sebBo13

I got a set of used 997 Turbo wheels (19", wide body) for my 2007 Carrera2 off this forum which came without TPMS sensors. I installed the wheels without the sensors initially and they fit perfectly. Ride was great as well, no vibrations at all. Tires are Bridgestone Potenza RE050A 245 front and 295 rear.

I then had the tire sensors installed along with an alignment. Reason for the alignment was that my last set of rear tires were worn down very unevenly on the inside with a camber of close to 2 degrees. So I asked them to reduce the camber of the rear tires (they are 1.5ish now).

Now it gets tricky - right after I left the shop I accidentally went over a killer speed bump at less than 5 mph that hit the underside of the car right behind the front axle. It didn't feel like anything broke but it sure was a good bang. When I went on the interstate I noticed clear vibrations on the steering wheel starting at 55 mph. They had only put in 34 psi in the front tires and 39 psi in the rears, so I inflated the tires to the recommended pressure which improved things a bit. I then brought the car back to the alignment shop for road force balancing. The vibrations got a lot better but I still feel them at 60-75 mph. I think I noticed that things improve a bit when the tires warms up.

This does not really make sense to me.
Could the shorter and presumably stiffer sidewall of the tire (19" vs 18" on the old rims) need some "warm-up" time? I guess these tires also were not really made for 40 degree weather.
Could the speed bump have damaged anything under the car that would explain my problem?

nevadakid

I replaced my sensors and the tire shop said it was useless balancing the tires.
When I got the car back, at 65+ mph, there was a lot of vibrations.
Came back to the store to have the tires balanced and what a difference. no more vibrations.

Try balancing your tires at another shop

sebBo13

That was my first idea as well, but this shop is specialized on alignments and balancing and has a great local reputation, so I have as much faith in their work as I could have in anybody's work. Regardless, this would probably be the first thing I try unless somebody else posts other plausible ideas as to what could be the cause of my problem.

semicycler

These cars are picky about tire pressure. These settings are recommended for partial load, 1-2 passengers without luggage. Generally you will have better handling at the partial load settings. The settings on your drivers door frame sticker are for full load - max passengers and full luggage. See your owners manual for more details.

Yes it could. If you have your original wheels I'd put them back on and test drive the car to see if the problem stays with the car or moves with the Turbo wheel set. If it goes away check the new wheels for a bent rim or bulges in the sidewalls, especially on the inside edges. If it stays with the car check the tie rod ends, sway bar drop links, and LCA's for anything loose or bent.

chuck911

In reading the whole story I'm seeing a lot of details about vibration after mounting TPMS sensors but nothing about balancing after mounting TPMS sensors.

Is it true? They mount sensors and then don't rebalance?

The OP mentioned having a lot of faith. Which is fine. Faith is good. Not gonna be the one to knock faith. It is good for the soul. For the Porsche though, professionalism is the way to go.

Verboden

I am confused about the sequence of events from the OP.

You got a new set of rims, had them installed with new(?) tires on all 4 wheels but without the TPMS?

At this point in time your alignment was suspect due to poor wear on the previous tires?

You drove the car for some period without problem. How many miles?

You then had the alignment done and new TPMS sensors installed, keeping the existing tires?

Before any extensive driving was performed you hit a speed bump that appears to have caused a solid part of the underside to be impacted. Can you recall if the impact felt like it was as you were going over the bump or on the way on the downside?

sebBo13

Here is the sequence of events:

- Got the Turbo wheels that came with the tires on but no TPMS (previous owner had harvested them).
- Mounted the wheels and drove them for about 100 miles (all fine)
- Sold my old wheels (without the tires), harvested the TPMS sensors
- Had a tire shop install the 1-year old sensors in my new wheels and do alignment (vibrations started), drove 50-100 miles.
- Road force balancing (before I could test the effect I hit the speed bump)

I cannot quantify the impact any further, it felt to me that unless something critical is located right behind the front axle (12-15 inches) the impact shouldn't have caused any major damage. Regardless, if things don't improve I will definitively have the steering components checked out.

I talked to my indy today and he said that tires often develop "flat spotting" over night when it's cold which would explain that things improve when the tires warm up. Also, I think my tire pressures might have a little bit on the high side with 39-46. I am planing on driving the car for a bit tomorrow and see what happens if the tires get really hot.

sebBo13

Looks indeed like they did. In retrospect this seems odd to me too.

1990nein

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Verboden

OK, the order of events makes sense.

I looked at my front end just behind the wheels and if you hit the speedbump straight on then the impact you felt would likely be the frame. At the speed of impact you could not have bent a rim. So lets assume no suspension damage.

So 2 things changed from the point where you had correct handling. A new alignment and wheel balancing (consider the TPMS install part of balancing).

Simple enough to have the shop verify the balancing. Maybe a wheel weight was loose and the speed bump popped it, stuff happens.

What I wonder is if the wheel/tires you got has a wear pattern from the previous owner. It sounds like your new alignment was a noticeable change from the existing. I had my C4S at the shop for a track focus alignment and during the shop test ride the mechanics felt a heavy vibration and the first thing they wondered was whether it had any tire wear.

sebBo13

After a longer drive today the vibrations were pretty much gone, so my indies theory might have been right. I will probably still have the tire rebalanced at a different shop.
Thanks for all your input!!

JW911

If you noticed a vibration right after having them balanced, you should bring them back to the shop that balanced them and tell them you have a vibration and you want them to recheck the balance. This should not cost you anything. I suspect you either have a misbalanced front wheel, or wheels. Or you bent a wheel going over that speed bump. Which is indeed possible if it slammed as hard as you describe. Either way, a re-check of your balance will determine this. No sense is starting over with a new shop that will only charge you money as soon as they take the keys from you. Start with the guys that were supposed to get the balance right the first time.