Every driver should know how a car jack works, as this simple tool is essential for changing a flat tire or performing basic maintenance. Understanding what is a jack for a car is fundamental knowledge that can get you out of a roadside bind and back on your journey safely. This guide will explain everything you need to know, from the different types of jacks to how to use one correctly.
What Is A Jack For A Car
A car jack is a mechanical device used to lift a vehicle off the ground. Its primary function is to raise one corner or one side of the car, providing clearance to work underneath it. While most people associate a jack with changing a flat tire, it is also used for tasks like brake repairs, suspension work, or routine inspections.
Every vehicle comes with a factory jack, usually stored with the spare tire. These are designed for occasional emergency use. For more frequent or demanding jobs, mechanics and enthusiasts use heavier-duty jacks. The core principle is always the same: to create a stable, elevated workspace by applying force to a specific point on the vehicle’s frame.
The Primary Functions Of A Car Jack
A car jack serves several key purposes for both emergency situations and planned maintenance.
- Tire Changes: This is the most common use. Lifting the car allows you to remove a flat tire and install the spare.
- Undercarriage Access: Jacking up the vehicle provides room to inspect or replace components like brake pads, exhaust parts, or suspension linkages.
- Emergency Repairs: In a pinch, a jack can provide the lift needed to free a vehicle stuck on a curb or in deep snow.
- Maintenance and Detailing: Some owners use jacks to lift the car for thorough cleaning of the wheel wells and undercarriage.
It is crucial to remember that a jack is for lifting only. It should never be used as the sole support for a vehicle you are working under. Once the car is lifted, you must place sturdy jack stands under the vehicle’s designated support points before getting underneath it.
Different Types Of Car Jacks Explained
Not all jacks are created equal. They vary in design, lifting capacity, and ease of use. Choosing the right one depends on your vehicle and your needs.
Scissor Jacks
This is the compact, X-shaped jack that comes standard with most cars. It operates by turning a threaded screw with the included lever, which closes the scissor mechanism and lifts the vehicle. They are lightweight, portable, and store easily. However, they have a low lifting range and can be unstable on uneven surfaces. They are best suited for emergency tire changes on level ground.
Hydraulic Floor Jacks
Common in garages, these jacks use hydraulic fluid and a pump handle to lift heavy loads with minimal effort. They have a long handle and wheels, allowing you to roll them into position. Floor jacks have a much higher lifting capacity and range than scissor jacks, making them ideal for serious DIY work. They are, however, large, heavy, and not designed for storage in your trunk.
Bottle Jacks
Bottle jacks are another hydraulic option, but they stand vertically like a bottle. They offer a powerful lift in a relatively compact, sturdy package. They are often used for trucks and SUVs due to their high lifting capacity. Their small base can be a disadvantage on soft ground, and they typically have a smaller lifting range than a floor jack.
Hi-Lift or Farm Jacks
These are tall, manual jacks that use a series of pins and a walking beam. They are extremely versatile and powerful, capable of lifting a vehicle from its bumper or wheel. They are essential for off-road recovery situations but are complex to use and can be dangerous without proper training. They are not recommended for standard roadside tire changes.
How To Safely Use A Car Jack
Using a jack incorrectly is one of the most dangerous things you can do with your car. A falling vehicle can cause serious injury or death. Always follow these steps precisely.
- Find a Safe Location: Pull completely off the road onto a firm, level, and stable surface like asphalt or concrete. Avoid dirt, gravel, or slopes. Turn on your hazard lights and set the parking brake. For manual transmissions, leave the car in gear.
- Chock the Wheels: Place wheel chocks or large blocks of wood against the tires that will remain on the ground. If you’re lifting the rear, chock the front wheels, and vice versa. This prevents the car from rolling.
- Locate the Proper Jack Point: Consult your owner’s manual. Never jack the car on body panels, the oil pan, or the axle. Look for the reinforced metal pinch welds or dedicated jack pads along the side, or the central front/rear jack points if using a floor jack.
- Position the Jack Correctly: Center the jack’s saddle or pad directly under the designated jack point. Ensure the jack is sitting flat on the ground and is not on debris.
- Lift the Vehicle Slowly: Operate the jack smoothly and steadily. Stop lifting as soon as the tire has enough clearance to remove it (usually 1-2 inches off the ground). Do not lift higher than necessary.
- Support with Jack Stands: This is non-negotiable. Slide jack stands under a solid, reinforced part of the vehicle’s frame, as specified in your manual. Slowly lower the jack until the vehicle’s weight rests securely on the stands. Gently shake the car to test stability before proceeding.
- Lowering the Vehicle: After your work is done, reverse the process. Use the jack to slightly lift the vehicle off the stands, remove the stands, then slowly lower the jack all the way down.
Common Mistakes To Avoid When Using A Jack
Even experienced drivers can make errors that compromise safety. Be aware of these frequent pitfalls.
