Vibration in steering wheel at certain speeds

Hello all. I have a 1999 C2 911. I bought the car a few months ago and have noticed a problem that doesn't seem to go away. When I hit certain speeds (49-52mph and 69-73mph) I get a vibration/shake in the steering wheel jerking the wheel left and right. When I go a little faster or slower, it goes away. It's present about 80% of the time. 20% of the time its fine and the steering wheel is perfectly smooth. The problem seems to come and go as it feels, but I have noticed that some road surfaces make it worse. I'm guessing I have a bushing that is worn out. I tried to re-balance the front tires, and then I went and put new front tires on. It didn't help at all. The vibration still comes and goes at different speeds. Any advise would be appreciated. Thank you. If this has been posted elsewhere, please link me.

Check in the following order: 1 Tire pressures in front tires, 2 check balancing and wheel roundness 3steering rack

also check the front and rear wheels' bearing as well

Front tires are new and air pressure is good. I'm thinking it's something that falls in and out of alignment. In a turn, the wobbling reduces significantly. But when i straighten it out again, it resumes. I think the culprit is some component that when put under pressure seems to align or at least not shake back and forth.

i think the lack of pics is messing with the balance and/or roundness of your tires.

Have a trustworthy alignment guy look at it. Could be alignment, bent wheel, tie rod, steering rack, shock, bearing, brake rotor, poor fitting wheel centers, spacers or other things. Have it looked at and don't just throw money at random parts hoping. Gl and post resolution

Alignment center sounds like the best idea. No point wasting time and money replacing working parts. I'll update with results.

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Intresting. I get a vibration from my winter wheels that I don't get on my summer wheels. The center caps are loose and wind up almost falling out when I return from a drive. Could THAT be causing my vibration issues?? I posted a question about how to fix loose center caps on non-Porsche 17" twists, but got no answers. I was thinking of using a heat gun to pry the little plastic tabs out more. Or, using a rubber band to make the fit tighter so the caps will stay put.

No - your problem is something entirely differant winter tires can have flat spots from storage... or maybe the wheels you bought/have are out of round... or the centers are too big....a good tire shop can check them for trueness for little money.

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Damn, I want a simple solution that solves my problem for nothing! I had the fronts balanced without issue. Usually if the wheels weren't true, they would mention it. I'm taking the center caps off and going for a ride tonight!

There are do it yourself (DIY) pages with pictures for the bearings R&R online here if you want to service them. It didn't appear to be an american style of service by just popping the hub off so give yourself some room and time if you go that way.

This may not be of any help to the questions posed here so far, but I found that spurious front wheel vibrations occurred after a DE event. Why? Because my wheels would pick up glops of track tire goop on the inside of the rim. I don't run track tires. Never have. But many others do, and my tires would pick that up and put little lumps of it on the inside of the rim. By cleaning off the inside of the rims after an event, I completely eliminated the frequency of tire balancing I was doing. And although those glops attach themselves when the wheels are hot, they pluck right off when the wheels cool. Not saying this is the answer for the OP, but just like leaves in the radiator openings, things happen.

Good points, extra goop on the tire = extra weight, causing the wheels to be out of balance. I don't have any goop on my wheels though. I was having this same problem (vibrations at certain speeds) on my 944. I had the wheels balanced, rims checked, etc. Nothing worked. Then, a genius mechanic took the tires off the rims, and found water (from a lame gas station air compressor) sloshing around in there! Fixed the problem and my 944 was smooth as silk after that, up to 100 mph! You never know.

Since new tires were tried and the same symptom were present I gotta figure it wasn't dirt attached inside the rim or a case of wear making the tires out of round and balance. The only things I can figure hasn't been asked is if there is any slack in the steering. One slight move to either side should have direct and instant results with no slack. If there is a little slack it might also be a case of the wheels tracking on there own in that slack area and highlighting imperfections in alignment and suspension. I do wonder if you have a bad habit. I highly recommend you never turn the wheels while the car is sitting stationary. Tire belts can be dislodged even if the newer tires aren't as prone to the problem. You can't see the belts are screwed up becuase they are internal. Make sure the car is rolling before doing steering inputs or at least only do a very minor input then roll to get the rest of the turn in. Messed up belts will exhibit what you refer to. No turning the wheel the contact patch is stationary.

To be a little more clear on the issue, I'm not turning the wheel when the vehicle is stopped. When I drive down the lane and feel the shaking, I can swerve in the lane and as long as I hold the car in a turn in the lane, the shaking will stop. It's not that I can get it to stop by wrenching the wheel left and right before I take off from a light. The weird thing is, sometimes I don't feel anything at all, then a minute or two later, it will come back. It's gotta be something that has some free play in it, and turning the car in a turn eliminates the free play enough to stop one of the wheels from shaking left and right. I don't know what it is. I can't imagine that this problem is unique.

Check wheel bearings, all susp. bushings, bad (weak,or leaking) strut, brake caliper pad or piston hanging up, then have someone that is very familiar with P-cars align it - be sure to let them know of the problem you are trying to correct to allow them to check as needed. Be sure to let us know what fixes it.

