"vommmm" sound/noise coming from front-end

[xfimpg]

I'm hitting my head against the wall on this one so I thought to ask in here.

I have this pulsating "vommm, vommm, vommm" noise coming from front-end (I think that's where it's coming from). It's frequency is almost like a heartbeat of 60bpm, and I can feel it in the steering wheel when it's making this noise.
Here's the kicker: I only hear this noise between 65 and 75 mph!

I've had this problem on 3 different sets of tires (toyo, good year, snowtracker).

This is what i've had done so far:
- alignment and tire balancing
- greased intermediate shaft
- replaced left and right bearings
- replaced rack and pinion including inner tie-rod ends

Mechanic assures me that everything in the front is rock solid and we checked for any loose parts.

Anyone have any ideas?

[MagicRat]

Years ago my family owned a 1983 Cutlass Ciera that did the same thing. The pulsing noise is like a harmonic (sympathetic) vibration that comes and goes. I think its related to a standing wave interference effect, that is, you have two seperate sources of vibration in the front end. Between 65-75 mph, the vibration frequencies of these two sources overlap, creating the pulsing noise/vibration.

Look here for more info:http://en.wikipedia.org/wiki/Normal_mode#Standing_waves

So, imo you have to look for anything that is out of balance, or can vibrate, including rotors, drive axles, CV joints. Also, look at the rims to see if they are bent or distorted.

[xfimpg]

Originally Posted by MagicRat

Years ago my family owned a 1983 Cutlass Ciera that did the same thing. The pulsing noise is like a harmonic (sympathetic) vibration that comes and goes. I think its related to a standing wave interference effect, that is, you have two seperate sources of vibration in the front end. Between 65-75 mph, the vibration frequencies of these two sources overlap, creating the pulsing noise/vibration.

Look here for more info:http://en.wikipedia.org/wiki/Normal_mode#Standing_waves

So, imo you have to look for anything that is out of balance, or can vibrate, including rotors, drive axles, CV joints. Also, look at the rims to see if they are bent or distorted.

Thanks for the info MR.
I do have a top-plate on the left shock (correction! i meant right shock) that needs replacing, still very driveable but stiff when turning back from full right.
Mechanic says that couldnt be causing the problem, but maybe that combined with another (loose) part could be the problem?

[maxwedge]

Bad engine mounts can cause this as the normal drivetrain harmonics can be transmitted thru the body.