Tech Tip: Engineering the Complete Brake Job

Tech Tip: Engineering the Complete Brake Job

When brake linings are replaced, always follow your friction supplier's guidelines. As a rule, linings should be replaced with ones made of the same basic type of material as the original linings (or better). Replace semi-metallic with semi-metallic, ceramic with ceramic, and nonasbestos organic (NAO) with NAO - or upgrade to ceramic.

 

By Larry Carley
Technical Editor

When brake linings are replaced, always follow your friction supplier’s guidelines. As a rule, linings should be replaced with ones made of the same basic type of material as the original linings (or better). Replace semi-metallic with semi-metallic, ceramic with ceramic, and nonasbestos organic (NAO) with NAO — or upgrade to ceramic. The best advice here is to recommend premium grade linings as opposed to standard or economy grade linings. Premium linings will usually give your customer the best performance, longevity and overall value.

If you are installing a loaded caliper assembly on one side of a vehicle only, make sure the pads have the same approximate friction characteristics as the ones on the opposite side. If a different grade of friction material is used, it can increase the potential for a brake pull.

Unless the rotors and drums are in near perfect condition (no scoring, minimal runout, etc.), resurfacing should be considered a must to restore an optimum friction surface. Rotors should be resurfaced to OEM specifications.

If rotors are worn to minimum thickness, or can’t be resurfaced without exceeding the minimum or discard specs, they must be replaced.

Rotors should also be replaced if they are cracked, have hard spots or are severely corroded.

It’s the same story with drums. If a drum is cracked, has hard spots, is bell-mouthed, or the inside diameter exceeds maximum specs or a drum can’t be resurfaced without exceeding the limit, it must be replaced. Also, both drums should have about the same amount of wear. If the difference in wear is greater than about .040 inches, both drums (or rotors) should be replaced even if only one is at or near the discard limit.

As for drum hardware (self-adjusters, return springs, shoe springs, etc.) and disc hardware (caliper slide pins, bolts, bushings, sleeves, etc.), anything that is obviously worn, damaged or badly corroded should always be replaced.

If a return spring or shoe spring is stretched or discolored, it has probably suffered heat damage and must be replaced. But many brake experts say it’s a good idea to replace springs anyway when doing a complete brake job regardless of the spring’s appearance to assure like-new brake performance and to minimize the chance of a comeback.

The cost of new springs and other hardware is only a small portion of a complete brake job. Yet it can save you many dollars in lost labor revenue if you end up having to do the job over because you reused old hardware and it failed.

The MAP guidelines say it is not necessary to rebuild or replace calipers or wheel cylinders unless they are leaking, cracked or damaged. But as we said earlier, many experts believe replacing or rebuilding these components on high mileage vehicles is well worth the extra cost to minimize the risk of future problems.

As for brake fluid, every brake job (complete or not) should include a fluid change. But surveys have found that half of all cars and light trucks that are 10 or more years old have never had their brake fluid changed!

You can’t really judge the condition of the brake fluid by its appearance. Brake fluid may darken as it becomes contaminated with moisture, but some fluid does not. The most accurate way to check the condition of the fluid is to use an electronic tester that boils a small sample of fluid, or to use chemical test strips that react to the corrosion inhibitors and trace copper in the fluid.Tests have shown that after only a year of service, the brake fluid in the average vehicle can contain as much as 2% water. After 18 months, the level of contamination can reach 3%, and continue to climb to as much as 8% or more as time goes on.

As for the ABS system, no parts should have to be replaced unless something isn’t working properly. Wheel speed sensors can sometimes give bad readings if their magnetic tip becomes contaminated with metallic debris from the brakes. A simple cleaning may be all that’s needed to eliminate the problem. A major ABS problem such as a failed modulator or control module, on the other hand, will be a major expense to replace.

You May Also Like

EV Battery Charging: What You Need to Know

As EV owners begin to look for qualified service shops, a charger will be an advertising beacon at your shop.

Charging EV car

Some equipment you can’t live without, and it seems as if it’s always in use. What that equipment is seems to change over time, as the ebb and flow of automotive technology has a strange way of turning one-time profit centers into dust collectors.Think of all the equipment that is now just in that forgotten corner of the shop, such as the old R-12 machine and the brake lathe. Then, there’s the big old Sun Scope, and the rarely used wall-mount strut spring compressor. Equipment falls out of favor for many reasons, whether it be old technology or just a trend in service.You can just as easily remember all the new equipment you’ve bought over recent years, such as A/C machines, scan tools, TPMS tools and ADAS equipment. Just when you think you can’t possibly need something else, more technology comes along, and this time it’s thanks to the vehicles nobody can stop talking about. But love ‘em or hate ‘em, electric vehicles (EVs) are here to stay.They might not need gas, but they need “juice,” and you’re going to have to charge them, meaning you’re going to need a charger and a base knowledge of the factors surrounding EV charging.There are different levels of chargers, the understanding of which is of initial importance, and, in short, the higher the number, the more powerful the charger. Level 1 chargers are considered emergency chargers, and most EVs come with them. They operate off 110 volt alternating current (AC), and their downfall is they can take as much as 40 hours or longer to charge the battery on some of the latest EVs.Level 2 chargers are the minimum that an automotive service shop should have, but they are well suited for the job, and are quite simply the best choice for the majority of shops. Level 2 chargers operate off single phase 240 volt AC and are almost 10 times faster than a Level 1 charger. You may still have a charging time of two or three hours, but this is an acceptable amount of time.

AAM to Supply e-Beam Axles for Future Stellantis EV

The future program will feature both front and rear e-Beam axles that include AAM’s integrated 3-in-1 e-Drive technology.

Wrenchers Doubles Repair Tool & Equipment Offering

More than 25,000 lifts, tools, and equipment from 39 brands available online or by phone.

Myers Tire Supply Introduces MTS Xpresstm

The innovative solution to consolidate purchases and control inventory costs.

Experiencing What the Tool Industry Has to Offer

ETI held its annual ToolTech conference April 17-19 at the Hyatt Regency Tamaya Resort in Santa Ana Pueblo, New Mexico.

Sandia Mountains

Other Posts

LIQUI MOLY Develops Liquid Thermal Manager for EV Batteries

The automotive chemical specialist is expanding its range for all-electric vehicles with Battery Coolant EV 200.

May 2023 Vehicle Care RockStar: Johnny Weber

Johnny Weber exudes confidence in his abilities to lead the band through proficiency over pageantry.

Variable Valve Timing Systems

Variable valve timing systems allow today’s engines to maximize performance and drivability.

Continental Tire Upgrades Test Tracks for EVs

Continental expanded its EV charging infrastructure at three company-owned test sites in Sweden, Germany and the U.S.