Car Care Automatic Transmission


  1. Continuously Variable Transmission
  2. Filters
  3. Flywheel / Flexplate
  4. Transmission Fluid
  5. Transmission Gaskets & Sealing
  6. Tourque Converter
  7. Transaxle

Continuously Variable Transmission

Description: A Continuously Variable Transmission (CVT) uses an arrangement of pulleys and bands to achieve an unlimited variation between the highest and lowest ratios. Unlike conventional automotive transmissions, CVTs do not employ a graduating arrangement of fixed gear ratios to deliver power transmission. CVTs have seen spotty vehicle applications over the years, but have staged a recent comeback due to improving and emerging technologies.

Purpose: CVTs help the engine stay closer to its most efficient operating range, which can help both performance and fuel economy. CVTs may also offer manufacturers different economies of scale for transmission manufacturing.

Maintenance Tips/Suggestions: CVTs require a different maintenance regimen than conventional manual or automatic transmissions. Refer to your car’s owner’s manual for specific recommendations for CVT maintenance.

Filters

Description: Automatic transmissions/transaxles use a filter on the inlet side of the transmission’s hydraulic pump. Different types of filtering media may be used including a fine mesh screen, paper, or felt for filtering media.

Purpose: A transmission filter prevents harmful contaminants from entering the hydraulic system, where they can increase wear and cause scoring and sticking of hydraulic control valves. Additionally, if a major part fails inside the transmission, the filter may prevent pieces of that part from contributing to a more catastrophic transmission failure. Normally transmission filters trap metal chips from hard parts like gears and bushings and the normal fine material that results from wear of the hydraulic clutch facings and bands.

Maintenance Tips/Suggestions: Your car’s automatic transmission filter and fluid should be changed periodically according to the schedule in your owner’s manual. Although some maintenance schedules may claim that the transmission fluid or filter doesn’t need to be changed for the life of the car, remember that the average driving situation falls into the “severe” maintenance category due to short trips and stop-and-go driving. Some shops offer transmission flushing and filling, which is intended to remove more contaminants than simple draining of the transmission. If you decide to have this service performed, make sure that the transmission pan will be removed in order to change the filter before refilling it with new fluid. If the filter is not replaced, contaminants from the old fluid, along with those dislodged during the flushing process, could impair flow through the filter and lead to transmission problems.

Flywheel / Flexplate

Description: The flywheel for most automatic transmissions/transaxles is simply a stamped-steel disc with a ring gear located at the outer edge for engagement with the starter’s pinion gear. With this type of flywheel, the torque converter has no ring gear. Some cars use a more modest flywheel known as a flexplate, which is all that’s needed because the torque converter itself has a ring gear located on its outer edge.

Purpose: The flywheel, or flexplate, mounts to the engine’s crankshaft and also serves as a mounting location for the torque converter. Consequently, the flywheel or flexplate transmits engine torque to the torque converter housing. The flywheel’s ring gear also serves as an engagement point for the pinion of the starter motor when cranking the engine. Because of the lightweight design of the flywheel or flexplate, it does not help to smooth out power pulses from the engine like the flywheel does on a car with a manual transmission. On cars with automatic transmissions, the torque converter provides this function.

Maintenance Tips/Suggestions: The flywheel/flexplate does not require regular maintenance. Sometimes, the ring gear may suffer damage from improper starter engagement or alignment. If this is the case, the ring gear or flywheel may need replacement.

Transmission Fluid

Description: Automatic transmission fluid is specially formulated oil TM containing numerous additives to withstand gruelling operating conditions. There are several different types of automatic transmission fluids and should be used according to the recommendation in your car’s owner’s manual.

Some examples include:

DEXRON® III/MERCON® – Recommended for all automatic transmissions requiring DEXRON® III, DEXRON® IIE, DEXRON® II, DEXRON® or MERCON ® transmission fluids. It can also be used where fluids meeting Ford ESP-M2C138CJ or Ford M2C166-H specifications are required.

ATF+3® — Formulated exclusively for Chrysler Corp. automatic transmissions/transaxles where a Chrysler MS-7176, Mopar® or Mopar ATF+3® is specified.

Type F (FLM) is a specially compounded fluid meeting the latest Ford ESW-M2C33F and is compatible with all M2C33 series Ford specifications. In all 1983 and later model Ford automatic transmissions use DEXRON ® III/MERCON ® or MERCON ® V Automatic Transmission Fluids.

Purpose: Automatic transmission fluid serves a multitude of purposes. Among other things, it cleans, cools, lubricates, transmits force, transmits pressure, inhibits varnish build-up and protects the transmission on a day-to-day basis.

Maintenance Tips/Suggestions: Owner’s manual recommendations on transmission fluid changes vary considerably and may go as high as 160,000 kilometres or more. For best results, have your car’s transmission fluid and filter changed every two years or 40,000 kilometres. Always use the type of fluid specified by your car’s manufacturer. This information can be found in the owner’s manual or on the end of the transmission dipstick.

The overwhelming majority of transmission failures are heat-related, and automatic transmission fluid breaks down rapidly when subjected to high temperatures. Driving conditions such as trailer towing, quick stops and starts, ascending and descending mountains, and wheel-spinning in slippery conditions are but a few scenarios that can devastate the life of the transmission fluid. Although changing the fluid yourself is not difficult, it’s probably best left to a qualified service technician. This is also a good time to drain the transmission fluid from the torque converter, if possible. Consult your technician to see if this can be done.

