Bad vibration in your 89 Chevy silverado 350 5.7 L 2wd you have heard it all bad tranny drive shaft axle and rear end guy says would not cause a vbratrion after 45mph?

While a bad transmission, driveshaft, axle, or rear end *can* cause vibrations, it's true that those components are more likely to cause vibrations at lower speeds or under specific conditions (like acceleration or deceleration). A vibration that *only* starts above 45 mph suggests the problem lies elsewhere.

Here are some more likely culprits for a vibration starting at 45 mph in your '89 Chevy Silverado:

* Wheels and Tires: This is the most common cause of high-speed vibrations. Check for:

* Tire balance: This is the most likely culprit. Improperly balanced tires will cause a vibration at higher speeds.

* Tire wear: Uneven tire wear (cupping, feathering) can induce vibrations.

* Bent rims or wheels: Damage to the wheels can cause imbalances and vibrations.

* Wheel lug nuts: Ensure all lug nuts are properly tightened.

* Steering components: While less likely to cause a vibration *only* above 45 mph, worn tie rod ends, ball joints, or other steering components *could* contribute to a vibration felt through the steering wheel at higher speeds.

* Driveshaft imbalance (but a different type): While the mechanic might be correct that a severely damaged driveshaft would likely cause issues at lower speeds, a *slightly* unbalanced driveshaft might only manifest itself at higher RPMs/speeds. This is less common than tire/wheel issues.

* Engine balance: Less likely, but possible. An internal engine imbalance could cause a vibration at higher engine speeds. This is less common but could manifest this way.

Troubleshooting Steps:

1. Start with the simplest and cheapest: Get your tires and wheels balanced and inspected for damage. This is the most likely solution and the first step.

2. Check tire pressure: Ensure all tires are inflated to the proper pressure (check the sticker on your driver's side doorjamb).

3. Inspect the wheels visually: Look for any bends or damage.

4. Have a mechanic inspect the driveshaft: While less likely the primary cause of a vibration only above 45 mph, a quick visual inspection for damage and balance is still worthwhile.

5. Check steering components: Have a qualified mechanic inspect your steering components for wear.

Only after addressing the above should you suspect more complex issues like internal engine problems. The mechanic's dismissal of the other components might be too quick, but the fact the vibration only starts at 45mph makes those less likely. Focus on the wheels and tires first.