Ask nearly any classic Pontiac owner about the effort required to actuate the factory-installed clutch. Back in the day I remember being stuck in traffic in my original 1965 four-speed GTO, and the resulting knee pains the next day. We lived with that gargantuan clutch pressure back then because there was no alternative, and we didn't know any better! Not so anymore. After replacing the factory-style unit in a friend's Firebird, we were shocked by the difference a modern clutch can actually make. The reduction in pedal pressure is unbelievable and makes driving a stick shift a genuine pleasure! Plus, since it's not visible to the judges, a restored vehicle still looks stock!
We installed a Centerforce Dual Friction 11-inch clutch: pressure plate and disc assembly (PN CF361675), a self-aligning throwout bearing (PN N1716), and set it all up for the trans input shaft using a 26-spline alignment tool (PN 53026). The transmission is a Muncie M21 (26-spline input shaft) transferring power to a 3.55-geared, GM 10-bolt Posi.
The Dual Friction design distributes pressure evenly, completely around one side of the clutch disc, while the opposite side uses a friction facing to concentrate clamping pressure on the flywheel, maximizing holding capacity. The two friction facings, combined with the pressure plate, create a smoothly activated and awesome gripping clutch. Hence, Dual Friction!
The weights perform a complementing task. As rpm increases, so does the centrifugal force created by the weights. This force pulls up and out, increasing the diaphragm pressure, creating more clamping force through the pressure plate and disc to the flywheel. It's certainly a unique setup that works as well as it looks.
The lucky recipient of this clutch is a 1971 Firebird Formula that has been upgraded with a street/strip 455-cid engine. The clutch that was in the car is an antique finger style that had seen too many stoplights. It was starting to chatter, and that, combined with the leg pressure required, brought about its removal and the installation of the Centerforce unit. A new flywheel to accommodate the larger clutch was also installed. (Always have your existing flywheel surface machined, or install a new flywheel when replacing a clutch.)
Also, always check the height and diameter of the new throwout bearing against the one you removed. They must be identical in height and diameter, or you might wind up with a serious clutch-adjustment problem. The Centerforce bearing is a GM factory replacement style to be used with a stamped steel fork.
Follow along and we'll show you the basics of replacing the clutch in your Pontiac. It can be done with an array of normal car-guy tools, plus a torque wrench and trans jack to support the engine. If you are doing it on the garage floor, always use four heavy-duty jackstands and a dependable floor jack. It's obvious we did the install on a lift, which makes it a lot easier to take the photos.
Having a friend along to help (remove the trans) will also make the job go smoother. You can remove and replace the clutch in several hours, providing you don't run into any unexpected problems. We'll stop the process after replacing the new parts and the bellhousing. You can reinstall the trans, linkage, crossmember, driveshaft, and so on, as you removed them.
Should you choose to make friends with your left leg, contact Centerforce first to discuss which clutch will be right for your driving and leg-muscle needs. Having a factory assembly manual might be a good idea, along with a digital camera during the disassembly, both for photographic reference and for proper clutch adjustment information.
Having a friend along to help will also make the job go smoother
We lived with that gargantuan clutch pressure back then because there was no alternative, and we didn't know any better!