Your moving the wheel to end the shake sounds like bearings you need to replace real soon. I deleted a lot in my first post and left it at just the do it yourself stuff finadable online here. Here's pretty much what I left out. Bearing that exhibit these symptom generate a lot of heat while taking a lot of damage. The heat can almost weld the bearing in place and cause damage that will require replacing more than the bearings. Don't drive the car anymore till you get in there and replace the bearings if they are bad. Inner and outer bearing slack, bearing shot or what ever it is that needs to be eliminated. With the bearings out there can't be any play in them. They should only roll. Packing is easy with grease in your hand and mashing the grease through the bearings. Even if the bearing look good its probably best to replace them. Good luck. Like I said it doesn't look as simple as the other cars I've had. Read about wheels on and off precautions since banging the calipers and rotors is a problem.

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By design, the 996 wheel bearings are sealed bearings. This is not to say they couldn't be removed and packed, but if you have to do that you probably should be replacing them anyway. FYI -The bearings themselves are not that expensive.

The problem has been solved, but still doesn't make too much sense. It turns out the problem was wheel spacers on the front wheels. The car came with wheel spacers when I bought it and I never thought that could be the problem. I took them off, put the tires back on, then went for a spin. No vibration at all. Cars spins up to 100+ without shaking or vibration. Lesson learned: take off wheel spacers.

Good to hear Ghostrideradv! Wonder if those spacers were H&R branded ones or some generic ones? I'm hoping they aren't H&Rs since I am thinking of getting a set...

Thanks for letting everyone know what ever variety wheel spacers weren't compatible or weren't true. Good deal dumping them. I gotta say some guys on here that have or some time in the furutre might end up wanting to use wheel spacers would really like to know what brand had the problem. You might add the mix of components like wheel and tires sizes.

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Nice. Glad you solved your vibration issue...without help from the specialist.

Glad you found the problem and resolved it. Thanks for reporting the solution.

what the heck is a wheel spacer and why would anyone use them?

spacers are plates of metal (usually aluminum) that go between the wheel and the hub to "space" the wheel further out of the fender.. you use them to cause wheel vibration and stress to your driving experience mostly for looks, sometimes for clearance - and they come in prices from very cheap, to WOW Really? - the better ones dont seem to cause the vibration is the the selling point I suppose. I run them on my car for looks - yet they are not shiny so I ofter wonder what I was thinking (note with spacers you ALWAYS need longer bolts to put the wheels back on ---- ALWAYS!

While I'm glad you isolated the issue, spacers inherently don't cause vibrations. Any element that is not true or plane will cause vibration. Cost does not determine whether or not a part is true or round, and most machined parts that cost more than a nickel are true, because computers do the milling at all pricepoints The parts in question were not new, and the most common time to damage a spacer is when mounting it. Hubcentric Porsche & H&R spacers and any other TUV stamped part should be fine. Many factory cars have shipped with spacers, and Porsche has sold them for years. I always found the (rennlist) aversion to them pretty funny Best, Hans

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****! I just deleted a nice post! OK - Not true, not all spacers are created equal. Some are CAST and not all machines are tooled in a way to reproduce good parts. Any cast part that gets NO secondary machining operation to true up the part will cost less and so the cost of a part IS part of what determines its ability to work better. If a shop turns the front and back of any part and the tooling and or machines being used are not set up right then the effect will be that the centers are not concentric to each other and thus causing the same sort of issues. Actually to make a spacer right with it being flat, parallel and concentric is not as simple as just making a spacer (note the thinner spacers only need be flat and parallel as the center of the wheels still rests on the cars hub) The thicker ones have a center for the hub and a matching center for the wheel that have to be held very close. not an easy task if you are using a POS machine. Castings are almost never flat - and are cheap, buy them and you will regret it. SO - Yes.... price CAN be a factor in how well these work.......

I'm not sure what brand spacers they are. They aren't stamped with "H&R" or any other recognizable brand. They are about half an inch thick. I'm guessing they're some Ebay junk. With that said, free spacers to anybody that wants them....PM me. I'm running 225/18 front and 295/18 rears. Turbo wheels. I would have never thought the spacers were the culprit. I've never run spacers on any other car I've owned, but foolishly figured it couldn't be the cause. I was talking to a mechanic friend of mine and he was explaining to me vehicle harmonics. He was saying it could happen on any car, but it could be exaggerated with spacers. He said when a car hits a certain speed, all the little vibrations in the car will begin to shake or vibrate in harmony, causing an amplified vibration/shaking felt through the entire car. He said it happens a lot on big rigs and is similar to a speed wobble on a motorcycle. Like the handle bars on a motorcycle or the steering wheel on the car, the energy causing the vibration is trying to release anywhere where there is room to move. This may explain why the shaking would happen on some roads and not on others and also why turning the car would lessen the vibration. I'm guessing binding the car in a turn would flex the chassis and steering components just enough eliminate the harmonics, similar to touching the string of a guitar to stop the sound. Well, anyway, I hope this is helpful to anyone considering running no-name spacers.

PM sent - wait PM's dont work unless you have 10 posts... hurry and say something (shut up you guys! LOL)

My two (more) cents just to add to the spacer frakas. I have spacers on my 99 C2 coupe and they have been there for 10 years with no issues. Made by TechArt. The Porsche factory offers spacers as an option on most new Porsche 997's and Cayman and Boxsters. Go to the Porsche website to the Build-your-own section and then to the Exterior items (color and wheels). Spacers widen the track of the car. A wider track improves the handling. That is what they are intended for. But they also can make a narrow wheel/tire combo fill a wheelwell visually. Like everything, too much of a good thing can be harmful or down right dangerous, such as the ridiculous wide offset wheels gig a few years ago in certain ethnic neighborhoods.