vibration/hum at high speed

[redhead]

I took my car out to Peachland, B.C. few days ago and noticed a slight hum with a weird vibration at around 130-140 km/h but not at higher or lower speed. It seemed to come from the middle to the back of the car. Definetely not from the front. I had a wheel bearing go on my 1972 Mach 1 and it was very similar except the vibration was amplified around 10 times! It felt like a nobby off road tire. The tires were balanced about 2 months ago so they should be fine but you never know. Maybe the driveshaft, center driveshaft bearing, guibo, wheel bearings? My car has a tiny clunk when parking in reverse when I let off the clutch from the driveline. Maybe related? Where should I check first?

Oh by the by, average speed 160-180 km/h, 12L per 100k, and maxed it out at 225km/h with 2 people and luggage. Solid at that speed, no vibrations nothing. It still had some left then ran out of road and had to turn. I was also giving her with a 740il from 120km/h up to 180km/h for around 10 mins and he could BARELY pull away from me, even in the turns although mine is lowered w/ bilsteins. I think I hurt his ego not being able to show his tailights to my 15 year old, 228,000km, 1.8L $5200 car. He didn't even look at me when passed!

Thanks gang,
Eugene

[ptownTSI]

do you have a 318is?

[AdironRider]

I feel like a 740il would have the balls to beat a 318, but I dont know from experience. I doubt if he was really trying that he wouldnt be able to make your car his bitch.

Anyways, sounds like something driveshaft related. Does the vibration come through the steering wheel? That could mean something with the front suspension (most likely ball joints)

[delatlanta1281]

Off the line, you would be with him, but those cars are muscle at speed. Check your driveshaft, I doubt it is that. When our wheel bearings go you start to hear them at higher speeds and as they get worse you hear them at lower and lower speeds. Are you running rims with spacers? When were they replaced last? Everytime you do your breaks you need to check them.

[redhead]

My car is a 1991 318is. It is stock except for the following items :

- Alpina spring and matching Bilstein shocks
- K&N panel filter
- Platinum +4 plugs
- Dinan chip

My thoughts exactly on the 740il's capacities. Believe me I was just as surprised at the time! But all I can comment on my experiences and the way he was driving his car. It was back and forth between us with the emphasis on him never being able to get an upper hand. The type of highway we were driving on is a mountainous region two-three lane highway with a lot of curves and straightaways at high speed and constantly changing elevation.

As far as I can feel it doesn't go through the steering wheel. It feels and sounds like it's coming from below the rear seat area and back. You can feel the resonance through the car.

Stock rims and tire size. How do you check your bearings?

TIA,
Gene

[HST]

Could be your center support bearing