- Using Only the Jack for Support: Never, ever crawl under a car supported only by a jack. Jacks can fail or settle. Always use jack stands.
- Jacking on Unsafe Surfaces: Soft or uneven ground can cause the jack to sink or tip. Always find a firm, level spot.
- Incorrect Jack Point Placement: Jacking on the wrong spot can cause severe damage to your vehicle’s body or mechanical components, and lead to a collapse.
- Over-Lifting: Lifting a tire too high puts extra strain on the jack and makes the vehicle less stable. Lift only until the tire clears the ground.
- Using a Damaged or Inadequate Jack: Inspect your jack before use. Don’t use a jack with cracks, leaks, or bent parts. Ensure its weight rating exceeds your vehicle’s gross weight.
- Forgetting to Chock Wheels: This simple step prevents the car from rolling off the jack or stands.
Choosing The Right Jack For Your Vehicle
Selecting a jack involves more than just grabbing the first one you see. Consider these factors to make a smart choice.
First, know your vehicle’s weight. Check the owner’s manual or the driver’s side door jamb sticker for the Gross Vehicle Weight Rating (GVWR). Choose a jack with a maximum lift capacity that exceeds this number. For a typical sedan, a 1.5-ton (3,000 lb) jack is often sufficient. For trucks and SUVs, look for 2-ton (4,000 lb) or 3-ton (6,000 lb) capacity.
Next, consider your primary use. For trunk storage and emergencies, a reliable scissor jack is fine. For home garage work, a hydraulic floor jack is a worthwhile investment due to its speed and stability. If you have a lifted truck or go off-roading, a Hi-Lift jack might be necessary, but get proper training first.
Finally, look at the jack’s minimum saddle height and maximum lift height. The minimum height must be low enough to slide under your car, especially if it has low ground clearance. The maximum height must be high enough to lift your tire off the ground with room for a jack stand underneath.
Essential Jack Accessories For Safety
A few additional items can make using a car jack much safer and easier. These are recommended for any serious DIYer.
- Jack Stands: A pair (or two pairs) of robust jack stands are the most important safety accessory. Never work without them.
- Wheel Chocks: Rubber or metal chocks are designed specifically to prevent rolling. Keep a set in your trunk.
- Gloves and Safety Glasses: Protect your hands from sharp edges and your eyes from falling dirt or debris.
- A Solid Piece of Plywood: This can be placed under the jack on soft ground to create a stable, level base.
- A Flashlight or Work Light: Proper illumination is crucial for seeing jack points and working safely, especially in low-light conditions.
Maintenance And Inspection Of Your Car Jack
Your jack is a safety-critical tool. Regular checks ensure it will work when you need it most. For hydraulic jacks, inspect the piston and seals for any signs of fluid leaks. A leaking jack will not hold pressure and is unsafe to use. Check the hydraulic fluid level periodically and top it up with the correct fluid if needed, following the manufacturer’s instructions.
For all jacks, look for any cracks, bends, or significant rust on the metal components. On scissor jacks, ensure the screw mechanism turns freely and is well-lubricated. Test the operation of the release valve on hydraulic jacks to make sure it opens and closes smoothly. Store your jack in a clean, dry place to prevent corrosion. If you find any damage or malfunction, replace the jack immediately—do not attempt to repair it yourself.
Frequently Asked Questions
Where is the jack in my car?
The factory jack and tire change tools are usually stored in the trunk. Common locations include under the trunk floor mat, in a compartment on the side of the trunk, or secured near the spare tire. Consult your vehicle’s owner’s manual for the exact location in your model.
Can I use any jack for my car?
No. You must use a jack with a weight capacity that exceeds your vehicle’s Gross Vehicle Weight Rating (GVWR). Using an under-capacity jack is extremely dangerous. Also, ensure the jack’s physical dimensions (like minimum height) are compatible with your car’s clearance and jack points.
What is the difference between a jack and jack stands?
A jack is a lifting device. It is designed to raise the vehicle. Jack stands are support devices. They are designed to hold the vehicle securely in place after it has been lifted. You use the jack to lift, then you place jack stands under the frame, and then you lower the car onto the stands. The jack is then removed or left in place as a secondary safety measure, but the stands bear the weight.
How often should I check my car’s jack?
You should visually inspect your car’s factory jack every time you check your spare tire, which is recommended every six months. For a jack you use regularly in your garage, perform a quick functional check before each use, looking for leaks, damage, or smooth operation.
Is it safe to change a tire on the side of the road?
It can be if you take proper precautions. Always get as far away from traffic as possible, use your hazard lights, and set up warning triangles if you have them. Follow all the safety steps for using your jack on a level, firm surface. If the roadside is uneven, sloped, or too close to fast traffic, it is safer to call for roadside assistance.