I just installed some brand new Eibach springs and a new set of Hankook tires on my 2007 Carrera S and the car feels very flighty, almost unstable like... Especially at higher speed when I accelerate (70 mph +). I have not had the alignment done yet as we want the springs to settle for few weeks.

Does anyone have this experience or have any idea why????

The car actually feels better before when I have stock springs and SportContact 3 tires. It feels more planted before and very secure at high speed (even at 150 mph).

I'm baffled.

 

I think you answered your own question. A proper alignment should remedy the symptoms baring any issues with the install/mounting.

 

Ok, I hope so... Gonna wait two weeks before I get the alignment done. The car feels so floaty right now and not planted like it should with lowering springs, I've read a lot of comments about the Hankook tires being floaty, so not sure if it's the tires or the springs/alignment.

I wonder if anyone has the same set up and if they experience the samething when they first got the Eibach springs and Hankook tires.

 

Hankooks that a while to break in. My guess is that you need an alignment, but that's not the cause of the float - it's the tires. Once they break it, you'll feel more stable. People talk about 500 mile break-in. Might take 1k miles.
Get the alignment though - that just makes sense after doing the springs...

 

I agree with the break in for the tires. I'm running Hankook EVO's and they take a few miles to get broken in. I didn't get the symptoms that you are speaking of, however they were very unstable in corners before break in, now they are sweet and quiet!

 

Lowering the car will probably give you some toe out in the rear. This will make the car quick in turns, but darty on the highway. It will also wear the crap out of the insides of your rear tires. There is very limited "settling", probably as well off to just align it when you have them installed. You'll probably see a big difference after the alignment.

 

First as others have noted you need an alignment. Depending on where the toe is you could do a fair amount of damage to the tires if you put too many miles on them.

The springs shouldn't settle. After installing the springs on your car, if it was on a lift and all of the bolts were tightened with the suspension in full droop, the bushings will be in a bind. When the full weight of the car is placed on the suspension the bushings are not in their normal/angular position due to the new ride height. As a function of time and miles the bushings/mating surfaces will reach an equilibrium point.

For springs to 'settle' it would imply that in a very short time they had exceeded the yield strength of the wire used in the manufacturing process.

 

My Hankook's (New rears only) actually triggered my PSM to engage around certain corners and my back end would wiggle in the turns. Freaked me out. The car also felt very unstable at high speeds as well. I had the car in to the shop and even another alignment. Finally after finding nothing the dealership recommended I either take back the tires or let them break in. I let them break in and all the issues went away. I am not sure I will go with them in the future - Super Sports for me!

 

I've noticed the same thing with these tires but I don't have the "break in" miles yet. I had the alignment done at the time my coil overs were installed. I opted at the time to not have it corner balanced and since regretted that. Next time it's in for service I'm going to get that done.

 

Thanks for all the feedbacks... I'm gonna have the alignment done in the next two weeks or so. Hopefully the Hankooks will break in after 1k miles.

I've had Hankooks on my 2007 750Li and it was wonderful from day one, maybe Porsches are more sensitive Like some girls.

 

+1 on tire break in. Had em, hated em, specifically the "flighty feeling", which settled down to a gummy sensation after the break in. At 9000 miles I chucked em in favor of driving Michelin PSS much better tire. My alignment was spot on (best indy alignment guy in San Diego) and the car was lowered with Bilstein coil overs.

 

I think you need to leave the suspension slightly loose until you put the car down on wheels and then tighten up everything to avoid the bind issues alan refers to above--the bushings have some resistance to movement and will attempt to return to the state they were originally installed in---

 

bdgs1,

Thanks for the clarification. That is what I do when changing suspension parts.

 

I have about 500 miles on mine (standard c2s) and the car feels much more "twitchy" and squirelly at the front then the old P0's that came off. My dealer told me to run front tires at 40 psi and rears at the standard 44 psi. I had major cupping on the inside edge of the old P0's-- due to, according to the dealer, my not running them at appropriate PSI...

But the car sure feels all over the road when pusing it compared to the P0's.

I knew that the Hankooks would not be as great as Michelins and Pirelli's-- but I didn't expect -- THIS bad...

 

40/44 psi sounds high to me. What are your hot/running pressures?