If your transmission has started slipping, you might be tempted to ignore it, especially if the slippage isn’t particularly severe. However, it’s never a good idea to ignore a slipping transmission.
A slipping transmission isn’t necessarily on the brink of failure, but going too long without repairing a slipping transmission can potentially cause bigger problems down the line.
In addition, driving with a slipping transmission can be pretty unsafe, so unless you have no other choice you should always avoid driving with such a transmission. In this article, we’ll be explaining what exactly transmission slippage is, why it happens, and everything else you might need to know about this issue.
What Is Transmission Slippage and What Are the Symptoms of It?
In both manual and automatic transmissions, the gears within the transmission need to properly mesh together to send power through the transmission. Slippage occurs when the gears do not properly grip each other, causing the transmission to slip in and out of gear.
Both manual and automatic transmissions can slip, although the symptoms associated with slippage can vary depending on what type of transmission you have, since manual and automatic transmissions are built differently. Here are the symptoms of slippage to look out for, depending on what kind of transmission you have:
Manual
- Strange noises like grinding or whining during gear changes
- The transmission falls out of gear for no reason
- The transmission can’t be put into gear
Automatic
- The transmission makes grinding noises when changing gears
- The transmission refuses to upshift, or upshifts and then immediately downshifts
- A smell like something is burning
- Gear changes feel rough
- When stepping on the gas, the engine speed increases but the car doesn’t move any faster
- You can’t engage reverse gear
Why Is My Transmission Slipping?
Even if you’ve determined for sure that your transmission is slipping, it can be tricky to determine what the source of the problem actually is. Transmissions can be pretty complicated pieces of hardware and contain a lot of parts that can break or wear out.
Related: Why Does My Car Shake When I Accelerate?
Below are the most common reasons why transmissions tend to slip. Depending on how well you take care of your transmission, your slippage might be caused by one or more of these issues.
1. Transmission Fluid Problems
Issues with transmission fluid are the most common cause of transmission slippage, at least in the case of automatic transmissions.
It’s important to note that automatic transmission fluid is considerably different from manual transmission fluid. While manual transmission fluid merely acts as a lubricant within the transmission, automatic transmission fluid acts as a lubricant, a coolant, and a hydraulic fluid and provides the gears with just enough friction to engage and disengage smoothly.
Loss of transmission fluid due to a leak will invariably result in slippage in an automatic transmission. In a manual transmission, low levels of fluid won’t cause slippage but will eventually cause the transmission to seize up.
Going too long without changing your transmission fluid can also cause it to eventually start slipping. As time goes on, the fluid starts to break down, and contaminants start accumulating in the fluid. When this happens, the fluid loses its coolant properties, which, of course, causes the transmission to overheat.
If you want to check the state of your transmission fluid, you can use the color of the fluid to determine how fresh it is. Fluid that is new and still in good condition will be either bright red or pink in color, while old fluid will be much darker and appear brown or black.
2. Broken Transmission Bands
In automatic transmissions, bands are used to engage the different gears within the transmission. It can be tricky to explain the function of transmission bands without knowing how an automatic transmission works, so let’s quickly go over that now.
Unlike manual transmissions, which use a different gear wheel for each of their speeds, automatic transmissions use multiple gears of varying sizes simultaneously to achieve different speeds. The gears in an automatic transmission are controlled by a series of clutches and bands.
In this case, a band is literally a steel strap that wraps around one of the gears in an automatic transmission. When the car requires a gear to disengage from the rest of the transmission, a piston causes the band to tighten around the gear, which prevents it from turning.
If a transmission band breaks, wears out or becomes misaligned, it can cause the gears to start slipping. Transmission bands are more likely to wear out when your automatic transmission fluid gets too low or dirty, so this is just another reason to change your transmission fluid regularly.
3. Worn-Out Gears
Over time, the gears in your transmission are going to wear out, especially if they overheat or don’t receive enough lubrication. Once again, this is why you should always be diligent about changing your transmission fluid, since doing so can go a long way preventing your gears from wearing out prematurely.
In a properly functioning transmission, the teeth of the gears fit together perfectly, which helps the gears grip each other. When the gear teeth start getting worn down or rounded out, they lose the ability to push against each other with sufficient force, which, of course, causes slippage.
In rare cases, your gears might slip thanks to a manufacturing defect, but for the most part, the gears only tend to slip thanks to normal wear and tear.
4. Worn-Out Clutch
While both automatic and manual transmissions use clutches, the way they use them is completely different.
A manual transmission uses a clutch to disengage the transmission from the engine’s flywheel, while an automatic transmission contains multiple clutches (known as a clutch pack) that allow the individual gears in the transmission to turn with each other. If a manual transmission is slipping, the cause of the issue is more often than not a bad clutch.
If you’re not familiar with how a clutch works, here’s a quick rundown for you. The clutch is connected to the transmission and is essentially the medium between the transmission and the engine.
