What does it mean if a car’s transmission—also known as a gearbox or tranny—slips? The term refers to the transmission spontaneously “slipping” out of one gear and into another, often Neutral.
A slipping gearbox can not only harm your car, but it’s also more likely to create a hazardous situation. Can you imagine losing engine power while merging into traffic or passing another car?
For these reasons and more, your best bet is to address tranny slip at the first signs of an issue.
So, what does transmission slip feel like?
When a transmission slips out of gear, the engine will spin freely for a moment before shifting. This can result in an RPM surge—possibly faster than the motor is built for—without the car speeding up.
Drivers often describe shifting as feeling sluggish, slow, and rough. Moreover, don’t be too surprised if you hear clunking sounds during shifts, which is another common symptom.
In this guide, I will cover slipping transmissions in more detail, including causes, symptoms, and fixes.
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7 Causes Of Transmission Slipping
1. Low/Old Transmission Fluid
The most common reason for tranny slip is low or old automatic transmission fluid (ATF).
Automakers usually suggest checking ATF levels monthly and changing the fluid every two to four years. Doing so ensures the ATF remains free of impurities that can cause lasting damage.
2. Faulty Solenoid
A solenoid is an electromagnetic device that aids in controlling how much ATF flows through your car’s gearbox.
If the solenoid fails, the tranny won’t receive enough ATF. This can cause it to slip and overheat, leading to costly repairs—possibly even a full transmission replacement.
3. Worn/Broken Transmission Bands
Transmission bands are flexible steel straps that link the gears of an automatic tranny together.
Worn or broken bands are less likely to secure the gears correctly, resulting in transmission slips. Moreover, broken bands can even lead to the gears not engaging at all.
4. Malfunctioning Clutch
Clutches are usually associated with cars that have manual transmissions. Yet, even automatics have clutches, which work in much the same way.
If a clutch goes out, shifting behavior will likely become erratic. This includes delayed, unexpected, or rough shifts and—you guessed it—gear slipping.
5. Bad Torque Converter
Simply put, a torque converter transmits the engine’s rotational power to the transmission so it can shift gears.
If a problem arises with the converter, torque may not transfer through the gearbox properly. This can cause slipping that worsens until shifting is no longer possible.
6. Regular Wear And Tear
There shouldn’t be too much surprise here, as nothing is immune from general wear and tear.
Transmissions are incredibly complex and have many moving parts that can become compromised with age. Still, most last well beyond 100,000 miles before having any issues like slipping.
7. Software Problems
Software issues can also be behind a slipping gearbox. Transmission software relies on input from different parts to optimize shifts. But, if readings are off, slipping may occur.
Once diagnosed as a software issue, a shop may be able to flash the system to fix the problem.
What Does A Slipping Transmission Feel Like?
A working transmission will let the engine RPMs climb before downshifting to a lower gear. Yet, when a tranny is slipping, it can randomly “slip” into Neutral before shifting into the right gear, resulting in the engine spinning freely for a moment.
Drivers often describe a slipping transmission as feeling sluggish, slow, or rough when changing gears. Moreover, don’t be too surprised if you hear clunking as the gearbox shifts.
Besides potentially harming other parts of your car, transmission slip is also a safety concern.
If the tranny slips while you’re merging into traffic, passing a vehicle, or in some other precarious situation, it could result in an accident.
Can You Drive With A Slipping Transmission?
Yes, you can technically drive a vehicle with a slipping transmission, provided the issue hasn’t progressed too far.
However, you really shouldn’t, as you risk causing significant damage to not just the gearbox but the engine as well. To the repair shop? Sure. Back and forth to work for three months, hoping nothing happens? Probably not a good idea.
Besides accelerating the decline of your car’s transmission—a repair often costing over $5,000—you also put the engine at risk.
When a tranny slips out of gear and the engine free spins, the RPMs may surpass what the motor is built for. Left for too long, the engine may develop overheating issues, upping the odds of blowing the head gasket or cracking the block.
How Do You Fix A Slipping Transmission?
If your transmission starts slipping, the first thing to do is check the ATF level. If there’s sufficient fluid and it’s still fresh, the issue likely stems from something else. But you’ll need to add more if the tank is low or empty.
For step-by-step instructions on how to inspect and change the transmission fluid, check out the below video from Jiffy Lube:
If you’d rather pay a shop to change your car’s transmission fluid, expect to spend between $80 to $250. For more details on the costs of changing ATF, check out our guide.
Beyond ATF levels, any other cause of transmission slipping—like a bad torque converter or solenoid—is best handled by a professional. While you can attempt the repair yourself, most would do best to outsource the issue.
Avoid Transmission Slip And Other Problems By Following A Routine Maintenance Schedule
Following a routine service schedule is the best way to protect against slipping and is sure to extend the life of your gearbox.
Most maintenance schedules suggest flushing the ATF every two years and changing the filter and pan gasket every two to four years. For more information on scheduled maintenance, be sure to review our detailed service guide.