Your customers are one of the most important aspects of your business. And when they need your help, you need to be ready with the knowledge and the answers that will help them. This month, Counterman presents some of the most pressing issues surrounding the following topics and what customers are asking.
Q: My customer is buying a replacement compressor for an older vehicle with an R12 A/C system. Should he also retrofit it to R134a when he installs the new compressor?
A: Now would be the best time to do a retrofit. If your customer is a do-it-yourselfer, you cant sell him R12 refrigerant unless he has taken and passed a certification course. That means he can only buy R134a or an alternative refrigerant.
Most remanufactured compressors for older vehicles are now engineered to be compatible with either refrigerant. But some original equipment compressors on older vehicles are not compatible with R134a. Compressors with Viton seals include Tecumseh HR980, some Keihin compressors and some Panasonic rotary valve-style compressors (Nissan). These compressors must be replaced if an older vehicle is converted to R134a.
Compressor durability is also a concern with some applications. Because R134a raises compressor discharge pressures and increases the compressors work load, some lightweight compressors may not be rugged enough to tolerate R134a over the long haul. This applies to the Harrison DA6 and Ford FX-15 compressors. The Harrison DA6 can be replaced with a HD-6, HR-6 or HR-6HE compressor. The Ford FX-15 compressor can be replaced with a FS-10 compressor.
Theres really no reason to retrofit a vehicle to R134a as long as the R12 system is cooling properly and contains a normal charge of refrigerant. A/C systems designed to use R12 will cool best when charged with R12 refrigerant. Even if the system leaks, repairing the leaks and recharging it with R12 is usually the least expensive repair alternative.
Retrofit makes the most economic sense when the A/C system needs major repairs such as a new compressor, condenser or evaporator.
Q: What parts are needed to do an R134a retrofit?
A: Most vehicles will require two to three cans of R134a refrigerant, a can of R134a compatible compressor lubricant (POE or PAG oil), a new accumulator or receiver/drier with X-7 desiccant, and the required adapter fittings for the high and low service ports. The A/C system must also be labeled following the retrofit to warn others that it now contains R134a instead of R12.
Converting to R134a typically reduces cooling performance somewhat, and may require some additional modifications to improve cooling performance. This may include installing a larger or more efficient cooling fan for the condenser, installing a larger or more efficient condenser to improve heat transfer and replacing the original fixed orifice tube with a variable orifice tube to improve low-speed cooling performance.
After the changes have been made, the A/C system should be recharged to about 85 to 90 percent of its original capacity with R134a. This will usually give the best cooling performance.
Q: What kind of compressor oil is required for a retrofit?
A: It depends on the application and situation. If the original compressor is not being replaced, the most common procedure is to drain out as much of the old mineral oil as possible and replace it with an equal amount of POE oil. POE oil is the universal choice for this type of retrofit because it is compatible with residual mineral oil in the system and R134a refrigerant.
If the compressor is being replaced with a new or remanufactured unit, follow the lubricant recommendations of the compressor supplier. Some may specify POE oil, while others may specify a particular grade of PAG oil.
Almost all newer vehicles that have factory R134a systems require a specific type of PAG oil. The viscosity of the PAG oil will vary (46, 100 or 150) depending on the type of compressor used.
Q: Should I tell my customer he should also replace his condenser if his compressor has failed?
A: It depends on the application. The condenser is an expensive item to replace, but it may be necessary to prevent a repeat compressor failure.
When a compressor fails, it often throws a lot of debris into the A/C system. The outlet hose from the compressor connects to the condenser, so the condenser becomes a garbage dump for anything the compressor spews out. The condenser also tends to collect sludge that may be in the system, too. If these contaminants are not removed, they can circulate in the A/C system when it is recharged with refrigerant and plug the orifice tube and/or ruin the new compressor.
On some vehicles, the condenser can be flushed instead of replaced. Flushing with a cleaning chemical that has been approved for this purpose may remove most of the debris. But flushing may not remove all of the debris. Flushing does not work very well on parallel flow condensers because the liquid follows the path of least resistance. It may rinse out most of the tubes but leave others plugged with debris (which may dislodge later and ruin the new compressor.)
