There are generally two types of transmissions used in cars or other vehicles. Manual transmission and automatic transmission. But sometimes there is a problem with gear hard shifting in manual and automatic transmissions. The gear shifting problem is mostly observed while downshifting from high to low gear.
Through this article, you will learn in detail about the main causes of hard shifting in manual and automatic transmissions
Why is Hard Shifting in Automatic & Manual Transmissions?
The most common cause of manual or automatic transmission hard-shifting is low or bad transmission fluid. Additionally, a worn clutch or failure of transmission-related components can also cause a hard-shifting transmission.
Causes Of A Hard Shifting In Manual Transmission
Hard shifting in a manual transmission can cause worn clutch components, such as a clutch disc or pressure plate, or low or contaminated transmission fluid. Additionally, an incorrectly adjusted shift linkage or internal transmission problems, such as worn synchros or bearings, can also cause hard shifting.
1. Bad Clutch Master Cylinder
There are two types of clutches commonly used in manual transmissions. One is a simple wire clutch, and the other is a hydraulic clutch. A hydraulic clutch works on the basis of hydraulic pressure in a fluid. A hydraulic clutch has a hydraulic master cylinder attached to the pedal. which builds up the pressure of the fluid when the pedal is pressed and sends it through the pipe to the output hydraulic cylinder fitted in the transmission clutch.
The piston of the cylinder in the transmission opens when the hydraulic pressure is applied and pushes the clutch rod, which is operated by the clutch. and connects or prevents engine power from going to the transmission. But sometimes the hydraulic master cylinder is not able to send a sufficient amount of fluid pressure due to damage or leakage.
Due to this, the clutch does not completely block the power of the engine from going to the transmission, causing the shifting of a manual transmission to become harsh. Or the gear may be completely stuck when the engine is started.
2. Worn or Damaged Clutch Pressure Plate
The clutch is a major part of a manual transmission. The pressure plate in the clutch assembly operates the clutch. The pressure plate serves to engage and disengage the clutch from the flywheel of the engine. The pressure plate engages the clutch with the engine flywheel with great force.
Due to which the entire power of the engine reaches the transmission. and removes the clutch plate from the fly wheel of the engine with full force, due to which the vehicle starts moving and stops. But sometimes the pressure plate in the clutch is weak or worn out and unable to disengage the clutch plate from the engine’s continuously rotating fly wheel.
Due to this, the power of the engine does not stop going completely to the transmission even when the clutch is pressed. And manual transmission starts having shifting problems. Or the gear may get stuck completely. However, manual transmissions can also make shifting harsh if other parts in the clutch system fail. such as,
Bad or leaking release cylinder
Excessive clutch cover wear
Clutch release bearing failure
Clutch release fork failure
3. Release Bearing & Fork Issue
The release fork is mounted on a ball stud inside the bell housing of a manual transmission’s clutch system. The clutch sleeve operates the cylinder fork. The clutch fork is mated to the release bearing when pressure is created by depressing the clutch pedal. The release bearing is then pressed against the diaphragm at the pressure plate.
This removes engine power from the transmission as the pressure plate is continuously engaged with the flywheel of the engine. If the fork or release bearing of your vehicle’s clutch system is damaged. Your vehicle’s engine is then unable to fully extract power from the transmission. Due to this, stiffness can be experienced during the shift.
4. Clutch Release Cylinder
This part converts the hydraulic pressure of the master cylinder into mechanical force, which controls the clutch fork. However, these are clearly signs of a bad slave or release cylinder when you have to depress the clutch pedal more flexibly or go too far down. The release cylinder is unable to push the fork. Due to which stiffness can be experienced during gear shifting.
5. Damage Synchronizer Rings
Synchronizer rings are used in manual transmissions. Synchronizers, or synchro rings, are used to smoothly mesh the teeth of a gear during rotational motion. Synchro rings allow the gear to engage with the hub sleeve. Synchronizers are made of copper or brass metal.
But sometimes stiffness can be experienced during gear shifting due to worn or damaged synchronizers in manual transmissions. This problem is usually worse when shifting from a higher to a lower gear while the vehicle is in motion.
6. Damage Gears
A manual transmission has a bunch of gears. In which counter gear, reverse gear, first gears, second gear, third gear, fourth gear, fifth gear, sixth gear and some vehicles can have even more gears. The state of rotation in these gears depends on the shape and teeth of the gear. In a manual transmission, each gear has two types of teeth.
