Automatic Transmission Service

Typical Cost: Low - Medium
Mobile Repair? Yes in most cases
Typical Lead Time: 48 - 72 hours due to part lead time

What does an automatic transmission do?

Automatic transmission is a type of vehicle gearbox that automatically changes the gears whilst in motion. These gearboxes are not the same as Semi Automatic versions, which are in fact a manual gearbox that is automatically controlled.

How does an automatic transmission work and what are the components?

The most common form of automatic transmission is hydraulically operated with a torque converter and a gearset.

The torque converter is a fluid coupling, connecting the engine to the gearbox. In essence this replaces the function of the clutch as it connects and disconnects the engine power to the gears allowing the vehicle to come to a standstill without stalling the engine.

The gearset is a group of planetary gears that provide the required gear ratios and thereby alter the speed of the output.

Automatic transmissions use a special fluid, Automatic Transmission Fluid or ATF for short. This fluid is pressurised by a pump to control the various clutches and bands. An electronic speed sensor controls the pressure produced.

On modern automatic transmissions, the valves are controlled by solenoids actuated by the transmission Control Unit (TCM).

ATF provides the lubrication to the moving parts, wear and corrosion protection and is there to transfer the mechanical power. This is why regular servicing of an automatic transmission is vital to change this fluid (and its filter where fitted) in line with manufacturers recommendation. Failure to do this can result in many issues, such as transmission overheat, solenoid failure, jerky gear changes and even total gearbox failure.

Typical symptoms that require an automatic transmission service.

If a gearbox hasn’t had its scheduled service, the likelihood is that you will experience some of the following indicators

• Failure to select gears
• Failure to change up and down smoothly (or in some cases, not at all)
• Jerks on gear changes
• Jolts as you change from Park to Drive
• Transmission overheat warnings
• Transmission Control Unit warning lights

What happens during an automatic transmission service?

There are many different processes required depending on the manufacturer, some of which may include all the following or just some

The mechanic will
* Raise the vehicle and get the gearbox up to temperature if required by the procedures.
* Remove the gearbox drain plug, or insert a syphon pump down the filler tube.
* Removed the gearbox sump where applicable so the filter can be accessed.
* Cleaned the parts before a new filter is installed and the sump refitted with a new gasket or sealing compound.
* Fill the gearbox with the correct ATF for the gearbox and application in accordance with the manufacturer's procedure.
* Use a diagnostic tool in some cases to refill the gearbox in stages..
* Run through the gearbox selection routine
* Road test the vehicle.

What to search for on the ClickMechanic site?

Automatic transmission service

How much does it cost to have an automatic transmission service carried out?

The cost of an automatic transmission service depends on your car and what parts your car's manufacturer recommends.

Find out what you could save by having your automatic transmission service carried out by ClickMechanic, by selecting your vehicle
https://www.clickmechanic.com/bookings/car

FAQ’s

What type of oil is used?

Automatic Transmission Fluid (ATF) is of paramount importance to the operation of the gearbox. Each manufacturer will have specific requirements and these are adhered to during the service.

Is the filter changed during the automatic transmission service.

Unless otherwise specified, yes it is.

Why is an automatic transmission more expensive than an engine oil change?

ATF is a specially formulated oil for the purpose. Some of the recommended long life oils are incredibly costly per litre and some gearboxes can take 7+ litres!

Can I supply my own parts?

No, we will not fit customer supplied parts unless they are a brand new item, purchased from a dealership with the receipt as proof of purchase. There is no flexibility over this due to insurance and warranty issues.

What happens if the mechanic finds that the automatic transmission doesn't require servicing and the problem is due to another issue?

In this scenario, the mechanic will provide a no obligation quote for the correct repair. Should you accept this, the mechanic can alter the booking accordingly. If you decide not to go ahead with the alternative repair, the mechanic can change the booking to a call out and diagnostic booking and charge according to the time spent with the vehicle and call out.