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Safety First

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by John Gunnell  More from Author

Keep Your Classic Corvette Roadworthy

Let’s get one thing straight: safety is not sexy. It is not a numbers-matching big-block, a cheap barn-find Chevy, or a trophy wife who loves car shows. We’ll bet that when you walked out into the garage today, checking your brake fluid level wasn’t at the top of your list of things to do.

However, keeping your Corvette in safe running condition should be of the highest priority: after all, that isn’t a brand-new Accord you’re driving around in (thank God!): it is an old performance vehicle with tons of moving parts. Keeping those parts in good shape might make the difference between a nice drive, or a nightmarish breakdown. Interested now?

Safety service on classic Corvettes actually begins with some lubrication requirements. Changing engine oil is a general maintenance item, but if you overlook lubrication of the steering linkage, transmission shift linkage, parking brake assembly or accelerator linkage, safety problems could arise.

As Bryan Herndon of the Zero-to-60 Garage (www.zeroto60garage.com) in Sherwood, WI, used a power greaser to lube steering linkage fittings on John Bergstrom’s ’67 Corvette, he explained that old GM factory lubricant specs, such as the 6031M grease mentioned in early Corvette shop manuals, may or may not still be available. “A water resistant EP chassis lubricant is all you need,” he said.

According to Bryan, your neighborhood auto parts store can supply most lubricants you’ll need. For instance, any good 90W oil will work, as well as the GM Axle Oil in the shop manual. However, special lubricants like GM Positraction Differential Additive should also be on your shelf. Bill Turney, another Zero-to-60 technician, said it is a friction modifier. “It reduces friction to let the gears slip a little when you go around a corner,” Bill explained. “Many positraction axles will have a plastic tag that will say to use only the slippery stuff,” Bryan noted. 

 

LINKAGES

Whether your car has an automatic transmission or a stick shift, lubrication of the shifter linkage is considered a safety service. If the linkage binds, it could affect your ability to control the car. Shop manuals may call for water resistant EP chassis grease for the shift linkages and contact faces of transmission control levers, but Herndon prefers squirting just a little engine oil on them.

Bryan uses Kendall Super Blu High-Temperature L-427 grease on the Corvette parking brake cable, cable guides and operating links and levers. For obvious reasons, parking brake lubrication is especially important on stick shift cars with no parking gear. He applies it with one of those brushes with a short rolled-metal handle. Another assembly you don’t want to bind is your accelerator linkage. The accelerator pedal lever can be lubed with a little engine oil.

Michael Jonas of Stainless Steel Brakes Corp. is a Vette enthusiast who gives seminars at events like Corvette Funfest. “Regreasing or adding fresh grease can sometimes cause problems,” he warns. “The power steering valve should never be over-greased. It will cause failures and make the control valve pull in one direction. If you have a rear wheel bearing greasing tool, you can add too much and blow the seal out of the axle. The same goes for adding too much differential fluid. I think it’s better if you just inspect for leaks and deal with them as they occur. If it ain’t broke, don’t fix it.”  

 

BRAKE FLUID

Naturally, checking your brake master cylinder fluid level is a safety service operation, and is especially important if your stock classic Corvette has a single-circuit system. Dual-circuit braking systems came into use around 1967. On older master cylinders, you have to remove the cover and look inside to make sure the fluid level is not more than a quarter-inch below the lowest edge of the filler opening. On later cars, the master cylinder may have a monitor or see-through plastic reservoir with the proper fluid level mark molded into the plastic.

Many shop manuals covering classic Corvettes will recommend either Delco Supreme No. 11 or DOT-3 hydraulic brake fluid or the equivalent. However, many enthusiasts prefer DOT-4 fluid. DOT-4 is not silicone-based like DOT-5.0 or 5.1.

 

POWER STEERING FLUID

Topping off power steering fluid is also important if you want a safe car. On a Vette, the hardest thing about this may be finding where the dipstick is hidden. If the power steering fluid is warmed up to about 150 degrees F, the level should be between the “hot” and “cold” marks on the dipstick or filler cap indicator. If cold (about 70-degrees F), the level should be between the “Add” and “Cold” marks. Top off with GM power steering fluid 1050017 or an equivalent. Remember that power steering fluid doesn’t have to be changed periodically.

 

WASHER FLUID

If your classic Corvette has windshield washers, keeping the fluid reservoir filled is another safety service. Older Corvettes may have a bag to hold the fluid. Plastic jugs came into use later. There have been many types of systems used over the years, so follow the recommendations in your owner’s manual regarding what type of fluid to use (store bought is probably fine) and how high the fill level should be. If you drive the car in cold weather, change to a fluid that won’t ice up.

 

TIRE ROTATION

The purpose of regularly rotating tires is to achieve more uniform wear, which makes your classic Corvette safer to drive. Recommended rotation patterns have changed over the years, so follow the advice in your factory owner’s manual. If you don’t have a manual, plan on 6,000- to 8,000-mile rotation intervals or do it if you see uneven wear. The first time is critical. If you notice uneven wear, check your alignment or look for mechanical problems.

