Automatic transmission jerks can be a frustrating issue for drivers. Automatic transmissions need more frequent attention from the driver than do manual gearboxes.
A jerk can be caused by a number of things, including the automatic gearbox jerking. Insufficient transmission fluid (ATF) fluid levels might be a typical problem. Clogged oil filters, coolers, worn-out friction discs, a failed oil pump, and valve body and/or solenoid issues are all possibilities.
Inadequate car care, whether by the owner or the mechanic, is to blame for each of these issues. Most of the time, basic transmission maintenance is all that’s needed to keep it running smoothly.
Experts who purposefully mislead their consumers by claiming that the automatic transmission on their cars does not require any maintenance are also out there.
What causes an automatic transmission to jerk?
You may notice these symptoms in your car’s automatic transmission after purchasing a new vehicle and driving it for around 100 thousand kilometers (62, 000 miles). This figure is, of course, approximate and conditional.
We’ll go over all the reasons your transmission might jerk in the sections that follow.
Using an incorrect automatic transmission fluid
In order to meet the specific standards of each car manufacturer, transmission fluid must have a specific viscosity and performance characteristics. The car’s automatic transmission will jerk and kick if the fluid has the wrong characteristics.
In the winter, you’ll notice the transmission jerking when you start the car, especially if the car has been parked for a long time at a low temperature. When you warm up, the issue goes away.
Using the improper oil, which thickens in the cold, will not allow the automatic transmission to function normally. As a result, you’ll want to go with a lighter oil.
A bad automatic transmission oil filter
Metal chips are created as a result of normal wear and tear in the transmission parts, and the more wear and tear there is, the more chips there are.
Over time, the AT oil filter will become clogged with metal particles and be unable to provide the correct volume of fluid. This will cause the operating pressure in the system to drop, which will have an impact on the friction discs.
A lack of stopping power and a lack of force will cause these discs to slip. That’s why shifting gears during acceleration and braking might cause you to feel jerks and shaking.
When the fluid level is extremely low, the discs are put under even more stress, which can lead to disc burnout in the worst-case scenario. An automatic transmission that experiences jerks while hot is a prime example of this problem.
Simply said, the answer is obvious. The transmission fluid filter must be checked regularly and the correct ATF fluid must be used, as indicated by the manufacturer. The fluid and the filter should also be changed on a regular basis.
Failing friction plates
When shifting gears, the automatic transmission’s friction plates function as a clutch. They compress and expand as a result of the transmission fluid passing through the system under pressure.
The plates will not be able to compress and decompress with sufficient force if the pressure is insufficient. In the absence of oil, they will just move along each other, eventually heating up and igniting.
These plates wear out, resulting in a jarring sensation when you shift gears. In addition, the transmission fluid wears out significantly more quickly and loses its usefulness. The jerks, kicks, or twitches will be felt more strongly and you will hear, in most cases, unpleasant crunching noises coming from the transmission when the discs are worn or simply burned.
It’s also possible that shifting gears will become difficult. It is difficult to fix the automatic transmission without disassembling it and opening it up.
A failing automatic transmission oil cooler
This part’s primary function is to keep the AT fluid cool. Because of this, the fluid becomes extremely hot and burns when its performance declines. Consequently, the overall performance of the automatic transmission will be compromised for the reasons already mentioned.
Replace old fluid under pressure, and you’ll have a problem with the cooler. High-pressure devices are inserted in the gap between cooling radiator and automatic transmission when executing this technique. The old fluid is then drained from the system and replaced with a new one.
There is no need to replace the oil filter or flush the box tray, which includes the radiator, in this procedure; however. As a result, dirt at the bottom of the transmission rises to the surface and clogs several transmission components, including the radiator, oil filter, hydraulic plate, and solenoids.
Small pipes and honeycombs dot the radiator, and they’re all blocked with dust. Because of the burns, the radiator’s efficiency will be greatly reduced when the temperature rises.
For example, if you want to eliminate the jerkiness when shifting gears, you can clean the ATF radiator. Changing the AT fluid under pressure, changing the oil filter, and cleaning the radiator should be avoided in the future. Despite the additional cost, this will increase the overall life of the automatic transmission.
A failing hydraulic plate
The valve body is another name for this hydraulic plate. The AT fluid is forced to flow through a network of tiny channels in this component. Fluid runs through each gear channel, causing the clutches to compress or expand depending on the applied pressure.
There will be insufficient pressure to operate the clutches if these tubes become clogged with unclean liquid. If they can’t contract and compress, you’ll notice jerks in the automatic transmission’s behavior.
