*Photos by: Fidanza Performance
If you were to ask just about anybody with a performance vehicle what the most commonly upgraded component on their vehicle is, you’ll more than likely hear “clutch” as their response. It totally makes sense, too, because it’s often the one component that sees severe abuse on a regular basis.
Although most of us here are quite familiar with clutches, how they work, what they do and even how to replace them, many enthusiast often find themselves stuck in making a decisive decision when it’s time to upgrade. With so many different choices out there from various manufacturers and materials, it can be relatively confusing when it comes time to making your selection.
Rather than relying on various sources from message forums to the know-it-all at the local weekly car meet, we’ve decided to reach out directly to the experts in the industry. In particular, our friends at Fidanza Performance, to provide additional insight in making the right clutch selection for our vehicles. Fidanza has been producing some of the highest-quality clutch related hardware on the market for years, and with them being so close to us here in Ohio, it made total sense to give our buddy, Jeff Jenkins, a call for a quick Q&A session!
What we’ll be discussing is the various types of materials, application selections, installation tips and tricks and break-in procedures. We’ll also touch on aluminum and steel flywheels, their benefits, how they’re used for various applications and when they’re needed.
Selecting the Right Clutch for Your Application:
GM EFI: Often, an enthusiast will purchase a clutch based on what they’ve read on an internet forum or what their buddy used in his build, as opposed to doing real research and selecting a clutch package that’s right for their particular vehicle. What are some quick tips to consider when making a clutch purchase?
Jeff Jenkins: First and foremost the best tip I can give is to not over buy the clutch, find a clutch kit that has similar power handling capabilities to what you expect to be running when your project is finished or to what you are currently running, you’ll want to have a bit of a buffer but excess is not always better. What works best with a higher power application may not be best for light to moderate powered cars. The clutch although a key component in getting the power to the ground still needs to be able to slip when necessary to avoid larger driveline issues or worst case damages. There are many factors that come into play besides the power rating, however this is a critical one that should not be overlooked.
GMEFI: Because the late-model GM market can vary from LS-swapped third-generation F-cars to highly-modified modern Silverados built for the dragstrip and even the autocross. Should that person base their selection more on the horsepower/torque output of the vehicle, the weight of the vehicle or how the vehicle will be used? Or all of the above?
JJ: All of the above items are key when it comes to choosing the right clutch. However weight is often one of the factors that many people overlook, especially when it comes to engine swaps. A stock LS clutch may handle gobs of power when in a lighter sports car but it wasn’t designed to handle that and move a 1 ton pickup off the line. This is where a performance clutch with a higher clamp load on the pressure plate comes into play. Most high performance clutches will have the ability to transfer the power and handle the weight due to the clamp loads the pressure plates reduce, compared to a stock unit even minimal changes from 10% and up will increase the capabilities and the amount of weight a clutch can handle.
GMEFI: How far can I take single-disc clutch, before it’s time to upgrade to a twin-disc? What are the limitations, and suggested applications of each? For example, we’re currently in the beginning stages of building a supercharged, LS-powered ’84 Trans Am with a 6-speed and a projected output of roughly 700 rwhp. It’s going to be a road race/autocross car that will see just as much street use as it does the track. Which Fidanza application should I choose for a vehicle like this?
“There is no per-say, “best material,” they all have a place in motorsports whether its drag racing, tractor pulls, autocross, or street use.” -Jeff Jenkins
JJ: Single disc clutches have come leaps and bounds over the years and can handle much more power and abuse than previously, without giving up many of the positive driving characteristics they are known for. Knowing the limitations of the friction materials used in clutches is what one should look at before considering switching over to a twin disc clutch. It is a common mis-interpretation that a twin disc will always handle more power and is necessary for higher power street applications,which is not always the case.
Lately many consumers have been introduced to the world of twin discs through the eyes of the OEMs switching some of their vehicles over to them, leading to the usual issue of ” my buddy has one and I should too.” Many times there is a single disc clutch that would work perfectly fine in the place where they are considering a twin disc and sometimes with better results. Cost-wise, twin discs are coming down and allowing more people to consider them when upgrading; this can create an issue because many times they don’t consider the other changes a twin brings along with it. In the end, it really just boils down to the consumer getting all the information that is necessary to make an informed decision between both a single and twin disc setup.”
GMEFI: When investing in a clutch kit, which is the best material to choose from? What are the pros and cons of the following materials?
