As the miles have racked up on our '05 GTO, we began to notice the clutch was wearing out. Though the factory clutch on the LS2 GTO has served us well for over 58,000 miles, it began to show signs of slipping with a few of our recent power additions and some heavy use at the track.
To better wade through all the clutch choices available in the aftermarket, we sought some direction. We got in touch with James Pogrebetsky of Billet Prototypes on LS1gto.com and explained our situation to him. The GTO is constantly at autocross events and occasionally the road course. It sees street duty nearly every day and there are plans for some more power. There's nothing worse than investing money in a new clutch and finding that it won't hold the power.
Which Clutch?
After hearing our concerns, James suggested the Monster Level 3 clutch with one of the company's lightweight billet-steel flywheels. "The Level 3 features a fine balance of perfor-mance and comfort," he says. "It's not uncom-mon for people to experience clutch chatter and poor driveability on a high-performance clutch, but the Level 3 has been great at minimizing that. When properly broken in, chatter is kept to a minimum." As a distributor for these clutches, he has a lot of experience with them.
Clutch chatter is no fun. It occurs when you begin to release the pedal and the clutch disc pucks are trying to grip the pressure plate as it rotates, constantly gripping and releasing. This causes the car to shudder or vibrate when you take off from a stop. It's embarrassing, and can be destructive to the clutch and drivetrain. Sometimes it's just inherent in the design and can't be prevented with a break-in procedure. Monster claims its design minimizes it or eliminates it all together.
A quick look at the Monster lineup shows an impressive cast for increased power support. Level 1 is designed as a stock replacement that can handle a little more grunt, around 425 hp. Its carbon-organic compound does this with the help of the Monster heavy-duty pressure plate and SFI-certified flywheel options. The next option is Level 2, which has a claimed holding power of around 525 hp/tq. It's a dual-friction design and is marketed as having a smooth engagement.
With our new Monster Level...
With our new Monster Level 3 clutch and lightweight flywheel, our '05 GTO negotiates the twisties with a more responsive engine and a better gripping clutch. Shifting was made easy thanks to the smooth GMM Ripshift shifter, too.
Our clutch was shipped in...
Our clutch was shipped in this sturdy wooden box; they are now shipped in heavy-duty cardboard boxes that protect all the components inside from shipping damage. This is very important when dealing with parts that are precision balanced. Included is the clutch alignment tool, pilot bearing, throw-out bearing, flywheel, disc, and pressure plate. If you purchase the Premium package from Monster a new slave cylinder will be included as well. Note the trademark Monster green on the pressure plate.
Here is Monster's billet steel...
Here is Monster's billet steel flywheel (left) and lightweight billet steel flywheel (right). There is a 10-pound difference between the 18-pound aluminum and 28-pound standard unit. This is where your engine gets its more responsive throttle. The reduced weight helps the engine rev quicker, assisting in positive downshifts. There were no balancing issues either as all Monster clutches come balanced from the factory. (Note: like our shipping container, Monster now uses a different flywheel design that is made in the U.S. You can see these new units on Billet Prototypes or Monster's website.)
The Level 3 is the most popular clutch that Monster makes; it has a reputation for holding big power in heavy cars. The claim is that 700 hp/tq is no problem for this cera-metallic-material clutch. It's also a multi-puck design, unlike Levels 1 and 2. Level 4 was designed for engines over 700 hp/tq to 775. To take things even further, Level 5 was introduced for cars making 825 hp/tq and for those pushing 900 hp/tq, there is the insane Level 6.
Since our GTO was putting out less than 400 rwhp, the Level 3 would allow for a substantial power increase in the future. For this clutch and flywheel upgrade, we originally wanted to include before-and-after dyno testing, but our factory clutch was slipping too much on the dyno, so we were forced to leave it out.
Why Choose A Lightweight Flywheel?
The lightweight billet-steel flywheel's reduced weight over the stock steel one is a big plus for our intended application of autocross and open track use. The benefits go a little deeper than just rotating mass, however.
On a road course, you're constantly rowing through gears. Typically 2-3 and 3-4 upshifts with 4-3 and 3-2 downshifts. The more responsive your engine is, the better your chances are of achieving that perfect downshift with a crisp rev-match. Bolting Monster's lighter flywheel behind our engine reduces rotating mass by roughly 10 pounds, which is a considerable amount.
The downside is that an already "grippy" clutch has less rotating mass to clamp onto thanks to the lighter flywheel. This, in theory, could cause the clutch to react differently than drivers are used to, but it can be overcome with some seat time.
Since installing shifters...
Since installing shifters on the late-model GTO is a royal pain that requires lowering the transmission, we decided to install a GMM Ripshift shifter while the transmission was out of the car. (We covered an installation on this shifter in 2006. Therefore, visit highperformancepontiac.com to see the full installation on this car.)
There really is no comparison...
There really is no comparison to the stock shifter, which incorporates a multi-linkage system, and is cumbersome and indirect. GMM's Ripshift shifter is built in Australia and is available through Speed Inc. It has extremely strong centering springs that prevent any accidental 2-1 shifts, helping you slide into the 3 gate with ease. Best of all, it has a solid feel, unlike the "knife in a mustard jar" factory shifter.
The first task is to remove...
The first task is to remove the center console inside, which is easily done by removing this screw underneath the radio stack. After that, the console cover can be pried up and the shifter boot goes with it. The shifter is then removed.
Johnny and Jose then carefully...
Johnny and Jose then carefully remove the factory two-piece driveshaft. Three 18mm bolts and three 19mm nuts hold it in.
Next Johnny Ramirez and Jose...
Next Johnny Ramirez and Jose Morales from D Revolution Motorsports remove the exhaust. Since our GTO has American Racing headers, the mid-pipes can be slid off with the Corsa crossover pipe.
After disconnecting the reverse...
After disconnecting the reverse lockout solenoid, speed sensor, and hydraulic line to the throwout bearing, Jose supports the transmission with an adjustable transmission jack before removing the four 16mm bolts that hold the transmission crossmember.
Once they remove the eight...
Once they remove the eight 13mm bolts that hold the transmission to the bell housing, it can carefully be lowered on the jack. Johnny chains the transmission to the jack once its clear of the car to prevent it from slipping off.
With the factory clutch exposed,...
With the factory clutch exposed, Johnny and Jose unscrew the six 13mm bolts that hold the bellhousing, and remove the clutch by taking out its six M-10 x1.50 bolts.
Here Johnny holds the Monster...
Here Johnny holds the Monster Level 3 clutch disc (left) next to our worn factory disc (right). You'll notice that the Monster clutch disc uses what is called a "multi-puck" system. According to Johnny, the benefit to the multi-puck system over the factory style is that "the clutch may have less surface area, but its cera-metallic material is considerably more aggressive than the factory clutch disc, so the holding power is increased." That puts us right in line with our goals for a more responsive pedal around the autocross and road course.