Most Likely Causes:
* Tires: This is the most common cause. Uneven tire wear, out-of-balance tires, or tires with damaged belts can all cause vibrations at specific speeds. Check your tires for:
* Wear: Look for uneven wear patterns (cupping, feathering).
* Balance: Take your tires to a tire shop for balancing. This is inexpensive and often solves the problem.
* Condition: Inspect for bulges, cracks, or embedded objects. Replace any damaged tires.
* Wheels: Bent or damaged wheels can also cause vibrations. Inspect your wheels carefully for bends or cracks. They might need to be repaired or replaced.
* Driveshaft: A worn or unbalanced driveshaft is a common cause of vibrations in this speed range. This requires professional diagnosis and likely replacement or repair. Symptoms often include a clunking or whirring sound as well as the vibration.
* Wheel Bearings: Worn wheel bearings can create a vibration that worsens with speed. You might also hear a humming or growling noise. A mechanic can check for play in the bearings.
* U-Joints: Worn U-joints in the driveshaft can also cause vibrations, especially noticeable around 45-55 mph. They should be inspected by a mechanic.
* Differential: Problems with the differential (rear end) can cause vibrations, but this is less likely to be isolated to that specific speed range.
Troubleshooting Steps:
1. Start with the simplest and cheapest: Check and inflate your tires to the correct pressure (see the sticker on your driver's side doorjamb). Visually inspect them for wear and damage.
2. Get your tires balanced: Even if they *look* fine, this is a crucial step.
3. Have a mechanic inspect the wheels: Look for any bends or damage.
4. Test drive after each step: After balancing tires, for example, take it for a test drive to see if the vibration is gone.
If the vibration persists after checking tires and wheels:
You'll need to take your Grand Caravan to a qualified mechanic for a proper diagnosis. They can inspect the driveshaft, U-joints, wheel bearings, and differential to pinpoint the source of the vibration. Be sure to mention the specific speed range in which the vibration occurs.
Important Note: Ignoring a vibration can lead to more serious damage and potentially dangerous driving conditions. Don't delay getting it checked out.
