Corvette Knock-Off Wheels - Technically Speaking

James Berry Aug 1, 2011 0 Comment(s)
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Q: My '66 Corvette's knock-off wheels are constantly loosening up on me, and I'm concerned that one might eventually come off while I'm driving. I love the look of the wheels, but this anxiety keeps my ride in the garage and not on the road. The weather is getting perfect for cruising, and I need to know how to keep the wheels on the car. Any advice would be greatly appreciated.

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- Ray
Via Email

A: Back when aftermarket wheel offerings were scarce, racers chose knock-off wheels for several reasons: They were lighter than the steel stockers, they improved braking performance by reducing heat, and the single knock-off nut made for fast tire changes in the pits. Non-racers sought them out because they provided a stylish enhancement to any Corvette's looks.

Your particular situation usually occurs after you've removed the wheels for service, as you might when replacing the brakes or tires. The problem is typically due to improper installation, so never let anyone install your knock-offs unless they have experience working on C2 Corvettes. In addition to installer error, there are certain component failures that could also be responsible for your problem.

Let's start by discussing the proper way to install a knock-off wheel, according to the manufacturer. Next, we'll address some of the mistakes commonly made.

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Every set of knock-off wheels should consist of the following components:

&bull Four knock-off wheels
&bull Two lefthand adapters
&bull Two lefthand spinners
&bull Two righthand adapters
&bull Two righthand spinners
&bull Four center cones
&bull Four center caps
&bull Four knock-off lock pins

Tire Installation
When having tires installed, make sure the equipment used won't scratch or damage your wheels (Image A, next page). A good wheel balance will help prevent vibration at speed. An unbalanced or improperly balanced knock-off wheel/tire assembly can cause excessive vibration and contribute to wheel loosening.

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Wheel-Adapter Fit
Make sure you install the wheel adapters on the correct side of your Corvette (Image B). Some wheel adapters are marked "right" or "left." Always remember that these reference points are based on being seated in the driver seat, looking toward the front. With American cars, the left side is the driver side and the right side is the passenger side.

Some wheel adapters aren't marked. If yours aren't, just remember the following:

• On the driver side, the spinner will tighten onto the wheel adapter in a clockwise direction.
• On the passenger side, the spinner will tighten onto the wheel adapter in a counterclockwise direction.
• When tightening the spinner onto the wheel adapter, it will always spin toward the rear of the vehicle, regardless which side of the vehicle you're on.
• When removing the spinner from the wheel adapter, it will always spin toward the front of the vehicle, regardless of which side of the vehicle you're on.

When installing a wheel adapter, all mating surfaces must be clean and free of any dirt, grease, slag, or other debris. Install the adapter by aligning the vehicle wheel studs with the holes in the adapter and tightening the lug nuts to 75-85 ft-lb of torque. It's acceptable to use your original lugs.

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Make sure the wheel adapter seats flush against the wheel, with a minimum of free play between the adapter drive pins and the wheel drive-pin holes.

If a wheel is not tightened correctly, the movement from acceleration and braking can cause an elongated wear pattern to form in the aluminum where the adapter pins are inserted. Excessive wear can create free play between the adapter and the wheel, potentially causing the wheel to work its way loose over time.

Install the knock-off wheel-and-tire assembly flush against the wheel adapter by aligning the small holes in the back of the wheel with the wheel-adapter drive pins (Image C). Note that there have been instances reported in which the wheel's drive-pin holes were mistaken for its lug-nut holes. If installed incorrectly, the wheel won't seat when tightened and could provide a false torque reading. This can allow the wheel to loosen and possibly come off. If you're using the correct long lug nuts when installing the wheel adapters, it should be almost impossible to improperly index the wheel.

Spinners
Knock-off wheels are designed to tighten as they rotate. The driver-side wheel rotates counter clockwise as the car is driven. The knock-off spinner is righthand threaded so it tightens as the car rolls forward. The passenger-side wheel rotates clockwise as the car is driven. The knock-off spinner is lefthand threaded so it tightens as the car rolls forward.

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Remember that just because it says "left" on the knock-off, that doesn't mean left side; it means lefthand thread. Think of it this way: Righthand threads go on the left side, and lefthand threads go on the right side. This configuration will always tighten the wheel as you drive.

