Full Face Sprung Hub

If you primarily use your car as a daily driver you will want a clutch that is easy to modulate, operates quietly, and offers long life and smooth engagement. The best type of clutch disc for this application is a sprung, full-faced disc. A full-faced clutch disc offers all of the aforementioned characteristics which are ideal for a vehicle that is driven in stop and go traffic. There are different clutch friction materials available depending on the clutch manufacturer each with its own inherent characteristics.

Organic: This friction material will have smooth engagement and is typically found in stock clutch discs. The organic material makes the clutches perfect for daily use and can recover from being burnt or overheated where as most materials can not.
Kevlar: This friction material offers the same smooth engagement of an organic disc, but has a higher coefficient of friction. The downside to the Kevlar friction material used in these discs is the additional heat they attract which when used aggressively can cause premature warping the associated stress cracks to both the flywheel and pressure plate friction surfaces.

Both friction materials typically require an initial break in period of 500 miles (please refer to manufacturers specific recommendations regarding clutch break in).

6 Puck Sprung Hub

If you frequently compete in some form of motorsports and your application requires the higher torque capacity that these discs have, a puck disc may be a good choice for you. These discs feature a ceramic friction material and in some cases sintered iron. Unlike a full face disc, race discs have a high coefficient of friction that allows them to hold higher torque capacities even though they have less surface area. The reduction in surface area and a lower weight generally allow you to shift faster than a full face disc of the same size. The drawbacks to using puck style discs are harsh engagement, chatter, increased driveline noise, and reduced pressure plate and flywheel life when used on the street for "stop and go" driving. Most manufacturers will not recommend a puck style clutch for daily driven cars, however if your daily driver has a lot of torque or you drive aggressively, a puck disc may be a cheaper option than buying a multi disc clutch kit.

Multi-Disc Clutch

Over the past five years the use of multi-disc clutches has risen on street cars with over 500 ft pounds of torque. Initially these clutches were made for "off road use", but with the increasing amount of power being made by street cars their popularity has increased. The benefits of going to a multi disc clutch are the capability to hold a lot of torque without the added pedal effort normally associated with an equivalent single disc clutch. In most cases the lower inertia and smaller diameter of these clutches and their discs allow for quicker acceleration and faster shifting compared to single disc units. Although the benefits mentioned may seem attractive to performance minded enthusiasts, these clutches are not recommended for daily use. They generally make more noise than single clutches, experience chatter, have harsh engagement, reduced clutch life, and can cost twice as much as a single disc clutch for the same application.

Aluminum Flywheel

Another component associated with a clutch upgrade is a lighter flywheel. The reduced inertia of a lighter flywheel will allow the engine's RPM to climb faster and improve throttle response. There are 3 types of lighter weight flywheels on the market, Aluminum, billet steel, and forged chromemoly steel with each having some inherent advantages, but all achieving the same goal in the end which is reduced weight.

Aluminum: These flywheels feature a 3 piece construction of aluminum, a steel ring gear, and a replaceable friction surface (they cannot be resurfaced).
Billet Steel: These flywheels are made up of a billet steel section with a steel ring gear and will most likely be the cheapest of the three options. They can be resurfaced.
Chrome-moly Steel: These are forged 1 piece flywheels that are typically offered in 2 weights that allow the user to choose the weight that best suits their needs. These can also be resurfaced.

Typically the heavier flywheels will be best for daily driving and drag racing. Lighter flywheels are better suited to road racing use or applications where the lowest possible inertia is a priority. While a flywheel that is lighter than the factory unit can improve performance, the reduced weight of some flywheels may cause issues that can be categorized as annoying and not harmful to the car's operation. On some Subaru applications it may cause a CEL (check engine light). On cars that come equipped with dual mass flywheels, using a very light flywheel may create noises that aren't harmful, (called torsional vibration) but will be audible. On some applications it may require greater throttle input to get the car moving smoothly especially on inclines or steep grades.