 If by chance your classic Corvette has a temporary-use spare, don’t figure it into the rotation system. When you have five full-size tires, follow any regular tire rotation pattern from any manual, but start with your spare in the right rear position. Then use the tire that would have gone in that position as your spare.

 

TIRE PRESSURE

Checking the air pressure in your tires is an important safety service. Do not assume that modern tires, even if designed to look old fashioned, should be inflated to the same pressure as tires of the 1950s-70s. Check sidewall markings or ask the company you bought the tires from for the correct inflation pressure. Also make sure you know the recommended cold or hot readings so you can get accurate readings, whether you’re home or driving on the road.

 

TIRE CONDITION

In addition to inflation pressures, check the condition of your tires. Look for excessive wear or damage to the thread or sidewall. Look for bent or cracked wheels. Use a torque wrench or torque bar to make sure all wheels are tightened to factory specs. If your classic Corvette has drum brakes, check the brake adjustment, following the procedures outlined in the factory shop manual or an aftermarket repair manual. If you cannot get a proper adjustment, your brake linings are worn beyond safe limits and must be replaced. If the car has disc brakes, check to see if the pads are worn down, or whether the rotors are scored.

 

PADS AND ROTORS

Jonas says that an entry-level set of good pads and rotors is fine for regular driving. “If your Corvette seems to push a little or slide when you apply the brakes, that means your pads are getting tired or your rotors are getting smooth,” he says. “A lot of mechanics will tell you to just turn the rotors (on a lathe), so I should explain why you should never turn rotors. Turning one basically thins the life of the rotor.”

A good rotor, if you maintain it properly, will usually last the life of your Corvette. Do this by making sure your pads don’t go all the way down to the bolts where they hit the metal on it. He says it’s impossible for mechanics to machine rotors the way the factory does. “The rotor is the heat sink in your braking system and absorbs heat, but it can’t absorb as much if it’s thinned out.” The ideal combination is a hard rotor and soft pad. Hard rotors are a question of good metallurgy, rather than design. “You can tell the hard rotors by their shine,” he explains. “Low-grade rotors are dull, not shiny. High-grade rotors have more chrome, stainless steel and carbon in them and that is what makes them shine more.” 

 

EXHAUST SYSTEM

For safety’s sake, check your Corvette’s complete exhaust system, including the catalytic converter, if it has one (usually 1973 and later, but you do find ’57 resto-mods with them). If your Corvette has external exhaust and you’re using a car-lifting device that lifts on undercar jacking pads or frame members, you may have to use wooden blocks as spacers to make sure the exhaust shields and chambers have clearance and don’t get damaged.

Check body areas near the exhaust system. Telltale signs of a leak into the passenger compartment include brown or black soot or water inside the car. Look for broken, damaged, missing or out-of-position parts. Also inspect for open seams, holes, loose connections or other conditions that could cause a heat build up in the floor pan. Such problems can also let exhaust fumes enter the car. Make repairs immediately. To maintain the integrity of a system, if you replace the muffler, replace the exhaust pipes and resonators behind it, too.

 

SUSPENSION

Check both the front and rear suspensions on your Corvette. On C1 cars, look for sagging rear leaf springs. Up front, check ride height to see if one coil spring or the other is overly weak. Look for looseness, damage or missing parts in the steering system and suspension. Look for incorrect movement, vibration, looseness, wear, unnatural or unusual bends, heavy scrapes, lubricant leaks, dents, dings, tears, egg-shaped holes and torn or gooey rubber boots.

With a small, powerful flashlight, sight along brake lines and fluid lines for any damage or leaks. Look for boogered-up brass fittings that are crooked or have stripped threads. Look for lines that are loose or nearly rubbed through. Check for rust. We like to replace the mild steel lines on all our classic cars with stainless steel duplicates made by Classic Tube (www.classictube.com) or Inline Tube (www.inlinetube.com). We also have wheel cylinders and master cylinders re-sleeved with stainless steel at Brake & Equipment Warehouse (www.brakeplace.com) or White Post Restorations (www.whitepost.com).

 

BELTS

Checking engine drive belts is considered a safety service, probably because a broken belt could strand you in an unsafe location with cars screaming by your Corvette on a long stretch of road. Check to see that your belts have the proper tension, as per your shop manual. If you see wear, cracks or signs of frayed rubber, replace the drive belt immediately.

 

ADJUSTMENTS AND CHECKS

Check and adjust your parking brake, especially on a stick-shift Corvettes. A factory shop manual or general repair manual covering your model year will give detailed instructions for the proper adjustment. Do not pull up or push down on a parking brake actuator with more than normal force. This can damage the parking brake, or cause it to become stuck with the braking action on.

Earlier we recommended lubricating your car’s accelerator linkage. Now it’s time to check the underhood throttle linkage for damage or missing parts. Any issues with the linkage could cause interference or binding and, in a worse-case scenario, make the throttle stick open causing you to lose control of the car.  You’ll have to remove the air cleaner assembly to get at the linkage. Drip a little engine oil on the pivot points to lubricate them and prevent binding.

Special thanks to John Bergstrom, Jim Wagner, Bryan Herndon, Bill Turney, Michael Jonas and Al Wagner for their help with information and photo arrangements.

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