There are small teeth on one side and big teeth on the other side. Synchronizers allow the small teeth of the ring gear to engage with the hub sleeve. But sometimes, due to the grinding of teeth in manual transmissions, the gears become difficult to engage. Because of which you can feel stiffness during the shift. Also, in manual transmissions, worn out gears can cause strange noises during shifting and rotational motion.
7. Worn Hub Sleeve
Worn sleeve hubs in manual transmissions can also make shifting harsh. The slew hub is also known as the synchronizer hub. The sleeve hub often moves to the right or left. The sleeve engages the teeth of the hub gear with the synchronizer ring. If the sleeve hub is damaged or worn in a vehicle with a manual transmission, then you may experience stiffness during shifting.
8. Worn Gear Hub
This internal gear, which is a gear ratio-changing system, serves as a link between the gears but is unable to rotate freely. This part primarily sits behind the third and fourth gears and in between the first and second gear. It becomes difficult for a manual transmission to change into first gear when the first gear malfunctions.
9. Low Level Clutch Fluid
Hydraulic clutch is mostly used in modern technology vehicles with manual transmission. Fluid is used in hydraulic clutches. The clutch fluid builds up under pressure when the pedal is depressed. Thereby, the release cylinder is operated, which acts to push the clutch fork.
But sometimes the clutch master cylinder is unable to build up pressure due to a low clutch fluid level. Due to this, the clutch system does not function fully. Hence, stiffness may be experienced during gear shifting due to a low clutch fluid level.
10. Low Level of Transmission Fluid
Fluid or gear oil acts as lubrication in the transmission. Due to this, the gears of the transmission impart rotational motion without any additional friction. The lubrication allows the gear selector in the transmission to move left or right to change gears smoothly. But in many transmissions, the fluid level gets low.
Due to this, a lack of lubrication can be seen in the transmission gears and other parts, which causes the transmission of your vehicle to start making noise and increases the possibility of more wear and tear on the transmission. Also, hardness may be experienced while shifting gears when the transmission fluid is low.
11. Bad Gears Shifter Cable
Often in the cabin of cars or other vehicles, the gear shifter controller and transmission are not in a straight line, so the linkage road cannot be connected directly to it. In such vehicles, a shifter cable is used to connect the transmission fork to the gear shifter.
Because this shifter cable is flexible, it can be moved in any direction. But many times the shifter cable starts getting stuck due to being old. Due to which hardness can be experienced during gear shifting
Causes Of A Hard Shifting In Automatic Transmission
Common causes of hard shifting in an automatic transmission include low transmission fluid level, bad or contaminated fluid, faulty shift solenoid, bad torque converter, or problems with the transmission control module.
1. Low Fluid Level
The main cause of most of the problems in the automatic transmission of vehicles is the low level of fluid. Due to this, there is a lack of lubrication in the internal parts and gears of the automatic transmission.
Due to this, there is a problem shifting the gears. Also, in automatic transmissions, the gears can wear out due to friction, and worn or corroded gears can produce noise. Hardness can be felt during shifting due to low fluid levels in the automatic transmission.
2. Bad Transmission Fluid
In this problem, the transmission fluid level may be full. But transmission fluid of the wrong grade or contaminated or burned fluid can also cause stiffness during shifting in an automatic transmission.
Because the correct grade of transmission fluid is recommended by the vehicle manufacturer for the automatic transmission of every vehicle, automatic transmission fluid can usually lose its lubrication between 60,000 and 80,000 miles. Therefore, be sure to change the automatic transmission fluid on time.
3. Failed Sensor or TCU
Automatic transmissions in vehicles have a solenoid sensor. This sensor sends transmission gears and speed signals to the vehicle’s ECM. Due to which you will be able to do gear shifting easily during sufficient speed. This sensor alerts you to your mistake. A bad solenoid sensor sends a bad or incorrect signal to the vehicle’s ECM.
Due to this, your vehicle is not able to shift out of first gear in an automatic transmission. Hardness experienced during shifting in an automatic transmission can also be caused by a failed solenoid or sensor. To check this, you can scan with the help of OBD digital scanner. so that you can find the problem in the automatic transmission.
