When you've upped the horsepower on that underhood mill and you're ready to put that power out to the driving wheels, don't neglect the rest of the drivetrain. The extra ponies won't help you fly any faster if any part of the transmission, driveshaft, or final drive fails you. At best, you may be spinning your wheels; at worst, you may end up leaving pieces of your drivetrain on the ground.
For those of you still rowing your own boat or stirring your own soup, which is to say, shifting a manual transmission, the clutch should be a main concern. A clutch is considered an eventual wear-and-tear item anyway. Even with careful driving, many cars will need a clutch replacement by the time they reach 100,000 miles on the clock. Add the HP bump that you created when you followed one of our earlier articles on engine, air intake, or exhaust upgrades, and you're likely looking at drastically reduced clutch life anyway.
The good news is that we at CARiD have lots of choices when it comes to heavy-duty clutch kits. All of the "kits" include clutch disc, pressure plate, and throwout bearing. Many also include a new flywheel and a clutch installation/alignment tool. While I would hesitate to refer to a clutch assembly R&R (remove and reinstall) as a DIY job, if you have access to a lift that gets your car high enough to stand under, and if you have access to either a transmission jack or several buddies to manhandle the potentially heavy gearbox out of the car, you may be able to complete this task yourself. (I personally know of someone who replaced a clutch in his Miata in his driveway.) Be smart, be prudent, and plan ahead whether you pay a shop to do the job or tackle it yourself.
Terminology
When perusing all the performance clutch kits on our site, you will come across a number of terms which are important to understand. We'll list and briefly describe some of these terms below:
- Flywheel: The flywheel is bolted to the rear of the engine crankshaft, and its smooth surface provides a contact point for the clutch disc. While technically not part of the "clutch assembly", the flywheel obviously plays a critical role in clutch performance. Some clutch kits include a new flywheel. With some kits that do not, the clutch manufacturer requires that a new or properly resurfaced flywheel be used with their new clutch kit.
- Dual-mass flywheel: A dual-mass flywheel is a two-section flywheel that acts as an insulation against vibration between the engine and transmission. Dual-mass flywheels tend to be factory fitted on newer and high-performance model vehicles. Some performance clutch kits require that a dual-mass flywheel be replaced with a single-mass flywheel.
- Stage 1/Stage 2/Stage 3 Clutch Kits: Some clutch kits use a Stage Number to help identify the level of clutch performance. Broadly speaking, a Stage 1 kit is for street use; a Stage 2 kit might be best for combined street and track driving; and a Stage 3 kit could be best for only racing. You may even see Stage 4 and Stage 5 kits.
- Clutch friction material: You will come across clutch disc material described as organic, ceramic, cerametallic, carbon, or copper. The more exotic materials will perform better but will be accompanied by higher prices. We suggest that rather than base a purchase decision on the material itself, the performance attributes of the kit be matched to your intended use and driving style.
- Single-disc versus multi-disc clutch: Most OE and indeed, most performance clutch kits consist of a single disc sandwiched between the pressure plate and flywheel. But there are options. Some higher-performance kits include two or even three clutch discs, with a floater disc in between. A multi-disc setup increases the amount of friction material and allows that material composition to be customized for its mating surfaces. Of course, such complexity increases the kit's pricing.
- Puck or pad count: While most clutch discs are completely round and resemble a flat dish, some racing discs sport separate pads, also known as pucks. You may come across 4-, 6-, or 8-puck designs. The pucks reduce the overall size and weight of the disc and allow quicker engagement and disengagement. Tradeoffs include harshness, grabbing, and more rapid wear. Most puck-design clutch discs are for racing applications.
Using The Refine Search Menu
On the left-hand side of the screen, you can access what we call our Refine Search menu to narrow down your clutch kit options. For example, "disc quantity", which refers to multi-disc clutches as described above, can be selected here:
Similarly, the site will display clutch kits which include or exclude a flywheel, by making the appropriate choice here:
In addition to the expected year/make/model and engine family menu choices, you can narrow down your selection based on disc material and number of pucks.
Selecting Your Clutch Kit
When deciding on a performance clutch kit, the two major questions to answer are: how much additional horsepower did you add to your ride, and what type of driving will you be doing? Be truthful with yourself, because it is possible to purchase "too much clutch". Clutch kits designed primarily for racing will be very uncomfortable for street driving. You can expect more aggressive engagement, higher pedal effort, increased gear rattle, and poor drivability in stop-and-go traffic with a racing clutch installed in a street vehicle.
Almost all of the performance clutch kit manufacturers provide plenty of specifications and suggestions about what kind of clutch might be best for your automotive needs. As an example, see the chart below from Centerforce. This chart does an excellent job of comparing performance attributes with intended usage. You will find similar guidance on our website for all of our performance clutch kits.
Performance Clutch Kit Examples
ACT (Advanced Clutch Technology) offers this Heavy Duty Street Single Disc Clutch Kit. Note that the title describes much of what you need to know. These kits are designed primarily for street use. ACT claims that this kit offers increased clamp load, light to moderate pedal effort, organic and copper disc material for better heat transfer, and longer friction life.
The SPEC Stage 1 Clutch Kit uses a molded carbon and organic lining for smooth clutch engagement and long-lasting clutch life. The steel-backed disc allows high clamping loads and tolerates high temperatures. SPEC claims this kit works well for street as well as many track/off-road applications.
South Bend Clutch (motto: "We motivate the shiftless") offers an extensive lineup of performance clutch products. Their Stage 2 Daily Clutch Kit uses organic disc material with a high metal content, resulting in an increased clamp load with little or no change in pedal effort. Many of these Stage 2 kits include a new flywheel (pictured). South Bend Clutch recommends this kit for daily, street, and moderate race use.
The Competition Clutch brand Stage 4 Sprung Strip Series Clutch Kit is for very high horsepower applications. The kit features a 6-puck disc and high performance pressure plate, and includes the needed bearings and alignment tool. Combined, these items provide a 250% increase in torque capacity. Note that with such high pressure and high performance components, a 300-mile break-in period is recommended.
The Centerforce Dual Friction Series Clutch Kit is somewhat unique, in that the included clutch disc has a different facing on each side of it. The pressure plate side has a traditional full facing, for longevity and drivability, while the flywheel side is segmented, puck-style, for a more positive engagement and improved holding capacity.
EXEDY, a well-known name in performance clutches, offers this Stage 1 Organic Racing Clutch Kit. Its features include organic friction fibers bonded with high heat resins, heavy-duty rivets, and a ductile iron pressure plate for anti-burst protection at all temperatures. EXEDY suggests that this is the clutch for cars with a slight HP bump, and for drivers who want a higher clamping load with only slightly higher pedal effort.
While you're shopping for clutch kits in our Performance Transmission Department, don't forget to check out separately-available flywheels (again, some clutch companies don't include a flywheel, but recommend or require a new one). You'll also find clutch linkages, shifters, and even complete manual transmission assemblies. Enjoy your 3-pedal vehicle while you can, and be sure to teach the next generation how to drive a stick!