Flushing may also not work well in condensers with extremely small passages (the type with extruded aluminum flat tubes). Where it does work is on serpentine condensers with large tubes. But even on these it may miss some debris. Whats more, the hoses and other parts must also be flushed to clean the entire A/C system.
If a customer does decide to flush rather than replace, he should install an inline filter in the condenser outlet line for added protection. The filter should trap any debris missed by the flush. Also, installing a protective screen in the compressor inlet hose can protect the compressor from any debris that may be lurking in the suction hose or evaporator.
BRAKES
Q: When doing a brake job, which items must be replaced, and which items should be replaced?
A. The "must" items include anything that is worn out, broken or defective. The "should" items include anything that may be nearing the end of its service life or may affect braking reliability, noise or performance.
The basic purpose of any brake job is to restore safe braking. Ideally, that means restoring the entire brake system to "like-new" condition – but that doesnt always happen.
Professional technicians often base their replacement recommendations on experience and "industry-accepted practices." A more formal set of inspection and replacement guidelines is available from the Motorist Assurance Program (MAP) at www.motorist.org.
The MAP "Uniform Inspection and Communication Standards" cover the brakes as well as every other system on a vehicle. These standards define how certain parts should be inspected and what conditions require replacing the part.
As a rule, parts must be replaced if they are worn beyond minimum service specifications (based on OEM specifications), are inoperative, broken, defective or severely corroded. Parts that typically fall into this category include brake pads and shoes that are worn thin, cracked or contaminated with brake fluid or grease, brake rotors that are worn to minimum thickness, cracked, warped, full of hard spots or severely rusted, drums that are worn to maximum diameter, bell mouthed, cracked or severely rusted, calipers and wheel cylinders that are leaking or sticking, springs and other hardware that are weak, broken or severely rusted, brake backing plates that are badly worn or rusted, brake hoses that are cracked or leaking, and master cylinders that are leaking internally or externally.
Replacing worn out and broken parts is always a "must." But nothing is ever cut and dry in the automotive repair business. Some parts may be in a borderline condition, still good but obviously on their way out. Replacing these parts may not be absolutely necessary just yet, but sooner or later they will have to be replaced.
Labor is often the most expensive part of a brake job, so often it makes sense to go ahead and replace borderline parts that may still be "good" according to the MAP definitions. This includes parts that may still be within acceptable service limits but are reaching the end of the road. Replacing these parts now for "preventive maintenance" increases the parts bill but reduces the risk of a comeback and usually eliminates the need for additional brake work later on – which can save the vehicle owner considerable repair dollars in the long run.
One item that should always be replaced when the brakes are relined is the brake fluid. Old brake fluid is usually contaminated with moisture that promotes rust and corrosion in the calipers, wheel cylinders and brake lines. Moisture also lowers the boiling temperature of the fluid, which may increase the risk of fluid boil and pedal fade under hard use. So always remember to recommend a can of fresh brake fluid to every customer who is buying brake parts.
High-mileage calipers and wheel cylinders are additional items that should often be included on the "should replace" list even if the old parts are not yet leaking or sticking. Why? Because calipers and wheel cylinders eventually succumb to internal corrosion. You cant see it from the outside, but inside the pistons and bores are usually rust, pitting and even sludge. As the piston bore becomes rough, it wears the seal and may cause leaks or piston sticking. Calipers with phenolic pistons are not immune to corrosion either because the caliper housing is usually cast iron.
Noise is another valid reason for replacing some brake parts. If the original equipment brake pads on a particular vehicle are noisy, the pads may need to be replaced to eliminate the noise.
Performance upgrades may also require replacing perfectly good stock brake parts with aftermarket performance parts. Common upgrades include installing premium high-temperature pads and/or drilled and vented rotors. Drilled rotors are especially popular as much for appearance as for performance. Drilled rotors provide better cooling but they also look great behind a set of custom alloy wheels.
