Brakes (FAQ)
From Nissan 350Z & 370Z Wiki
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What brake pads make the least dust
- A lot of our members have used the Hawk HPS pads and the EBC Greenstuff Pads with great success at cutting down the amount of brake dust.
What should I use to paint my calipers?
- Most people recommend using a caliper paint made by G2 or Folia Tech. It's a paint that must be brushed on by hand, and requires prepping of the surface as well as a lengthy drying time. However, it appears to hold up quite well over time and gives a nice finish.
- You can also purchase spray-on caliper paint for much cheaper. You need to make sure you mask off with newspaper the entire wheel well, rotor, and the section of the car you are working on in order avoid painting parts other than your rotors. Additionally, it would be advisable to do this when it is not windy outside.
- Engine paint should not be used. The temperature of a brake caliper can far exceed the operating temperature of your engine. If this happens the paint will peel off.
- Regardless of the type of paint you decide on, it would be best to leave the caliper in place to do the painting. Be sure to mask off anything that shouldn't be painted but is at risk of exposure. If you decide to take the caliper off of the rotor before painting, do NOT let it dangle by the brake line. When you are done, follow the directions on the paint and wait long enough for it to dry before putting the tires back on your car and driving it.
- Be prepared to spend a weekend on this project to do it right.
When should I replace the brake pads
- I replaced my pads at 30k miles and they were completely gone. I would suggest doing them at 20k miles.
How big can you go with a big brake kit?
- Most of the big brake kits require at least 18" wheels. You can always go custom but may require larger wheels.
How to stop squealing brakes
- Brake pad squeal is one way to warn other drivers that you and your car are about to arrive. If you make enough noise, they think they are about to become intimate with a runaway garbage truck (pedestrians will yank small children back from the curb). There are several factors that cause brake squeal. The primary reason is usually the brake pads themselves. Many of the carbon metallic brake pads, such as Cool Carbon, etc. are the worst as far as squealing. This is due to the composition of the pad material itself. The OEM pads are usually relatively quiet in comparison. Thus, the solution may be as simple as changing to a different brand of brake pad. Excessive brake pad wear, warped rotors, misaligned calipers, loose calipers, loose wheel bearings, incorrectly sized pads, glazed pads or rotors and sticky pistons may also cause your brakes to sing high alto in the anvil chorus.
- If your brake pads and braking system are in good condition and you experience squeal just as you are almost stopped, this is usually the brake pad vibrating against the rotor/caliper, causing the rotor to ring like a bell. If you experience noises at other times, check to make sure your brake pads are in good condition and show equal wear. Sometimes a piston will hang up and cause excessive wear and failure of one pad. Check all of your pads to make sure that one is not down to the metal backing plate. The backing plate does not have quite the coefficient of friction as do the brake pads and will usually dig nasty grooves into your rotor for good measure. If you experience clunking noises, a vibrating pedal, or a screeching sound, you should have your entire brake system checked by a qualified mechanic. If you wait too long, the next sound you hear may be "crash".
- One option to help reduce the brake pad symphony is to install brake pad vibration damper pads. The vibration dampers that several suppliers sell are a self-stick fiber material that adheres to the back of the brake pad backing plate. Some models are manufactured with a mushroom shaped button spring in the center. The button spring fits tightly into the piston and the fiber disk adheres to the backing plate of the pad. The theory is that the fiber disk will help cushion (i.e., soften) the vibration of the brake pad. The second part of the theory is the mushroom button will help pull the pad away from the rotor when the piston retracts after the brake is released. This resulting extra clearance will reduce/eliminate squeal. Sometimes they work, sometimes they don't.
- A second option is to coat the back of the brake pads with a quality anti-squeal compound. Wurth makes a couple of nice ones. Wurth Anti-Squeal Spray is an aerosol spray that puts a thick heat-resistant polymer adhesive on the back of the pad to help cushion the pad from the caliper pistons and help the pad retract with the piston. A second option is Wurth DBQ -2200 that comes in a can with a top that looks like a liquid shoe polish bottle. This is applied to the back of the brake pad like a shoe polish. I have found that a combination of the vibration dampers and a coating of one of the brake anti-squeal compounds usually reduces low speed squeal to a tolerable level. (At least parents stop yanking their children back from the curb.)
