Alignment, braking and Steering question

I changed all the control arms and the tie rod ends on 1999 996 Carerra. I took it to an alignment place recommended by two local shops that do Porsche work. On the way home the car tracked great on the high way and the steering wheel is right on. All seemed well. The car handles well, and is much less twitchy with the new control arms etc. A real difference. As you can see one of the rear arms was a little bent by the previous owner... But... As I got to a stop light to take a left turn I was slowing coming to a stop and was turning a tiny bit to the left. As I hit the brakes the car wanted to swerve to the left sharply. I was going maybe 5 mph and held on just fine, but it did not do that on the way to the alignment shop. The next day while taking a right turn, and going just as slow, with the wheel turned slightly to the right, the car did the same thing to the right. Going straight and hitting the brakes hard the car goes dead straight so it does not seem to be a brake issue. Even making a turn with hard braking before, it does not swerve. Is this happening because of something the alignment shop did or did not do?

Something may have come loose, take it back to the alignment shop and have them check it. Also, could be your tires or a bent rim.

Should have said...it happened on the way home, right after leaving the shop. As it was great on the way over,and 4 hrs later was an issue, I think its the alignment but am not sure how that would affect the slow braking.

I sometimes experience such strong steering impact under braking at low speeds when the road is severely crested, meaning, the ruts from all the vehicles driving that road are deep. Might�ve been that?

Who did the replacement work?

I'd start by simply checking to make sure everything is tight. I've found these cars characteristics can change quite a bit with alignment spec, including "tram lining" or slow speed effects like you've described.

My guess would be a toe out condition. If memory serves me correctly, factory alignment spec calls for a slight toe out to facilitate turns, however, what you are describing indicates that your toe out exceeds the recommended spec. You could actually measure your toe out by taking a reading from the front of your front tires, say from the middle tread at a specific height of one tire across to the middle tread at a specific height of the other tire. Then repeat the same process at the rear of the front tires, and the difference in measurement divided by two will tell you how much each front tire is toed out. Compare that number with the recommended toe out spec and verify whether the alignment shop did their job. Best of luck.

BTW, if you attempt the above described process, be sure the car is on level ground, that the wheels/steering wheel are dead straight and that your tire pressure is correct in order to get the most accurate measurement possible. Just sayin.

Tire pressure? Did they change that by chance?

How many questions about how you use the car and how you want it to turn in did they ask you.. If they didn't spend about 10 minutes talking about how you drive the car.. they did a toe and go.. In other words they just lined it straight,, maybe or maybe not to the Porsche spec.. There are few shops that can do a multi link suspension alignment to the level these cars need.

I wasn't suggesting the shop altered the OP's tire pressure, just suggesting it be checked to eliminate a potential variable prior to taking a measurement.

I did the control arms my self and set the cams and the tie rod ends back as close to the previous settings as possible. I marked everything before removal and set it back. That bent control arm was on the rear left. Tire pressure was set before I left to have it aligned. I filled the tank on the way to have it aligned. the ruts in the road might just be it. The intersection where this seems to occur has them. I will put up some strings and check the toe and if suspect, head back to the shop. They were recommended by two euro car repair shops as the best ones in the area for Porsche's. Will put it on a lift and check all the torque settings too. Thanks

Make sure you aligned the control arm bolt before tightening. There are two notches that need to be aligned.

Pretty sure I did that. I recall it was in the manual to align those. Now I am second guessing myself.... Will crawl under and have to verify that. I did torque it under load as called for ever where these attach to the chassis.