First Post but need urgent advice
 

Hi everyone from the UK. I own a 2000 Boxster S with 111,000 miles on it. Have been meaning to join for a while but recent events have made me get on with it. I hope you guys have got some ideas...

Last week I had all my bushed parts replaced. Control arms, drop links, (ARB bushes not replaced) tuning forks, inner and outer tie rods and so forth. I then I had a full alignment done. Now though its started squirming like a bastard at the rear. This is when it goes over undulations and bumps , changing lane on the motorway. At first I thought its new bushing and its 18 inch tyres tram-lining so its normal but in the wet this morning its frankly scary. At one point going pretty straight on the motorway ( and I wasn't going fast) I thought the back end was going to go for a second. The tyres are PS2's and under a year old. Tyre pressures checked and appear ok. What could be causing this as I didn't have this problem before and I've seen the bushings on the old parts and they were in a poor state.

New parts interacting with old shocks? Old ARB bushes? I was told the shocks weren't great but not terrible.
I was told rear tuning forks didn't need doing? I'm now suspicious of this.
Old top mounts?
Bad alignment done by Porsche. Seems unlikely but needs mentioning.
Some thing loose on the new parts?
Just wondered if this was symptomatic of something well known on these that I'm just ignorant of.
Sorry to start on a downer everyone but needs must.
Thanks to you all

PS The Beginning should have said. Hi everyone. I'm from the UK.

Have you checked that the eccentric bolts on the lower control arms, and toe arms are tight. The second is some what harder. There is a steel sleeve that has a tapered inner hole, in the bearing carrier for the control arm and the rear toe arm. They are just pressed and crimped into the aluminum housing. They can be popped out while removing the arm if you use a forked tie rod pry bar.

I had a one of the tapered steel bushing pop out of the rear bearing carrier while replacing the rear toe link. I did not notice that it was gone until I test drove the car. When I'd step on the gas the car wanted to shift, and about the time the rear started to grip in a corner it would twitch. I had to replace the bearing carrier.

If it's worse in the rain, my immediate thought it tire tread depth. You may also want to check that the tires were not reinstalled backwards. Short of that, someone may have made a mistake putting your suspension components back together.

Need a good look at your alignment specs. It sounds like the rear is toe-out.