Passenger Seat Vibrate
 

I am having this ongoing issue that the passenger seat will vibrate front to back rapidly while on the highway. I recently got all my suspension checked, replaced rear upper control arms, got 20" 87s roadforced balance on a hunter gsp9700. This happens on my winter wheels and my summer wheels, but it is considerbly worse on the 20" because of the weight im guessing.

What could be causing this? It must be something in the rear of the suv, something suspension related? Bushing?

Any ideas? Thanks!

If all the suspension is straight/good, the tires are still round and didn't have excessive road force/happens with both sets of wheels etc. I'd look at things in the driveline like the driveshaft's center support bearing and the axle shafts.

Thanks i'll get my indy to look at it, although i am not confident that they can find the issue.

The dealer may cost a little bit more for diagnosis, but if they get it properly diagnosed isn't it worth it?

Yes but it is hard to find good help these days, seems like i need to supervise everything they do......

It is even worse this morning on the way to work, the steering wheel will shimmy back and forth if i let go of it, and the whole truck shakes. It is more dominent at 80km/hr and 110km/hr. Does not feel safe at all.

I just replaced my steering rack with a reman last week, i wonder if its no good? Do they need to be balanced or anything? Grrr stupid vehicles.

The steering rack wouldn't cause that. Are you really sure all the suspension is tight and the wheels are 100% properly balanced?

Yup!

I just got back from my indy mech, he toke it for a drive and noticied right away a front driver stuck caliper. The rotor was red/rust compared to the right side which was clean as a whistle. Also the wheel on the FL was a lot hotter than the FR.

He says i need to order 2 new rotors for the front, a set of pads, and at least 1 caliper.

So my caliper is no longer seized. I still have a pretty bad passenger seat vibration though around 100km-120km/hr, it just shakes a good 2-3 inches front to back and the suv doesnt ride smooth like it should. I also have a small shake in steering wheel around 80km/h.

I am going to get my wheels checked again from my friend on another hunter9700. Otherwise i am out of ideas!

I have a shake at those speeds (not in the seat only wheel) just did the front brakes as well. Wheels balanced 3 times on GSP97BMW .. All looks good also got brake fluid flush and all looks good from caliper. I think it my be my poly front thrust arm bushing... otherwise where both from ontario and both out of ideas too :)

I replaced both front thrust arm bushings 2 weeks ago, along with inner/outer tie rods. I have replaced both rear left and right upper control arms, sway bar links, front lower control arms, ball joints, and reman zf steering rack. Also got a 4 wheel alignment done 2 weeks ago.

My suspension feels solid, just the highway vibration that is really bugging me.