I am trying to diagnostic this random vibration that occurs once in a while.
There are days where I can go up to 140km/h + without vibration. There are times that when it happens, the steering wheel vibrate so badly that its hard to get up to 80km/h without it vibrate violently.

Wheels are balanced and vibration Not only happened on acceleration, so I doubt is the axle. All bushing in the front are in good condition.

I do have slight pulsation in my brake at the moment.
When the vibration happens, I suspect the caliper might be sticking. The pulsation in the brake will be a lot more intense.

Just want some insight before I start purchasing parts and start replacing the front brake.

Car is a 07 TSX 6MT.

 

One possible cause is the calipers are "sticking" and the pins need to be regreased.
Once I started regreasing pins I realized how much they needed it.
I now do this every time I change the pads.
I also change the pin boots if they are 5 years old or greater.

I use Permaex Silicon Ceramic Extreme brake lube (red label)

 

Do you have aftermarket wheels or OEM? If you have aftermarket, make sure the hub-centric rings are in good shape. I had that issue recently. Replaced the rings and the vibration went away.

 

I know this is an old thread, so just posting for informational purposes, to whoever reads this in the future.

I had THE EXACT same problem in my auto '06. It was indeed a seized front caliper. Had to swap the caliper. Hope this helps :-)