Part III

75 must-do mechanical inspections for 1963-1982 Corvettes

text and photography by John Pfanstiehl

Rear Suspension

Pull out on the bottom of the tire while pushing in on the top. The first clearance you feel is that of the wheel bearings. This clearance should feel about the same when the tire is grasped at the three o'clock and nine o'clock positions. Pull harder on the bottom of the tire while pushing in on the top and the next (and larger) clearance is that of the differential yokes.

Check the condition of the rubber cushions and washers on the lower end of the shock. The dish-shaped washer should be installed so that it curves away from the rubber, not toward it as shown here. Although a 3/4-inch wrench is used on the nut, it only requires about 35 pounds of torque.

The four bolts that attach the half shafts to the spindle flange should be grade eight and should not be threaded all the way to the head. The original style of French locks should be used, not lock washers, or the flange can work loose to create a clunk upon acceleration or deceleration.

The shims on the front end of the trailing arm should be tight, and there should be several on each side. If the alignment shims are only on one side, a bent trailing arm is likely.

Inspect the rubber snubber that is mounted to the frame. On disk brake-equipped cars, make sure the brake line is tucked close to the caliper so the snubber doesn't squash it when the suspension bottoms out. Note that the lock washer goes next to the head of the upper shock bolt, not next to the nut as many people assume.

It's normal for the inner end of the strut rod to appear twisted when the suspension is hanging down, even if the bushings are in excellent condition. Visually inspect the bushings as much as possible to see if the rubber has been worn or forced out on one side.

Differential And Springs

Watch the movement of the yokes with respect to the differential as an assistant pulls out on the wheel. The movement should be less than 1/8-inch, and the yoke should reach a definite stop in its outward movement. If the yoke comes out 1/4-inch or more, the circlip has come off the yoke and the differential should be disassembled. Wearing yokes were a common Corvette problem for a number of years.

The upper cushion of the carrier front mount can't be seen, but it often is heard as a loud clunk in the rear when quickly letting off on the gas. Reach up to feel the condition of the cushion. If it is pushed out of place or is separating, replace it.

Look closely on the inside of the carrier's front bracket for evidence of movement. If the rubber area shows a lot of movement, the bracket's holes probably have become elongated and the bracket needs to be replaced.

Remove the cotter pins and tighten the through bolts. Also tighten the four bolts that hold the strut rot bracket to the carrier. These loosen up often enough that I use a thread locker whenever installing them. The bolts should be grade eight and have lock washers and flat washers.

Don't worry if there are some surface cracks in the rubber cushions for the spring bolts; they can become compressed and worn looking without causing any problems. The bolt and washers should be in good condition. I'd recommend staying with the original style grade eight bolt. Examine the washer. The edge next to the cushion should be rounded. Many people install it the opposite way, but it really makes no difference except for authenticity. If the washer has no rounded edge, make certain the hole is not too large - the wrong washers were sent as replacement for many years.

When the car is sitting on the ground, cautiously check the center spring bolts for looseness. Do not overtighen them, and make sure the housing is not broken where the rear two bolts are attached.

Other Rear Underside Inspections

Check the bumper bolts, which are often missing or loose. Remember they go through fiberglass, and a barely snug bolt is better than cracked glass.

Drop the spare tire to make sure both the rim and the tire are still usable. Also make sure the lock or the threads aren't too corroded to work if the spare is ever needed.

Try to get your fingers between the exhaust pipe and the rear spring. If there isn't about 1/2-inch clearance, the pipes are likely to hit and rattle. If the clearance is over one inch, the pipes may occasionally drag on bumps. For appearance, both pipes should have about the same clearance.

If the pipes are rattling or are not centered, look at the alignment and condition of the exhaust hanger. The bolts rattle loose and the rubber gets stretched and distorted over the years.

Pull on the parking brake cable to feel if it moves freely. Inspect the rubber seal at both ends, but the majority of 1963-1982 Corvettes are no longer driven in slush and snow, so the condition of the seal isn't that critical, particularly if the cables are well lubricated on the inside. Check each of the "Mickey Mouse" spring clips that help hold the cables in position in their brackets.

At least once, have the frame rails blown out using an air gun with a long tipped nozzle. The area in front of the rear wheels collects the most dirt and debris, and that is where moisture collects and frame rust is at its worst. It is also worth the effort to blow out any similar frame pockets such as by the carrier front bracket and by the front of the trailing arm.

-John Pfanstiehl is a contributing editor to Corvette Fever and is author of the new Corvette Weekend Projects by HP Books.

Author's Note: Thanks to John Dubois of VanSteel Mint Restorations, 1141 Court St., Clearwater, FL 34616 for the use of his lift and his 1964 coupe for many of these photos.


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