Some states such as California have strict rules about replacing brake parts. If parts are not worn to minimum service specifications, are not broken or defective, the rules say replacement is unnecessary and may even be illegal (for a professional technician) – unless the vehicle owner is upgrading his brake system or wants the parts replaced. The purpose of such laws is to protect motorists from being ripped off. But such laws also hinder the ability of professional technicians to make valid judgment calls.
Q: Are all replacement rotors the same?
A: Absolutely not. Though different brands of rotors may all look the same, there can be significant differences in metallurgy and finish that affect friction, braking effectiveness, stopping distance, pad life and noise.
Quality replacement rotors are manufactured to meet certain OEM specifications. The metallurgical properties of a rotor determine its strength, noise, wear and braking characteristics. The casting process must be carefully controlled to produce a high-quality rotor. You cant just dump molten iron into a mold and hope for the best. The rate at which the iron cools in the mold must be closely monitored to achieve the correct tensile strength, hardness and microstructure.
When iron cools, the carbon atoms that are mixed in with it form small flakes of graphite, which help dampen and quiet noise. If the iron cools too quickly, the particles of graphite dont have as much time to form and are much smaller in size, which makes for a noisy rotor.
The rate of cooling also affects the hardness of a rotor. If a rotor is too hard, it will increase pad wear and noise. Hard rotors are also more likely to crack from thermal stress. If a rotor is too soft, it will wear too quickly and may wear unevenly, increasing the risk of pedal pulsation and run-out problems.
The composition of the iron must also be closely controlled during the casting process to keep out impurities that may form "inclusions" and hard spots. One rotor manufacturer says they sample the molten iron every 15 seconds to make sure the composition is correct. The molten metal is also poured through ceramic filters that trap contaminants. Even the sand thats used to make the molds is specially treated to control moisture content. This helps keep the sand in place and prevents core shifts that can affect porosity, dimensional accuracy and balance.
The grade of cast iron thats used in a rotor may even be changed to suit a particular application. One aftermarket rotor manufacturer uses a special grade of "dampened iron" to make replacement rotors for 1997-2002 Chevrolet Malibu and its sister vehicles (Olds Alero, Olds Cutlass and Pontiac Grand Am). In this case, the original OEM rotors turned out to be too noisy, so General Motors switched to a dampened grade of iron to cure the problem.
Another difference thats hard to see is the design of the cooling ribs between the rotor faces. Vehicle manufacturers use a wide variety of different cooling rib configurations in their rotors. They do this to optimize cooling for different vehicle applications. There are currently about 70 different rib configurations in OEM rotors. Some ribs are straight, some are curved and some are even segmented. Some rotors are directional, and some are not. Some rotors have evenly spaced ribs, while others do not. Some ribs radiate outward from the center, and others go every which way.
Some aftermarket rotor manufacturers use the same rib design and configuration as the OEM rotors, while others do not. Some change the rib design to simplify the casting process or to reduce the number of different rotor SKUs in their product lines. But changing the rib design changes the airflow, cooling and noise characteristics of the rotor – which may make things better or worse depending on the application. Thats why some aftermarket rotor manufacturers say the best approach is to use the same basic configuration as the original equipment rotor.
One brake manufacturer showed us a cutaway of an offshore "economy" rotor for a particular vehicle that had 32 ribs. The OEM rotor, by comparison, had 37 ribs and provided up to 8 percent better cooling than the economy rotor when tested in the laboratory. And because the OEM rib design ran cooler, pad life was 28 percent longer than the economy rotor.
Another aftermarket brake manufacturer showed us test results that proved their rib design improves cooling and makes their rotor three times quieter than a competitive rotor. The recorded sound levels showed noise as high as 85 decibels screaming out of the Brand X economy rotor compared to only 40 to 50 decibels from their own "premium" quality rotor.
Q: What are the advantages of "loaded calipers?"
A: Convenience, reliability and ease of installation – these are the main selling points of loaded caliper assemblies. A loaded caliper comes with everything needed to replace a caliper: a new or remanufactured caliper housing, new or reconditioned pistons, new friction pads, plus the shims and related mounting hardware that are needed to install the caliper on the vehicle. All the technician has to do is remove the old caliper and pads, resurface or replace the rotor, bolt on the loaded caliper assembly and bleed the brakes. Its the closest thing you can sell to a brake job in a box.
