C5 Corvette Clutch And Flywheel - C5 On A Shoestring

Our Drivetrain Buildup Gets Underway With A Clutch-And-Flywheel Upgrade

Rob Crum Dec 26, 2006 0 Comment(s)
Vemp_0612_01_z C5_corvette_clutch_flywheel New_performance_parts 1/12

The new Fidanza aluminum Flywheel, S.P.E.C. Stage 2 clutch parts, and Mid America-provided GM master and slave cylinders await installation on our Shoestring C5.

As laid out in the first installment of our "C5 on a Shoestring" series, our plan is to extract Z06-quality performance from our '97 coupe for substantially less than the typical asking price of a pristine late-model Vette. Since engine performance is critical to our project, the first order of business involves upgrading the driveline to handle the increased power. And, as many modified-C5 owners will attest, the driveline hardware most in need of fortification is the clutch-and-flywheel assembly.

After researching the various market offerings, we decided that a Fidanza aluminum flywheel (PN 198571; MSRP $379.99) and a S.P.E.C. Stage 2 Kevlar clutch kit (PN SCA 092; MSRP $429.99) would meet or exceed our demands while staying well within our budget.

Aluminum flywheels have long been the preferred choice in performance applications, since they sap less horsepower and place less stress on the engine than do heavier steel units. This particular flywheel is milled from 6061 T-6 aluminum, which combines light weight and high strength with excellent heat-dissipation characteristics. The friction surface itself is 1050 high-carbon steel, which is secured with military-grade fasteners. The shrink-fitted ring gear, also 1050 steel, is heat treated and secured using Grade 8 button screws. This flywheel works with any type of clutch disc, including Kevlar, ceramic, sintered metal, and organic material.

Vemp_0612_02_z C5_corvette_clutch_flywheel Original_clutch 2/12

These photos show the original clutch, just prior to removal.

Since we will be using our C5 primarily for street duties, with occasional forays onto the strip and track, the S.P.E.C. Stage 2 clutch was a natural choice. It is specifically designed for mild to moderately modified vehicles whose drivers demand both long life and superior driveability out of their driveline parts. The Stage 2 kit comprises a high-clamp-pressure plate with a high-torque spring hub that resides over a pure Kevlar disc. The package also includes a performance roller throwout bearing, as well as a clutch-alignment tool that is custom-fitted to the splines of our system.

Considering all the work involved in installing a new clutch and flywheel in our C5, it made sense to also change out the clutch hydraulic master and slave cylinders while we were at it. We called upon our friends at Mid America Motorworks, who supplied us with the proper GM/AC Delco units for our '97 (PN 614331 and $164.99 for the master cylinder; PN 6143321 and $119.99 for the slave assembly).

Vemp_0612_03_z C5_corvette_clutch_flywheel Slave_cylinder 3/12

A close-up view of the original slave cylinder shows why it's typically a good idea to replace this unit along with the clutch-and-flywheel assembly.

Even though many of the installations we will perform on our C5 can be completed in a home garage, when it came to the clutch assembly, we decided to enlist the services of a professional. In fact, unless you have a lift, specialty jacks, power tools, and several very good buddies to help you, using an experienced Corvette technician is probably the way to go.

Here's why: Although the C5 does have its clutch and flywheel attached to the crankshaft, as has been done with all Vettes since the '53, the car's driveline differs from that of its predecessors in one significant way. Starting in 1997, the transmission was no longer installed directly on the bellhousing. Rather, it was attached at the rear axle in a transaxle arrangement and linked to the bellhousing with a torque tube. As a result, a clutch change is not as simple as it used to be.

In fact, the exhaust system and under-pan covers must be removed, and virtually all of the rear suspension has to be unbolted from the transaxle unit and rear crossmember. You also have to detach both of the axle halfshafts and rear-brake assemblies. Then you can lower the rear suspension and transaxle crossmember (using that specialty jack we mentioned earlier), unbolt the torque tube from the bellhousing, and slide the tube back to free up enough space to remove the clutch, flywheel, throwout bearing, and slave-cylinder pieces.

Vemp_0612_04_z C5_corvette_clutch_flywheel Crossmember 4/12

After detaching the numerous suspension and brake parts, we lower the rear suspension crossmember far enough to allow the torque tube and transaxle to be slid back. It's a very tight fit, and care must be taken to avoid damage.

We spoke with Jeff Harkey, service director at Bill Buck Chevrolet, in Venice, Florida. Bill Buck is a Chevrolet dealership that specializes in new- and used-Corvette sales and service through its "Corvette Connection." Jeff explained that the time the factory allotted for this job is eight-and-a-half hours, for a labor charge of $637.50. Jamie Bogdas, the lead Corvette powertrain technician at Bill Buck, further informed us that the shortest span in which had seen the job done was a still-tedious six-and-a-half hours.

We were even more troubled to learn that several specially designed tools were required for the installation. One in particular (PN J36221) is designed to separate the actuator-cylinder hose from the master-cylinder hose in the hydraulic system. Without it, you may spend a very long time trying to separate the two, possibly damaging them both in the process. With all of this in mind, we decided to forgo trying the installation by ourselves.

Instead, we called on friends Steve Keech, Phil Maltese, and James Gregorius, at Keech's Automotive in Sarasota. The three have extensive experience with high-performance vehicles, even lending a hand in the creation of the new Motion Super Cars. They also build custom race engines for almost every motorsports competitor on the west side of Florida.

Vemp_0612_05_z C5_corvette_clutch_flywheel Torque_tube 5/12

After sliding the torque tube out of the bellhousing, we use additional jacks to hold the driveline pieces in place. As you can see, there isn't a lot of room to work with here.

Once the new parts were installed, we subjected the car to approximately 450 miles of gentle stop-and-go driving. According to the parts' manufacturers, this routine allows everything to seat properly, ensuring both maximum performance and a long service life.

Even driving in break-in mode, we can tell that the engine accumulates revs much more quickly than before, and that the clutch feels more responsive and communicative. Pedal pressure and feel are also back to factory specifications, thanks to the new hydraulic parts. We did experience a little bit of roughness in shifting, most likely due to air's having worked its way into the clutch hydraulic system when we changed out the cylinders. We'll try re-bleeding after the break-in period and let you know if that clears up the problem.

For now, we'll continue to enjoy the freshly restored driving characteristics of our Shoestring C5 and to look forward to the horsepower modifications we have planned in the near future.

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