Evaluating the ACT Heavy Duty Clutch and XACT Prolite Flywheel for the Honda S2000
Vince, our FNG, drives a Honda S2000 that serves as his daily driver. The S2K takes him to work and school day in and day out. However, the Honda also serves as a track day vehicle seeing duty at Willow Springs, Buttonwillow and Cal Speedway. After serving reliably for 80,000 miles the clutch suddenly went out on Vince on his way to work.
We now had a good opportunity to evaluate something. A performance clutch for a daily driver is a tall order. Not only does it have to work smoothly without jerking and being a pain in the neck with a heavy stiff pedal, but it also has to hold more power and stand up to track abuse.
We have found that there are more features and more engineering going into a good heavy duty street clutch than there is in full race clutches, which really only have to hold power and be light. If you are interested in what makes a good dual purpose clutch check this out as we install it and a lightweight flywheel in our FNG's daily.
The ACT clutch's HD pressure plate has a torque capacity of 370 lb/ft which should be more than enough for our intended use. It has a thicker 4 stage heat treated diaphragm spring with 39% more clamping force than the stock Honda pressure plate.
You can see in this picture that the ACT hub has dual springs and the springs are much stiffer than stock. This prevents hard bottoming out and keeps the hub from pounding apart. The center hub and spring retainer is a troublesome area on the stock clutch disc that often breaks and ACT beefs it up using thicker material.
The organic material gives a smooth engagement and is non abrasive for long life while the wire and Kevlar act as reinforcement giving burst strength and helping with heat resistance. Bursting is when the friction material fails and shreds apart due to a lack of tensile strength. Friction material is under both shear and centrifugal load and has to have a degree of strength.
If you look at the edge of the disc you can see a wavy flat spring under the friction material. This is called a marcel spring. It helps make clutch engagement smoother by initially compressing flat as the clutch starts to engage.This gives a more gradual engagement and allows the driver to start smoothly without grabbyness and stalling.