Automatic transmissions come in a wide variety of shapes, sizes, and designs. The earliest automatic transmissions in automobiles only came in 2 speeds and varied the gear ratio based on fluid pressure. Today automatic transmissions can have upwards of 8 or 9 speeds with many different ways of getting the power from the engine to the transmission. Many of these new transmission designs are to help optimize engine efficiency by keeping the engine in a specific operating RPM to help meet stricter emissions requirements.
Even with the advent of newer more sophisticated transmission, the vast majority of the cars on the road today still operate with a torque converter driven automatic transmission that uses a planetary gear set and hydraulic pressure to operate. For a quick overview of how a planetary gear set can provide different gear ratios in your transmission, check out this article from How Stuff Works on planetary gear sets.
If you suspect your automatic transmission is slipping, you need to first understand how power is transferred from your engine to your transmission. Instead of having a clutch like a manual transmission, your automatic transmission has a torque converter. This device transfers power from the engine to your transmission through a fluid pump. The benefit of the torque converter is that if your vehicle comes to a stop, the torque converter will allow the engine to spin freely so your motor can idle. The drawback is that the engine side of the torque converter always has to be spinning at least a little bit faster than the transmission side to continue pumping the fluid. The slip you’re feeling in your transmission could simply be your torque converter transferring power to your transmission.
You can tell for sure when your transmission is slipping if you start to have hanging or slow shifts. A hanging shift is when your transmission shifts much later than you anticipate it and seems to hang at a higher RPM before finally moving to the next gear. You can tell this is happening by noticing your engine RPMs rising higher than usual during normal acceleration.
If find your transmission slipping or if your car jerks when shifting gears, there could be a few different causes. First, your transmission may be worn out. The bands and clutches that cause gear changes may have gotten so worn that their friction surfaces have become smooth and are no longer holding this stationary when they should. Unfortunately, you can only prove that this is the case by removing and taking apart your transmission. Once you’ve gotten that far into it, you might as well simply rebuild it. Another thing that may be causing your transmission slipping would be old or worn out transmission fluid. The materials used to build a transmission are chosen specifically due to the way they interact with the transmission fluid used. The wrong materials and fluids together will cause too much friction and hard shifts, or the opposite problem of low friction and sloppy shifts.
Over time your transmission fluid will lose some of its lubrication and friction modifying properties. As these properties change, so will the shifting in your transmission which could lead to the problem you’re having.
Last, if you’ve got a low transmission fluid level it can slipping in your transmission. Besides lubricating things, the fluid in your transmission provides hydraulic pressure to move the clutches and bands and cause the shifts to happen in your transmission. If you’ve got a low fluid level, it can create a low pressure situation which can cause shifting problems.
If you find a low fluid level in your transmission make sure to top it off with the manufacturer’s recommended type of transmission fluid to make sure you don’t cause more problems. Also, add BlueDevil Transmission Sealer with your top off fluid to restore the seals and gaskets in your transmission to stop any leaks to make sure you don’t end up with a low transmission fluid level again.
To learn more about BlueDevil Transmission Sealer and how it can keep your transmission running safely, click on the banner below!
You can also purchase BlueDevil Transmission Sealer at any of our partnering local auto parts stores like:
- Advance Auto Parts
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- Pep Boys
- Fast Track
- Bumper to Bumper Auto Parts Specialists
- S&E Quick Lube Distributer
- DYK Automotive
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