The demand for loaded calipers continues to grow because they save technicians time and effort. If the calipers on a high-mileage vehicle need attention, its hard to tell what condition they are in internally until the pistons are removed. If the original pistons are steel, they are usually badly corroded and need to be replaced. Whats more, the caliper bores will probably be rough and pitted. This requires careful honing to restore the bore surface so it wont damage the piston seal and hold pressure. Even then, the caliper may leak when reassembled.
Calipers may also be worn or damaged. Wear on the mounting surfaces is common and can allow unwanted vibrations and noise. Cracks represent a potential safety hazard and always require the caliper to be replaced.
Replacing a worn or leaky caliper with a new or remanufactured one eliminates most of the risks associated with rebuilding calipers. And since the pads usually have to be replaced as well, it makes sense to get everything in one box.
Preassembled calipers also help eliminate some of the common mistakes that are often made when replacing calipers, things like leaving off anti-rattle clips and pad insulators that prevent noise, forgetting to bend pad locating tabs that prevent pad vibration and noise, and reusing corroded caliper hardware that can cause a floating caliper to hang up and wear the pads unevenly.
Most aftermarket brake suppliers have loaded calipers in their product lines. Coverage is typically limited to the more popular vehicle applications. Even so, more and more applications are being added every year for a wide range of cars and light trucks.
Q: Are all loaded calipers more or less the same regardless of who supplies them?
A: The calipers themselves will either be new castings or reconditioned OEM castings for the vehicle they fit. So in that respect there may not appear to be much difference from one brand to another. But some suppliers pay more attention to detail than others, and the suppliers may go to greater lengths in the recondition process to assure a top-quality product. Cosmetic differences may also be apparent and are always an important selling factor with the end user.
Another difference youll find in loaded caliper assemblies is the type of friction linings included by the supplier. Some suppliers increase their product coverage and/or minimize the number of different part numbers by offering loaded assemblies with "generic" semi-metallic or NAO linings. Other suppliers are more selective and use "application-specific" friction materials that are more closely matched to the OEM friction material for a given vehicle application. The advantage with this approach is that it more closely matches OEM brake performance and stopping power, which reduces the risk of a dissatisfied customer and a comeback. But it also increases the number of SKUs needed in their product line.
As a rule, loaded calipers should be sold and installed in pairs. This will eliminate any mismatch of friction materials side to side that might otherwise cause a brake pull.
Q: Are all "ceramic" disc brake pads the same?
A: Are all pizzas the same? Of course theyre not, and the same goes for disc brake pads that contain ceramic-based friction materials.
Each brake supplier has their own definition of what "ceramic" means. Ceramic has become a hot buzzword for marketing brake pads. How much ceramic content is actually in the pads and what type of ceramic materials are used can vary greatly from one brand of pads to another.
Linings containing ceramic fibers were first introduced back in 1985 on some OEM applications, and are now found on nearly a third of all new vehicles including many Japanese models that are made in the U.S. In recent years, ceramic pads have also been introduced into the aftermarket by brake suppliers.
As a rule, ceramic pads contain no steel wool or fibers. Instead, ceramic and copper fibers are used to handle the heat. Annoying brake squeal is virtually nonexistent because the ceramic content helps dampen noise and moves vibrations to a frequency beyond our range of hearing. Whats more, the dust produced by some ceramic pads is a lighter color and is less visible on alloy wheels.
Friction materials contain many different ingredients including various types of reinforcing fibers for strength (ceramic, fiberglass, aramid and other mineral fibers), metallic strands (steel, brass, titanium, copper, etc.) for dissipating heat, fillers and other substances for modifying the friction characteristics of the material, and binders and phenolic resins to hold it all together.
Most semi-metallic friction materials contain at least 60 percent steel by weight. Low-metallic materials are ones with less than 30 percent ferrous content. Nonasbestos organic (NAO) materials contains little or no iron or steel, and usually have several times as many ingredients as semi-metallic compounds. As a result, NAO compounds are more complex to develop and manufacture.
