Back in July of this year, we introduced our newest project car, Project Lucky 13. If you’ve read the introduction article, you’ll know that our ’13 Camaro was purchased at an auction as a theft recovery vehicle, with plans for a new 7.0-liter LS7 V8 powerplant and a Tremec TR6060 six-speed manual transmission.
Since we plan to take our road-racing Camaro to as many track days as possible, we wanted to equip it with a clutch that can handle the abuse. For that, we hit up Mantic Clutch for advice on choosing a clutch for our unique track-inspired project build.
Our all-new LS7 crate engine will benefit greatly from a new Mantic clutch upgrade.
What Is Our Goal?
For a Street and Track Day vehicle, the sprung hub ceremetalic discs will take a lot of abuse. – Geoffrey Gerko, Mantic Clutch
Our Camaro was originally equipped with a GM six-speed automatic transmission. However, when we purchased the Camaro at an auction, the car was a theft recovery. The thieves had stripped the car of its factory engine and transmission. Although our plans call for this Camaro to serve primarily as a daily driver, we still want to road-race the car and hit up the occasional canyon run or track day as much as we can.
That’s why we’ve decided to convert the car to a more corner-carving oriented Tremec TR6060 6-speed manual transmission rather than simply install a replacement automatic. With high performance in mind, we’ve also decided to forgo using the OEM clutch that was included on our LS7 crate engine, in favor of a unit that will handle the extended-abuse of our daily-driven road-racing application.
Geoffrey Gerko, North American Sales and Technical Manager at Mantic offered his expertise and helped educate us on how to choose the correct clutch for our application. Our goals for Lucky 13 dictate the need for a high-performance clutch assembly that can handle the abuse, without sacrificing street drivability. Gerko says, “For a Street and Track Day vehicle, you really can’t beat the sprung hub ceremetalic discs. Excellent drivability, smooth engagement and the ability to take a lot of abuse.”
Choosing A Clutch For Our LS7-Powered Camaro
Mantic 9000 Series Sprung Street Cerametallic Twin Disc Clutch Kit
What’s in the box:
Two 9-inch Twin Centrametallic sprung centre cushioned button-type clutch discs
Gerko recommended Mantic’s 9000 Series Sprung Street Cerametallic Twin Disc clutch kit for our application (PN M921205). The twin-disc clutch kit is composed of two, nine-inch diameter sprung center cushioned button-style discs made of a cerametallic material. The kit also includes the necessary pressure plate, flywheel, slave cylinder, and all of the required hardware and fittings. Gerko informs us that the kit has been assembled and rigorously tested before it even steps foot in our shop, which is an added peace of mind, as we’re still in the process of building the car.
The included Mantic 9000H series flywheel features a machined billet steel construction, and is considerably lighter than the OEM counterpart. During the installation we found that the new flywheel weighed a full 10 pounds less than the OEM LS7 flywheel. The flywheel provided in the kit is designed to mimic the characteristics of the OEM assembly, at only half the weight. This implements a tolerable level of NVH, while improving performance by decreasing the amount of rotating mass on the drivetrain.
The clutch assembly has a rated torque capacity of more than 1,000 lb-ft of torque at the crank. This leaves plenty of room for us to grow once the car hits the track. The LS7 crate engine has yet to be installed on our ’13 Camaro, which made installing the new clutch a breeze for us. Normally, this would have required us to remove most of the exhaust, the transmission crossmember, and the transmission to perform the installation.
Top left: The OEM LS7 clutch assembly before removal. Top right: Removing the OEM clutch assembly. Bottom left: Installing the new lighter Mantic 9000 series twin disc assembly. Bottom right: Complete installation of our new high-performance twin disc clutch assembly. With our LS7 crate engine on an engine stand, installation couldn't have been any easier. Removing the factory clutch assembly begins with removing the pressure plate and the single clutch disc, followed by unbolting the OEM six-bolt flywheel. Installing our new Mantic clutch was a breeze, as the process can be completed in a reverse order of the disassembly.
Considering A Clutch Choice
Mantic offers a variety of clutch disc materials depending on the application and the goals for the car. Gerko has over a decade of experience in the industry, and an extensive background on the materials and contrasts.
We inquired with Gerko what the benefits of our kit using a cerametallic material are. He says, “Cerametallic is a combination of ceramic and metallic material. It has an excellent coefficient of friction and provides exemplary heat resistance and smooth engagement properties. The material bonds very well to itself even in the thinnest of areas. Cerametallic material also has a consistent wear pattern, which greatly aides in the life of the clutch.”
He continues saying, “The choice of Friction Material will have a significant effect on Drivability. We work very hard to match the correct material with the intended use of the vehicle to best serve our customers. For Project 13, the benefits of the kit we provided is a clutch assembly with OEM drivability that will confidently handle over 1,000 lb-ft of torque at the crank. This gives you the best of both worlds; smooth drivability to get to the track and excellent durability while you are turning some laps.”
Gerko also relays the pros and cons of some of the more common materials used below.
Pros: Smooth engagement, excellent drivability, and moderate coefficient of friction.