Tightening Procedure
Now let's review the preferred procedure when installing a knock-off wheel on your vehicle. Position the car off of the ground, with no weight on the tires. Apply Loctite to the wheel-adapter threads. Install the knock-off wheel assemblies flush against the wheel adapter by aligning the small holes in the back of the wheel with the wheel-adapter drive pins. Make sure your adapter seats flush against the wheel, with a minimum of free play between the adapter drive pins and the wheel drive-pin holes.

Have a helper step on the brake pedal. Hold the wheel firmly onto the wheel-adapter pins while centering the spinner onto the wheel center cone; tighten by hand (Image D). Tighten the spinner further by striking its wings several times with a lead hammer. Don't be afraid to hit the spinner, as lead is softer than chrome.

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After you've pre-torqued all of the wheels, lower the vehicle to the ground—with your helper still applying brake pressure—and tighten the spinner further by again striking its wings with a lead hammer, using several hard blows (Image E).

Note that both the spinner and the wheel adapter possess semicircular grooves. As you finish tightening the spinner with the lead hammer, the grooves on the wheel adapter and the spinner should align to form a circle; this will allow you to insert the knock-off pin. Never loosen the spinner to achieve knock-off pin alignment. Rather, continue to tighten the wheel until proper alignment is achieved.

Once you're satisfied that the spinners are properly tightened, insert the knock-off lock pins into the holes formed by the semicircular grooves on the wheel adapter and spinner (Image F). You'll notice that the knock-off lock pins are slightly tapered; the smaller end is inserted first. It may be necessary to lightly tap on the pins to allow clearance for the center cap to snap into place. Take care, though, as the pins are easily bent.

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Don't place all of your confidence in the lock pins' ability to secure the wheels. They are simply an additional safety measure, and they won't prevent an improperly installed wheel from coming loose.

Now that all four wheels are installed on the vehicle, use a fine marker to place an indexing mark across each spinner and onto its corresponding wheel center cone. Draw a straight line across the top of the adapter onto the edge of the spinner (Image G). This mark will give you an immediate reference point to see if the spinner is coming loose during your testdrive.

Drive the car extremely slowly while listening for any strange sounds that might indicate that the wheel isn't properly tightened. After a short distance, inspect the index marks for alignment. If they aren't aligned, the spinners were not tightened adequately and are too loose. Re-torque the spinners before trying to drive the car any farther. Take several short testdrives involving left- and righthand turns before moving on to the next step. A wheel that is coming loose will sometimes make a clicking noise or cause the car to pull. If you notice either of these signs, stop immediately.

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Once the wheels are properly installed, it's recommended that you check them often for tightness. As an added, more permanent, safety precaution, you can place a small piece of gray striping tape across the spinner and onto the wheel center cone where you made your indexing mark. The tape will blend in with the wheel and will not wash off when the car gets wet. Check regularly to ensure that the tape has been disrupted or torn; if it has, do not drive the car. This is an indication that the wheel is becoming loose.

Specialty Tools
There are a number of knock-off–specific tools available in the aftermarket. These include a suction-cup puller tool that can be used to remove the center caps without scratching or bending them, a common result when using a screwdriver. The cost of the puller tool is around $10.

Also available are knock-off wrench tools (Image H) that can be used for tightening spinners without damaging the chrome plating, as can happen over time when using a lead hammer. Keep in mind, however, that these wheels were designed with the hammer method in mind, and using a wrench deviates from Chevy's recommended installation procedure. For this reason, most Corvette mechanics still feel more comfortable using a hammer. Knock-off wrench tools range from $200-300.

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If the foregoing procedures seem daunting, or you're still afraid of losing a wheel, you may want to consider purchasing a set of conventional bolt-on rims and installing them in place of your stockers. Most large Corvette suppliers offer bolt-on wheels that look very similar to your original knock-offs and can be installed without modification. Good luck, and I hope to see you out driving your car. vette

Questions?
Got a question for our Tech Corner expert? Just jot it down on a paper towel or a lightly soiled shop rag and send it to us at VETTE Magazine, Attn: Technically Speaking, 9036 Brittany Way, Tampa, FL 33619. Alternatively, you can submit your question via the Web, by emailing it to us at vette@sorc.com. Be sure to put "Technically Speaking" in the subject line.

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