As for ceramic-based friction materials, ceramic is only one of up to 20 or more ingredients in the formula. The type of ceramic used and the percentage content will vary from one brand to another depending what the manufacturer is trying to achieve. Most aim for the best combination of low noise, good braking performance, good fade resistance and long life. Most ceramics do an excellent job of meeting all of these criteria.
Q: With so many different brands and types of brake pads available today, how do I select the "right" replacement linings for a given vehicle application?
A: The "right" set of brake pads are those that provide safe braking, low noise, long life and good value for the money.
According to a recent Babcox survey, over 90 percent of brake technicians say they prefer to install "application specific" brake linings.
"Application-specific" is a marketing term that means a set of replacement linings are engineered to closely match the friction requirements of different vehicle types and platforms. It may be an "off-the-shelf" compound, a modified compound or a brand new compound that provides the best combination of noise, braking performance and wear for a particular car or truck. In many instances, application-specific aftermarket brake linings are very similar to, if not identical to, OEM brake linings.
One aftermarket brake supplier said they now use about 40 different friction compounds in their various product lines to achieve application-specific coverage. Another supplier said they currently have 25 different compounds in their line, and will be adding more as needed to keep pace with new models and changes at the OE level.
The braking requirements of a Lincoln Navigator are obviously different than those of a Kia Rio. Vehicle size, weight, brake type (disc or drum), the design of the calipers and rotors, front-to-rear brake balance and how the vehicle is driven are all factors that influence the selection and development of a particular friction compound. Consequently, a friction formula that works well on one application might not be the best choice for another. So aftermarket brake suppliers use a variety of different friction compounds to cover the diverse mix of vehicles that are on the road today. There are probably several hundred different compounds being produced by friction suppliers worldwide.
The "right" replacement linings, therefore, are any brand or type of lining that makes your customers happy.
Q: Whats the difference between "premium" pads and "standard" pads?
A: The price and performance of pads differ. In recent years, aftermarket brake suppliers have introduced new lines of premium pads and even "ultra-premium" brake linings. Most of these pads are "application specific" and may include a mixture of ceramic, semi-metallic and/or NAO formulas in the product line. The only thing they all share in common is the best all-round braking performance the supplier can provide – and a higher profit margin for jobbers and installers.
Compared to standard pads, premium pads generally provide better stopping power, increased fade resistance, longer life and quieter operation. Most premium grade pads incorporate such features as chamfers and slots. Some have built-in shims to control noise and vibrations. Some premium pads are also "preburnished" to eliminate many of the problems that can occur if the pads are not broken in properly.
When brake linings are manufactured, the resins that bind the ingredients together are not fully cured. When the linings are later installed on a vehicle, the heat produced by normal braking bakes the linings and cooks out the residual chemicals from the resins to improve the friction characteristics of the lining. But if the brakes get too hot before the linings are fully cured, it can "glaze" the linings causing noise and performance problems. So to eliminate the need for a break-in period, some brake suppliers fully heat-cure (burnish) the linings.
CHASSIS
Q: What kind of replacement shocks are best for Sport Utility Vehicles (SUVs)?
A. It depends on the how the SUV is driven. Different types of driving require different types of shock valving and construction.
For a smooth ride, a low-pressure gas shock with relatively soft valving works well. For extra control when towing or driving on rough terrain, a stiffer shock or a high-pressure monotube shock would be better. If the suspension has been raised to increase ground clearance for off-roading, shocks with longer travel are required to keep the dampers from bottoming out.
One type of shock that works well in a wide variety of situations is an adjustable shock. Manually adjustable shocks typically offer a range of settings from soft to extra firm. Electronic adjustable shocks are also available for adjustments on the go. Adjustable shocks are available in gas-charged twin-tube and monotube designs for most SUVs including many of the new "mini-SUVs" such as Honda CRV, Toyota RAV4, Kia Sportage and others.
Q: Do shock absorbers affect driving safety?
A. Absolutely. They are part of the "safety triangle" which includes stability, steering and braking.
Stability is of particular concern to SUV owners because of the high center of gravity on many of these vehicles. Stability can be lost in an instant if the shocks are weak and something happens that causes a sudden shift in weight or direction (a tire blow out at 75 mph, swerving to avoid an obstacle in the road, etc.).
