Content of the material
- What does a car overdrive do?
- What is overdrive used for?
- What Are the Benefits of OD?
- 1. Fuel Efficiency
- 2. It Saves Your Car Brakes
- 3. Minimizes Pollution
- 4. Extends Lifespan of Car Parts and Accessories
- How To Turn Overdrive On?
- Should I use overdrive while towing a trailer?
- Should I use O/D off when slowly cruising?
- Can you save gas with overdrive?
- Should I turn O/D off while driving on an incline?
- Can anything go wrong with my overdrive?
- What can I do if my overdrive isn’t working?
- What if my overdrive is already broken?
- When to Keep Overdrive OFF
- When Towing Heavy Loads or Carrying Cargo
- When Driving Up a Steep Hill
- When Driving Down a Steep Hill
- Recent Posts
- Are There Instances Where I Should Turn Off Overdrive?
- ABOUT US
- When to Turn Off Overdrive
- 1. Hauling/Towing
- 2. Erratic Shifting
- 3. Overtake Another Car
- 4. Engine Braking
- History of Overdrive
- Direct Drive
- What is overdrive in a Ford Expedition?
What does a car overdrive do?
A car overdrive is designed to increase the number of gear ratios in your vehicle’s transmission. The purpose of overdrive is to allow the vehicle to run at reduced RPMs while cruising on the highway. This decreases strain on both the engine and the drivetrain while increasing fuel economy. An overdrive operates by locking out one of the gears in the transmission, causing it to act as an overdrive gear.
What is overdrive used for?
Usage. Generally speaking, overdrive is the highest gear in the transmission. Overdrive allows the engine to operate at a lower RPM for a given road speed. This allows the vehicle to achieve better fuel efficiency, and often quieter operation on the highway.
What Are the Benefits of OD?
OD has several benefits. Some of these are the following:
- Fuel Efficiency
- It Saves Your Car Brakes
- Minimizes Pollution
- Extends Lifespan of Car Parts and Accessories
1. Fuel Efficiency
The OD feature holds several benefits that motorists may not realize. For one thing, it helps your car to consume better fuel for trips on the highway. The car will shift automatically into 5th gear above the speed limit if this mode is enabled.
2. It Saves Your Car Brakes
Overspeeding also saves brakes when you’re slowing down. This is because braking is done in fewer revolutions. It will cause the brakes to wear much slower and prolong their life.
3. Minimizes Pollution
If you truly understand and use the OD feature effectively, you will reduce the amount of pollution. Your car will have up to 1/3 fewer emissions than using a conventional transmission.
4. Extends Lifespan of Car Parts and Accessories
Besides these, the OD is also beneficial in extending the life of your car’s various accessories. These accessories include the following:
- Steering pump,
- Water pump,
- Smoke pump,
- Generator, and
- Air conditioning compressor.
How To Turn Overdrive On?
When you turn on overdrive mode, the car changes and increases its rpm speed to maximum, giving out more power than in normal driving mode; with overdrive, you can go faster without taxing the engine or without it being so loud.
If you have a manual car, you can find a button saying overdrive near your car’s gear shifters. You can switch it on to use the overdrive feature.
But in automatic vehicles, the car is one overdrive mode as the default mode by almost all car companies.
So when you shift gears, it will automatically be on overdrive mode to give you maximum power and rpm at high speed with overall better performance.
But if you live in a town where you have a rush and can’t drive at high speeds, don’t forget to turn back off the overdrive mode. The overdrive mode is usually used on highways with a lot of space to accelerate.
Should I use overdrive while towing a trailer?
Although it’s highly recommended that you always have your OD on when towing a trailer, there are situations when you should turn it off. If you notice the RPM constantly shifting between 2000 – 2400, this means that your engine is under high load which can cause damage to the internal parts of the transmission. Therefore, make sure to turn your OD gear off in these cases.
Should I use O/D off when slowly cruising?
You may notice that your RPM starts to drop after you’ve reached 60 mph on the highway. This means that it’s time to switch gears by using the OD gear. At speeds of 50 mph and below, even though you’re driving in the optimal speed range of 32 km/h – 50 mph, turning on the OD will not help whatsoever.
The reason behind this is that you’re driving either too fast or too slow and the gears cannot mesh correctly, resulting in very high RPMs. Therefore, if you want to conserve fuel and keep your transmission efficient, it’s best to switch down a gear before entering the highway and keep the OD off until after 60 mph.
Can you save gas with overdrive?
Having your overdrive off can save gas if you drive in a fuel-efficient way. If you rev the engine too much when you are not accelerating, it will waste more gas than having your overdrive on.
If you drive at appropriate speeds and don’t rev the engine too much without acceleration, then having your overdrive on saves gas.
Should I turn O/D off while driving on an incline?
It’s advisable that you know when not to use the OD gear during uphill/downhill driving. This is because your car changes gears automatically to match the amount of power needed. Although this allows you to maximize fuel efficiency, it also means that your car will change gears at a speed that might be fast or slow for you.
Thus, if you want to have better control over the RPMs, always turn off the OD gear when driving on an incline/decline.
Can anything go wrong with my overdrive?
If your vehicle experiences too much strain from an overdrive, it might cause internal damage to other components in your drivetrain. In some cases, this can lead to critical failures, including the failure of your engine thrust bearing, an expensive component.
What can I do if my overdrive isn’t working?
In most cases, you should be able to diagnose a faulty overdrive by inspecting it visually and through the use of a computer diagnostic system. If your transmission has an electrical connector that monitors and diagnoses the performance of your unit, you should hook up the connector to your diagnostic system to pinpoint any issues.
If there are no obvious signs of trouble, it’s best to have a certified mechanic inspect your overdrive unit for problems.
