Like all domestic cars of its era, the '71 Corvette is equipped with a 12-volt, negative-ground electrical system, with an alternator providing power while the car is running. While this type of system is basically safe, the electrical hardware in our Stingray was nearly 40 years old, so we decided to carefully inspect it for issues. Under the hood, we checked the wiring harnesses for bare wires or chafed insulation. We then checked the car's lights, all of which worked after replacing a couple of bulbs. Unfortunately, a previous owner had installed a pair of electric fans, and the wiring was a mess. To rectify this, we removed the fans and wiring and replaced them with the stock engine-driven fan and factory fan shroud. The worst thing we found, however, was evidence of a fire under the hood, in the area of the HVAC box. Though the damage was minor and looked to have been repaired, we checked the wiring and discovered what was likely a contributing factor in the fire. The fuse for the heat and air-conditioning had been wrapped in aluminum foil in an apparent attempt to make a shorted fan operable. While we've seen this done more than once, we still can't believe people are willing to risk their cars by bypassing the fuse, which is a safety device. We quickly removed the foil-wrapped fuse and replaced it with a fuse of the appropriate amperage rating, then moved on to find the remainder of the car's electrical system in roadworthy condition.
Continuing on, we placed the car on a lift to inspect the undercarriage and brakes, and to change all the fluids. We always like to change the oil, transmission fluid, and differential oil in any recently purchased vehicle, as the previous owner may have neglected to follow fluid-change intervals while the car was up for sale. While draining the fluid from the engine and transmission, we carefully checked the brakes for any signs of wear or leaks, checked the universal joints (all six of them), and looked over the suspension bushings and steering to evaluate their condition and verify the proper installation of the cotter pins. Fortunately, the brakes, suspension, universal joints, and steering on our car had been serviced recently, and were in great shape just like the previous owner claimed. With those checks completed, we finished changing the oil and transmission fluid and addressed the rear differential.
Because every C3 came equipped with an independent suspension, the car's differential presents a specific problem when it comes to routine service. Since the differential's center section is an integral part of the car's chassis, the rearend cover can't be removed without first removing a significant number of rear-suspension components. Not wanting to disassemble the suspension just to change the gear oil, we had to choose between siphoning the fluid out with a suction device (which won't completely remove the old fluid), and drilling a hole in the housing to modify it for a drain plug. Since we'll likely be driving this vehicle aggressively and will therefore need to service the fluids fairly often, we opted to install a drain plug by drilling and threading the bottom of the center section housing with a 1/8-inch pipe tap. There are kits available that allow you to perform this modification, or you can get all the necessary items at the local hardware store. Since we had all the tools and the proper plug in our shop, we simply performed the work there.
Otherwise, our '71 Stingray seemed fit for the road, despite being "cosmetically challenged," as Editor Heath wrote in his recent column. The engine recently had been rebuilt and runs fairly cool with good oil pressure. The clutch and pressure plate had also been replaced by the previous owner, so with our inspection and maintenance complete, we deemed the car ready for a road trip. To build confidence we began driving short distances, and have since gradually increased the length of our jaunts. So far, we've made the 60-or-so-mile round trip to the office and back without incident and have been putting the car through its paces regularly on the street. Next month, we'll tackle the Vette's subpar aesthetics, and possibly head to the dragstrip for some baseline testing.
We still haven't named this project, so be sure to send us your suggestions and let us know what modifications you'd like to see performed. As always, we can be reached at vette@sourceinterlink.com.
Servicing the engine (right)...
Servicing the engine (right) and transmission oil is fairly straightforward, so we performed those tasks and moved on to the suspension and brakes.
We inspected the calipers,...
We inspected the calipers, rotors, and brake pads for signs of wear and found them all to be in great shape. We also checked the lines for signs of leaks, corrosion, or dry rot, but found none. Since the prior owner claimed to have recently rebuilt the brake system on this car, it was not surprising to find these parts in good shape.
We took advantage of the car...
We took advantage of the car being on the lift and tightened up the parking-brake cable for proper operation.
Working our way toward the...
Working our way toward the rear, we found one of the strut-rod jam nuts loose on the passenger side. These should be checked fairly often, as driveline vibrations or wheel hop can loosen them. Fortunately, the other nut was tight and the strut rod hadn't moved, so we tightened the loose nut and moved on.
Servicing the rearend in our...
Servicing the rearend in our Corvette presented a dilemma. Since removing the differential cover meant disassembling much of the suspension, and because suction devices can't remove all the fluid, we decided to drill a drain hole and tap it for a pipe plug, making future differential-oil changes more practical.
After drilling the differential...
After drilling the differential at its lowest point, just ahead of the cover, we used a magnet to remove any shavings that may have ended up inside the housing.
Using a 1/8-inch pipe tap,...
Using a 1/8-inch pipe tap, we threaded the 21/64-inch hole we had drilled in the housing. We again used the magnet to recover any metal shavings.
After performing the drain-plug...
After performing the drain-plug modification, we flushed the differential with clean fluid to wash away any small shavings we didn't recover with the magnet.
After draining the differential...
After draining the differential fluid through our newly drilled hole, we serviced the unit with fresh gear oil and limited-slip oil additive.
Our project C3 has come a...
Our project C3 has come a long way in a short time, but it still needs some work. Next month we'll improve the car's appearance, and then we'll be ready for some heavy modifications as we turn our Stingray into a real performer. We'd love to hear your ideas regarding modifications and potential project names, so send your suggestions to vette@sourceinterlink.com.
The threaded hole was then...
The threaded hole was then sealed with a 1/8-inch pipe plug. There are kits available for this modification, but we found everything we needed in our shop. As an alternative, all the necessary items to install a differential drain plug are also available at most hardware stores.
After finishing our inspection...
After finishing our inspection and maintenance, we dropped the lift and took our new project car for what turned out to be a problem-free maiden voyage. Having purchased this car for $5,600, and spent only a couple of hundred more to get it roadworthy, we're very pleased with its performance.
With our differential serviced,...
With our differential serviced, we checked all six universal joints. We found them to have been replaced with heavy-duty units by the previous owner.