Since I have owned five third gen RX-7, a friend called me to ask advice on his 2003 RX-8.....as if I should know about his car. Anyway, looking for advice on his problem.. The car starts OK and runs OK until it reaches about 30 mph. Then a significant vibration starts and continues until the car reaches about 50 mph. Above 50 mph there is no vibration. I have not driven the car and have only this description from the owner, who has little mechanical experience. He does not know if the vibration is engine related or drive train related. Any suggestions where to tell him to look first?

 

well if there's no issues with the engine then maybe it's possible with the engine mounts. I have vibrations here and there even with the AC on but I've looked and was told it was the engine mounts collapsed.. but even if it was that it would affect the car at all times.. how rough is the vibrations and is it the entire car vibrating or parts of it? see if there's anything with the wheels, suspension, or even brakes... and if that's not it then maybe check the chassis and see if there's anything rubbing or touching or loose underneath it.. these are what I would do though if I had that issue.

 

Thanks. I'm trying to diagnose a problem over the phone for a car I have never seen, but wanted to help the guy out if I could. Thanks for your help.

 

No problem, I know it dosent help without you seeing it but it's something I hope

 

Sounds like it could be wheels and tires. If they aren't balanced properly, you can get vibrations at certain speeds.