When the clutch is engaged, it is pushed up against the flywheel, which is attached to the crankshaft. The clutch is made with a friction material, which allows the clutch to grab onto the spinning flywheel and send power through the transmission.
When the clutch is disengaged, the throwout bearing moves the clutch away from the flywheel, which disconnects the engine from the transmission. This allows the engine to spin freely while the gears are being changed.
As time goes on, the friction material of the clutch naturally starts to get worn down, which prevents it from gripping the flywheel as effectively. The more worn down it gets, the more the clutch loses its ability to engage, and the more slippage occurs.
The throwout bearing can also wear out over time, which won’t cause slippage but will eventually prevent you from being able to disengage the clutch at all.
5. Bad Torque Converter
Torque converters are for automatic transmissions, as clutches are for manual ones. While torque converters are functionally the same as clutches (both allow the engine to disconnect itself from the transmission), these two pieces of hardware work in very different ways.
A torque converter uses a fluid connection to transfer power from the engine to the transmission. It’s a little tricky to explain how this works, but we’ll do our best.
Inside a torque converter, there are two fans and some transmission fluid. One of the fans, which is referred to as the impeller or the pump, is attached to the flywheel. The other fan, which is called the turbine, is attached to the transmission.
Since the pump is attached to the flywheel, it always spins at the same speed as the flywheel. The spinning pump moves the transmission fluid through the torque converter, where it hits the blades of the turbine, causing it to spin. This is how power is transferred through a torque converter.
When the gas pedal isn’t being pressed, the pump still turns, but because the engine isn’t turning very fast the pump can’t move the transmission fluid with enough force to make the turbine spin also. This is how a torque converter is able to disengage the engine from the transmission when it needs to.
Torque converters also wear out over time, as you might expect. When this happens, the pump might not be able to send the right about of transmission fluid through the turbine blades, which can cause the transmission to start slipping.
6. Bad Solenoid
A solenoid is a component that converts electrical energy into mechanical energy. In an automatic transmission, the solenoid controls valves that regulate the flow of transmission fluid within the transmission.
An automatic transmission requires a certain amount of internal hydraulic pressure in order to change gears properly, and the solenoid ensures that the right amount of pressure is always achieved. If you’r transmission solenoid stops working, however, this can result in an inadequate amount of fluid being sent to the transmission.
If your transmission isn’t receiving enough fluid, it’ll start slipping and overheating almost immediately.
7. Software Issues
Transmission slippage issues as a result of bad software are pretty rare, but they do still happen. The most notable recent example is the infamous Ford PowerShift transmission, which came in the 2011-2016 Ford Fiesta and the 2012-2016 Ford Focus.
Because of the design of this particular transmission and the way the ECU was programmed, the PowerShift couldn’t handle fast acceleration or other quick changes in speed. This caused a shuddering sensation while accelerating and extremely rough gear changes.
If you’ve investigated all other possible causes and you’re still not sure why your transmission is slipping, there’s a slight chance it could have something to do with your car’s software.
Can I Drive a Car with a Slipping Transmission?
Unless you have literally no other choice, you should never drive a car with a slipping transmission. We’ve mentioned this already, but driving a car with a slipping transmission is not only a great way to make your existing mechanical problems worse, it’s also a safety hazard.
Transmissions don’t slip on their own when they’re working properly, so if you notice some slippage occurring, it’s a sure sign that something inside your transmission has worn out or broken. Don’t make the mistake of thinking the problem might go away with time; if you ignore a slipping transmission, it will only get worse.
If your car is slipping in and out of gear while you’re on the move, this can be a pretty serious safety issue. Slipping a gear can prevent you from being able to accelerate in a situation where you might need it (such as merging onto a highway), and a badly-slipping transmission can cause the whole car to shake, making it harder to control.
How Do I Fix a Slipping Transmission?
As we’ve shown, there are many ways a transmission can start slipping. Depending on what the source of the problem is, the method of fixing can vary greatly. In most cases, however, fixing a slipping transmission means replacing one or more parts.
A transmission flush can sometimes solve the problem of slippage, but only if you manage to catch the problem very early on. If you go too long with worn-out transmission fluid, other components of your transmission will start to break down also, and simply replacing your transmission fluid won’t solve the issue anymore.
Is It Worth It to Fix a Slipping Transmission?
This really depends on how much your car is worth to begin with. Transmission repairs can be quite expensive, depending on what part of your transmission needs to be replaced. At the very least, you should expect to pay at least a few hundred dollars to fix your transmission; at the most, transmission repairs can cost well over $1,000.
- If you need to replace your transmission outright, the cost is even higher. Replacing a transmission will cost you at least $1,200 in most cases, but depending on the make/model of your car, you may end up paying over $3,000 for a new transmission.
- If you’re talking about a new car, it’s probably worth it to fix a slipping transmission, since the cost of the repair will only be a fraction of the current value of the car.
- If you’re talking about an older, used car, however, the better choice may be to cut your losses and get a new car, as the cost of repairs might end up being more than the car is actually worth.
