Continued Humming Slight Vibration at 60 MPH

[Tom Johnson]

Has anyone exprienced this before?
1. Only on the freeway at 60 MPH and up, a loud humming sound with a slight vibration occurs.
2. This does not happen any other time, but about every other day, and only on the freeway immediately following a merge off of the onramp onto the freeway as I am getting up to around 60 MPH.
3. When I put the auto trans. in nuetral, there is no difference and nothing subsides
4. I turn off the engine, the sound does not stop at this point, and as the car slows down to about 45 MPH, the sound and vibration stops. I then restart the engine and speed up and everything is fine. No more sound/vibration until the next couple of days.

[Tom Johnson]

Re: Continued Humming Slight Vibration at 60 MPH

FYI- My Vette is a C4.

[Mike McKown]

Could it be the pavement? *NM*

[Duke W.]

Re: Continued Humming Slight Vibration at 60 MPH

Both the noise and vibration are probably tire related. Tire noise is an issue on modern performance cars with big tires and a lot of noise can be transmitted into Corvettes, particularly the rear. Tire/road road is a particular problem on C5 Z06.

If you can't solve the vibration problem via wheel balance, have the wheel/tire analysed for radial force variation on a Hunter 9700.

Also, be aware that most modern cars should have their tires "match mark" installed on the wheels. The wheels should have some kind of mark (often a faint white dot) that should be matched to the red dot on the tire. This aligns the low spot on the wheel with the high spot on the tire. This is not a new system, but a lot of tire busters don't know about it.

Duke

[Tom Johnson]

Will check this out, how about the Air Flow Sensor

Thanks and I will check the tires/wheels. Also, when I took the car into the shop, they could not find any problems. Simply because was not as frequent as it is now- at least once a day. But, they did replace the relay switches and said the Air Flow Sensor showed up on the computer as faulty, but when the checked it again, it was fine. Since a used AFS is about $200.00 I have been waiting this one out. I understand that if this is faulty, it could effect the torque converter, etc.

[Duke W.]

Re: Will check this out, how about the Air Flow Se

I'm not familiar with the diagnostics on C4 engines and have never worked on one.

Duke