- A third solution is to coat the area of the pad backing plate that contacts the caliper piston with a THIN coating of high temperature anti-seize. You do not have to coat the entire backing plate, only the area that is in contact with the piston. The key words are THIN and HIGH temperature. You do not want anti-seize to run onto the front of the pads or the rotor. This is somewhat like waxing your brake pads. I use Wurth CU1100 that resists temperatures up to 2000 degrees and apply small circles to the piston contact area. This is not as effective as the above, but allows for quick changing of the brake pads.
- The type of driving and resulting braking requirements will usually determine the best solution for you. I use anti-seize on my track car where the brakes are used heavily and the pads are changed very frequently. On a street car you may wish to consider the combination of pad silencers and anti-squeal compound. I cannot over emphasize the importance of maintaining your braking system in top-notch condition. If you are not confident in your brake repair abilities, please take it to a qualified mechanic. Something will stop your forward momentum, it may be your brakes or it may be one of numerous less desirable options.
Definitions
Brake Fading
- Brake fading, or brake fade, is a condition in which the brakes loose some of their friction potential, usually due to excessive heat build up on the braking surface or friction material. It most commonly occurs during repeated hard braking, or braking while under a very heavy load (lots of extra weight, or downhill)
- The most common type of brake fade is due to boiling of the brake fluid. This causes the hydraulic pressure on the calipers or servo to lessen, there by reducing overal brake pedal feel and/or stopping distance.
- Different types of fluids have different boiling points, depending upon your application it may be well worth spending extra money for a brake fluid with a higher boiling point, provided it is within the correct DOT classification.
- The second type of brake fade is pad fade. The pad basically melts due to the extreme heat. This can be compensated for by having a brake pad that suits the use of the car. Race pads for track days, and street pads for the street. Having a track pad all the time will not work because on the street it will most likely not reach its optium operating temperature.
- Some things that can be done to prevent brake fade are proper dissipation of heat, and in more extreme conditions air ducting to cool the friction material/surface.
Calipers
- The brake caliper is the assembly which houses the brake pads and pistons. The pistons are usually made of aluminum or chrome plated iron. There are two types of calipers: floating or fixed.
- A fixed caliper does not move relative to the disc. It uses one or more pairs of pistons to clamp from each side of the disc, and is more complex and expensive than a floating caliper.
- A floating caliper (also called a "sliding caliper") moves with respect to the disc; a piston(s) on one side of the disc pushes the inner brake pad till it makes contact with the braking surface, then pulls the caliper body with the outer brake pad so pressure is applied to both sides of the disc.
- Floating caliper designs are subject to failure due to sticking. This can occur due to dirt or corrosion if the vehicle is not operated. This can cause the pad attached to the caliper to rub on the disc when the brake is released. This can reduce fuel mileage and cause excessive wear on the affected pad.
Disc Brake
- A disc brake stops movement by forcing a friction material (brake pad) against a rotating metallic or synthetic disc. Disc brakes come in many different sizes, and include many different features.
Drum Brake
- A drum brake stops movement by forcing a friction material (brake shoe) against a rotatating metallic drum. Drum brakes come in many different sizes are are widely accepted as inferior to disc brakes in automobile applications.
Fluid
- Brake fluid is a type of hydraulic fluid used in brake applications in automobiles and light trucks. It is used to transfer force under pressure from where it is created through hydraulic lines to the braking mechanism near the wheels. It works because liquids cannot be compressed. Braking applications produce a lot of heat so brake fluid must have a high boiling point to remain effective and must also not freeze under normal temperatures. These requirements eliminate most water-based solutions.
- Brake fluid can come in a number of forms, standardized under the DOT (Department of Transportation) standard. DOT 2 is essentially castor oil; DOT 3, DOT 4, and DOT 5.1 are composed of various glycol esters and ethers; and DOT 5 is silicone-based. Most cars produced in the US use DOT 3.
