1986-1988 Chevrolet Nova Brake Noise: Squeal, Grinding and Pulsation Causes

By Core Brake Parts Tech Team — Circleville, OH warehouse

Most brake noise on a 1986-1988 Chevrolet Nova comes from three places: a squeal from worn or poorly installed front pads and hardware, a grind from pads worn to the backing plate or rear shoes worn to the metal, and a pulsation in the pedal from uneven front rotor thickness. The Nova is a simple car with power front disc brakes and rear drums, so each noise points to a short list of parts you can check in an afternoon.

How the Nova's brakes are laid out

The fifth-generation Nova was built at the NUMMI plant in Fremont, California, a joint venture between General Motors and Toyota, and it is a rebadged version of the Toyota Sprinter, a close relative of the front-wheel-drive Corolla of the same era. The base car came with a 1.6-liter four, 13-inch wheels and power front disc and rear drum brakes.

That layout matters when you are chasing a noise. The front discs do most of the stopping on a front-wheel-drive car, so they wear fastest and make most of the squeal and pulsation complaints. The rear drums also carry the parking brake, so they are the usual suspect for scraping, clunking or a groan at low speed. Before buying parts, confirm what is on your car: pull a front wheel and a rear wheel and look. A car this old may have had brake parts swapped over the years.

Squeal: vibration, shims and hardware

Wagner puts it plainly: vibration is the main source of brake noise, and it usually comes from rust, distorted or loose components, or worn and weakened original parts. On a Nova that has sat for years, that list describes almost every front caliper you will find.

Bendix explains the mechanism in more depth. When pad and rotor lock together under braking, the pair vibrates at a combined frequency, and hot spots on the rotor change the friction as it heats up. If that frequency is in the range your ear can pick up, you get a squeal. The fix is to stop the vibration from reaching the caliper and the knuckle, which is exactly what shims and insulators do. Bendix notes that shims add mass to the pad, damp vibration through rubber or nitrile coatings, and act as a heat barrier.

What to check and fix on a squealing Nova front end:

• Shims. If the old pads have no shims or the shims are rusted and peeling, the new pads need fresh ones. Wagner recommends a slight coat of silicone brake lubricant on the back of a constrained-layer shim only, and no chemical compound at all on pads with a bonded insulator.
• Anti-rattle clips and pins. Wagner calls for replacing worn anti-rattle clips, springs and pins, and making sure the guide pins move freely so the pad does not drag. A brake hardware kit is the cheapest noise fix on this car.
• Caliper faces. Clean rust from the piston face and the pad contact surfaces so the pads sit parallel to the rotor.
• Rotor surface and cleanliness. Bendix stresses a smooth, true machined surface wiped down with brake cleaner before assembly.
• Break-in. Wagner's burnishing procedure is 20 slow-downs from 50 mph to 20 mph with light pedal pressure and about 30 seconds between each. Skipping bedding is a common reason new pads squeal.

A squeal that happens while rolling and goes away when you press the pedal is usually the pad's wear indicator, a small steel tab designed to chirp against the rotor when the pad is getting thin. That one is a warning, not a nuisance. Replace the pads.

Grinding: worn friction or neglected drums

Grinding is metal on metal, and on this car it has two common sources.

Front pads worn through. Once the friction material is gone, the steel backing plate scores the rotor. You will usually see deep grooves and a lip at the rotor edge. At that point the rotor is almost always scrap, so plan on new front rotors along with pads rather than trying to machine a badly scored disc.

Rear drums and shoes. Drum brakes hide their wear. A Nova that has not had the rear drums pulled in years can have shoes worn to the metal, a broken return spring, or a self-adjuster that has rusted solid. Wagner lists dust and grit buildup as a noise source and recommends washing brake parts with soap and water and a bristle brush. Pull both drums, check shoe lining thickness against the minimum in the service manual, look for fluid wetness at the wheel cylinders, and check the drum surface for a deep ridge. If you need brake shoes, replace them as an axle set with new springs and adjuster hardware.

Grinding that comes and goes over bumps can also be a stone or rust flake trapped between the rotor and the splash shield. Pull the wheel and look before you order anything.

Pulsation: usually not a warped rotor

A pedal that pumps under your foot when you stop from highway speed is one of the most misdiagnosed brake complaints. Both Wagner and Power Stop trace it to disc thickness variation, or DTV: the rotor is slightly thicker in some spots than others, so the caliper piston is pushed in and out as the rotor turns and you feel the fluid movement through the pedal.

