Car Jerks When Shifting: One of our specialties here at LifeOnFour is transmission problems. Most of the articles I write are based on my experience from owning many different cars and having lost many hairs over transmission problems and big bills. We talked about the 14 most common transmission problems, we covered why an automatic transmission starts shifting hard, we talked about DSG automatic transmission problems and we also covered CVT transmission and CVT transmission problems. Not to brag, but we do know what we are talking about when it comes to automatic transmissions.
Today we are answering a question that is not easily answered: Car Jerks When Shifting From Park To Drive, Why?
We will break down all the possible reasons why an automatic transmission could be jerking forward as you shift from Park to Drive. Stay with us!
Reason Why Your Car Jerks Or Jumps Forward When Shifting Out Of Park
Before we start we must say that even though our list of reasons why your car might be jerking or jumping forward as you shift out of Park is big, all of these do have a sensible connection as to why the jerking motion happens. Diagnosing this issue purely based on internet research is impossible, we only provide the guidelines upon which you or your mechanic should investigate further on.
Low or dirty transmission fluid
This is probably the most common reason why a transmission starts jumping, jerking or lurching as you shift out of park. Transmission fluid should lubricate and smoothen out all of the internal movements of an automatic transmission. If there is not enough transmission fluid or if it is dirty and worn out, a typical symptom is jerking as you shift out of park. You may also experience hard shifting, slipping, and jerking throughout the gear shifts. Make sure you replace your transmission fluid regularly to prevent major transmission damage!
Malfunctioning transmission pump
The job of the transmission pump is to compress and supply transmission fluid in order to lubricate all the moving parts inside the automatic transmission like the torque converter and hydraulic actuator. When the transmission pump starts failing, you might hear loud whining noises and increased occurrences of jerking and hard shifting. When the pump fails, you restrict the transmission of fresh “lubricant” which leads to rough operation of the transmission. The whining noise of a failing transmission pump is extremely noticeable, don’t miss it!
Blocked transmission filter
The transmission filter should be replaced regularly, just like the transmission fluid. Failing to do so can result in excessive strain on the transmission pump which is doing everything in its power to provide fresh and filtered transmission fluid to the moving components of your automatic transmission. As the transmission filter gets blocked and dirty, you risk damaging your transmission pump and starving your transmission of fresh transmission fluid which leads to jerking, slipping and hard shifting.
Faulty shift solenoids
Shift solenoids are responsible for controlling the flow of transmission fluid based on the signals given by the transmission control unit (TCU). The TCU dictates how much and where should the transmission fluid be transferred to. If the shift solenoids fail, they can deprive certain areas of the transmission of the much-needed lubrication which can lead to shifting problems such as jerking when shifting out of park and more.
Malfunctioning transmission control unit
Imagine the transmission control unit or TCU as the brains behind the operation of smooth shifting. Based on the inputs of various sensor readings and signals, it dictates when and how should the gears be changed and it even dictates how the automatic transmission is lubricated by “giving orders” to the transmission pump and shift solenoids. If the transmission control unit malfunctions, a number of things can go wrong, the symptoms can vary greatly. However, our technical advisor to LifeOnFour did mention that a faulty TCU could be the culprit behind the jerking motion as you shift from park to drive.
Worn out mechanical parts
An automatic transmission contains many mechanical parts, all of which can get worn out due to high mileage, worn out or low transmission fluid or improper handling. Worn-out clutches for example can make the car jerk forward when shifting out of park, they can also cause delayed engagement. A worn-out torque converter can cause the same issue. The point is that damaged and worn-out transmission parts can lead to jerking.
Worn-out engine mounts
This one is surprising and even more surprisingly common. The function of an engine mount is to hold your engine attached to the chassis and minimize the vibration and absorb the shock of a running engine. They are partly made out of rubber which deteriorates with time and due to environmental factors. As they fail any jerking, even that of the transmission will be more noticeable and even more annoying. As you shift out of park, your parking pawl disengages the “holding” function of your transmission which can cause a slight jump of the car, especially when parked on a hill. With bad engine mounts, that slight jump is incredibly noticeable.
Worn out universal joints of the drivetrain
While it is not common, worn-out universal joints of the drivetrain can be the reason behind the forward lurching of your car when shifting from park to drive. The excessive play in those joints allow the car to jerk forward. Again, we have only heard that this can be the reason, but have not seen actual cases of this in real life.
Change The Way You Park To Avoid Jerking When Shifting Out Of Park (Parking Pawl Function)
Everyone who knows a thing or two about automatic transmissions knows that relying on the Park function to hold your car when parking on a slight incline or decline is a sure way to end up with transmission problems.
It is also one of the reasons why your car is jerking forward or backward when shifting from park to drive. The thing that holds the car in place as you shift to Park is called a parking pawl. It is essentially a piece of metal with a “tooth” that latches into the output shafts gear. If you only rely on that tooth and gears to keep your car in place, you are soon going to be experiencing trouble and jerking when shifting out of park is one of them!
To learn how to correctly park your automatic car, click here!
How To Fix Transmission Jerking Or Jumping Forward
There is no answer to this question. There are numerous reasons why your car jerks when shifting from park to drive. Based on that, we cannot offer a universal solution. What you need to do is visit a specialized transmission workshop that will carry out a full diagnosis and provide you with the exact reason for the jerking.
Based on the diagnosis, you will also receive an estimate of costs which can range from 200$ for a simple transmission fluid replacement or 2000$ and more if your transmission needs an overhaul. It is highly important that you do not ignore this problem because it will only get worse and more expensive to repair if further damage is done.
Is Transmission Jerking Dangerous?
If your car jerks when shifting from park to drive it is only right that you are worried. Any kind of unexpected jerking or lurching is considered dangerous. It can be enough to bump into the car that is parked in front of you or push you off the ledge. You never know, so be careful and take care of the problem as soon as possible.
Conclusion And Recap
While a slight vibration when shifting out of park is normal, jerking and jumping forward or backward is never normal. If you are buying a car, do not let the salesman convince you that any kind of jerking is normal.
The most common reasons why your car jerks when shifting from park to drive include:
- Low transmission fluid
- Dirty and worn-out transmission fluid
- Worn out internal transmission parts
- Blocked transmission filter and transmission pump problems
- Faulty shift solenoids
- Faulty transmission control unit