Car Shakes When Going Over 70

Experiencing a car shaking when going over 70 mph (or roughly 112 km/h) can be a concerning and potentially dangerous situation. This vibration isn't just a minor annoyance; it's a sign that something is amiss with your vehicle's mechanical components. Ignoring this issue can lead to further damage and compromise your safety on the road. This article explores the common causes of car shaking at higher speeds, offering insights into troubleshooting and potential solutions to help you address the problem.

Common Causes of Car Shaking at High Speeds

Several factors can contribute to a car shaking when exceeding 70 mph. Identifying the specific cause is crucial for effective repair. Here's a breakdown of the most frequent culprits:

1. Tire Problems

Tires are often the first place to investigate when a car shakes. Here's why:

Unbalanced Tires: This is perhaps the most common reason for shaking at higher speeds. When a tire isn't properly balanced, one section of the tire is heavier than another. This imbalance creates a vibration that becomes more pronounced as speed increases. You'll typically feel the shaking in the steering wheel, seat, or the entire vehicle.
Out-of-Round Tires: A tire that is no longer perfectly round will cause a rhythmic bouncing or shaking as it rotates. This can be caused by manufacturing defects, uneven wear, or impact damage.
Tire Wear: Uneven tire wear, such as cupping or feathering, can disrupt the tire's contact with the road and create vibrations.
Tire Separation: Internal damage to the tire, such as belt separation, can cause bulges or weak spots that lead to shaking and a potential blowout. This is a serious safety hazard and requires immediate attention.

2. Wheel Issues

The wheels themselves can also be a source of vibration:

Bent Rims: Hitting potholes or curbs can bend a wheel rim, causing it to wobble as it rotates. This wobble translates into shaking at higher speeds.
Loose Lug Nuts: While less common, loose lug nuts are a serious safety concern. They can cause the wheel to wobble and potentially detach from the vehicle. Regularly check your lug nuts to ensure they are properly tightened.
Damaged Wheels: Cracks or other structural damage to the wheel can weaken its integrity and lead to vibrations.

3. Suspension Problems

The suspension system plays a crucial role in maintaining stability and ride comfort. Worn or damaged suspension components can contribute to shaking:

Worn Shocks or Struts: Shocks and struts dampen the suspension's movement, preventing excessive bouncing and vibration. When they wear out, the vehicle becomes more susceptible to shaking, especially at higher speeds.
Ball Joint Issues: Ball joints connect the suspension to the wheel hub. Worn or damaged ball joints can cause looseness in the suspension, leading to vibrations and steering instability.
Tie Rod End Problems: Tie rod ends connect the steering rack to the steering knuckles. Worn tie rod ends can cause play in the steering system, resulting in shaking and difficulty maintaining a straight line.
Worn Bushings: Suspension bushings cushion the suspension components and absorb vibrations. When they deteriorate, they allow excessive movement and contribute to shaking.

4. Brake Problems

While brake problems typically manifest as vibrations during braking, they can sometimes contribute to shaking even when not applying the brakes:

Warped Rotors: Warped brake rotors can cause a pulsing sensation during braking. However, if the warping is severe, it can also lead to shaking even when not braking, particularly at higher speeds.
Sticking Calipers: A sticking brake caliper can cause uneven brake pad wear and drag, which can generate vibrations.

5. Drivetrain Issues

Drivetrain problems are more common in rear-wheel drive or all-wheel drive vehicles, but can occur in front-wheel drive vehicles as well:

Worn U-Joints: U-joints connect the driveshaft to the transmission and differential. Worn U-joints can cause vibrations that become more pronounced at higher speeds.
Damaged Driveshaft: A bent or damaged driveshaft can also cause significant vibrations.
Differential Problems: Issues within the differential, such as worn gears or bearings, can lead to vibrations.

6. Engine Problems

Less frequently, engine problems can cause vibrations that are felt throughout the vehicle:

Misfires: An engine misfire occurs when one or more cylinders fail to fire properly. This can cause a rough idle and vibrations that may be felt at higher speeds.
Loose Engine Mounts: Loose or broken engine mounts can allow the engine to vibrate excessively, transmitting those vibrations to the chassis.

Troubleshooting Car Shaking at 70+ MPH

Diagnosing the cause of car shaking can be tricky, as the symptoms can be similar for different problems. Here's a step-by-step approach to troubleshooting:

Observe the Symptoms: Pay close attention to when and how the shaking occurs. Is it constant, or does it only happen at certain speeds? Does it worsen during braking or acceleration? Where do you feel the shaking most prominently (steering wheel, seat, floor)?
Inspect the Tires: Visually inspect your tires for signs of uneven wear, bulges, or damage. Check the tire pressure and ensure it's within the recommended range.
Check the Wheels: Look for bent rims or loose lug nuts. If you suspect a bent rim, have it inspected by a professional. Tighten any loose lug nuts to the correct torque specification.
Test Drive: Carefully test drive the vehicle, paying attention to the shaking. Try to isolate the conditions under which the shaking is most pronounced.
Professional Inspection: If you're unable to identify the cause of the shaking yourself, it's best to take your vehicle to a qualified mechanic. They have the tools and expertise to diagnose the problem accurately and recommend the appropriate repairs.

Solutions and Repairs

Once the cause of the shaking has been identified, the following repairs may be necessary:

Tire Balancing: If the tires are unbalanced, a tire shop can rebalance them using specialized equipment.
Tire Replacement: If the tires are out-of-round, worn, or damaged, they will need to be replaced.
Wheel Repair or Replacement: Bent rims can sometimes be repaired, but severely damaged wheels may need to be replaced.
Suspension Repairs: Worn shocks, struts, ball joints, tie rod ends, or bushings will need to be replaced.
Brake Repairs: Warped rotors may need to be resurfaced or replaced. Sticking calipers should be repaired or replaced.
Drivetrain Repairs: Worn U-joints, damaged driveshafts, or differential problems will need to be addressed by a qualified mechanic.
Engine Repairs: Engine misfires need to be diagnosed and repaired, which may involve replacing spark plugs, ignition coils, or other components. Loose engine mounts should be tightened or replaced.

Preventative Maintenance

Regular maintenance can help prevent car shaking and other problems:

Regular Tire Rotations and Balancing: Rotate and balance your tires every 6,000 to 8,000 miles to ensure even wear and prevent imbalances.
Proper Tire Inflation: Maintain the correct tire pressure to maximize tire life and fuel efficiency.
Suspension Inspections: Have your suspension system inspected regularly for signs of wear or damage.
Brake Inspections: Inspect your brakes regularly for wear and damage.
Wheel Alignment: Ensure your wheels are properly aligned to prevent uneven tire wear and handling problems.

Ignoring a car shaking when going over 70 mph can lead to more significant damage and compromise your safety. By understanding the common causes, troubleshooting steps, and preventative maintenance measures, you can address the problem effectively and keep your vehicle running smoothly and safely. If you are not comfortable performing these tasks yourself, always consult a qualified mechanic. Safe driving!

Remember: Your safety is paramount. If you experience significant shaking or instability, pull over to a safe location and have your vehicle towed to a repair shop. Don't risk driving with a potentially dangerous condition.