Common Reasons Your Transmission is Slipping

Get a grip!

A transmission and mode selector on a 2019 Toyota RAV4.
Toyota

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Ford is in the midst of a massive settlement in which it’s suffering the consequences for producing and delivering faulty transmissions in Focus and Fiesta compact cars. A frustrated hoard of customers complained about several issues with the PowerShift six-speed automatic transmission, including slipping caused by faulty programming. 

It’s become one of the biggest transmission recalls ever, but software is just one of many things that could cause a transmission to slip. Valves, fluids, gears, clutches, and gears are all susceptible to issues that could cause the mechanism to falter. Transmissions are some of the most complex components of an automobile, and if things aren’t working in harmony, the driver is going to feel it. 

Despite the complexities, maintaining your transmission fluid is a simple and effective way to prevent these issues from happening. ease the mind of transmission worries and keep your vehicle running smoothly for longer. A lubricated transmission is a happy transmission. Learn how and why your fluid affects the rest of the transmission, as The Drive’s manic informational team explains the reasons your transmission is slipping.

What Is a Transmission? 

As part of a vehicle’s drivetrain, a transmission is a device that interprets power from the engine and passes it along to the wheels to move the vehicle. The most common types of transmissions in average consumer vehicles are manual transmissions, traditional automatic transmissions, and continuously variable automatic transmissions (CVT). 

A manual transmission is one that requires a clutch pedal and gears actuated by the driver using a gear shifter, while an automatic transmission does not require a clutch pedal and runs through its gear sets on its own. A CVT is a different type of automatic transmission that uses belts or chains paired with pulleys to create smooth acceleration without gear steps. 

In simple terms (transmissions are extremely complex machines), the main components of a transmission are the torque converter, the valve body, and the planetary gear sets. 

The torque converter is the device that transfers and multiplies energy from the engine, the valve body controls gear and fluid timing, and the gears determine the drive ratios. Different gear ratios make for different acceleration, speed, and driving characteristics.

An automatic transmission taken apart to show the inside of a torque converter.
Depositphotos

A torque converter is split apart to show its insides.

What Does a Transmission Do?

Inside a car, the driver sees a manual stick shift or an automatic shifter, whether that’s a column shifter, a push-button shifter, a rotary dial shifter, or a shift lever. A stick shift will typically be labeled, “R, 1, 2, 3, 4, 5, 6,” dependent on how many gears the car has, while an automatic transmission is typically labeled “P, R, N, D, L,” with a couple numbers and an S occasionally making appearances. On an automatic transmission, P stands for park, R stands for reverse, N stands for Neutral, D stands for Drive, and L stands for Low gears. Change the shifter, change the transmission.

Automatic Transmission

In a car with an auto transmission, putting the vehicle into Drive engages a set of gears. A transmission receives engine power from the input shaft and sends it to the wheels via an output shaft. On automatic transmissions, the gears constantly change to accommodate throttle input and speed. When at a stop, an automatic transmission automatically disengages.

Manual Transmission

In a car with a manual transmission, sometimes called a standard transmission or a stick shift, the driver is required to move the transmission through the gears using a clutch pedal and the hand shifter. The driver depresses the clutch pedal each time the vehicle needs to shift into another gear. 

In short, both automatic and manual transmissions transmit energy from the engine to the drive wheels. Now, onto what’s interrupting that transmission of energy.

Why Is Your Transmission Slipping? 

A slipping transmission is a symptom of a bigger problem. Let’s figure out what’s going on and, hopefully, assuage your fears.

Fluids

Like an engine without motor oil, a transmission without transmission oil will fail. The transmission also might act up if the levels are too low or too high. In the case of slipping, the transmission fluid is likely low or has been contaminated.

Gears

Think about how gears work. Sets of teeth grip each other and push each other along. If those teeth are worn down due to low or contaminated transmission fluid, age, and general wear, they won’t be able to grip as effectively. This could also lead to slippage.

Bands and Clutch Packs

Transmission bands and clutch packs are internal mechanisms that are used to engage or brake the gears. Wear over time can eat at these components and make them less effective. If they underperform, your transmission might slip.

Solenoid

A transmission solenoid controls fluid distribution. If it’s faltering, the transmission is not getting proper amounts of vital fluid. Without fluid, the transmission could slip.

Torque Converter

A torque converter is the primary connector between the engine and the transmission. If it fails or is not operating correctly, the transmission will reflect that.

Software

Computers might be smart, but without artificial intelligence, they’re still limited to what humans program into them. If there’s an error in programming, it could lead to or cause transmission slipping or stalling. Ford’s PowerShift transmission is a perfect example.

An automatic transmission.
Depositphotos

An automatic transmission housing is often shaped like a bell.

How To Fix a Slipping Transmission

You might expect that the first step in fixing a slipping transmission is changing or flushing the fluid, but that’s not the case. 

If the transmission is slipping, it likely means it already has worn internal components. In some cases, friction material from things such as the clutch packs might be worn off and floating around in your used fluid. Although that’s bad, the friction material might still be aiding with creating necessary friction. If that fluid is replaced, the result might be even worse slipping. 

Additionally, adding new fluid where soiled fluid resided might move particles and contaminants around and further damage the transmission. 

At this point, you could try using a product such as Lucas Transmission Fix Stops Slip, but that rarely works. If your fluid is bad, that’s typically an indication of a larger issue that requires a professional diagnosis. Transmissions can be repaired and rebuilt, but because they are so complicated, fixes are typically left for the guys who do it for a living. Unfortunately, transmission repairs can cost thousands of dollars. 

The best way to prevent bad fluid is to perform changes and/or flushes roughly every 40,000 miles, or at intervals specified by the manufacturer, when the transmission fluid still looks decent.

How To Check, Add, and Change Transmission Fluid

Depending on your vehicle, how you maintain your transmission will vary. Some systems are completely closed and will require professional service. Likewise, a full transmission flush requires a specific machine only found at service centers. However, if you’re just looking to service the transmission fluid and change it out, that’s a job for your home garage. Learn more from The Drive’s guide to transmission fluid.

The gears inside an automatic transmission.
Depositphotos

Automatic transmissions automatically switch gears.

FAQs About a Slipping Transmission

You have the questions, The Drive has the answers!

Q. What Does a Slipping Transmission Feel Like?

A. A slipping transmission is easy to recognize if you know what you’re looking for. Symptoms of a slipping transmission include sudden losses of power, jerkiness, hesitant upshifting, and high revving.

Q. Can You Drive A Car With A Slipping Transmission?

A. Technically, yes, the car will run with a slipping transmission (until it goes bunk), but we advise immediately driving home to your garage or to a shop where you can diagnose the issues. The longer you drive with a slipping transmission, the higher likelihood you will damage its internal components.

Q. How Much Does It Cost To Fix A Slipping Transmission? 

A. If a fluid change or refresh resolves your issues, the bill stops at the cost of the fluid. However, if your transmission is slipping because of damaged parts, you’ll be out thousands of dollars for a transmission rebuild or replacement.

Q. Can a Transmission Flush Fix Slipping?

A. Yes, your fluid might be the issue, whether it’s contaminated, too high, or too low. However, a flush is typically done with a professional machine at a shop, so it’s not an easy home garage job.

Featured Products 

Red Line API GL-4 Manual Transmission and Transaxle Lubricant, 1 Quart

ACDelco Professional Dexron Synthetic Automatic Transmission Fluid, 1 Quart

Castrol Transmax Dex/Merc Synthetic Automatic Transmission Fluid, 1 Gallon

Got a question? Got a pro tip? Send us a note: guidesandgear@thedrive.com