The Centerforce clutch features a patented design, which relies on centrifugal force to increase its clamping pressure. The Centerforce clutch features weights attached to its diaphragm fingers. With rpm, these weights move outward and exert more pressure to the clutch-plate surface, the clutch disc and the flywheel. The result is a much greater clamping force, without heavier springs or a stiff pedal.
Centerforce offers three street versions of this clutch system. The original Centerforce I offers 30 percent more clamping power than an OEM clutch and is a great upgrade for a stock vehicle. The Centerforce II boosts the clamping pressure by up to 60 percent over OEM. It is recommended for mildly modified rigs and works well for heavy towing, commercial use and general four-wheeling.
 Here is where it all started....  Here is where it all started. Perhaps this former pilot bearing was never greased when the truck was built. Whatever the reason, it failed with just 49,000 miles on it. The silver lining to the whole mess is that Jane wound up with a much better clutch. |  On the left, what a Ford Power...  On the left, what a Ford Power Stroke pilot bearing should look like. And on the right, what was left of Jane's bearing after just 49,000 miles. |  A look at the center of the...  A look at the center of the OEM clutch disc shows the center splines tweaked from running on an angle. All other related components also showed signs of angular wear, due to the heavy clutch riding on the unsupported input shaft for thousands of miles. Inside the transmission, the unsupported shaft wore on an angle long enough to finally cause gear shifting to become difficult. Since the ZF tranny and OEM clutch are rather noisy from the get-go, no unusual noises were detected. |
The Centerforce Dual Friction is the company's extreme-duty unit, and the one we chose for Jane. Providing up to 90 percent more clamping force than the stock unit, the Dual Friction is not just a cover, but also includes a disc. Centerforce's disc features carbon-fiber friction material laid out in a puck-type design. The Dual Friction is designed for high-horsepower/high-torque applications and is recommended for extreme four-wheeling.
Installing the Centerforce Dual Friction clutch is no different than installing any other clutch. To go with the all-new clutch assembly, Jane's flywheel was replaced with a new one from Centerforce. This assured that all the clutch-related components were new and balanced to one another. No part of the old clutch system was left in the bellhousing. In fact, even the bellhousing is different, it being integral with the transmission.
Jane has logged more than 5,000 miles with her Centerforce clutch and new tranny, with 3,500 of those miles towing the 9,000-pound load of Killer Bee Jeep and trailer to and through the mountains of Colorado, where she smoked two Dodges (pulling lighter loads) over several 10,000-foot passes. So far, the clutch has worked flawlessly. The only noticeable sign that major surgery has occurred is that the pedal pressure is slightly lighter than stock. This belies the fact that a much stronger clutch resides at the other end of all that plastic spaghetti. It is reassuring to know that Jane's clutch is now up to the task of dealing with her considerable power.
Along with clutches, Centerforce offers SFI-certified billet flywheels, allowing you to create a matched set for your new clutch. Modern hydraulic linkages offer no adjustment, and have very little tolerance for flywheels that have been turned down more than a few thousandths of an inch. When installing a new clutch, you always want to start with a fresh surface on the flywheel. By machining your old flywheel on a lathe, you achieve that new surface, but you cut down the overall thickness of the 'wheel. Cut too much, and the hydraulic throw won't compensate. You may find yourself thinking you've worn out a clutch in 40,000 miles, when its only the linkage that can't travel far enough to make up for the few thousandths of wear that's happened to the disc in those 40,000 miles. To avoid all this, a new Centerforce flywheel was installed in Jane.
All installed and ready for a tranny. All Centerforce clutch assemblies are fully balanced and they install just like any other clutch. In 5,000 miles of use, with more than half those miles spent towing something, Jane's new clutch has provided smooth engagement and a light pedal feel. Overall, she gives no hints that she has had major surgery.
Plain Jane - Part 1
Plain Jane - Part 2
Plain Jane - Part 3