- Glycol based fluids are 2 times less compressible than silicone type fluids, even when heated. Less compressibility of brake fluid will increase pedal feel. Glycols are hygroscopic and will absorb water from the atmosphere, reducing the boiling point of the fluid and degrading hydraulic efficiency. Changing fluid on a regular basis will greatly increase the performance of the brake system, but this is often not a concern in passenger cars. On the other hand, changing fluid at least every several years will preserve the life of brake system components (by removing accumulated water and other contaminants) and increase the overall reliability of the brake system.
- Polyethylene glycol and other brake fluid ingredients may be corrosive to paint and finished surfaces such as chrome and thus care should be taken when working with the fluid.
Lines
- Brake Lines are metallic or rubber and metallic hoses that allow brake fluid to flow from the master cylinder to the proportioning valve then to either brake calipers, wheel cylinders, or a combination of both. Brake lines are normally replaced and not repaired, as then endure high pressure. A popular upgrade is installing stainless steel lines in place of the stock rubber lines. Although this will not improve braking distance, it can improve brake pedal feel, thereby allowing the driver to modulate the pedal accordingly under braking.
Master Cylinder
- A master cylinder is a pump and reservoir mechanism, either all metal or a combination of metal and plastic, which creates pressure, when the plunger is depressed. The upper portion of the unit is the reservoir, which contains brake fluid, it can be one container unit or separated into two chambers.
- A two chamber unit will separate the front brakes from the rear. The lower unit, the actual pump, has a plunger that enters the cabin of the car which the brake pedal is attached to with a rod mechanism. Typically, there are two lines that are connected to the master cylinder that joins it to a proportioning valve. The one line controls the front and the other controls the rear brakes.
- The master cylinder creates high pressure to the fluid and when internal damage occurs, the pedal will sink to the floor board and proved little to no breaks. It is vital that a master cylinder is bled before installing and the whole system is bled once installed, to remove any air that might have been trapped.
- Bench bleeding is a process in which plastic clear tubing is routed from the break line ports of the master cylinder to the reservoir, filled with brake fluid, and the plunger is depressed until all air is out and only fluid is seen passing through, or no bubbles are formed at the reservoir. When re-installing the master cylinder, air must be bled out of the rest of the lines starting from the furthest cylinder (or caliper) to the nearest. There are several ways of bleeding the lines, one is vacuuming the fluid from each bleeder valve, another is pumping the system with the brake pedal and holding it while the valve is opened then closed before pumping it again, until a solid flow of brake fluid is released. Another is using a container at the valve with fluid and a hose from the valve to the container, and pumping the pedal several times until there are no bubbles forming in the container.
Pads
- A brake pad is a material that lies between the piston and the rotor's surface inside the brake caliper. Powered by hydraulic pressure, the pads force themselves against the rotors surface, providing the friction needed to stop the vehicle.
- When purchasing aftermarket brake pads it is important to note the operational temperature as some will take considerably longer to effectively stop the vehicle when cold.
Parking Brake
- Most vehicles include a mechanical parking brake system (also called an "emergency brake") which operates on the rear wheels. These systems are very effective with drum brakes, since these tend to lock. The adoption of rear-wheel disc brakes caused concern that a disc-based parking brake would not effectively hold a vehicle on an incline. Though some early vehicles (like the Toyota 2000GT) did use the disc for the parking brake, others used a tiny drum brake embedded inside the rear disc.
- Today, most cars use the disc for parking, though some still rely on separate drums. The advent of electric parking brakes will change the rear caliper configuration substantially.
Rotors
- A disc-shaped component that revolves with hub and wheel. The brake pads are forced against the rotor to provide a friction surface for the brake system, so as to slow or stop a vehicle.
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This page is part of the brakes category. To learn more about related items click the links below. Components: Big Brake Kits • Brake Lines and Accessories • Brake Pads • Brake Rotors FAQs: Big Brake Kit (FAQ) • Brake Definitions • Brake Pads (FAQ) • Brake Rotors (FAQ) • Brake Troubleshooting Guide Tutorials: Adjusting The Parking Brake • Brake Fluid Bleeding • Brake Inspection • Brake Pad Bedding • Brake Pad Installation • Brake Rotor Installation |
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