Lurching is caused by a mismatch between wheel and engine speed as the clutch engages. Release the clutch more slowly so their speed is synchronized gradually.
Rough jerking when shifting
It might feel like a jerk, clunk or thud. This is usually caused by troubles with the vacuum, transmission fluid or a faulty sensor. The vacuum modulator valve helps older vehicles determine when to shift gears.
First of all, the gap between first and second is usually larger than between other gears. This means the input shaft RPM will drop by a larger amount during the 1 -> 2 shift than during other shifts. And this makes it somewhat trickier to match the speed of the engine and input shaft when you engage the clutch.
It could be due to worn-out friction material or a pressure plate defect (or combination of both). It could also be caused by an oil leak contaminating the clutch plate. If there is a fault with the clutch, you will need to find out whether it's a mechanical issue or whether the clutch facing has been contaminated.
What's the secret to changing down gear smoothly? Maintain light pressure on the accelerator pedal as you press the clutch down, change gear and then clutch up gently (or the car will jerk). Using the accelerator will raise your engine speed to match your road speed, ultimately giving you a jerk free gear change.
When the transmission jerks between gears or the transmission is shifting hard, it should be taken as a warning that your transmission needs repair. When a transmission is shifting hard or slipping it's time for an inspection.
This is often a sign of low transmission fluid or a faulty transmission control solenoid. As you know, automatic transmissions use pressurized hydraulic fluid to change gears.
In second gear, 10 mph road speed is equivalent to 800 rpm engine speed; 30 mph road speed is equivalent to 2,400 rpm engine speed. etc. You will only stall the engine if you try to go slower than any of these speeds in that gear.
Slipping gears are usually due to normal wear and tear, which causes them to not engage properly and to slip in and out of sync. It is rare, but there might be a malfunctioning set of gears in the transmission, which is usually due to bad original manufacturing.
While braking, you should always depress the clutch.
Well, stalling the car especially with transmission load will take a serious toll on your vehicle's gearbox assembly. So, it is always advised to depress the clutch when braking, at least to begin driving with.
If you're driving slowly below 10mph and want to stop then press the clutch before the brake so that the car doesn't stall. You're more likely to stall or have a shaky stop if you're driving slowly below 10mph and press the brake first then clutch.
A car that surges or jerks at high speed is potentially dangerous, especially in heavy traffic or in bad weather. If your vehicle jerks at high speed, you should stop driving it and have it inspected by a mechanic.
Grinding, Jerking, or Shaking
Shaking and jerking are good indicators of transmission trouble. Gear grinding is a common symptom in manual transmission vehicles. Automatic transmission failure often begins with some hesitation during gears shifting. Some might describe this a “slipping,” as well.
Typically, when your transmission begins to fail you may start to notice some form of difficulty when changing gears. Occasionally you may hear or feel a clunk noise when you shift gear. Another sign of a rough shifting is difficulty in accelerating to the speed for the gear that it is in.
Another way to look for transmission problems is to hold down the brake pedal with one foot while stepping on the gas pedal with the other foot so you can rev up the engine. Make sure the parking brake is on during this time, and don't rev the car for longer than a few seconds.
When changing gear, take your foot off the accelerator and press down on the clutch completely before switching to another gear. Changing the gear correctly will ensure that your car stays healthy. Listening to the engine while driving will enable you to understand the car when it needs a gear change.
Under normal driving conditions, this means changing up if the rev counter reaches between 2500-3000rpm. Under hard acceleration, you will change up a gear when you feel the acceleration drop away, which is usually above 6000rpm in a petrol-powered engine, but less if it's diesel-powered.
Hard, and sometimes impossible shifting into first and reverse is caused by the clutch disc not moving away from the spinning flywheel. This is commonly referred to as the "clutch is not releasing". The number one cause is the hydraulic system that operates the clutch is leaking and has low fluid.