JJ: There is no per-say, “best material,” they all have a place in motorsports whether its drag racing, tractor pulls, autocross, or street use. The biggest decision one needs to make is knowing what they plan to do with their vehicle. From there they will heave plenty of options based on what type of driving or racing they will be doing. Every type of material has its own set or pros and cons and the consumer should do their research before making their final decision. I have listed a few below for each type of material:
- Organic — This one is great for an everyday driver/weekend warrior, will generally provide an OEM feel without the harshness of a racing clutch, while handling higher power output and abuse over an OEM clutch. This material is known for smooth engagement, long life expectancy and an easy break-in procedure. However it is not a high power handling material and is not suited for constant track abuse.
- Kevlar — This is a highly durable material and holds up well under abuse and higher temperatures than organic. It is similar to an organic with a smooth engagement and can be used in street applications, however it is more prone to issues from temperature variation and if overheated will ruin the disc. It will slip during break in periods and can overheat, great care is necessary while breaking in the disc to avoid glazing the surface and ruining the friction material.
- Ceramic — Great for heavy track use and higher power street applications, it is a very gritty surface allowing for better power handling with less noise and chatter characteristics than some of the other rough materials, but also has a lower temperature rating. It is commonly found in multi disc clutches. This material will wear the flywheel faster than others when used in street applications and is known for chatter or shuttering on street vehicles.
- Carbon – Similar to ceramic with its higher power handling capabilities but is a bit more flywheel friendly and has better wear characteristics, with a lower temperature rating. This material is a better suited for street applications vs ceramic and will usually have less shuttering during engagement.
- Sintered Iron — Is designed for Use in very high torque and horsepower applications such as pulling trucks. I would not recommend this for anything that would be used off the track due to its abrupt engagement and wear characteristics. This style material is known for its on/off style engagement, their is no slipping the clutch and it requires a very high clamping load pressure plate. One very important thing that I want to repeat is that you DO NOT want to buy more clutch than necessary. A simple organic clutch can and will handle a large variety of uses from street or strip to auto cross racing and usually covers the majority of consumers needs. Some racing organizations even require the use of this type of clutch disc which just goes to show its capabilities.
“The number one tip is to always follow the manufacturers recommendations for a correct break in.” – Jeff Jenkins
Clutch Installation Tips/Break-In Procedure
GMEFI: What installation/break-in tips can you offer our readers who typically choose to wrench on their own vehicles, as opposed to having a shop handle the work? How soon is a clutch ready for competition? How long (or quick) is the break-in procedure?
JJ: The number one tip is to always follow the manufacturers recommendations for a correct break in. For example our V1 organic street/strip clutch requires a short break in period with mild driving habits and no racing or spirited driving for the first couple hundred miles, where our V2 ceramic racing clutch only requires one or two hard slips to properly set it. With that being said every manufacturer will have their own set of guidelines for the proper break in requirements and you should always follow them as best as possible to avoid any issues, if you are unsure about any portion, it’s usually best to contact their technical department for better information.
Various Clutch Types:
GMEFI: There are various clutch types on the market from various sources, including 3-puck, 4-puck, 6-puck, multi-disc, windowed, segmented and full face. Tell us more about these different types and for what applications they would be used in.
JJ: Every type of disc will have a unique wear characteristic and are designed for specific uses. When looking at a puck design clutch it is not necessarily the puck count that matters, it is the type of material used on those. A 6-puck organic may not handle what a 3-puck ceramic can, but switch the roles and a 6-puck ceramic may be complete overkill for your street car. Any time you move away from a full face disc you are losing some of the cushioning that the disc offers, which can create other concerns such as shuttering, chatter, smoothness, etc. This is not always a bad thing, but on a street car, may not be suitable or liked for daily driving. This is more of a personal decision on what you feel is acceptable; some have no issues with chatter during the life of the clutch, where others may be completely turned off by a slight shudder during engagement.
Aluminum vs. Steel Flywheels
GMEFI: A common idea is to replace the OEM steel flywheel, with an upgrade to a lightweight aluminum flywheel. When is a lightweight flywheel needed or necessary? Which applications could benefit from them, and which ones wouldn’t?
JJ: Lightweight flywheels are a great source to free up existing power that a vehicle is already making – they do not add horsepower or torque, they allow what you already have to transfer through the driveline to the wheels. They are great for most racing applications and street use with minimal driving habit change needed. Some may notice a small RPM difference in launching a car on a drag strip, usually less than a few hundred RPM, and others on a road course can go into corners hotter and accelerate out quicker.
That being said it is not always better to go lightweight, sometimes you need the momentum of a heavier flywheel such as in rock-crawling or in very heavy vehicles. A lighter flywheel would cause these vehicles to lose their momentum during driving, and either stall, or not have the power to get up and over an obstacle.