As you might have anticipated, the primary cause of this problem is the failure to replace the AT fluid in time or to do so under pressure, as the case may be. The only way to clean these channels is to remove and disassemble the gearbox, which can be very expensive.
Plate wear is also a major factor. There are two plates here, and a third unusual plate sits between them. The solenoid’s rod, which is shaped like a ball, sits against it.
As a result, the system’s pressure valves are shut (locked). An precise match exists between the hole in the supplied plate and the specified ball.
When shifting gears, the hole fractures, resulting in a few minor hiccups. Replacing the aforementioned plate is the only way to fix this issue. However, removing the AT for diagnostics and repairs is required.
The hydraulic plate channels are supplied with transmission fluid by special valves called solenoids, which open and close precisely at the proper time.
For mechanical damage or aging, the solenoid may eventually fail over time. As a result, the solenoids either do not close or open the channel, which results in the transmission jerking when shifting gears, resulting in the transmission malfunctioning.
The fact that they’re constructed of cheap, flimsy plastic only serves to exacerbate the problem. Most of today’s autos use plastic solenoids. As a result, they can melt, lose their shape, and cease performing properly at high temperatures.
Metal solenoids are not affected by these issues. In order to service the solenoids, the hydraulic plate must be disassembled, cleaned, and adjusted, including the solenoids.
Other reasons why automatic transmission jerks
If the car’s AT isn’t properly calibrated, it can jerk.
A bad Electronic Control Unit (ECU)
The jerks in the automatic transmission can be caused by a malfunctioning ECU. Errors can occur in the software. Changing gears will cause the automobile to jolt, and it may also cause additional problems.
When shifting gears, the AT won’t react and the engine speed will be unpredictable. An ECU computer diagnostic is required in this situation.
The laptop with the appropriate software and connectors should be brought along to the automobile rather than driving with the car in this state.
If you don’t have the expertise to repair the ECU, you should leave it to a trained professional who can guarantee their job.
A bad automatic transmission oil pump
Fewer than 1% of the time, the AT fluid pump fails. Although the pump’s design is relatively sturdy, it might also malfunction due to mechanical damage or a manufacturing error.
Transmission fluid will no longer be able to circulate at working pressure, or it will simply stop doing so under these circumstances. A reduction in pressure can cause jerky shifts and even total transmission failure.
Bad ECU wiring
The ECU sends electrical signals to the relevant wires on the automatic transmission, which controls it. Older autos, and in certain cases, entirely torn wiring is common.
Causes that are not related to transmission problems
The jerks felt when shifting gears may be caused by something other than a faulty automatic transmission. Make sure the throttle valve is clean to guarantee optimum air flow.
The air filter is the same. Transmission shifting shocks are reduced, and automatic transmission shift times are lengthened, when the throttle valve and engine air filter are cleaned and replaced.
Worn engine and transmission mounts can cause jolts and jerks when shifting gears. A rubber insert is sandwiched between two metal plates to form these mounts.
The rubber loses its characteristics and wears out over time, especially when subjected to vibrations. Switching between gears appears jerky as a result of this. The best way to get rid of this is to buy fresh mounts.
Role of additives for automatic transmission against jerks and shocks
The following functions are served by transmission additives designed specifically for automatic transmissions:
- increasing the smoothness of the transmission, especially when switching gears;
- the increased service life of both individual transmission elements and the automatic transmission as a whole;
- reducing the noise in the AT;
- Protection of individual elements of the car’s transmission;
- Protection of plastic and rubber parts;
- cleaning the At fluid from metal debris and dirt, which will increase the service life of the oil filter;
- prevention and elimination of transmission fluid leaks from the system;
- eliminating jerks when operating the automatic transmission.
Liqui Moly’s additive showed its worth. In terms of automatic transmission additives, this is one of the best. It keeps oil from leaking out, cleans and protects the seals, and regenerates them all at the same time.
It is recommended that these additives be added to the AT fluid no more than three times per transmission oil, every 20.000 km or 12.400 miles.
However, there are other factors that can cause your car’s automatic transmission to jerk, and they’re not related to the transmission. First, if you notice any jerks or kicks when shifting gears in an automatic transmission, you should run computer diagnostics. If there are any mistakes, it will be clear just how serious the issue is.
Keep an eye on your car’s automatic transmission and have it serviced often to avoid future issues. When driving in rough conditions, avoid using the automatic transmission at all costs.
Transmission fluid and an oil filter should be replaced first if the transmission isn’t being removed. Remember, don’t rush through the replacement. If the fluid was the source of the jerks, this should put an end to them. An oil change won’t do the trick, so you’ll have to take the transmission out and get it diagnosed at an auto shop. This is a costly process, but one that is very necessary.