simsgw

No kidding. I'd be throwing things by now. Maybe the bloody car.

Whoa! We're closing in on something here. I have had cars shake like that at idle, but never a Porsche. This is a problem, Jay. Maybe not the problem, and certainly not the only problem, but you need to pursue this. An imbalance like that is probably in the power pulses, because I don't believe the engine has balance weights that might be dislodged, let alone a separate balance shaft. Whatever it is, it needs to diagnosed.

Yes. Or at least offer a possibility that would get the car off his rack. I'm not cynic enough to complain that it also justifies a bill to your CPO provider. Besides having no reason to question his honesty, I personally find that most shops have enough work already. They don't need to invent more. However, the combination of wanting to help you and also get the rack open for more paying work both induce him to accept that diagnosis quickly. So yes, it is quite possible that whatever causes that out-of-spec road force reading also made it look like the half shaft might have a problem.

I agree about multiple issues. Maybe only two, but it would take at least two problems to satisfy my intuition at this point. That shaking at idle is not to be dismissed, but I can't quite stretch my imagination to have the source of that cause the Hunter results you report. Assuming the technician is poorly trained is too glib. Quite possible of course, but too much of an easy way out. I can see ways that a shake at idle becomes a shake at speed however. The problem can have harmonic effects. I'd buy only two problems: one in the drive train and another in that wheel/tire combination, and the two combining to make it a miserable ride. Not less than two and maybe more.

Not necessarily. The handling of turnover in used cars, especially with a CPO inspection, would catch this we would hope, but in fact it is often a brisk process and the mandatory test drive might have been done by someone who noted that a wheel balance was needed but in fact never repeated the test drive, assuming as most of us would that a balance job would fix the feeling.

The change of wheels before purchase could excuse that problem also (whatever it may turn out to be) so we don't have to assume malignity on the part of the dealer. How much have you talked to that selling dealer about this?

Unless one of these approaches turns up answers to both problems soon, I think you need to pursue the return of this car. Either by persuading the dealer to take it back as good will, or failing that, talk to a lawyer with experience in "implied warranty" cases in the state of sale. Obviously, the first option is to be preferred, but sometimes the good will of the people we deal with bumps into an upper-level manager who has to approve such actions and is having a bad day. Or month or year.

We owned an NSX for ten years, always servicing it at the same dealer who picked it up one day when we weren't feeling well. The driver took it back down an ill-chosen road and crashed it. He was devastated. The service manager was mortified and got the general manager involved right after notifying us. The GM offered to swap the original loaner for a more luxurious model while our car was repaired, and we were down to negotiating something like replacing the worn leather on the driver's seat to make up for the loss of value, until... Until the owner got involved. She said "Like Hell" and called to suggest we use our own insurance. "After all, it could happen to anybody. Besides, I need that service bay. When can you have the car towed away?"

Our insurance carrier is USAA, who is excellent in fact. They would have had it repaired more comprehensively than the dealer I'm sure, but they flatbedded the NSX to a shop of my choice almost a hundred miles away, and we learned that the damages went way beyond the value of the car. We quit tallying the estimate at $40,000. USAA cut us a check, gave us a low-interest loan on any replacement we wanted to buy, and then sued the pants off her. (Well, technically, it was arbitration between USAA and her insurance company; and realistically she probably can still afford pants, despite what it did to her rates. Mine are fine of course.)

And that is how I ended up with a new Porsche -- answering questions on Rennlist. Lots of good and bad trade-offs in life. Maybe you'll discover that car was the one that James Dean died in and at auction it brings... no, that couldn't be... Well, maybe you'll end up better off somehow, Jay.

At the very least, reversing a sale is not so big a deal as replacing an NSX, so the owner may not get involved at the selling dealership. And if you agree to take another Porsche instead of wanting your money back, this might even fall strictly within the purview of the sales manager, who can agree to the deal, get another sale on this month's books, and then dump this car on the service manager to find an answer to these symptoms. He can definitely get PCNA tech support to figure it out, so it's a win-win situation, right? Well, at least it would be a win for you, and that's all that matters to us.

Good luck.

Gary

simsgw

Yikes! This is contagious? Back away, just back away.

Seriously, I can't possibly think of anything else to suggest, Hoffa. I hope you both get this figured out.

