Choosing a Clutch

We've covered the various parts of the clutch system, but now comes the difficult part: choosing which clutch is best for your application. Choosing the correct aftermarket Mustang clutch for your application means taking into consideration several operational features, including:

• clutch feel
• operating temperature range
• wear characteristics/durability
• clamping force
• the break-in period
• the clutch material

There are a lot of people that believe that if you choose a clutch made of extremely aggressive material, it will be better for the car, no matter what situation you drive in. This is actually not true. Choosing a clutch that is too aggressive for the driving you do means compromising on some of the above features.

NOTE: Every clutch, regardless of type, has a break-in period. This means you need to be careful not to overheat from excessive slipping. Always follow the suggested break-in guidelines, or you risk clutch failure.

Before you buy a clutch, you need to ask two questions to understand the characteristics of your car:

1. How much power does your Mustang make?
2. How is it used? (street driving or track use, or a combination of both)

You’re also going to want to know which type of disc you will need – puck-style or full disc? Should I get one with or without a torsion dampener? And what material should the clutch disc be made of? Should you go with a compound or Kevlar, or a Carbon-Kevlar mix? What type of flywheel should I get: steel or aluminum? The amount of information out there can be dizzying, but we’re here to make sense of it for you.

Types of Discs

There are two types of clutch discs – full discs and puck-style.
Full Disc
You will find that OEM replacements, and aftermarket clutches meant to be like stock, usually have full disc clutches.

Puck-Style Discs
These discs – available in multiple puck configurations – cool better than full discs. This style of disc is usually found in clutches meant for racing applications.

Torsion Dampener

Clutch with a Torsion Dampener
Also called the sprung hub disc, in this type of disc, the hub floats in a spring loaded assembly, which is attached to the carrier plate – the circular metal plate that holds the friction material. When the hub is loaded – when the clutch is engaged – the springs help absorb the load, rather than transfer it directly to the carrier plate. This keeps the shock of aggressive engagement from damaging the drivetrain.


Example of a clutch with a torsion dampener.
In the clutch plate on the right, note the spring loaded circle that surrounds the hub.

Clutch without a Torsion Dampener
In this case, the hub is connected directly to the disc carrier plate.

Example of a clutch without a torsion dampener.
In the clutch plate on the left, note that the hub is riveted directly to the plate.

Clutch Disc Material

There are many different types of material used on clutches. It would be impossible to go into detail about all of them, so let’s just talk about the most common ones.

Organic
Organic really means that the clutch disc is made of a blend of several different materials.
The disc is generally steel-backed, and the material includes metal fibers that are woven into a multi-compound material. Most stock clutches are made of organic material such as fiberglass, which is similar to a brake pad.

Clutches made of organic material are generally very similar to the OEM clutch, and are known for smooth engagement, long life, broad operating temperature, and a very low break-in period. An organic clutch will stand up to hard use, but it won’t be able to take repeated abuse because it will overheat. However, as long as you don’t continuously overheat it, it will return to almost full operational condition when it is overheated.

Carbon-Kevlar Mix
The materials in these discs are segmented together to make a very friendly material for your car. A disc made of this material has a similar feel to stock.

Kevlar
Kevlar is a highly durable material that is more resistant to hard use. It has similar engagement to discs made of organic material, but it may glaze slightly in stop-and-go traffic. However, with Kevlar, once you’ve broken in the disc, if it glazes over it doesn’t stay that way. It can overheat and will go back to its original state once it has cooled down. This doesn’t mean you can completely cook the clutch and have it still be okay, though. If you “cook” your clutch, the disc will not return to its original form.

Ceramic
This is a more aggressive material, so it will hold more power. However, there will always be some clutch chatter – the rough grab and release that comes when there is no slipping – with ceramic discs.

Hybrid Carbon/Ceramic/Organic
These discs have organic material on one side and a segmented carbon or ceramic material on the other. The idea behind these is that the organic side will help smooth the engagement and reduce the shuddering from the segmented side. However, they can be used in the same situations as regular organic clutches, though the carbon or ceramic side will wear the flywheel and pressure plate surface faster in traffic situations.

Carbon
Carbon is a material that can withstand a lot of heat. However, clutch engagement is more abrupt, and the flywheel surface will wear faster, especially in traffic situations. Still, carbon is more flywheel-friendly and slightly more durable than ceramic.

Ceramic
Like carbon, ceramic discs can also withstand a great deal of heat – more than carbon. Ceramic discs will cause the flywheel to wear faster, and puck-style discs with ceramic can result in slight shuddering when used in stop-and-go traffic situations.

Sintered Iron
This is the type of material you want your clutch to have if your Mustang is strictly a racing car. Clutch discs made of sintered iron can withstand very high temperatures, and will accommodate more that 700 hp. Engagement is immediate on or off, and a clutch disc made of this material will require a special flywheel surface.

A sintered iron disc is primarily used in high-horsepower, endurance racing applications. If you run quarter-miles only, than this is not the clutch for you. Clutches like these do not work as well when the weather is cold, and a high-durability flywheel surface is required. If you use a standard flywheel with a clutch disc like this, be prepared to change it out after every race.

So, how do I choose a clutch?

At the risk of being repetitive, DO NOT BUY MORE CLUTCH THAN YOU NEED. If you have a mildly modified car, you don’t want to purchase a clutch that is meant for a racing application, and vice versa. Putting a clutch meant for street driving on a race car means that it will not last as long as you may need it to.

A simple organic disc will handle a very wide variety of use, including street driving and racing. A Kevlar disc is a good choice for a Mustang that races heavily on the track or the road, especially if you have forced induction. Carbon and ceramic discs should be left to high-horsepower Mustangs that see lots of drag racing, or are only track/drag cars. And sintered iron should only be used on high-horsepower, endurance racing Mustangs.