On trip to Tail of the Dragon, need help - sudden vibration

So I'm 600 miles into my pilgrimage to the Tail of the Dragon. My 996 C4S has been running perfect until today when I drove the car hard (lets say 7-8/10) through about 20 miles of switchbacks and mountain roads between NY state and Vermont. The roads also had lots of frost heaves - no harsh impacts but definitely a workout for the suspension. The car then developed a vibration much like a wheel had come out of balance - the vibration worsens with speed. Also, the steering wheel now has a small amount (couple of degrees off dead center each way) play when at a full stop. At speed there is no play at all. Both these issues occurred all of a sudden after this hard section of driving. I stopped into a service centre in the middle of nowhere Vermont, and had all four wheels re-balanced. The front passenger was out over 2 ounces apparently. Hoping that would solve it, but it didnt. Still vibrating, with increase commensurate with vehicle speed. Any ideas what the problem could be based on what Ive described? I'm hoping to get it sorted and not have to scrap my trip and head home. If it may matter, I completed full rotor and pad replacement + fron swaybar droplinks just before leaving on the trip (I checked the drop links when the wheels were off for balancing, all tight and no play). But no problem at all first 600 miles so I can't see these services having to do with the problem that's come up after hard driving. Cheers for any and all help gents.

I would have gone with the wheels first just like you did. To bad that did not solve the problem... Next I would look at the suspension... You need to find a competent Porsche shop right away and sort it out! Good Luck!

If it's constant vibration and commensurate with increase in speed, I'm thinking wheel bearing or warped rotor. Did you buy good rotors? Did they have any extreme temperature shocks?

I would go to a porsche dealer, tell them to give it a look over and see if they find something broken if its a dramatic vibration they should see something sounds like a wheel or rotor, you didnt see anything wrong with the wheels off?

I would get the FWD components checked out by the nearest qualified shop. Starting with the driveshaft.

I'm betting you lost a weight, and the balance you got wasn't correct. The last time I got tires, it took five tries between two shops to get the balance right (will never go back to the first). Was your "hard section of driving" a lot of curves, or were you braking a lot as well? Rotors don't unexpectedly warp during a road trip, and even during hard street driving, it's not something that happens as often as the Internet suggests. A wheel bearing would be my other suspect. If Byprodriver's hunch that the FWD stuff might be the issue, disconnecting the FWD components is a fairly simple operation if you decide you want to stay on the road...

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Oh yeah: It's an AWD! That throws a whole lot of other suspects in! As Homer Simpson says: Doh! 5CHN3LL: Aren't you glad you gutted out the FWD stuff?

Rotors are Sebro, and I was not too hard on the brakes. I was much harder on them bedding them in and all was fine. The shop not getting the balance correct sounds like a reasonable hypothesis as the vibration is exactly like having a wheel out of balance. The only conundrum is how this steering wheel issue also plays into the problem. Maybe they're completely unrelated but I doubt it considering they both appeared at the same time. I'm shacked up in Manchester, VT now for the night. Search it on google maps and you'll see I am in the middle of nowhere. Anyone have any recommendations on competent shops along the Appalachian corridor between say Albany and Tail of the Dragon? Looks like closest porsche dealer is 2.5hrs east of here, wrong direction. On a positive note, I hear this place is INSANE on weekends with wedding after-parties and the such, took me 5 places before I found one with vacancy! Should be better than Lake Placid NY last night where I was the only paying patron in the bar (maybe the entire town? Quite possible).

Automobile Associates in Avon CT [phone removed] Due south of you. Hoffman Porsche in Hartford Ct if you need service on Saturday. When are you heading south? Feel free to call me at the house [phone removed] if you need more help. Bill New Hartford CT

found a porsche center in mechanicsville, NY but service is closed saturdays. Im an hour outside of Albany, NY and it's on my route anyways - anyone with any insight with Albany? I may just start calling around to euro or performance shops and see who's open tomorrow morning.

Wife had same thing happen the other day on Audi Q7, re-balanced and check all suspension joints. Answer was Low speed balance didn't account for a bent and cracked wheel, bend was much worse than the crack. Second wheel this summer, should have known. These are Chicago roads!

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Any chance you didn't notice the steering symptom until you started paying attention to the vibration symptom? i.e. any chance they're coincidental? This is not an accusation - this sounds like something I would do. "Damn, there's play in the wheel now. And dammit, now there's a scratch on the Porsche crest, too!" Hope it's cheap and easy to fix.

Interesting, I too was wondering about a bent wheel. The place I stopped today was a Chevy dealer - what are the chances that the service manager who helped me out with the last minute balancing is also a PCA instructor and 930 owner. I managed to get his cell and we're meeting for dinner tonight. Will be going back to the chevy dealer in nowhere VT tomorrow for us to get up on the lift and inspect everything closely. Hoping not a trip-breaker.

It is a long ride, but Powertech in NJ is a good shop.

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Not recommending Vertex at all, Butt much cheaper than a New shaft. http://www.vertexauto.com/SubCategor...%20Shafts.aspx

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What a lucky stroke that was! I'm sure you will find something in the AM. BTW, raining down here near the Dragon anyway so take your time. Sunday afternoon and Monday will be better I think.

Hope you get back on the road. If you are near Asheville check out this road! Not as heavily traveled as the tail. http://www.thedevilnc80.com/

Yes, I went on 80 by accident, it was awesome. I like Little Switzerland Loop too.

My money is on a bent wheel.

If the steering wheel is no longer centered when driving or when you come to a stop sign, there is a chance that a control arm was somehow bent. If that was the case, you would need to replace the damaged component and get the car re-aligned. I'm hoping it's something simple vs. a bent component.

check tire pressures? having one low can throw your steering off a couple degrees, pretty crazy.

Good luck hopefully its something simple / cheap to get her working right again.

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+1 They are also harder to balance which may be why the balancing didn't address it.

So the verdict is in and the fix is done. You won't believe it. Car went in the air straight away - no play at all in the wheels or assemblies, nothing bent / torn / loose. Removed all under panels and checked drive shaft, front transfer case, all appeared to be normal. Triple checked everything just in case. I then mentioned that back in April, I removed the steering wheel to replace the turn signal stalk that had broken. We figured lets at least pop the airbag out and check, only 30 seconds to do. The retaining nut that holds the steering wheel onto the shaft had backed itself COMPLETELY off, only resting on a couple threads on the tip of the threaded rod before it would have just fallen off. About an inch of thread between where the nut was, and where it should be secured up against the wheel. A good tug towards my chest and the wheel would have been in my hands detached from the car. Insane. I followed a DIY when doing the stalk replacement, torqued the nut down to factory spec using a new torque wrench and even had the nut, rod and splines marked to ensure 100% alignment. How it backed off is beyond me. Car now drives normally again. $50 cash and I'm on my way again, what a turn of events. Thx for the help and feedback my fellow Rennlisters. Cheers

Well, I didn't see that one coming. Glad it was an easy fix and caught before you made the evening news.

The Nut behind the wheel?

Wow! Glad it out for you! Don't forget to post a ton of pictures for us!

How does that explain the vibration when the car is moving?