4. Cold Weather Effect
Often, this problem is seen more in the automatic transmissions of vehicles running in very cold places. because the transmission fluid is thicker at the beginning of the vehicle’s run due to cooling. Hardness can be experienced during shifting in an automatic transmission.
Because transmission fluid takes a while to reach its normal operating temperature. Thicker fluids reduce lubrication, making it more difficult for the transmission fluid pump to lubricate gears and other parts. Therefore, a good synthetic fluid should always be used in the automatic transmission of vehicles operating in extremely cold regions.
5. Adaptive Transmission Issue
Automatic transmissions in vehicles have an internal computer to control the engine’s RPM and feed the automatic transmission program. It is like a memory model for setting up an automatic transmission program. But when the vehicle is disconnected for any reason, the adaptive transmission of the automatic transmission may fail to feed the previous memory setting.
Due to which hardness can be experienced during shifting in automatic transmission. Sometimes this problem causes the automatic transmission to stop working completely.
6. Bad Transmission Vacuum Modulator
Your car’s vacuum modulator and vacuum lines determine how much load you are putting on it. By measuring the workload, the vacuum modulator receives pressure, which in turn initiates the gear shift process. Vacuum line damage can make shifting more difficult and jerky.
Due to this, you may experience hardness or another type of problem during shifting in an automatic transmission. A bad vacuum modulator can disable the entire transmission.
7. Bad Shifter Cable
Often in the cabin of cars or other vehicles, the gear shifter controller and transmission are not in a straight line, so the linkage road cannot be connected directly to it. In such vehicles, a shifter cable is used to connect the transmission fork to the gear shifter.
Because this shifter cable is flexible, it can be moved in any direction. But many times the shifter cable starts getting stuck due to being old. Due to which hardness can be experienced during gear shifting.
How To Fix A Hard Shifting Transmission?
To fix a hard shifting transmission problem, you must first determine whether the vehicle has a manual or automatic transmission. Because manual and automatic transmissions will have different procedures to fix the hard shifting problem.
How To Fix A Hard Shifting in Manual Transmission?
Check the level of the clutch fluid; if it is low, fill it completely.
First, check the level and condition of the manual transmission fluid, replace the fluid with a new one if the level is low or worn.
Inspect the complete clutch assembly. such as the master cylinder, release cylinder, fluid pipeline leakage, clutch fork, pressure plate and clutch release bearing.
You can check the clutch plate, pressure plate, and clutch release bearing by depressing the clutch pedal with the engine running. If any part of the clutch assembly is damaged, replace it with a new one.
Gears sticking together indicate a worn-out synchronizer ring. So you can change the synchronizer ring. But this is a more expensive process. Because in this the entire transmission has to be separated from the engine.
Check the gear teeth in the open transmission. If the gear is damaged, replace it with a new one.
Check the hub sleeve and gear hub; replace them with new ones.
Check shifter cable, if shifter cable is bad, replace with new one.
How To Fix A Hard Shifting in Automatic Transmission?
Check the automatic transmission fluid level and top it off if it is low.
Check the condition of the fluid, if the fluid is worn out, replace all transmission fluid with a new one.
Check the sensor. If it is a sensor related problem, then replace the sensor with a new one.
Check TCU (Transmission Control Unit) if any problem is found in TCU. Then it can also be repaired or replaced with a new one.
In extremely cold weather, leave your vehicle with the engine running for a while initially. so that the temperature of the automatic transmission fluid can return to normal.
Also check the vacuum modulator; if it’s bad, it can be repaired or replaced with a new one.
Repairing an automatic transmission is a task for an experienced mechanic and is more expensive than repairing a manual transmission.
FAQ’s
Q. Why are my shifts jerky?
The main reason could be the low level of transmission fluid. Low fluid can cause a lack of lubrication in the transmission. Also a bad synchronizer ring, broken or damaged gear, bad shifter cable and worn shifter control lever.
Q. Will a transmission flush fix hard shifting?
It depends on the condition of your transmission fluid. If bad fluid in your transmission is causing hard shifting, a transmission flush can be helpful in reducing hard shifting.
Q. Could low transmission fluid be causing hard shifting?
Yes, a low transmission fluid level can result in hard shifting in the transmission, because the lubrication of the transmission gets reduced due to the low fluid level. Fluid leakage is usually the main reason for low transmission levels.
