I have a 2006 4 cylinder JEEP Wrangler. Right around 50 mph the whole car starts to shake pretty violently. I have to slow down back to 40 to get it back to normal. I can seem to get past this most of the time by waiting to shift into fifth gear until after 50 mph but not always! Any ideas??? I seem to spill coffee on myself every day…
Sounds like the famous Jeep death wobble to me. Get it to a front end shop and have them check out your front suspension, particularly the track bar and steering stabilizer. Any good technician should know how to check the track bar, but just in case, here’s how it needs to be done. This is the only method of inspection of this part I have found that works and is reliable. With the wheels on the ground and the engine off, have an assistant turn the steering wheel back and forth from 10 o’clock to 2 o’clock while watching for play in either end of the track bar. Any play at all can cause this condition, and it can be frightening and dangerous, even becoming severe enough to cause loss of control of the vehicle and a crash, hence the name “death wobble”. Other suspected causes of your vibration include a defective or out of balance tire, bad wheel bearing, and bent rim (if you’ve smacked any curbs or bad potholes with it).