DTV does not start on its own. It follows lateral runout, the side-to-side wobble of the rotor as it spins. Wagner notes that most manufacturers hold lateral runout to two thousandths of an inch or less, and that even a small piece of rust on the hub-to-rotor mating surface can create it. As the wobbling rotor brushes the pad on every turn, semi-metallic pads wear thin spots into it and ceramic pads can deposit material in spots. Either way the thickness goes uneven.

Power Stop suggests measuring rotor thickness in at least six places with a micrometer. Their guidance treats variation up to .001 inch as acceptable and more than .006 inch as a clear sign of DTV. Other causes they list include incorrect rotor installation, misaligned calipers, rust and dirt buildup, and uneven clamping forces.

The fix on a Nova:

1. Clean the hub face down to bare metal before installing a rotor. On a car of this age the hub face is almost always crusted with rust.
2. Resurface the rotor only if it stays above its minimum thickness afterward. On an old car, new rotors are often the better buy.
3. Tighten lug nuts evenly in a star pattern to the factory torque value in the service manual, never with an impact gun at full power.
4. Bed the new pads so they lay down an even transfer layer.

Also check the front wheel bearings. Wagner lists loose or badly adjusted bearings and excessive hub runout as noise and vibration sources, and a worn bearing lets the rotor wobble no matter how true it is.

Which pads and parts to use

For a Nova that is driven daily, a quality ceramic or semi-metallic street pad with shims is the quiet, low-dust choice. Browse ceramic brake pads or our full brake pads range and match the part to your car before ordering.

If your Nova is a track or autocross car, we carry the Hawk Performance Blue 9012 front race pad for the 1986-1988 Nova. Blue 9012 is described as a medium to high torque compound with good modulation and low pad and rotor wear, built for road racing and rally use with an operating range of 250 to 1000 degrees F. Be honest about how the car is used: a race compound is designed to work hot, and on a cold street car it is not the pad to pick if your complaint is noise.

What to replace at the same time:

• Front rotors if they are scored, below minimum thickness, or measure outside the DTV limits above.
• Caliper hardware and slide pin boots on every pad job.
• Rear shoe hardware, and wheel cylinders if they show any seepage. See all brake parts.
• Brake fluid if it is dark. Use the fluid type printed on the master cylinder cap.

How hard is the job?

Front pads and rotors on a Nova are a good first brake job: a floor jack, stands, basic sockets, a C-clamp and brake cleaner. Seized caliper bolts are the main thing that stretches the time on a car this old. Rear drums take more patience because of the springs and self-adjuster, so do one side at a time and use the other side as your reference. Anything involving the hydraulic system, such as wheel cylinders or hoses, means bleeding the brakes afterward.

Frequently Asked Questions

Why do my new Nova brake pads squeal?

The usual causes are missing or unlubricated shims, reused rusty hardware, a rotor that was not cleaned or resurfaced, or pads that were never bedded in. Fix the hardware and run the burnishing procedure.

Does the 1986-1988 Nova have rear disc brakes?

The standard Nova uses power front disc brakes and rear drums. Check your car before ordering rear parts, since a car this old may have been modified.

Are warped rotors causing my pedal pulsation?

Usually not. Pulsation comes from disc thickness variation, which follows lateral runout, most often caused by rust on the hub face or uneven lug nut tightening.

Can I just machine my old rotors?

Only if they stay above the minimum thickness stamped on the rotor after machining and the hub face is cleaned. Deeply scored rotors from metal-on-metal grinding should be replaced.

Is a race pad a good idea on a street Nova?

Not for a daily driver. Race compounds like Hawk Blue 9012 are built to work at high temperatures and are a track choice, not a noise fix.

Sources

1. Eighties Cars: 1986 Chevrolet Nova sedan - NUMMI build, 1.6-liter engine, 13-inch wheels, power front disc and rear drum brakes
2. Wagner Brake: Brake System Noise - vibration as noise source, hardware, shim treatment, 20-stop burnishing procedure
3. Bendix: Brake Noise In-Depth - pad and rotor coupled vibration, role of shims and lubrication
4. Wagner Brake: Brake Pedal Pulsation and Disc Thickness Variation - lateral runout limit, hub rust as a cause
5. Power Stop: Pulsing Brake Pedal - DTV measurement points and limits
6. Hawk Blue 9012 HB191E.590 product page - compound description and 250 to 1000 degrees F operating range