What if my overdrive is already broken?
If your overdrive is already damaged or not working, then it needs to be replaced or repaired. If you need assistance, then contact your local mechanic as it isn’t an easy repair.
When to Keep Overdrive OFF
As we’ve seen, it’s better for your drivetrain if you keep your overdrive feature off when driving through rolling hills.
However, some vehicles have sufficient power to cruise through less steep rolling hills even when in overdrive.
Regardless, there are times when you need to keep the O/D off, and here are two situations.
When Towing Heavy Loads or Carrying Cargo
When carrying a cargo close to your vehicle’s payload or towing heavy trailers, keep the O/D OFF.
You’ll need to press the O/D button in most cars to deactivate it since it’s active by default.
Towing or carrying heavy loads forces the vehicle to shift down to lower gears hence sacrificing performance for greater torque.
Keeping your car in overdrive essentially locks it to the fourth low torque gear.
If the O/D remains on while towing, you’ll immediately feel that your car is less responsive and sluggish. It strains your vehicle’s engine and may stall it.
On the contrary, you can keep your O/D ON if you’re towing lighter loads on flat or gently sloping roads.
When Driving Up a Steep Hill
You might want to keep the O/D OFF if you’re driving up a steep hill and feel that your vehicle is struggling.
As we’ve seen, keeping the O/D ON locks your vehicle to the upper gear.
In most transmission systems, the upper gear is always overdriven and performance-based with the least torque.
Vehicles need maximum torque when going uphill or starting; hence always keep the O/D OFF in such situations.
When Driving Down a Steep Hill
Another situation that might necessitate turning the O/D OFF is when you’re driving downhill and would like to use the engine brake.
It’s especially the case when you’re towing a heavy load that may build up momentum and cause your vehicle to accelerate.
The good news is that your vehicle’s electronic control unit (ECU) won’t put the transmission in overdrive unless necessary.
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Are There Instances Where I Should Turn Off Overdrive?
Whilst this question appears in our FAQ section below, it is worth noting that there are very specific instances where you should turn off overdrive. The main one is when you are pulling a trailer or the car is carrying a heavy load. In either of these situations, the car will require more torque to get the job done.
The overdrive function reduces torque, giving your engine less of a mechanical advantage in these circumstances. Another instance where turning your overdrive off is appropriate is when the car is climbing a gentle slope. By disabling the overdrive when climbing a slope you ensure that the engine stays in third gear to gain enough climbing torque.
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When to Turn Off Overdrive
If you have a heavy load in your vehicle or you are towing, it might be time to turn off overdrive. By allowing the transmission to hit the highest gear, you could find the vehicle struggling. This problem might be more prevalent when going up hills or steep inclines.
In fact, most car manufacturers recommend turning the overdrive off while towing. If in doubt, follow the advice given in the owner’s manual.
2. Erratic Shifting
In most cases, the transmission should shift smoothly without a problem. However, if you notice the transmission is continually shifting between the top gear and the one below it, you might want to turn it off.
Allowing the vehicle to do this continuously is damaging to the transmission. In most cases, you will only notice it when the car is attempting to gain speed, such as when you are going up a hill. Turn overdrive back on as soon as you hit the level ground again.
3. Overtake Another Car
When you turn the overdrive off, the transmission is forced to shift down. When the gear drops, the RPMs increase, giving you more power to increase speed.
You could overtake other cars to pass with overdrive turned on. However, having it off helps the car to be more responsive and forceful, thereby cutting down the amount of time needed.
4. Engine Braking
Whether you need to come to a stop or you are heading downhill, you can use more than your brakes to slow down. The engine is capable of slowing the car down by increasing the RPMs.
Some people will argue that engine braking is bad for your vehicle, but there’s no proof that is true when used correctly. If your brakes are getting hot, it might be better for your car to rely on the engine for a little.
History of Overdrive
To understand what overdrive is, we’ll have to go through what underdrive and direct drive systems are.
An underdrive transmission, much like the one used in pulley systems, slows the rotation rate in a system by either making the driven pulley larger or the crank (drive) pulley smaller.
In vehicles, an underdrive causes the engine’s crankshaft to rotate faster than the driveshaft- making for faster acceleration.
For example, the first gear is an underdrive one as the engine rotates two or three times faster than the driveshaft.
The second gear falls in between and the crankshaft rotates marginally quicker than the driveshaft.
The engine rotates at the same speed as the drivetrain in a direct drive system. In essence, it’s more of a 1:1 drivetrain to crankshaft gear ratio.
Most vehicles have the third gear as their direct drive.
The direct drive system is beneficial as it experiences no backlash and has a smooth torque transmission.
Also, here are some additional benefits associated with direct drive systems.
- Increased efficiency due to a lack of power loss that’s common with underdrive and overdrive systems.
- It’s simpler to design.
- Can deliver high torques over a wide range of speeds.
The overdrive became a standard feature when it was evident that the automobile market desired efficient cars.
And, fuel efficiency became a point of concern for most vehicle manufacturers, who then responded by adding a higher (overdrive) gear to their transmissions.
The higher gear puts the car in an overdrive mode, whereby the crankshaft rotates slower than the driveshaft.
The effect is that it alleviates the stress placed on the engine, making it burn less fuel.
Additionally, less strain means that your vehicle’s engine runs smoother and experiences less noise and drivetrain wear.
But why should vehicles have an O/D OFF feature? Let’s look at the importance of keeping overdrive off.
What is overdrive in a Ford Expedition?
The overdrive function itself is meant to be used if You are going at a constant high speed. If You are on the highway for example. It will lower the RPM of the engine, meaning that You will keep Your speed, but will put less strain on the engine.