Start Here

Using the vehicle selector to the right will present you with the correct selection of parts relevant to your specific vehicle.

Clutch Friction Materials Explained - Organic, Kevlar, Ceramic, etc.

It's hard to buy a replacement clutch, at least if you want to understand what you're buying. Between the variations in design, the jargon, and the lack of specifications, things can be confusing. Clutch manufacturers don't exactly make it easy, either. Many of the companies selling "performance" clutch kits are tricking consumers. They use bright paint and confusing terminology to make their products look good. They're hoping that consumers won't ask questions.

At Phoenix Friction, we want you to understand the clutch you're buying. This is why we created the clutch friction material comparison guide below. Every clutch friction material has pros and cons. If you understand what they are, you can buy a clutch that makes sense for your vehicle.

NOTE: If you'd like to view an image of the information below (or borrow the image for your own site), click here.

logo

Few auto parts are as mysterious as the modern clutch. From confusing and misleading industry jargon, to common misconceptions about clutch function, there's a lot of bad information out there.

Here's a rundown of the six common clutch friction materials with data and details that will make you a clutch expert!

Clutch 101

clutches

When the clutch is engaged, a spring-loaded clamp called a "pressure plate" pushes the clutch disc onto the flywheel, connecting the engine to the gearbox input shaft and the rest of the driveline.

The clutch disc ensures a smooth transition during every engagement, while also standing up to the abuse of this action.

If the clutch disc is going to last, it must be covered with a friction material that:

1) Can withstand the torque and RPM of the engine

2) Can withstand the clamping force of the pressure plate

3) Can manage the heat caused by engagement and disengagement

Finally, the clutch is usually required to engage and disengage smoothly (racing clutches, not so much).

clutch


The Six Types of Clutch Friction Materials

1 ORGANIC
Woven organic clutch disc
In almost all cases, woven is better than molded. For most vehicles, a woven organic clutch offers the best combination of performance, durability, drivability, and cost.

Organic facings are typically made from phenolic resins, friction modifiers like metallic powder or metal oxides, and compounded rubber. These facings come in two types:

Molded Facings, which are very affordable but lack strength. When tested at 500° F, an 11" OD/6.5" ID molded facing will burst at 5,000 RPM. At Phoenix Friction, we do not use molded facings.
Woven Facings, which include fiberglass yarn woven into the material to increase strength. The burst strength of an 11" OD/6.5" ID woven facing is over 10,000 RPM.

As you can see, woven organic facings are much stronger than molded facings, which translates to better life and performance.


Woven organic friction materials are commonly used in OEM applications, as they offer a good combination of smooth engagement, wear resistance, and strength.





2 HEAVY-DUTY ORGANIC

Heavy-duty organic clutch facings are similar to normal organic clutches in terms of engagement smoothness, but with more temperature resistance and durability.

Heavy-duty organic clutch facings feature more metallic content, which boosts heat resistance and reduces fade.


This gives these clutches resistance to temperatures as high as 700°F, at least for short periods, as well as increased burst strength.



Heavy duty organic clutch disc
Heavy-duty organic facings are just fine for most towing, hauling, and street performance applications. They're temperature-resistant, strong, and durable but still smooth.





3 CERAMIC
Ceramic clutches

Ceramic cluch button
Ceramic clutches are great for racing situations, where repeated engagement and disengagement leads to high temperatures.

Ceramic clutch facings are made from a mixture of copper, iron, tin bronze, silicon dioxide, and/or graphite. The material is sintered or brazed onto a backing plate, and then often riveted to the main clutch plate.

Ceramic clutch facings can withstand considerable heat - they can operate without fading at temperatures up to 1,000°F. This heat resistance makes them ideal for racing.

Finally, it's important to note that the ratio of static to dynamic friction is quite high for ceramic clutches. This means that ceramic clutch engagement can be abrupt.






KEVLAR ®

Kevlar® and Twaron® are trademarked names for para-aramid fibers that are often used to make clutch discs. Kevlar® and Twaron® have two key benefits: longevity and smooth engagement.

In terms of longevity, Kevlar® and Twaron® facings last 2-3 times longer than organic facings, all things being equal. Additionally, these fibers have a low static-to-dynamic friction coefficient, making them an ideal choice for applications where smooth engagement is essential (such as off-road driving, rock crawling, etc.).


While Kevlar® facings require higher clamping pressures than most materials – and have a long break-in period (1,000 miles) - their durability makes them a great choice for vehicles with stock or slightly modified engines.



Kevlar clutch disc
Kevlar®-type materials offer smooth engagement and last a long time. In terms of torque rating, however, a heavy-duty organic facing is often stronger.





5FERAMIC
Feramic clutch disc

Carbotic clutch facings are great for powerful diesel trucks. Otherwise, feramic facings are strictly for racing where quick lock-up is most important (like the drag strip).

With a high coefficient of friction and a high static-to-dynamic ratio, most feramic clutch facings are strictly for racing applications where quick lock-up is most important.

Feramic facings are made from a combination of steel, silicon dioxide, tin bronze, and graphite. Feramic facings can be full across the face or they can be buttons.

A special type of feramic clutch facing - known as a carbotic facing - is used in truck applications, offering ceramic-like temperature resistance with smoother engagement.





6 FERAMALLOY FACINGS

A newer material, FeramAlloy facings are likely to replace ceramic facings. FeramAlloy offers similar levels of wear and temperature resistance compared to ceramics, but with a much better static to dynamic ratio (and therefore smoother engagement).

FeramAlloy facings also have less "chatter" than ceramic facings.

Phoenix Friction is one of the first clutch manufacturers to begin offering FeramAlloy facings for use on heavy-duty applications (diesel trucks, commercial trucking, etc.).

For more information, visit PhoenixFriction.com.









Clutch Friction Materials Data

In order to understand the differences between clutches in terms of engagement and durability, we've assembled some friction coefficient (expressed as "µ") and fade temp data below.

Basically, the higher the temp, the more severe the application.


Type µ Range Fade Temp. (°F) Best Use
Woven Organic 0.25-0.3 600 Daily Driver
HD Organic 0.25-0.3 700 Most Street Performance, Towing, and Hauling Applications
Kevlar® 0.35-0.37 500 Longevity; Off-roading
Carbotic 0.45-0.48 750 Heavy-Duty Hauling and Towing; Commercial Trucking
Ceramic 0.4-0.6 1000 Racing
Feramic 0.5-.055 1000 Racing/Agricultural
FeramAlloy 0.4-0.6 1000 Heavy Duty Hauling and Towing; Commercial Trucking








If you take nothing else from our guide, we hope that you've learned how to spot a fake performance clutch. A real upgraded clutch kit is not an OE-spec replacement slathered in bright paint.

What's more, when you buy a clutch, be sure to call the manufacturer and ask two questions:

  1. What clutch material am I buying?
  2. Why did you select that material for this application?

If the manufacturer can't answer these questions - or if the explanations don't make sense - don't buy. There are plenty of clutch manufacturers that make good products.