For a vehicle to maintain steering control and stability in emergency situations, the shocks must be in good condition. Safe driving also requires tires that are in good condition, properly matched to the application (load rating, temperature, traction, etc.) and properly inflated for load and speed conditions. It also requires a steering system and linkage that is not worn, wheels that are properly aligned and brakes that can stop the same as when the vehicle was new.
A problem in any one of these areas can undermine the safety triangle and increase the risk of losing control in certain driving situations. Thats why the shocks, steering, tires and brakes should all be inspected regularly. And if repairs are needed, they should be done ASAP to restore the safety triangles foundation to a firm footing.
Q: How long do OEM-sealed wheel bearings typically last?
A. The design life is 150,000 miles, but many end up having to be replaced at 85,000 to 100,000 miles.
According to a recent Babcox Research survey, 51 percent of bad wheel bearings are found because the vehicle owner noticed an unusual noise coming from the wheel, 24 percent are found during a brake job, and 19 percent are discovered during an alignment.
A classic symptom of a bad wheel bearing is noise, so if a wheel is squeaking, chirping, squealing or moaning, the bearing should be inspected without delay. Other symptoms include steering wander or sometimes a pull to one side when braking.
Wheel bearings can be checked by grasping the tire at the 12 and 6 oclock positions and rocking the tire. If you feel any play, the bearings are loose and need to be replaced. The tire should also be rotated by hand to check for roughness or noise.
If one wheel bearing has failed, the bearings on the other wheels should be checked because all of the wheels have the same mileage.
On vehicles equipped with antilock brakes and hub assemblies with an integral ABS sensor or tone ring, the ABS warning light will come on if a wheel speed sensor is reading erratically or the signal is lost. The ABS system will set a fault code that corresponds to the sensor location (left front, right front, right rear or left rear) and disable the ABS system until the fault is fixed. On these vehicles, the only way to get the ABS light to go out is to replace the hub assembly (assuming the problem isnt a simple wiring fault or loose connector).
There is no way to disassemble and repair a sealed hub assembly. If the internal ABS sensor has failed or if the external ABS tone ring on the hub is damaged or badly corroded, the whole unit must be replaced.
Q: What causes CV joints to fail?
A. Like U-joints, CV joints eventually wear out from the accumulated effects of normal wear. Normally this doesnt occur until the joint has 80,000 to 130,000 miles on it. But CV joints can be ruined at any point in their life if the protective boot around the joint fails and allows the grease inside to leak out or be contaminated by road splash and dirt.
The rubber or hard plastic boot around a CV joint serves two purposes: it keeps grease in and contaminants out. If the boot cracks, tears or is punctured, the seal is broken and anything can happen. By the time the bad boot is discovered, its often too late to save the joint by replacing the boot.
Most CV joints give ample warning when they are failing, so by the time theyre making noise, they almost always need to be replaced. The classic symptom of a worn outer CV joint is a popping or clicking noise when turning. A worn inner CV joint on a FWD car will typically make a "clunk" when putting the transaxle into Drive, and it may create a vibration when accelerating or decelerating.
Replacement options include a new or remanufactured CV joint, or a complete halfshaft assembly. Many technicians prefer to install a complete halfshaft because its faster and easier.
Make sure the replacement CV joint or shaft has the same number of splines as the original, and that the overall length of the shaft is the same. Also, if the vehicle is equipped with ABS and has a wheel speed sensor ring on the CV housing, make sure the replacement joint or shaft has the same ring (the ring is often press fit on the joint housing).
Q: When should steering components be replaced?
A. When they are worn or damaged. Most steering parts are replaced when a vehicle goes in for an alignment and worn parts are discovered during the prealignment inspection, or when a tire wear problem or looseness in the steering prompts someone to inspect the steering gear and linkage.
The parts most likely to need replacing are the tie rod ends, idler arms (on rear-wheel drive vehicles with parallelogram steering), center links and sometimes even the steering gear itself (usually power rack and pinion steering).
Any looseness or play in a tie rod end is grounds for replacement becau
