HOW THEY WORK: The modern automatic transmission is based around planetary gears. A set of planetary gears consists of a sun gear in the center, 3 or more planet gears meshed with and encircling the sun gear, and a ring gear with teeth on the inside, encircling the planet gears. The speeds are obtained by holding one of the three gears, applying power to another, and taking power off the third. For example: hold the ring gear, turn the sun gear, get reverse off the planetary gears. Hold the planetary gears, turn the sun gear, and get a forward gear ratio off the ring gear.Automatic transmissions have one or more sets of planetary gears which are stopped by clutches and bands to get all the speeds and reverse.A band circles a drum and looks almost like a western style leather belt , but made of sheet metal covered with composite material. A hydraulic piston tightens this around the drum to stop a planetary gear element. Clutches have two types of elements: steel plates and composition on steel discs. The steel plates have splines (“teeth”) on the outside. The composition clutch material circular plates have splines on the inside. Usually several (often 6 or so of each) steels and composition discs are stacked together, increasing the “area” of the clutch pack. A hydraulic piston presses these together to hold a planetary element. News source: Econofix The first auto transmissions had one set of planetaries and had 2 forward speeds. The later 3 speed transmissions had 2 sets of planetaries, and the 4 speed transmissions had 3 sets. I recently rebuilt a Chrysler front wheel drive transaxle, and they were getting 4 forward speeds using only 2 sets of planetaries! A clever design, but it had a VERY complex set of servos to accomplish this! WHAT CONTROLS THEM?For the newer cars, the answer is simple! (Imagine that!) THE COMPUTER CONTROLS IT, taking in consideration your speed, throttle position, engine load, and other factors! Little solenoids supply fluid to those pistons and shift the tranny!For older (and many new) cars the answer is more complex. They have a “hydraulic computer” which compares hydraulic pressures versus spring pressures and applys and releases pistons to control the planetaries.The simplest ones shift using two inputs: throttle position, and governor pressure. A link goes from the gas pedal to the transmission. It moves a valve in the tranny. The more you press the pedal, the more it moves the valve, and the higher the THROTTLE VALVE PRESSURE is.The governor has two weights which are opposed by two springs. As the transmission spins, centrifugal force moves these weights outward against the spring pressure.The shift valves actually route fluid to the various hydraulic pistons (called servos) which operate the bands and clutches. Throttle valve pressure opposes governor pressure, delaying the shift when you’re “floorboarded”. When governor pressure gets high enough, the shift valve overcomes its spring pressure and shifts to the next higher gear.HOW THEY FAILThe actual clutches and bands usually last as long as the rubber seals in the servos. As soon as the pistons (servos) start to leak, the clutch elements fail rapidly. A “slipping” will be felt, or a “flare” where it slips when it first goes into gear then links up.It’s important to keep fluid in your transmission at all times. This is the main thing, especially newer vehicles. Transmission cooler lines are a big source of leaks. Check them and check your fluid regularly! FLUID AND FILTER CHANGESIt used to be GM recommended no fluid change until 100,000 miles!!! They don’t say that anymore, although many people DO go that long and longer without a change. As with many things, READ YOUR OWNER’S MANUAL!!!When in doubt, change the fluid at 50,000 miles. ALSO: Look at your fluid! when you check it, it should be a pink color. If it’s brown, change it. If it’s nice and pink, you probably don’t need to change it. They don’t make the transmissions as tough as they used to, and an inexpensive fluid change can avoid or postpone a very expensive rebuild!!!

