More alignment issues?

[KyBob]

Newbie here, please be gentle. Got new tires (Michelin Pilot Sport AS3+) and an alignment. My 2015 GT PP daily driver always seemed to have a twitch (side to side motion) especially on uneven pavement. But after the tires and alignment the car is almost undriveable at speeds above 60 mph. Any imperfection in the road causes a pronounced side to side oscillation that continues for seconds. More speed produces more intense oscillation. Checked the alignment details and everything matches Ford recommendations except for the front:right caster 6.2 (6.4 – 7.9). Is it possible that the nonadjustable castor 0.2 degrees off spec could be causing the problem, something loose in the IRS or bad alignment or could it be the Michelins? Suspension is stock PP I think, bought car used but the suspension component tags match the PP package. Any help is appreciated.

Sponsored

 

[Road Dog]

Side to side?

So is the front end of the car moving. I mean does the steering wheel turn back and forth or vibrate? Or is the back end of the car moving? Can you feel anything like feedback in the steering wheel?

 

[KyBob]

That is the strange thing, the oscillations seems to be coming from the rear end. The steering wheel does not move or vibrate, in fact at lower speeds (55 mph) I held the steering wheel with two fingers during an "event", no problem. At higher speeds the oscillation seems to increase in amplitude until I do something, move the wheel, slow down or hit the brake.

 

[SteveW]

My car developed a similar thing as yours that was very unsettling and I found a rear toe link had come loose. I found it by doing the basics like shaking each tire like when doing a tech inspection for an autocross event or how you would check for loose ball joints on other cars. There was slop from the suspension on one of the wheels.

 

[KyBob]

My car developed a similar thing as yours that was very unsettling and I found a rear toe link had come loose. I found it by doing the basics like shaking each tire like when doing a tech inspection for an autocross event or how you would check for loose ball joints on other cars. There was slop from the suspension on one of the wheels.

Thanks! Glad to hear there might be a simple solution. I will re-torque the toe links and see if that makes a difference. And then have a talk with the alignment shop.

Sponsored