NoPasaran

Hello, everyone
Haven't been here for a long while, primarily because my interest shifted towards motorcycles, but I still have my 2007 997 Turbo...which now has an unpleasant problem.

Background:
- The car is on 20 HRE P43 alloys, H&R springs and Michelin PSS tyres which have lots of thread left and no uneven wear (I had alignment done end 2013).
- The car is mostly standing in garage since end 2013, these days I move it maybe every 2 weeks for 50 miles.
- I just had big service done at official Porsche, spark plugs, coils, oils, and also RDK sensors in wheels.

Before I went to service I already had problem that when driving at speeds 50-60+ mph I felt vibrations through the steering wheel. This started suddenly a few months ago. At first I thought the tyres went "square" from all the standing, but driving around did not diminish the vibrations.

When I drove the car for RDK sensor change Porsche told me the problem could be improper wheel balancing(maybe one of those lead weights fell off) and they would rebalance the wheels after RDK installation (I think this is anyway standard procedure when tyres are taken off and put back on the alloys?).
I got the car back from service - the vibrations are still there. Now they are even stronger and the vibration frequency is higher.

BTW, I asked Porsche if that could be due to worn wheel bearings but they told me faulty wheel bearings would produce other symptoms. Besides, there are no vibrations when I drive slowly (30-40).

What could it be?

therock88

I would have suggested balancing as well..especially since the vibration occurs at the speeds you indicated.

If you feel they balanced all your wheels correctly, the next obvious place to look, is faulty or worn front end/steering components.

There is no magic here...If the wheels are true and balanced, something else is allowing the car to shake at that speed. Usually something like ball joints, control arms, etc. with play in them...

Good luck
DC

TT-911

^Flat spots in tires !
Try this :
http://www.ehow.com/how_7779179_fix-...ots-tires.html

Rogor

Most easy check is to change front wheel with another Porsche from which you know doesn't have the vibration (garage or friend maybe). When it's gone you know its the rims, tyres or bad balancing.
If the vibration is the same look for the disks, the driveline and so on, like above mentioned.

jhbrennan

Did they use Hunter (or equivalent high-end equipment) equipment and road force balance the tires? Also, I thought once flat spots (especially yours from extended sitting) occurred they stayed and that driving didn't eliminate them - not sure about this but road force balancing should be done.

ctony66

The thing about flat spots is that you can usually feel it at lower speeds also. It could very well be flat spots but you need to give a little more info. Does it start to do it at 50 and never stop all the way up to 70 and above? Does it do it on all road surfaces? even dead smooth? I had a wheel shimmy at speed and the dealer ended up changing the rack and struts (they obviously couldn't figure it out so they threw parts at it until it was fixed). It was probably a tie rod end. I have even seen rotors shake the wheel at speed. I would suggest driving it more and note the details of when it does it and any variables there might be. Like rogor said see if you can swap the fronts to see if it goes away first or have them rebalanced but ask to see the tire on the machine to see if it has any defects while up to speed. Just my two cents
cheers

TT Surgeon

Agree w rock, sounds like a balancing issue.

512bb

If it comes in around a certain speed and then goes away as you speed up, e.g., wheel shake around 60 MPH but not at 80 MPH then it's definitely the balancing. With these wheels and tires, the need to be balanced both around the circumference as well as depth of the wheel (i.e., weights on the inside of the wheel vs. the outside).

Check your wheels to see if there is any type of extra materials across from the valve as some wheels will already account for the TPS monitor's weight. Check out Mercedes and Corvette wheels and you'll see.

You should also check to make sure that your wheels are still true and round as potholes can change trueness in a hurry. It could be a combination of both too (wheel out of balance and not true).

The Pilot Super Sports should not square off at all as the new construction stops that - this according to the Michelin engineers that designed those tires.

Let us know what it ends up being.

Macster

Prompted by your comment: "maybe one of those lead weights fell off)"; but if you are using a tire shop that used the old style hammer on lead tire balancing weights you are using the wrong tire shop. The wheel balancing weights should be the adhesive kind which are stuck to the inside of the wheel. The spot to which they are stuck should be cleaned for to insure the weight doesn't come loose.

My WAG is there is a wheel balance problem. Generally just the static balance should be sufficient to ensure a proper tire/wheel balance but a Hunter (or similar machine) that can do a load force balance can be called for if the tire/wheel is suspected of still being "out of balance". I use the quotes because the combo may be in balance the tire may have suffered a belt break/rupture and the shifting belt may affect the tire's roundness. Or the wheel is bent and while the wheel/tire balances just fine the wheel's out of roundness mimics a balance problem.

However, either a bad tire or a bad wheel would manifest a vibration at all speeds. Thus I suspect a balance problem, still. One has to be careful. Unfortunately a place should take the customer's complaint seriously and do a proper rebalance but sometimes a shop doesn't and just, well, lies to the customer and the customer gets the wheel/tire back "balanced" when in fact it was not done again at all.

Be sure the tire inflation pressures -- at all 4 corners -- is correct. I have induced wheel/tire balance like vibration behavior with one of my cars by over inflating the front tires some, not much either, just a few PSI.