steering wheel vibration above 70Mph)

HI chaps Recently changed my wheels (18 inch Turbo twist) for Carrera 18 inch (bought from a fellow forum member) I had the wheels fitted before christmas but before I did I had them refurbed (see pics below) First long drive I did I noticed a shaking of the steering wheel about 70mph, I looked at the wheels and one front didn't appear to have any weights, took the car to Kwik Fit and had them balanced. The car has been on a few short runs but not over 70mph since, jus got back from Christmas away so got it out of the garage and went to Bluewater in it Today so the issue: the steering wheel is still vibrating (all be it not as bad) at 70mph and it seems to ease a little about 85mph, any suggestions? Is the balance still out or could it be something more sinister? The vibration wasn't there before I changed the wheels, the new wheels are correct 996 ones (not boxster ones with spacers etc) and the car is running the same tyres it was The car isn't pulling to one side and is handling and performing spot on other than this Any help would be appreciated Cheers Tom

Has the refurb left any paint on the hub mating surface at all? If so, make sure you remove all of it & see if that helps.

It still sounds like a balance issue to me. Try taking it to a better fitter. Do you have a Pro-Tyre in your area? They are usually pretty good. Also get them to check the front wheels are running true when they have them on the balancer.

Good call.

I'd jack them up in turn and carefully check for any run out, doesn't take much to cause a wobble. Rough check can be done spinning with something solid nearby for a reference. Wheels can bend a bit before they actually crack if they have hit something solid.

Thanks chaps, I will try and get them rebalanced tomorrow and report back Thanks Tom

Are the new wheels exactly the same offset as the old ones? If the offset is greater, then your tyres will be slightly closer to the suspension struts. This isn't a problem at low speeds as there's enough clearance between the tyre and the base of the strut. However, at higher speeds (about 70mph coincidentally), the downforce on the front of the car pushes the nose down and thus the strut rubs on the inside of the tyre causing a vibration. You won't notice this when jacking the car up as this lifts the front of the car body up and makes the gap look much bigger. Hence, if the new offset is slightly bigger, fit a spacer the size of the difference and you'll be fine. Obviously if the offsets are identical, ignore everything I've said! [ ] Cheers, Neil.

Thanks chaps Not sure if the wheels are the exact same offset however the new wheels are correct 996 ones, not the boxster ones. They came from a 996 C2 MY02 model identical to my own so I am assuming the rubbing wont be an issue? I am going to take the car back to Alloy Art where the wheels were done and get the problem rectified tomorrow, fingers crossed Cheers Tom

Design911s website shows the offsets for most 996 wheels http://www.design911.com/Porsche/996--911--1997-05/Alloy-Wheels-18-/pt72_60_-cma81-cmo110/ NB, they are often different!

Hi get the balance of the rear wheels checked! steering wheel vibration at 70 mph is often caused by rear wheels out of balance! Berny.

The fact you can "drive through" the vibration problem (eases @ 85mph) would suggest this is a balance issue. As Richard says, get them rechecked. Explain the problem to whoever you take the car to, and ask them to check the wheels first before removing existing weights; you will then find out if there was a problem with the balance being out. Note, there will always be small amounts of "out of balance" showing, but only 5 - 10 gms per side should be expected.

Got them re-balanced Will report back when I can get out for a good run Cheers Tom

Alright chaps Well, problem solved! I phoned Alloy Art who were great but couldn't fit the car in until tomorrow, so as Kwik Sh*t is just round the corner I took it back to them! Left it with them an hour and went to collect, the exact words he used were: "Yeah, those wheels were well out" When I reminded him it was them who'd done it only three weeks prior he gave me a load of garb about the machine being faulty and a new technican, blah blah blah Anyway, she's running like a dream now, sitting downstairs in my work car park in a US import Porsche (40 anniversary 911) Car Bra (got to avoid the evil winter stone chips) and with Ski rack (+ snowboard) on the roof all ready for a nice little run round the M25 tonight to the indoor ski centre at Hemel! Happy days, thanks for all the advice and guidance chaps Tom

I didn't realise thats what they were for!

Hi Richard - do you use and recommend the Pro-Tyres in Slough then? All the best Des

Hi Des I've used them for alignment (and tyres) in the past, but I now use a mobile chap for tyres, as he is cheaper, and a whole lot more convenient. He is based in Taplow. http://www.3ttyres.com/ He is very careful with wheels, and jacking the car, and I've never had any problems with balance.