I realize this posting does not really fit in the “Cars & Trucks Section.” Yes, it’s a little funky. This is to keep everything a little weird. Consider it a free bonus, covering secrets of the trade. However, I thought many Cars & Trucks do-it-yourselfers would find it of particular interest. There’s a lot of money and aggravation to be saved by following these recommendations. HVAC information for the do-it-yourselfer is hard to come by–it’s a protected turf. Many HVAC companies intentionally use “proprietary” parts, with no cross-reference to other brands. This is a key part of their strategy to prevent competition. Proprietary parts, licensing, part distribution control, and lack of DIY servicing information is how the industry protects itself. News source: Askme Help desk 1. Ensure outdoor condenser unit is level in both directions.2. Pour 8 parts water to 1 part bleach down the evaporator coil drain pipe 4 times per year, to prevent mold from developing.3. Replace air filter monthly. This prevents dust buildup on the evaporator coils, which interferes with proper airflow and can cause icing problems.4. Clean outdoor condenser coils in early April of each year with a garden hose. Remove front and side condenser coil covers and gently hose away dirt, grass, and debris. Straighten any bent fins with a fin comb. Don’t cut the grass around the condenser unit, while it is running.5. Remove high voltage cover plate and clean area of dirt, fire ants, and spiders each year. Fire ants and spider webs are dielectric and can prevent the contactor from working. Examine wiring for burning and capacitors (on single phase current units) for leakage and swelling. In order to check condenser capacitance, all wires must be removed first. Spread fire ant chemicals around condenser unit to keep ants from globulating on the contactor. They are attracted to 60 Hz current. Spray connectors with WD-40, making sure not to get any on the contactor’s contacts.6. Oil both condenser fan motor ports with 15 drops of ISO 32 (10 wt.) turbine oil each year. A 4 oz. Zoomspout Oiler from ACE Hardware costs $1.65. The finest synthetic lubricants, which I use, are Mobil SHC 624 and Amsoil RCH05. 7. Replace contactors (relay) proactively every 6 years. This is at the heart of properly maintaining an air conditioner and is the most overlooked preventive maintenance step. Some HVAC technicians will recommend replacing the whole outside condenser unit ($1,500), when only the contactor ($15) needs replacing. When contactor points open and close, they become pitted. As the cross-sectional area of the points gets cut in half, the resistance goes up by a square function (four fold). [Remember the formula for calculating the area of a circle = pi x r (squared)”> This results in the compressor motor becoming starved for electricity, which causes it to work less efficiently and can burn it up. Method: While the old contactor is still mounted, “crack loose” the four 5/16″ hex-head bolts securing the main “line” and “load” wires. Using a 5/16″ nut driver, remove the two hex-head mounting bolts to the old contactor, mount the new contactor, and then replace wire-for-wire from the old contactor to the new contactor. Use a pair of needle nose pliers and a small screwdriver to assist you in removing and replacing wires. Sit on a chair and take your time, while you perform this task.In some areas of the country, HVAC supply houses won’t sell to you, unless you work in the industry. It’s a different story online. Here’s what contactors look like:[url”>http://www.famousparts.com/cutham12pold.htmlClick the contactor you are interested in; then, click the small picture you see to the right for the contactor’s specifications.Here is a very useful contactor cross-reference chart:[url”>http://www.white-rodgers.com/wrdhom/…pg_112_113.pdf8. Replace digital thermostat alkaline batteries every 2 years. Low batteries can play havoc with the thermostat and cause dangerous inadvertent Locked Rotor Amperage that can damage contactors and compressor motors. Ensure your thermostat has an anti-short cycle feature, which can save your unit when the power goes off and then slams back on.9. Obtain documentation on your air conditioner, while you can. Wiring diagrams and functional unit part lists are often in a plastic bag behind the high voltage cover to the condenser unit. It’s invaluable data that will be destroyed by weather, if you don’t get to it first. Keep the original in the house and replace a copy in the condenser unit. Record the data on the metal tag on the condenser unit–a lot of valuable data is even embedded in the model number;e.g., TTP036C100A2. Since there are 12,000 BTUs per ton, digits 5 and 6 tell us that this is a 3-ton unit.10. Check system cooling. As long as the temperature differential between the air coming out of the air duct closest to the furnace and the air return duct is at least 15 degrees Fahrenheit, then the freon level is probably fine. An additional check is to feel the large, low pressure, insulated return line to the compressor–it should feel cool and have condensation on it.11. Obtain a Fluke Model 16 HVAC digital multi-meter to check capacitors, temperatures, and other items. It also happens to be about the best DMM for diagnosing automotive electrical systems. A properly maintained air conditioner should last 25 to 30 years. 12. Remove filter and vacuum the air return area, which is underneath or leads into the furnace. On most units, this can be accomplished by removing the return air vent and vacuuming the inside area. This will increase air flow, by substantially reducing the amount of dust and lint that will be trapped by the filter. Finally, take your vacuum and/or air compressor and blow all dust away from the blower motor vents. Dust will collect and interfere with the proper cooling of the blower motor. It also can be a fire hazard.13. Wax your condenser unit, when you wax your car.Turn the thermostat OFF, pull AC disconnect to condenser unit, and turn off furnace breaker (power to contactor coil) before performing any work. Use non-contact voltage meter to verify power is off. Finally, use a large plastic handle screwdriver between contactor and ground to confirm power is off.

