just bought a 996 - now front end "wobble"!?

Hi all - great to find other people with a true passion for cars, especially Porsches. A couple weeks ago, I bought a Certified Pre Owned 2000 996 Cabriolet with 41,000 miles and everything is stock. The engine sounds and feels great, and everything felt tight as I drove home. Within 100 miles, I started to notice a bit of a "wobble" from the front end at certain speeds. I went back to the dealer, they had the alignment checked and adjusted and had the front tires balanced at no cost to me. I drive home, everything feels good, but within the next 100 miles, this wobble is starting to return, even if it is a bit more subtle than before. I have hit no jarring bumps or potholes. Any thoughts or similar experiences? It's something I want to fix of course, as I'm pretty **** retentive about liking my cars to be well aligned and straight, especially a Porsche! I've driven a couple others from the same time period with similar mileage and I don't feel this in other cars. I also am losing a little faith in the dealer, as a technician drove it and said it "felt fine to him." I live in Pasadena, CA in case someone can refer someone local that might be able to look at it.

the tires on my car are brand new Pirelli P-Zeros, which were installed free by the dealer after the initial complaint, so I don't have an uneven treadwear issue. That's one more reason I am so perplexed.

I was just going to ask if you have P-Zeros on the car. There are certain P-Zeros that just will not stay in balance, I think the 18's are the chief culprits ... might be the Assimetricos. Do a search on that and see if the dealer will swap them for Michelin's or Dunlops or something. If the tech can detect the wobble in the car, they could even swap a set of wheels to see if that cures it. That would rule out the suspension and narrow it down to the rims and tires. I had 18" P-Zero Rossos on my car and they were fine. I have 17" P-Zeros on my current 993 and they are fine, too, but I have heard of this issue before ... balance the tires, drive a little while and out of balance again. They seem to be prone to flat-spotting. https://rennlist.com/forums/showthre...161#post825161 Vic 95 C4

Are you sure the car doesn't have any accident history? I'd suspect suspension or wheel. Have the wheel rechecked for balance. Swap tires with another car and see if the problem goes away. Or, have dealer spin you wheel again.

Believe it or not but the problem that you have is not uncommon, and when it recurs after wheel balancing, it can be tough to diagnose. Here's a couple of suggestions. First, carefully check your tire pressure. It could be something as simple as a slow air leak in one of your tires. If the tire pressure is fine on all your tires, the next thing I would do is to carefully check each wheel for any damage. Even a slightly bent wheel could cause a vibration. If both the tire pressure and wheels are fine, I'd find the best wheel balancing guy in your area and have him check it out. Although a damaged frame will cause vibrations, they wouldn't be intermitten as they are in your case. So I'm thinking that it's a wheel or tire problem. Good luck.

check for spacers.

I don't think spacers are used on front, not to mention he's got a narrow body

my certified "new" car has the same problem. at speeds greater than 81, i notice a slight vibration in the frontend/steering wheel. it's more of an annoyance than a safety issue (I think!) but the 996 i traded in was smooth as silk at speeds well into the triple digits... problem is the dealer i purchased the car from is 800 miles away so hopefully they can do some sort of reciprocity with my local dealer??? btw, tire pressures are dead on and the dealer put on brand new Pirrelli assimetricos when they certified it...

I have spacers on a narrow body. Last year there was a guy on the board who put on spacers w/o noticing there were spacers already and had a wobble.

Any tire/wheel/spacer imbalance should be apparent immediately, and not get progressively worse with mileage. This is even more true of flat spotted tires which will shake the car when cold and smooth out as they warm up and become round(er). These cars are VERY sensitive to road surfaces, and our wide, low profile tires WILL flatspot when they sit. You may just need to get used to this! It is possible for the car to drive smoothly on certain roads, and others set off the shaking condition. I had either slightly out of round or permanently flat spotted tires which were fine on most roads and speeds, but shook the car at 85MPH on one particular stretch of road near my house. New tires cured this.

I have a 2000 C4 with the P-Zeros and its also a certified pre-owned car. It took a great deal of persistance to get it right for me as I had a vibration problem as well. In the end it was an out-of-round tire in the rear and at least 3 tries to balance the tires using a Hunter force balance machine. Its very good now, somewhat perceptible at a certain speed, but very very slight. All I can say is you will have to carefully rule out any tire issue by taking it back to the dealer.

That's an excellent observation. I remember test driving an E55 AMG about a year ago, btw awesome car, and it took about five minutes of highway driving before the steering wheel vibration subsided. I imagine the car sat on the Dealer's lot for a few days and the tire(s) developed a flat spot which disappeared after they were heated.

I tried patching a tire and it developed an incurable wobble and needed to be replaced.

Because this happens at certain speeds it most certainly is a balance problem due to one of the following in order of probability: Tire at any corner of the car. Wheel bent at any corner of the car. other roatating item such as rotors. Find someone other that the dealer who really knows how to balance tires. I use someone here in Minneapolis who does it for people who race Audi's and Porsche's. My car which is a 99 is perfect at all speeds. I currently have Michlen on the front and Conti's on the back!

Hi; I am assuming you went to Rusnak in Pasadena. Did Ken Yearly check the vehicle and tell you it was fine? If not ask to speak with him and have him check it. He is excellent, I have used him for more than 10 years on 2 different Porsches. He is a mechanic at Rusnak, Pasadena.

You guys are all awesome - I actually bought the car at The Auto Gallery in Woodland Hills - overall, they've been pretty good to deal with, but I think they are trying to brush me off on this issue at this point - I'm going to try to lean on them to swap the rims out to see if I have a bad one - they put brand new tires on the car upon selling it to me, so flat-spotting wouldn't seem to be the issue at this point - I guess I feel a little better knowing other people have run into similar problems. Funny thing is I don't mind things like paint chips that seem to be driving others crazy, but I sure do want the car to run smoothe. As for the question about accident history, the carfax is clean and I don't think they can certify it if there's a serious accident detected from the past - at least I hope not. Again, thanks for everyone's advice and rapid replies...Sean

99, no accidents, brand new Pirelli P-Zeros, 85mph wobble present here as well. Dealer stated it could be a bent rim. I try to drive the car as often as possible, so flat-spotting should not be the culprit.

allright - fresh from the head Porsche Techs mouth... The minor front end wobbles are from Pirellis most of the time. they have earned the nickname squirellis because of this. when i told him about the wobble, he said, "You've got Pirellis on there don't you?" Anyway, they spent an hour rebalancing them to near perfection (while I watched nicely) which took care of some of the wobble fortunately. now i just got trash these tires so i can get Michelins - anybody know how i can do that???