Transmission Gaskets & Sealing

Description: Automatic transmissions/transaxles use an arrangement of internal seals in clutch packs, servos, and accumulators. There are also several external seals. These can usually be found where there are any external linkage connections, where the torque converter engages the oil pump at the front of the transmission, at the output shaft of the transmission (rear wheel drive), and at the transaxle drive axle connections (front wheel drive). A gasket is used between the transmission oil pan and the transmission housing.

Purpose: Internal seals prevent leakage in clutch packs, servos and accumulators. These components are responsible for applying or absorbing pressure at various points inside the transmission/transaxle. External seals prevent the leakage of fluid outside the transmission/transaxle case and also prevent dirt from entering into the transmission. The oil pan gasket seals the pan to the transmission/transaxle case.

Maintenance Tips/Suggestions: Symptoms of internal seal leakage may include slipping, rough shifts, loss of some gear ranges, or no vehicle movement in forward or reverse. Symptoms of a leaking external seal or transmission/transaxle oil pan gasket usually can be seen as reddish-brown spots in your driveway or parking place, a burning oil smell from underneath the car, and frequent topping-off of the transmission fluid level. If your car shows signs of seal or gasket problems, have the transmission checked as soon as possible by a qualified service technician. If the warning signs are neglected, more serious transmission damage may result.

Tourque Converter

Description: The torque converter portion has the ability to multiply torque from the engine. The impeller (sometimes called the pump) has specially curved vanes and is driven by the engine’s crankshaft. The turbine also has specially curved vanes and is connected to the input shaft of the transmission. Adding a third element, the stator (also called the reactor), gives the assembly the capability it is named for.

The stator has vanes and is mounted on a one-way clutch, to allow it to freewheel in only one direction. The stator assembly is located between the impeller and turbine and redirects oil that bounces back off the turbine. The force of the redirected oil assists in rotating the turbine, resulting in torque multiplication. When the impeller’s speed is high and turbine’s speed is low, torque can be multiplied by as much as 2:1. When the impeller’s speed and the turbine’s speed are about the same, torque can be transferred at almost 1:1. Beginning around 1980, carmakers took the torque converter one step further by adding a lock-up function. Lock-up converters also contain a friction clutch that locks the converter impeller to the turbine, usually in higher gears. A solenoid-controlled oil passage, commanded by the car’s powertain control module (PCM), locks and unlocks the converter based on driving conditions.

Purpose: The torque converter, connected to the transmission/transaxle input shaft, connects, multiplies and interrupts the flow of engine torque into the transmission. The torque converter supplies torque to the transmission’s input shaft in two separate, distinct ways: hydraulic input and mechanical input (lock-up converters only). Hydraulic input comes from the torque converter’s turbine and the amount of input torque can vary depending on the operating conditions within the converter. Mechanical input results when the lock-up function of the converter engages. The end result is better fuel economy because all converter slippage is eliminated when the converter locks. The torque converter also helps to smooth out engine power pulses, as does the flywheel on a car with a manual transmission.

Maintenance Tips/Suggestions: The torque converter does not require any regular maintenance or adjustments, but it may be possible to change the transmission fluid in the converter through draining (if equipped with a drain) or with a transmission flushing and filling machine. Much of the transmission’s fluid stays in the converter and since the converter produces a tremendous amount of heat (the enemy of transmission fluid) there’s good reason to change it if possible.

Torque converter problems fall into two categories:
1) problems within the torque converter itself, or
2) problems within the torque converter clutch.

If you suspect a problem with the converter or transmission, have it evaluated by a qualified transmission specialist. With the complexity of today’s transmissions and torque converters, there’s no room for guesswork.

Transaxle

Description: An aluminium case containing a torque converter, an arrangement of planetary gears, clutches & bands, servos, a hydraulic system, solenoids, and a valve body. On front wheel drive cars, the transmission and differential are combined into a single housing called a transaxle.

Purpose: An automatic transmission/transaxle changes the engine’s speed and torque in relation to the speed and torque of the drive wheels. This keeps the engine’s output matched as close as possible to varying road speeds and loads. The torque converter, connected to the transmission/transaxle input shaft, connects, multiplies and interrupts the flow of engine torque into the transmission.

Maintenance Tips/Suggestions: Most of today’s automatic transmissions/transaxles do not require any regular adjustments. Check your owner’s manual to see if any adjustments are required. Owner’s manual recommendations on transmission fluid changes vary considerably and may go as high as 160,000 kilometres or more. For best results, have your car’s transmission fluid and filter changed every two years or 40,000 kilometres.

Fact is, the overwhelming majority of transmission failures are heat-related, and automatic transmission fluid breaks down rapidly when subjected to high temperatures. Driving conditions such as trailer towing, quick stops and starts, ascending and descending mountains, and wheel-spinning in slippery conditions are but a few scenarios that can devastate the life of the transmission fluid. Although changing the fluid yourself is not difficult, it is probably best left to a qualified service technician. This is also a good time to drain the transmission fluid from the torque converter, if possible. Consult your technician to see if this can be done.