Gary

fskof

Jay H, Where in Wi do you live?

Jay H

fskof: I'm in the greater Milwaukee area...20-30 minutes north of town.

997_rich

I get a bit of seat shake too at idle. Moreso than say a lexus or an audi sport sedan but in line with previous porsches I've driven- they're a bit "rawer" than many sport sedans. If you're missing on a cylinder, the display will throw a check engine light but you sound like you'd notice this and I don't think engine imbalance would cause the steering to shake at speed.. and it would be RPM dependent not speed dependent. That may be a red herring but a tech should notice a problem like this right away.

My vote based on the info you've given is that the front end is toed neutral or even toed out. My second vote is something going on with the front end bushings.

Good luck... one thing I've learned is that given enough time you can solve these issues or at least find the root cause(fixing it may not be financially viable). It just depends on if you care enough to keep chasing it instead of selling the car. It can be quite frustrating and I feel for you.

Jay H

Gary, I've kept the selling dealership in the loop on all this hassle. The saleman seems genuinely concerned, but can't do much of course due to the distance involved. They have offered to take the car in trade on any other vehicle in their stock.

Rich, thanks for your advice. It's a pain for sure, but either the car will get fixed (more money solves most problems) or moved on down the road. It's a flawless car otherwise.

Jay H

Just a quick update...

The final new winter tire has arrived today from The Tire Rack. The dealer called today and I can get the 997 in tomorrow for the mounting and balancing of these two new tires to replace the one out of spec rear tire and the one front that has a really high road force number. Hopefully they can fit in an alignment as well.

simsgw

That's great, Jay. It creates a safety net for your diagnosis efforts.

Gary

McCulla

I assume they'll take the car in trade at the price you paid, right? You've got many more $$$$ invested in head/heart ache by now, they should be willing to give you what you gave them.

hoffa

So since this thread got me thinking about my issue, I dug into it some more. I took it to my new favourite shop and they immediately put the car up on the hoist. They found a VERY VERY slight bend in the front right wheel. The guys who road force balanced the tire didn't notice it. Go figure. But that explains it.

Now that I know what it is, I will eventually buy a new wheel.

Jay H

I have not yet talked with the selling dealership as to what they may allow me on trade. I'm hoping that I don't have to go down that road just yet. They do not have much in their inventory that is in my budget or is of interest to me.

Let's see what today's eighth visit (in 8 weeks of ownership) to a service facility brings...

997_rich

Didn't you try both carrera III and carrera IV wheels previously? I thought you had tried 2 sets of wheels and tires.

But yeah, a bent rim will do it!

Jay H

The trip last Friday to the 2nd Porsche dealership revealed one left rear winter tire was completely out of spec and could not be balanced. They recommended that I replace that tire. Also, The Tire Rack felt that the 20 pound road force number that the front left tire is showing could very well give the vibration I'm feeling in the wheel. The dealership felt the same. So, it was one last thing to replace both tires before going after suspension components or brakes. Both Porsche dealerships feel there are no issues with either brakes or suspension and both dealerships have several hours of inspection labor spent on those areas, but at this point, I don't know for sure which shop's opinion to trust.

I've given up on the Carrera IV rims and summer Michelins for now. Those fronts are new, but shake worse than the winter tires on the Carrera III rims. I felt I should concentrate on one set of rims and tires and the winter set up was the best of the bunch. I have no idea if the Michelin dealership's Coats brand wheel balancer is in spec. It's not a road force capable machine either.

This is really confusing isn't it?

The service advisor at the dealership I took the car to this morning feels the shake at idle is normal. He's driven more 997's than all of us combined, so I trust his opinion on that issue.

Macster

Just to chip in there have been cases, not many, but enough that you need to keep the possibility in mind, that the winter wheels have a centering hole that is not properly sized. The tire/wheel will balance on the machine ok but when the wheel/tire is bolted up to the car the wheel is not centered and you have a shake.

Sincerely,

Macster.

Jay H

I've had this situation on a lesser car years ago where the rim did not center on the hub and caused tons of vibrations. However, both sets of rims I have are genuine Porsche parts.

I am also assuming the Carrera III rims are designed for the hubs on my '06 997.

The car is done. We'll see how it drives tonight...