The first thing you want to remember when jump-starting a car is that a slight possibility of explosion does exist. This is because hydrogen gas–which forms as a battery discharges and loses its fluid–is flammable, and a spark from the battery cables could, theoretically, set it off. We emphasize slight because the gas would have to be fairly dense around the battery for this to happen. This is unlikely unless the battery has been sitting for a long time and little or no air circulation has occurred in the area, but it is possible. That said, I should add that in the last 15 years I have performed at least 50 “jumps” on various automobiles (you see, I used to own a lot of Chrysler muscle cars) and have never had a problem. One of the keys to avoiding the big bang is to hook up your jumper cables in the proper order. Follow along and we’ll show you how. News source: Edmonds.com Step OnePark the booster vehicle close to the one that needs to be jumped, but not so close that the vehicles are touching in any way. You’ll want to use a good set of jumper cables with thick wire and clean clamps. As you are hooking up the jumper cables, make sure they don’t dangle into either engine compartment where they could get caught on moving parts (belts, fan, etc.). Turn off the ignition of both vehicles, set the parking brakes, and make sure that they are in either “Park” or “Neutral” depending on whether the vehicles have an automatic or manual transmission. Also, turn off all accessories like lights, radio and, if the vehicles are in a safe area, the hazard flashers. Step Two Begin the process by clamping one of the positive jumper cable ends (red) to the positive battery terminal (labeled with a “+” on the battery) of the dead vehicle. Be sure the connection is strong with the clamp securely “biting” onto the battery terminal. Step Three Connect the other end of the positive cable (red) to the positive battery terminal on the booster vehicle (again, confirm that a “+” is next to the battery terminal). If the terminals are corroded on either vehicle, you may have to scrape them with an abrasive such as steel wool to achieve a solid connection. Step Four Connect the negative cable end (black) to the negative battery terminal on the booster car (marked with a “-“). Finally, attach the other end of the negative cable to an unpainted metal surface on the engine of the dead car. Find an unpainted bolt or bracket that is as far from the dead battery as possible. This will provide a solid ground while further reducing the possibility of igniting any hydrogen gas. Step Five Make a final check to confirm that the jumper cables are not near any moving engine parts, and start the booster car. Let it idle for several minutes, depending on the state of the dead battery. If the dead battery is new and was drained by the lights being left on an extended period of time, it will probably start immediately. If it is an old battery or it has sat for a long time (more than a month) it will probably take awhile to charge it sufficently. Step Six Start the dead vehicle and let the two vehicles idle for a few minutes. If the dead vehicle refuses to start, don’t keep trying or you might damage the starter. If there is the possibility of additional problems, like a lack of fuel, don’t continue trying to start the dead vehicle until the other problem(s) are solved. Step SevenOnce the dead vehicle is started and running smoothly, disconnect the jumper cables in the reverse order that they were connected. As you disconnect them, be careful not to let the dangling cables fall into the engine compartments or touch each other. Step EightDrive the revived car to somewhere safe and secure before shutting off the engine. Depending on the battery’s condition, it might need to be jumped the next time it is started. To properly charge the battery, attach it to a certified battery charger and leave it connected for at least 12 hours. You can also take it to an automotive repair shop for complete charging. Driving the car for an extended period can also charge the battery, but this should be done only if the other two options aren’t available. A vehicle’s alternator is primarily designed to maintain a battery, not charge it from a complete drain

Several topics about ABS and pad replacement. It is essential that the hoses be blocked and the pressure relieved with the bleeder screw when pressing the caliper back into the bore. If this is not performed correctly it allows the gunk(from the seal) to enter the ABS system this usually presents itself as a ABS lite that wont turn off or it feels as if there is air in the system. A flush may cure the problem but it usually require serious and expensive repair or replacement of some ABS componets. Be cautios what you use to block the hose there are plastic pliers that clamp that work the best and they are not that expensive just be sure you do not damage the hose.Also any time I do a brake repair I replace the fluid, simply run fluid through the system until it runs clear no need to apply pressure just keep the MC full for all 4 wheels also on GM rear disc carefully inspect the slider bolts they are usually frozen as no one uses there emerg brake.