Clutches and Flywheels FAQs

[UltraMagneticAL]

There are many brands and "stages" of clutches and flywheels available in the market. So how do you choose which type to get? Let's start w/ some basics.....

How do Clutches Work?
A little knowlege about how they work may help you understand what you'll need. When you're buying a clutch kit, and the salesman asks you how much horsepower you have, I give you all rights and privelages to point and laugh at him. Then you remind him that clutches hold TORQUE not horsepower (remember, torque is defined as rotational force). Think of it like this: when the engine is running, if no outside force comes in to upset it, it will continue to run. The output function of the engine is to spin the crank as the pistons move up and down. The FLYWHEEL is bolted to the crank, the PRESSURE PLATE is bolted to the flywheel, and the CLUTCH disk literally is sandwiched between the FLYWHEEL and PRESSURE PLATE. The splines in the center of the clutch disk then connect to the main shaft of the transmission which feeds power to the gears (1-5, R), then to a differential, the axles, and finally the wheels. Since no machine is 100% efficient, can you see where you lose a lot of power/torque through the drivetrain?

So how does the clutch actually hold the torque? When the clutch pedal is up, those fingers encircling the pressure plate are pushing the clutch disk (which is connected to the transmission thru the splines as explained above) against the flywheel with X-amount of force. so if the clutch disk is being pressed really hard against the flywheel (which is always moving since it's attached to the engine), then the clutch has to spin also. and if the clutch spins, the transmission spins.

Clutch Stages
In this article, I'll describe the different Clutch Stages as individual components, and not as full kits.

Clutch Discs:
Stage 1 - Organic Discs - offer more grip than OEM
Stage 2 - 6-puck/pad discs - race application.
Stage 3 - 4-puck/pad discs - HARSH, but quicker engagement than 6-puck

Pressure Plates:
Most companies only make two stages for the Accord and Prelude.
Stage 1 - Heavy Duty Application (35-44% clamping force)
Stage 2 - Track Application (88-95% clamping force)
(Stage 3 - High-Torque Application 120-200% clamping force) - if applicable.

Lightened Flywheels
The stock Accord/Prelude flywheel weighs about 22 lbs. Most companies offer a 12-15 lb Light Flywheel or 8-10 lb Ultra-Light Flywheel. Better engine response, less load on the engine, and lower drivetrain power loss are just some of the benifits from using a lightened flywheel. However, the lighter the flywheel, the less inertia it can store. Remember from physics the Law of Conservation of Energy? "Energy cannot be created or destroyed". Well in the case of flywheels, most of the energy is being dumped into the transmission or stored in the flywheel as inertia (there are other outputs of energy, but they're irrelevant to our discussion). The higher the inertia stored, the quicker the stopped car will pickup, but because energy is going into the flywheel as inertia, it takes away from the energy going to the drivetrain.

What Should I Get?
For the average tuner, any clutch kit will do fine, it will just be a matter of preference, ie: how hard you want your clutch to pedal to feel and how directly you want it to engage. Any clutch kit you put together that contains a Stage 2 or Stage 3 disc will engage super rough. The Stage 1 disc will engage like OEM, but can handle more torque. Once you start seeing numbers over 200 ft-lbs TQ, then that's when you'll need to do some number crunching. Different companies have torque capacities for each combination of Pressure Plates and Clutch kits, so plan ahead of time.

When choosing your flywheel, it's important to plan on what duties the car will be performing. If you plan on road racing your car and subject it to conditions where stopping rarely occurs, then you'd want to get the Ultra-Light Flywheel since you'd want most of the energy to be in the kinetic form instead of being stored as inertia. In this case, the energy is almost going directly from the engine to the trasmission w/ little energy interferance from the flywheel/clutch assembly. For all other applications such as drag racing and street use, a Light-Weight flywheel is optimal since you still would need the response from a lighter flywheel, but the stored energy from inertia to give you some pickup from the line.

Feel free to ask questions if something's not clear to you, or add your thoughts if I missed something. Hopefully this article has shed some light on the mystery of this somewhat forgotten, yet very important, modification.

[AgaBoogaBoo]

How hard is it to install a new flywheel? What are some companies you can reccomend for the flywheel?

[UltraMagneticAL]

check out the product list i have posted in the stickies....those are all great flywheels....whatever application suits you best is what you should get. as for installation, it's moderately difficult even if you know your way around the engine/tranny....if you're a complete n00b to handling a wrench, i wouldn't attempt it without the help of someone who knows what they're doing

[Accord02Type-R]

i am planning on going for 75shot wet nx, what clutch should i get? i read your article and it seems like a 4 puck would be good, but does it engage really rough? also fly wheel wise, would ultra light fly wheel have any confrontation with a 75 shot? thanks

[UltraMagneticAL]

4-puck would be too rough hadcore for a low torque setup...

6puck may be stretching it too....a street disk would be sufficient enough for the f23 and nitrous....but you may want to get a harder clamping pressure plate. you'll still be around 200ft-lbs tq while on nitrous....so it's up to you...6puck would be a little rough and the street disk w/ a harder plate would be good too, but if you plan on building further beyond nitrous (maybe turbo?), then the 6 puck is the way to go.

as for flywheels, the ultra light flywheel is more of a road racing type flywheel...you'll save gas while traveling the highways and be putting more power down while it's moving already, but once you stop, you'll notice launching will be more difficult and getting around town will be more tiring.

[Accord02Type-R]

so what would u recommend flywheel wise? because of the 18's i've lost alot of power and i just want to get a lil back hehe, i know my car is not a race car but a lil go is always nice. i think i've lost about 50miles on my tank after i put on the 18s. And for the clutch wise so i should just go with a basic set up? i do plan on turboing it, but not for another 2 years or so, figured if i saved 150 a month i'd have it in 2 years or so haha.

[UltraMagneticAL]

not an ultra-light, but a regular lightened street flywheel is good. a basic clutch setup would be okay, but since you're planning on going turbo later, might as well do balls out w/ the clutch now.

[bonestock94]

im running a stock flywheel with an exedy cerametallic 3puck (thin) sprung clutch with a heavy duty pressure plate with my 75 wet shot.

[MKlein3004]

i am looking at putting new cams,cam gears,intake manifold, you know a little more than your average tuner, so would a heavy duty street clutch and a lightened flywheel be for me. Plan on doing all types of racing, like from 4o's, autoX and drag strip.

[UltraMagneticAL]

any little bit will help out....so yes, either a 6 or 4 puck disk is good along w/ a heavy duty plate. the flywheel will be up to you to either go ultralight or semi lightened....i'd go w/ the semi if you plan on seeing street driving.

[willrasmussen]

I just wanted to take the time to vouch for Clutchmasters in here. I got my stage II clutch and ~9 lb flywheel installed back in late December, and their products are totally awesome. My clutch never slips at all, and the flywheel gave me a really good boost in acceleration. If you get as light of a flywheel as I did you will have to completely relearn to race your car though. I would still definitely recommend getting the lightest one. Even with that and the upgraded clutch my car is still really easy to drive around town.

[UltraMagneticAL]

it may be easy for the driver to control, but it's hell on the engine and transmission to be doing stop and go traffic w/ an ultra light flywheel.

[willrasmussen]

Yeah, you do need to rev a little higher to get the inertia the same as it was with the heavier flywheel. I don't normally drive in rush hour traffic or anything so it's not too bad.

[UltraMagneticAL]

yah, for us cali people, traffic is an everyday thing....something to think about if you live in a heavely populated area also. i'd love to rock an ultra light flywheel, but i can't w/ the amount of traffic and stop and go driving i experience