Shop may have not done the install correctly, left something loose. It happens. The behavior OP described is absolutely not normal and only a few things can cause it. The service tech could have had a brain fart and left a bolt not torqued correctly, etc. All the references to "X73 sway bars" have me wondering. the X73 suspension is springs, dampers, and front/rear bars, all done as a package, and there are different rear sway bars depending on if the car is manual or PDK. Was this a complete kit?

 

Maybe they gave you a Mustang alignment

 

Need to know the alignment settings. A good start would be at about -1.5 camber in front and -2.0 camber in the rear. Toe in front should be 0.0 straight up and about 12 minutes of toe for the rear. If you don't have enough toe in the rear the car can be unstable at speed. My car is rock solid at 130-140 mph on the back straight at COTA. I have had about 6 slightly different alignments on my car over the years and am very familiar with how each has affected the handling. My mechanic is a previous PCA spec-Boxster national champion, so I have learned much from him over the years. If you have any questions, feel free to PM me. Hopefully your alignment is off and an update will make you happy with your car. good luck

The factory settings above are overly conservative, with built in understeer. You want the camber to be about equal or a little more in the rear for most street driving. A one degree difference is too much. If the person doing the alignment just wants to do the stock settings, then he does not know how to drive these cars. You want the guy who does the set ups for the folks with GT cars who go to the track and participate in HPDE days with PCA.

 

Check the rear toe bolts. Have heard these should only be aligned 4 times than replaced. At last DE the guy pitted next to me just picked up a beautiful GT4 that was all over the road. One of the shops doing support went through it and found one of these bolts was too loose. Tightening it made a huge improvement.

 

I recently replaced my full suspension on stock 06' cayman S with Billstein PSS9 B16's. I did it myself and tried to "eyeball" the alignment enough to drive it to the Porsche dealer for a true alignment. I drove it about 2 miles and *** end was everywhere. Took it back home and adjusted the rear camber and it was like a different car. I put it on the trailer to take to dealer since I didn't feel comfortable driving the 16 miles there. Once they were done, it was incredible. I would agree with what others have said about the rear. I would not have thought the Toe and Camber would have made the ride that much different, but it definitely does.

 

So I was able to drive the car again today. He did another alignment yesterday and upon explaining what's happening during drive, he said that suspension wouldn't do that to the car and it could be an issue with the hub or control arms. I said it wasn't happening before until I got the x73 kit installed. Below is the before and after alignment settings of the car. I asked for -1.5 f and -2.0 r with 12 minutes toe as recommended here. After the alignment, he said that he could only get the rear to -1.5 camber. Driving it earlier, it feels so much better. 30 mins on the freeway, it was stable even changing lane where before it wasn't as stable. Coming from a stop light tho, it did happen again reaching about 40mph. Also below is my rear dash cam video and you could see how the rear goes side to side accelerating from a stop. Very hard to tell on the video but you can feel it riding inside and I'm not even pushing it hard. The whole time it only happened at this part.




https://www.youtube.com/watch?v=DcK2...ature=youtu.be

 

First of all, the control arms and hubs ARE part of the suspension and if a front end alignment tech can't tell if there is a problem with a control arm and hubs or not, then he shouldn't be doing front end alignments on any car, much less a sports car like a Porsche. Change shops. Find a shop that specializes in track alignments and that does Porsche car alignments regularly. You will find they typically charge less than service garages charge, that has been my experience anyway. Better work for less cost.

EDIT: Forgot to say, I couldn't really detect clearly what you are trying to show in the video. I think I saw some back-n-forth left/right, but not sure how much or exactly when it started and stopped.

 

Yeh something is wrong. Are your tires in good shape and properly inflated? Seems like an eccentric is lose or maybe a bushing or ball joint is shot. How many miles on the car?

 

So the left rear had a toe-out after the first alignment?

That's a life-threatening misalignment.

 

Oh wow, i missed that negative sign! The fact that it was ever that out of spec makes me think something is up with that corner.

 

I think it's likely something is also up with the tech doing the alignment.