in less and less performance with the LSD acting more and more like a Open design.

Pump:This design works by hydraulically compressing a clutch pack together. The gerotor pump uses the housing to drive the outer side of the pump and the other axle shaft to drive the other one. When there is differential wheel rotation, the pump pressurizes its working fluid into the clutch pack area. This provides a clamp load for frictional resistance to transfer torque to the higher traction wheel. The pump based systems have a lower and upper limits on applied pressure, and internal damping to avoid hysteresis. The newest gerotor pump based system has computer regulated output for more versatility and no oscillation.

Clutch pack: Electronic limited slip differential systems use speed sensors, anti-lock braking system (ABS) sensors, accelerometers, and microcomputers to electronically monitor wheel slip and vehicle motion. In some systems the computer limits slip by varying the degree of locking in a mechanical LSD; such as Porsche's PSD system, which uses electro-hydraulic control of a mechanical LSD.

In other systems the computer uses the ABS system to control the slipping as follows. If either of the wheels on an axle is rotating unusually faster than the other, the computer will determine by how much it is slipping and will apply braking to it, slowing the spinning wheel down and causing the opposite wheels to gain speed and keep traction. One advantage of this system over mechanical LSD is that the vehicle steering and control is less affected. 

It also generates less stress on the drive train compared to a mechanical locking device, making it particularly suitable for vehicles with independent suspension. It can also be tuned for specific applications on and off road and at different speeds. A disadvantage is that it is less predictable when going over an obstacle, as the system needs time to react. Also, the wheel with traction will only have half of the available torque applied to it.

The Mitsubishi Active Yaw Control (AYC) electronically controlled rear differential uses a conventional open differential with an added planetary gear set to rotate two hollow shafts around the left hand drive shaft, one running at +15% speed, one at -15%. These can be progressively locked up to the left hand drive shaft via a hydraulic clutch pack under CPU control, increasing or decreasing the torque on that wheel in relation to the other. This allows a certain amount of rear wheel "steering" to provide stability control and performs the function of an LSD.

Gearbox/ transmission design have evolved rapidly over the last couple of decades with varied performance gains. Traditionally there were two options of manual or automatic designs, but recently they has been a trend for semi- automatic and even DSG gearbox/ transmissions. Read on for a quick overview on each design and the possible performance advantage.

Manual Gearboxes/ Transmissions normally come in two different kinds, Sliding mesh (unsynchronised) and constant mesh (synchronised). But it is normally a combination of the two when you take into account a reverse gear which normally has to be selected when stationary.

This is normally on the case on downshifts as you have a slower Gear ratio going up the Gears. Also Gear Clash or a noisy crunch is heard when you get it wrong and try to force the Gear in, causing damage.

Constant Mesh: a relatively new design and used pretty much in most new car designs, it uses Diagonal cut helical ( sometimes double) and are constantly meshed together. A dog clutch is used for changing Gear ( think of a microwave oven plate, connected to the rotating motor). 

On these types of designs, friction cones ( synchro rings) are used in combination of the dog clutch. It is commonly known that manual gearboxes/transmission yield weight savings, are cheaper to manufacture, also have fuel economy savings and generally have better performance then other types.

Common is most road cars in the luxury class, also pretty much the norm in the States. This type of Gearbox/ Transmission is simple to use, by selection Drive and with throttle application. The system will pretty much change gear for you with out driver inputs, reverse and manual gear selection is possible.

From a performance point of view, this type of system had a lot of Disadvantages compared to Manuals. Including heavier weight, more complex design with expensive repair bills, poorer fuel economy, less performance in terms of Gear selection times. For the mentioned reason, it's application in Motorsports was limited, but over the last decade the technology has come on with advancements to all these areas.

Some Drivers prefer the feel of the Manual set up, with the ultimate control in their hands. But with the evolution to semi automatic and DSG, the gaps between the two are becoming borderline.

Hydraulics are used to select Gears,with the selection being governed by fluid pressure. Instead of a clutch to control engine power and gear engagement, a fluid flywheel or torque converted is used. A torque converter is a type of modified fluid coupling, consisting of three rotating elements: a pump(driven by the engine), a turbine (drives the drivechain) and the stator (this separates the two and control oil flow from the pump and turbine).

The Fluid flywheel/ Torque converter has three states:

Stall: The engine can be revved hard, but no power is transmitted ( like the clutch being out on a manual) while the brake pedal is held down. This phase lasts slightly longer when the brake is released as the turbine and pump are at different speeds. Torque multiplication can reach there maximum (good for drag racing or in Turbo application).

Acceleration:The load is increasing, but there are still differences in the pump speed and turbine. Torque multiplication are less then in the Stall phase,

Coupling: The turbine has reached 90% of the speed of the pump, this is where torque multiplication has ceased. At this stage a lock up clutch is applied to try and increase fuel efficiency.

As mentioned before improvements as been made to try and even out the disadvantages with this system and there are some advantages in Motorsport applications. In some applications these characteristics do have there uses, for example in Drag Racing the Automatic Gearbox/ Transmission can be in the stall phase with high RPM. This is exactly what you need to get a fast launch speed  and it is possible to modify the Stall speed to increase the launch capabilities.

In Turbo applications, the ability to have the engine running at higher RMP is especially beneficial to keep the car in the powerband and boost pressure up. Due to the turbo running on exhaust gases, having the constant flow of exiting gas flow keeps turbo lag at bay which normally occurs when the throttle is released.

A semi-automatic transmission (known as clutchless manual transmission, flappy-paddle gearbox, or paddle shift gearbox) is a system which uses electronic sensors, processors and actuators to execute gear shifts on the command of the driver. Removing the need for a clutch pedal wear the driver otherwise needs to depress before making a gear change. As the clutch itself is actuated by electronic equipment which can synchronise the timing and torque required to make gear shifts quicker and smoother. The system was designed by automobile manufacturers to provide a better driving experience, especially in cities where congestion frequently causes stop start traffic jams.

Many modern semi-automatic transmissions can also operate in the same manner as a conventional type of automatic transmission by allowing the transmission's computer to automatically change gear, if the engine reached maximum Revs. Also having the ability to shift gears manually often via paddle shifters.

The twin-clutch gearbox/transmission, also known as the Direct Shift Gearbox (DSG) or dual-clutch gearbox/transmission. 

It can change gears faster than any other type of geared transmission and is a development of the sequential gearbox/transmission. Twin-clutch gearbox/transmissions delivers more workable power and at a better Rev range than a traditional automatic gearbox/transmission. 

Also it is a faster performer than a manual transmission and has been in use in Motorsport for some time. Originally marketed by Volkswagon (VW) as the DSG and Audi as the S-Tronic, twin-clutch gearboxes/transmissions are now being offered by several auto manufactures, including Nissan, Mitsubishi, BMW and Porsche.

Essentially a device which reduces the length of the Gear lever, this results in quicker Gear shift times. 0.2 or 0.3 of a second may not sound like much, but over a course of a race you could make hundreds of Gear changes, so the grand total of time same soon adds up. Even in Drag racing or 0-60 time sprints, using this simply modification can gain good improvements over standard equipment.

A point to bear in mind is the need for accurate and precise Gear changes though, as short shifters need more skill. In heated racing environments a missed change will cost you more then the few tenths you just saved getting up to speed.