2ndof2

This has been discussed before with suggestions that it may be caused by tie rod ends etc. Not sure what to look for. The wheels are in balance and the car was just aligned. Tires are fairly fresh as well. I do get some creaking coming from what is probably the sway bar but it sounds more to me like the dust covers on the front struts (if in fact my car has dust covers). Is the wheel shaking more common to worn struts, tie rod ends or something else? Car has about 70k miles and was lowered but I have no idea when the PO may have replaced the front shocks. Any tips on where to look or how to diagnose the problem?

Edward

One thing that helped eliminate my 50mph shake (though it has come back now after a few months) is cleaning out the brake rotors. Remember that this is a repiprocating component so any brake/road grunge caught in the numerous venting holes can be just enough to cause a slight shake. Twist a drill (by hand) to celan out all the holes, then follow with either compressed air or washing out with a hose ...water is probably better, but I did mine in my garage so... It worked for me anyway.

While you're in there, also clean out the insides of the front wheels. You may have picked up grunge that has deposited itself unevenly back there, as well. Then get the balance rechecked at a good shop.

But yes, worn suspension components and/or bushings can certainly create a wheel shake at certain speeds.

Edward

Robin 993DX

How often do you drive your 993? My 993 always shakes a little if parked for couple of days when I first start to drive it to freeway speed, goes away after about 10-15 minutes of driving once the tires gets rounded. (Tires flat spot from parking).

Another thing you can try is to check the torque on the lug nuts, I found that if you tighten it a little more than spec. 92 ft lb? It have less shaking problem. So I generally go with 105 ft lb on my lug nuts.

Ray Calvo

How do you know wheels were balanced right? 911-series are VERY sensitive to imbalance.

The dirt in the rotors or on the wheels would be my first guess. Also, I haven't looked hard, but I seem to remember that sometimes rotors had a metal clip (like a large staple) in one or more of the metal cross vanes between the rotor faces to act as a balancing fix. Maybe you had one and lost it.

RE worn suspension pieces; could be, but I would think that if that were the case you'd have noticeable play in the steering, and have a lot of wander. One thought to try - on a smooth straight road, at 50MPH or higher, wiggle the steering wheel back and forth rapidly from straight about 1". If the car doesn't immediately follow this movement, might have worn suspension parts. If it immediately responds and you don't have a front-end wander, would guess suspension is OK.

Question - when did all this shaking start? Right out of the blue? Slowly started and got worse? Or when you changed something? Might help in a diagnosis.

ceboyd

yes because steering shake can be due to so many things...

such as:

-flat spotted tires from sitting to long
-slipped belts on tires from age (too old) or just bad tire
-bent wheel (flat spotted)
-warped rotors

and more possibilities

2ndof2

Well lets see if I can rule out a few things here. First, I have been driving the car about 2x a week on weekends until just recently when I sold my 928 daily driver late last week. So sitting and flat spotted tires probably isn't it. I don't think its the brake rotors because I just did a brake job about 1000-1500 miles ago and put on new rotors. No clips or staples or anything in there. I also washed the inside of the front wheels while they were off. There is some strange sort of oxidation or something to the inside of the wheels so they aren't perfectly clean but who knows if thats it. The tire shop has some machine that I'm told tells if the wheel is bent or not and they said its good. Tires are about 6 months or so old and were swapped off my 928 but I didn't notice any uneven wear (will check that again). The steering feels pretty responsive but without driving another car with "fresh" suspension components, bushings etc. I really don't know how to tell the difference. I can only say that its alot more responsive than my 928 ever was but that car did need new tie rod ends and the front struts needed to be replaced. As for how long this has been happening I really can't recall the car not doing this. I usually didn't use the car that much except for some back roads driving and cruising around town so I either wasn't going 50 or I flew right past 50 so quick I wouldn't have noticed anything strange. Will check to see how the front tire wear looks again and inspect the tie rod ends or any bushings I can see. If these parts are all in good shape would worn shocks/struts be a potential cause? Its odd that its at around 50 mph and it always seems this is the speed that others mention when describing the problem. I will mention that I did notice the wheels did not spin freely when I first did the brake job. Is it possible that this is the problem and that the brake pads are still too tight against the rotors? I have noticed when the car sits after a few days that it seems the front wheel or wheels are binding up a bit. This MAY be the root cause. I don't notice anything else strange with regard to the brakes though.

2ndof2

Sorry for the double-post.....to clarify: The front wheels seem like they are stuck or have to be unstuck when I back the car out first thing after a few days of sitting. Feels like the brake pads being broken free of the rotors.

Edward

Hmmm, some friction in trying to rotate the tire by hand when on jacks is ok. The wheels do not have to spin freely. But you should not have to exert much force to turn it. If you are feeling significant sticking/binding in the morning backing out of your garage, you may have a sticky caliper that needs rebuilding. Raise the front end and see how hard it is to turn the wheels.

Edward

2ndof2

Uh oh, I hope thats not whats up Ed! Will check it out tomorrow and see whats what...

2ndof2

Checked each of the front wheels to see how they spin while jacked up. No more difficulty spinning them. Must have just been zero tolerance between the pad and rotor during the brake job. Come to think of it the smooth surface where the car is parked could be causing that binding feeling when backing out or it might just be washing the car and the thin film of rust on the rotor. No biggie. All is well there. Next easiest check is the wheel balance again. I did speak with the service advisor at the local dealership this morning while getting a few parts and he said during the alignment they inspected the tie rod ends and found them to be fine. I don't think the lugs were over-torqued enough to cause a problem and the tire wear is even. Wheel balance seems to be the next place to look.

p_carfan

Most likely scenario......Go some place with a Hunter electronic balancer.

Porscheologist

I am following your thread with great interest. My car does this same exact thing at 60mpg not a mile faster not a mile slower. My car also has around 70k and it is a daily driver. It has done this since I bought it. My guess has been front wheels/tire balance. Keep us posted on how it goes and if balancing fixes the problem.

cabrio993

Mine does this at around 58 mph. I try to never drive at that speed. It's like butter before or after this "barrier". I have had all front bushings, rod ends, etc inspected, wheels have been balanced several times. Car is aligned and corner balanced. Rotors have been cleaned.

I have found that by playing with different tire pressures, I can get it to almost go away, but I can still feel it some.

If you find what fixes it for you, please let me know!

Robin 993DX

I have been suffering from this problem since the car was almost new 6000 miles. So I am pretty sure there is nothing wrong with the car. I pursued many avenue to try to find a fix to this problem. And the only way I completely got rid of the shakes was an on car hand balance. Basically the wheel is spun with a mahine on the car and the "balancer" puts his hand on the car to feel the shakes and changes different weight settings and positions to get it perfectly balanced, he does this for all 4 wheels, and the car balance out perfectly! No shakes! Really black magic stuff, not sure how many place will spend the time to do this. I had this done when I lived in Atlanta at a place call "Gran turismo east", located in Chamblee tucker, GA.

So after the balance if I had to take the wheel off the car for any reason I also make a mark on the hub and the wheel, so that it goes back on the car the exact same order as it came off.

That's the only way I completely got rid of the shakes.

cabrio993

Hey Robin,

Thanks for the tip...good to know... I'll take the car to Grand Turismo and give them a try. They did an aligment for me and they were great.