GMEFI: We’ve recieved emails from some of our readers in the past, indicating that sometimes they could get a check engine light after installing a lightweight, aluminum flywheel. What is usually the cause for this? What are some of the ways to fix this issue?
JJ: There is a fine line between going lighter and being too light weight. Some manufacturer’s ECMs will see a difference in the rotating speed of the crankshaft and the camshafts, causing the CEL (check engine light) to come on. We have experienced this on some of the newer OBD2 systems and by designing the flywheel with a few less pounds being removed usually solves the issue. The other option that consumers have, would be to purchase an ECM programming system or software, when at the tuning shop they can change the values the system is looking for; therefore, removing the issue along with opening the door to many other tuning possibilities.
Clutch Pedal Pressure:
GMEFI: What are some ways to adjust it and how does clutch selection have an effect on it? What causes high (and low) clutch pressure?
JJ: The pressure plate design is what affects pedal pressure the most. This design is what will either gives a soft or hard pedal feel, and usually the higher the pressure plate clamp load is, then the higher the pedal pressure will be. On most older vehicles this was not adjustable – now this can be changed through the use of a hydraulic throw-out bearing and release setup.
You can also experience issues with pedal effort from clutch wear, misalignment, bad bearings etc. Most drivers will feel the difference as the clutch wears and even notice changes in the height of the pedal.
Many OEMs are switching to hydraulic design as it is more reliable self-adjusting and allows manual adjustments to be made if something does not seem or feel correct, removing many issues or concerns with the above mentioned items. This is a plus for the aftermarket as we can produce clutches to handle more power without the side affects of a stiffer pedal.
Component Mixing and Mashing:
GMEFI: A lot of enthusiasts who are on a budget, will try to piece together a clutch kit on their own from various sources; i.e., Fidanza clutch/Brand X flywheel, etc. For obvious reasons, it’s always best to purchase a flywheel and a clutch from the same manufacturer. But in your own words, can you elaborate a little bit more on why this is important?
JJ: Most manufacturers try to make parts that are of an OEM fit, however when it comes to clutches theirs many different variables that can affect its operation, from overall disc thickness, friction material thickness, hub and spring clearances, etc. If you put together pieces and parts there is a much higher probability that issues may occur, from basic fitment issues, bolt patterns, dowel pin sizing… to clearance concerns on the springs or hub assembly possibly hitting the crank bolts or interfering with the pressure plate diaphragm.
As much as manufacturers try to design their parts to have an OE fitment, once we start redesigning or modifying an existing part you open the door to creating issues, whether it’s a small oversight in clearances or something much larger.
GMEFI: Apart form what’s listed on the website, what makes Fidanza stand out amongst its competition from others in the industry? Tell us more about your manufacturing process and the materials used that differ from those other companies.
JJ: One of the key components to our manufacturing is that it is done here in the United States. We use USA manufactured raw materials to ensure we have the best quality product when completed; from our raw aluminum, to fasteners whenever we can. Other components are of OEM quality to ensure a good lifespan and fitment. We are also SFI compliant on many applications, these go through a rigorous testing process and can only receive this certification if they pass all aspects from fitment to strength and material quality.
“One of the key components to our manufacturing is that it is done here in the United States. We use USA manufactured raw materials to ensure we have the best quality product when completed…” -Jeff Jenkins
Not only our products manufactured in-house but we also design them here in-house to ensure the best quality of fitment, durability and ease of installation. Whenever possible we try to incorporate all key components to make them a direct replacement item that will work with any OEM product.
We pride ourselves on the fact that we manufacture our parts here in USA with US components all while being produced on USA made CNC equipment and believe that to be one of our best attributes. Racing has and will always be an automotive staple here in the states and we hope to continue growing and expanding with it.
GMEFI: Tell us more about your latest products, and perhaps, some of the products you may have in the pipeline for late-model and classic domestic vehicles. What materials/technology do you think we’ll see in the future in terms of clutches and flywheels?
JJ: Our latest releases are all LS-related with the newest one being our Twin-Disc clutch; they will be offered in two levels – an organic full face disc and a cerametallic puck disc. They include a new design for us through the use of an aluminum pressure plate vs the older stamped steel style and the kits will also include our world renown Lightweight aluminum flywheel. More information will be available soon on these.
Rick Seitz is the owner and founder of GMEFI Magazine, and has a true love and passion for all vehicles. When he isn’t tuning, testing, or competing with the brand’s current crop of project vehicles, he’s busy tinkering and planning the next modifications for his own cars.