Cons: Resistance to excessive heat build-up. Organic material clutch discs are mostly used in OEM applications, and are not meant to hold much power over the factory output.
Pros: Very consistent and will hold up to repeated abuse.
Cons: This material is for a race-only application. The engagement is extremely aggressive, and is not ideal for street use.
Pros: Moderate drivability and moderate resistance to heat build-up.
Cons: Poor coefficient of friction. This material requires an immense amount of clamping force to engage and disengage. Pedal feel is also sacrificed immensely.
Pros: Smooth engagement, decent drivability, and good coefficient of friction for heat-resistance.
Cons: For Carbon to work properly, it must be of the correct blend and weave; otherwise, it will fail quickly.
On the left side is the OEM LS7 clutch disc. While the stock clutch does an adequate job of holding the original 505 crank horsepower, though our application will benefit from upgrading to a smaller, lighter, and stronger assembly for the road course. The new Mantic clutch assembly on the right uses cerametallic clutch discs which are leaps and bounds above the OEM organic material clutch disc.
Engaging In Technology
Every clutch kit has it’s own advantages over another, with drivability and torque capacity as the most preeminent factors. Gerko explained to us that there are considerable advantages with a twin-disc composition clutch kit. He says that a smaller diameter, multi-disc unit is more ideal than a larger diameter, single-disc unit for greater overall drivability and torque capacity. Take a look at how we explain the differences below in greater detail.
Our new 9000H series billet steel flywheel from Mantic on the left side saved us a total weight of 10 pounds of rotating mass during the upgrade. That weight savings will contribute to a sharper throttle response.
Advantages of a multi-disc clutch include:
Increased torque handling.
Decreased pedal effort due to lighter weight, smaller diameter clutch discs.
Decreased moment of inertia.
Increased torque capacity with every additional clutch disc added.
Disadvantages of a single-disc clutch include:
Decreased torque transferred due to larger diameter, heavier clutch disc, which increases parasitic loss of horsepower.
Prone to excessive heat due to the single surface area being larger, leaving more of an area to cover when heat begins to dissipate.
Increased pedal effort due to larger diaphragm, impacting overall drivability.
Understanding Torque Capacity And Clamp Load
Per Gerko, “The Torque capacity of a clutch is affected by several factors. The main contributors are: clamp load, mean effective radius, coefficient of friction, and the number of friction surfaces. The multiplication of these factors is what determines the theoretical ‘maximum amount of torque’ the clutch can transmit. Mantic takes this number and puts in a conservative safety factor to account for the way the clutch will be used and driven. In reality, the Mantic clutches have a higher torque capacity than the rating suggests. It’s very rare that we see a clutch fail due to lack of capacity, as it’s almost always equated to use and rather abuse of the clutch. Things like excess slipping, riding the clutch, or even things like sitting at a stop light with your foot on the clutch pedal have adverse effects.
Mantic also makes use of a lower moment of inertia (MOI) which is a term sometimes misconceived in the industry. MOI is simply defined as the amount of force it takes to accelerate (or decelerate) a body about a central axis. In this case, how much horsepower must be exerted to speed up the flywheel and clutch assembly as well as moving the vehicle. The larger the diameter, the more power is required; and subsequently, the less which is available to put to moving the vehicle forward. This is where the Mantic 9000 series takes best advantage of MOI, by utilizing smaller diameter discs. Allows more power to be transferred to the pavement.”
Take a look at this flowchart Mantic was able to provide to us regarding the information above.
We’ve learned that pairing the right clutch to the correct application really is crucial. We have big plans for our project Camaro in the future, and upgrading the clutch is a fantastic safeguard for future upgrades. Gerko states, “The most important thing to remember with a cerametallic-clutch is to follow the proper break in and bedding procedure. It’s not complicated; drive the car a minimum of 500 miles, making routine stop and go driving before you perform any dyno testing or wide open throttle pulls. This allows the discs to properly bed themselves and transfer an ample amount of material to the friction surfaces, ensuring a uniform coefficient of friction for the clutch assembly.”
This allows the discs to properly bed themselves and transfer an ample amount of material to the friction surfaces, ensuring a uniform coefficient of friction for the clutch assembly. – Geoffrey Gerko, Mantic Clutch
Gerko adds that if the break-in procedure isn’t followed correctly, you can expect lose up to 30 percent of the total amount of clutch torque capacity. Yikes. He also says that the kit won’t require any additional maintenance, and to always follow proper driving etiquette on the street.
We were able to shed an impressive amount of weight with our new clutch assembly from Mantic, ultimately reducing rotating mass on the drivetrain, and increasing available horsepower which was lost due to parasitic loss prior. With the new assembly, we were able to shed just shy of 15 pounds. At the same time the clutch assembly is also able to handle more torque which should translate into a more reliable clutch as our project evolves.
With the current unmodified LS7 engine capable of 505 horsepower at the crank, our new twin clutch disc assembly is plenty enough to handle the power, and more. Stay tuned for our future updates on Project Lucky 13.