Torque is a stone-cold killer. While its more flamboyant partner, Horsepower, rakes in the magazine headlines and dyno-chart hosannas, Torque wages a quiet but unceasing campaign of mechanical mayhem against your Corvette's drivetrain, methodically seeking out the most vulnerable parts in the hardware chain and reducing them to smoldering handfuls of metallic granola.
Maybe you've been lucky, and your dealings with Torque have thus far been limited to the occasional lurid burnout or spine-straightening blast of straight-line acceleration. But if you ever plan to push your car to its limits on a racetrack, or enhance the output of its engine with aftermarket parts, chances are that your relationship with this twisted dynamo will eventually take a darker turn.
Fortunately, the current and previous Corvette generations are by now something of a known commodity, their chief structural weaknesses having long since been exposed on dragstrips and road courses around the world. Such experiences have prompted the development of a variety of heavy-duty replacement parts intended to better withstand Torque's destructive influence, and knowing which of these parts to deploy throughout your C5/C6's driveline can help ensure that everything stays together as you turn up the wick.
Two of the more failure-prone bits in the factory setup are the stock driveshaft couplers, which serve the dual purposes of attaching the shaft at either end while minimizing the transmission of noise and vibration into the body and passenger compartment. While the couplers work well in normal and light performance driving, their rubber construction makes them ill suited for use in high-output, high-rpm applications.
Early aftermarket replacement couplers were made of solid aluminum, which solved the frangibility problem at the expense of greatly increased NVH levels. The solution, developed by Prothane, came in the form of an aluminum coupler equipped with heavy-duty polyurethane bushings. Dubbed the Six Shooter for its resemblance to the cylinder of a revolver-type firearm, this unit is claimed to combine the durability of a solid-metal piece with the vibration-quelling properties of the factory rubber coupler.
When an acquaintance's '01 C5 went into the shop recently for a clutch replacement, we capitalized on the opportunity to obtain a pair of Six Shooters from Vette-parts mega-retailer Zip Corvette and bolt them up in place of the stockers. Zip VP Justin Abbott has installed the Six Shooters on numerous C5s and C6s in the recent past, so he has considerable insight regarding the need for this upgrade.
"Any [car] that is getting sticky tires, for either drag racing or road racing, or power adders such as a supercharger, turbo, nitrous--even a head-and-cam package" is a good candidate for the Six Shooters, Abbott told us. He added that manual-trans cars have a higher risk of coupler failure than do automatic ones, due to the higher shock placed on the driveline by the more-direct flywheel/clutch interface.
With our Six Shooters in hand, we moseyed over to Seffner, Florida--based performance tuner AntiVenom to document the R&R. Follow along as we take a closer look at the process, and get some inside information on a few of your Corvette's less-commonly discussed drivetrain components.
01 With the torque tube out...
01 With the torque tube out of the car, AntiVenom’s Greg Lovell uses a burly pair of pliers to remove the snap ring holding the output shaft in place. (Note: ’97-’99 C5s use bolts in place of the ring.)
02 Next, he stands the tube...
02 Next, he stands the tube on its end and taps the input shaft with a shot-filled plastic hammer. The tapping loosens the driveshaft so it can be removed from the tube.
03 Once loosened, the shaft...
03 Once loosened, the shaft should slide without too much effort. The large rubber ring running around its circumference limits lateral motion inside the torque tube. Only manual-trans cars have this feature.
04 This comparison photo...
04 This comparison photo shows three different driveshafts employed in various Corvette models. From top to bottom are the shafts used on the ’97-’00 manual/’97-’04 automatic (2-inch diameter), the ’01-’04 manual (3.25-inch), and the C6 Z06 (3.5-inch).
05 As you can see, the early,...
05 As you can see, the early, 2-inch shaft (right) uses a different bolt size than do the later versions (10 mm vs. 12 mm). Fortunately, Zip offers Six Shooters to fit both. The surface damage visible near the bolt holes of the smaller shaft was caused by a failed stock coupler.
06 Here’s a close-up look...
06 Here’s a close-up look at a new OEM driveshaft coupler. Interestingly, this very unit is also used on a number of BMW and Mercedes-Benz models.
07 Here’s what can happen...
07 Here’s what can happen when a stock rubber coupler surpasses its design limits. “It isn’t rotational force that kills them,” says Lovell, “it’s flex and twist.” A clunking noise emanating from underneath the car is the most common symptom of a failure.
08a While our subject car’s...
08a While our subject car’s original couplers were still in one piece, we thought it prudent to change them out before several planned engine modifications got underway...
08b ...Here, Lovell uses...
08b ...Here, Lovell uses an air wrench to loosen the retaining bolts and separate the driveshaft from the input shaft.
09 With that done, the stock...
09 With that done, the stock coupler can be removed from the input shaft. Simply repeat the process on the output side.
10 The Six Shooter from Zip...
10 The Six Shooter from Zip uses sturdy polyurethane bushings (in red) embedded in an aluminum housing. This “hybrid” design should offer an ideal combination of durability and NVH resistance.
11 Here’s a look at the Six...
11 Here’s a look at the Six Shooter as installed on the input side. Be sure to install the bolts into the metal-faced side of the coupler, as shown.
12 After repeating the process...
12 After repeating the process on the output side, Lovell slides the freshly fortified driveshaft back into the torque tube…
13 …and taps it into place...
13 …and taps it into place with the plastic hammer.
14 The final step involves...
14 The final step involves reinstalling the snap ring, bevel side up, to hold the driveshaft in place. With the drivetrain reassembled, a quick drive turned up…nothing. The car drove, felt, and sounded exactly like a stock C5. If taming evil Torque without sacrificing everyday functionality is your goal, the Six Shooter hits the bullseye. vette