What happens if you drive in 1st gear?

This Is Why It’s Difficult To Downshift Into First Gear

Changing gear can become an automotive art form when practiced and fully understood, forming a smooth relationship between ratios, engine speeds and differing shaft speed. Although first gear is generally only engineered to get a car off the line, hairpins and sharp corners can necessitate a change down from a higher ratio to the first cog.

If you have tried this before, you may have noticed just how difficult it can be to slot back into first gear, sometimes requiring a mechanically-unsympathetic shove. The most common situation that this occurs is when drivers are slowing down for a traffic light and pre-empt a downchange into first to get going again.

The problem is that the difference in ratios between second and first is large. So considering the job of a synchromesh is to bridge this gap, the synchromesh for first gear has to work a lot harder than in the rest of the transmission.

A synchromesh is almost like a small clutch that sits on the output shaft between gears, slowing or increasing the required gear’s relative speed to perform a perfect meshing of teeth within the transmission. So when trying to downshift to first, the relative speed difference between the output shaft and input shaft will be large compared to the other less-aggressive ratios.

A quick run-through of how synchromeshes work

Let’s take a 2016 Honda Civic’s transmission for example. The ratio for first gear is 3.6:1, meaning that for every 3.6 full rotations of the crankshaft, the gear rotates once. Second gear has a ratio of 2.1:1, third is 1.4:1, fourth 1:1, fifth 0.8:1 and sixth 0.7:1. As you can see, the difference in gear ratio gets smaller and smaller as you go up the gears, meaning the transition between each of them gets easier for the synchromeshes to perform.

The stiffness encountered when changing from second to first gear can also be experienced when committing the blasphemy of selecting second gear from fourth, skipping third gear. The difference in the speed of the input and output shafts of the transmission will be large, forcing the required synchromesh to work harder.

This MX-5 sprint run shows how first gear can be used for maximum acceleration out of tight corners

Solutions to help downshifting into first are double clutching and rev-matching. These will allow the transmission the chance to match the speed of the crankshaft, lessening the load applied to the synchromesh for first gear and aiding smoother shifts. Despite this, we wouldn’t recommend regular downshifts into first due to the strain it can put on the components within the transmission. So next time you feel that first gear is necessary to launch out of a corner, make sure you think about the required pedal inputs to perform a smooth shift.

What happens if you drive in 1st gear?

CHANGING GEARS IN AN AUTO

In many smaller cars the automatic transmission has 4 forward gears and one reverse gear. The driver uses the gear selector lever to set the transmission for parking, reversing, neutral or forward gears.

This selector is equipped with a lock button on the side to avoid inadvertently selecting the wrong gear.

When parked and stationary, P for Park is selected. In this setting the transmission locks to prevent the vehicle from moving. This setting compliments the use of the park brake. The engine only be started from this position or neutral, it cannot be started in a gear.

To move from Park to select another setting, the button must be used. This safety feature helps prevent unwanted or accidental vehicle movement.

Using the button R for Reverse can be selected, though this should only be done when the vehicle is completely stopped. The driver can without using the button then select N for Neutral. Neutral disengages the transmission allowing the vehicle to be pushed or roll freely. It is not recommended to select Neutral when driving, especially not when going down hill nor under heavy braking.

Again without using the button the selector can move from Neutral to D for Drive. This position allows the forward gears to change up or down depending on the speed of the vehicle and the position of the accelerator. For example under heavy acceleration the transmission will hold the lower gear until the optimum up-shift point is reached or the driver eases off the accelerator. Under light acceleration gears will change earlier to improve economy.

In some situations the driver can without depressing the selector button change to the 2 setting. This is not just second gear but rather will allow the gears to change between first and second gear only.

This position is used for extra power when driving up steep gradients for lower speed overtaking or to provide engine braking when descending prolonged steep gradients.

The 2 setting should not be used for braking, like before entering a corner.

To prevent inadvertently selecting first gear at high speeds to change into L for Low the selector button must be used. Selecting Low holds the transmission into low gear for driving up or down very steep slopes.

When moving up from Low the selector button is not required when moving to 2, Drive or the Neutral position. The instrument panel of many cars also indicates which setting has been selected.

Some vehicles will also have a power and economy switch on the centre console. Use economy whenever possible for normal driving.

Use Power only for sporty driving or when you need more engine power, such as driving in mountainous areas, towing or to overtake another vehicle in higher speed zones.

In many modern automatics the 4 th gear is often an overdrive gear, used for highway driving and/or good fuel economy.

In some vehicles there is an overdrive control switch beneath the selector lock button. During normal driving the overdrive switch should be left in the pressed-in position.

This will allow automatic gear shifting from 1 st to 4 th gear with the selector lever in Drive.

When quick acceleration or when going up or down long steep gradients, the overdrive button can be pressed to cancel the overdrive function.

The overdrive off indicator lamp on the instrument panel will illuminate and automatic shifting will only be performed from 1 st to 3 rd gear.

