Vibrations when cruising help

[jondaah]

Inspected every nook and cranny and still can’t figure it out.

I am getting a strong vibrations when cruising after 70mph. Most noticeable once I hit 85mph. The vibrations is more on the floor of the car, in an up and down motion, but it hits the steering too. Braking is fine.

The vibration is so bad, I’m on my 3rd set of rotors in 6 months. Note I only have 30k miles on the M2 Comp.

Here’s what I’ve done already, with attention to detail and proper torque specs:

1/ rear shocks replaced (M performance were leaking so got KW V3 shocks only)
2/ new BBS wheels + tires w/ proper balance
3/ alignment at reputable racing shop
4/ new rotors + pads
5/ wire brush + brake cleaner everything for a smooth surface on hubs, rotors, wheels

Next:
1/ replacing Lower Control Arms (LCA) and Tention Struts (TS) with stock bushings

If this doesn’t work, I don’t know what else other than the steering rack. What makes me think it’s the LCA/TS is when I took the car to the alignment shop, he said my front left was way way off, jokingly saying that’s for drifting. Also, changing to lighter BBS wheels w/ more narrow tires helped too.

[whitstap]

Tie rod ends if it’s sharp in the steering

[jondaah]

I was able to rid the vibrations at high speeds. Looks like it was indeed the tention struts or lower control arms.

Strangely enough, I couldn’t find stand out issues on the old LCA or TS. Small bits of rust on the TS and most ball joints, could be superficial.

Heavenly highway test drive !