FREQUENTLY ASKED QUESTIONS

1. Can you go from 2nd/3rd/4th/5th gear and straight into neutral or do you have to go through them all? Can I go from 5th to 2nd/1st?

Yes it is recommended that in a modern manual transmission you can skip gears when going up or down. For example; when accelerating you can if required change-up from 1st to 3rd, though 3rd gear may labour due to low engine revs. Alternatively when approaching a corner you may change from 4th or 5th down to 2nd without using the gears in between. Care needs to be exhibited to ensure you have the right speed for the gear. Many untrained drivers have a phobia about using the brakes (thinking the brake lights are a sign of weakness) and persist in the bad habit of using the gears to slow the car down. Gears are for going, brakes for slowing. As such under brakes you can skip down gears to get the most appropriate gear for the situation, but don’t use the gear selection itself to slow the car. Also be careful not to gear down from 5th to 2nd at high speed or with any lateral load on the vehicle and step off the clutch in 2nd, as the car could enter into a skid.

2. If your car is rolling down a hill in neutral and it picks up speed to say 20mph, can you skip a gear? Go directly into 2nd?

Yes you can, but why would you roll down a hill in neutral? If you must roll down a hill do so in a gear with your foot depressing the clutch. This way if the car gets up to much speed (with cold brakes) you can let off the clutch to get some retardation from the gears. Going downhill is the only time gears can be used to help retard the car as brakes used too much can overheat.

3. I heard some cars can get up to 50mph on 1st gear before needing to shift to 2nd. Does this mean that you rarely have to shift gears while driving to stay within speed limits? 50mph is more than fast enough for the city. Wouldn’t you be in 1st gear most of the time and have no need to go into 2nd except maybe on the freeway.

Yes some gears can get to high speed in first gear. But you would not drive around all the time in first as the engine would be carrying high revs allot, leading to poor fuel consumption, high engine temperature, increased fluid usage and increased engine component wear. The noise in the vehicle cabin would also be tiring. If you were driving at high speed in first and stepped quickly of the accelerator the effect would unsettle the car potentially leading to a skid. If for example you were cornering with high revs in 1st gear there would be weight transfer to the rear of the vehicle (due to acceleration) and by quickly letting off the pedal, the revs would drop rapidly and the weight would transfer to the front of the vehicle leaving the rear un-weighted. In a corner this can produce a tail-slide even in a front-wheel drive car. This effect is known as Lift-Off Oversteer Skidding.

4. Does it matter if it’s a 4/5/6-speed gearbox? The Corvettes have a 6-speed gearbox and the new Porsche Carrera GT has a 4-speed. What does the amount of gears have in relation to speed and acceleration. Is it better to have more?

The gearbox ratios in family cars are alot different to performance cars and racing cars. In a family car 1st gear is for driving up steep hills, driveways, towing boats up a boat ramp. 2nd/3rd/4th are for suburban driving. 5th gear is usually an overdrive gear that allows for economical motoring at freeway speeds but no greater acceleration. Therefore overtaking in 5th gear is not recommended as it takes longer and increases the risk of a head on collision. In a Porsche or similar performance cars the gear ratios are slightly different. In a performance car with a 6 speed gearbox, 5th gear is also used for acceleration. In many forms of motorsport the gear ratios and diff ratios are set for each track depending on its layout. The aim is to keep the race car in the meaty part of the torque curve to allow better performance. With most family cars a driver redlining each gear to achieve maximum acceleration is a fool. Best acceleration would be achieved by changing gears at the engine revs just past the maximum torque is achieved, depending on the next gear ratio. Drivers over-revving simply make more noise, wear more components and waste more fuel without achieving a performance gain.

5. When making sudden stops, should you be concerned about putting it into neutral so the car doesn’t stall? Like if you’re driving and someone jumps in front of you out of no where, should you worry about slamming on the brakes and stalling? I would think in those cases, you wouldn’t have enough time to hit the clutch, brake and put it in to neutral.

In a modern car with an electronic fuel injected engine and equipped with a catalytic converter in the exhaust system, when you take your foot off the accelerator does the engine revs on the tachometer drop slowly or instantly to idle? They drop slowly due to unburnt fuel being burnt and the process of the catalytic converter. Therefore in a emergency stop if you brake with no clutch depressed the engine revs and driving wheels are still connected resulting in the brakes trying to slow the car while the wheels still drive the car. Independent tests have found that braking and depressing the clutch as soon as possible can improve stopping distance by up to 10 yards at 55 mph. Don’t worry about the gears, don’t select neutral. But do depress the clutch.

6. If you roll down a hill in 1st gear but don’t push the gas pedal or brake do you pick up speed? Say max mph for 1st gear is 15mph, will your speed accelerate pass 15mph?

How do you roll down a hill in first gear. If you park in first gear and use the park/hand brake. By letting off the park/hand brake the car will not move forward if it is in gear. Try parking your car on flat ground with it in 1st and pushing the car. It won’t move.