mhm993

Wheel bearing.

G.I.G.

Thanks, Brainz. I just read your thread and it sounds like you're dealing with some frustrations as well. Were you ever able to get around to replacing the rear axle? It does sound like your vibration is slightly different, where it comes and goes and you don't feel it in the steering wheel. Mine is pretty consistent and can be felt in the steering wheel.

I bumped into my Indy yesterday at a car show. I was getting him up to date on what I've done (complete wheel swap with known, good wheels/tires) and the inspection of my axles. He said what I described about the axles sounded normal, but he wouldn't rule them out without looking at them. Something else he mentioned that I haven't thought of was the steering rack. My Indy is booked out a couple of weeks and I want a fresh set of eyes on the problem, so I'm going to take it into another shop I was referred to on Wednesday.

I'll try to check the wheel bearings myself later today and should know more Wednesday afternoon after I get it back from the shop.

G.I.G.

I had a moment to go out to my garage this afternoon to jack each wheel to check the wheel bearings. Both front wheels spun freely with only a little brake rub, which was consistent and did not oscillate. There was no noticeable wobble in the front or the rears, and everything felt solid. I don't hear any noise while driving either, so at this point I'm not inclined to think it's a wheel bearing that could be causing the vibration.

Brainz

I have not swapped the axle yet. Too many projects and it's Africa hot in Houston right now. My vibration isn't too bad -- many probably wouldn't notice -- so for the pending $1000 fix, I'll live with it for a while. I'll try to get around to it later this summer (on a cool day). I'm debating doing the wheel bearing on that corner at the same time as it shares a couple hours of labor.

G.I.G.

Here's the latest....

I took my car into another Porsche specialty shop that gets very good reviews. I told them all the steps I had already taken to diagnose the source of the problem (wheel swaps with known good wheels/tires, etc.). They test drove it and felt the vibration, then proceeded to go through the car tip to tail (tie rods, bushings, ball joints, shocks, axles, etc.) and everything checked out. They keep going back to the wheels, but I was quite certain after doing wheel swaps (fronts off a C2S Cab, whole set off a C2) that the issue wasn't coming from the wheels, and that the vibration persisted in my car even with a known, good set on all four corners.

One suggestion the shop made that I haven't tried yet is to put my wheels on another car to see if that induces the vibration into that car. I guess that is one way to determine conclusively if it is the wheels/tires, but I'm not certain that will tell me much more based on the fact that I had the vibration with good wheels on the car.

This is an aggravating process.

G.I.G.

Another round of wheel swapping....this time with by buddy's .2 C2S Cab with 43k miles on the clock.

We swapped all 4 wheels so we could spend more time on the road to determine if it is a wheel/tire issue in general rather than focusing on one wheel or a pair. I drove his car with my wheels on it first, then he drove it. I noticed a slight vibration on the same stretch of roads that I've experienced with my car, but it didn't seem quite as bad on his car with my wheels as it is when my wheels are on my car. Then we drove my car with his wheels, and he drove it as well. Similar situation, where his wheels seemed to make a slight improvement on my car, but didn't eliminate the vibration all together.

In general, there seemed to be some improvement with his wheels on my car, however, my car seemed to have more steering wheel vibration than his car regardless of wheel set.

Even though tonight's wheel swap was somewhat inconclusive, I still have to think my rear wheels could be the culprit, or at least a contributing factor to the steering wheel vibration.

My buddy seems to think my steering feels tighter than his (I suppose that is a good thing considering his car is newer with lower miles), which may indicate that slight vibrations or imperfections in the road would be more noticeable in my steering wheel than his.

Another observation: his axles were rock solid like my other friend's .1 C2. My axles have some in and out play (not side to side or lateral), which I've heard/read is normal. But I'm curious why two other 911's I've tested had zero movement, even in/out. I have to wonder if there might be something there with my axles not being 100%.

Here's what I think I'm going to do for next steps....

- Take it back to my Indy for another thorough once over, especially focusing on the axles. I trust the other shop I took it to, but the two times I mentioned the vibration to my Indy, it was always an "oh, by the way", then had them check the wheel balance. I wouldn't mind them going through it one more time, especially focusing on the axles.
- I might take my rear wheels to the wheel shop to at least look at it on a spinner (hard to spin them at home on the car considering it's a rear wheel drive car), but based on @qikqbn 's feedback and other stories I've read, I'm not completely sure straightening wheels (at least on these cars) will solve the problem, which leads me to my 3rd step....
- I think I'm going to bite the bullet and buy a used set of Carrera Classics from Wheel Enhancement. They're guaranteed to be straight and true, and I can have them refinished at an additional charge if I'd like to. I was considering having my current rears straightened, then having all 4 of my Lobster's refurbished this winter. But at this point, I think my time and money is better served getting a new (used) set of wheels and calling it a day.

I'm all ears if anyone has any different suggestions for a path forward.

Hass_Geschafte

To follow up with my issues - I received the Rennline 7mm spaces w/ mounting lip....and the vibrations returned. Removed them and the vibrations are gone again.

The Rennlines were wonderfully engineered. White on rice to the rotors. Mounting lip offered as much to grab as the stock hub. My take is that I've got some imperfection in one of the front wheels, tires, wheel bearings, or rotors (the only front items that have not been replaced). If you've got more than 50k on your inner/outer tie rods, LCA's, or shock mounts, I'd highly recommend swapping those out. You'll need to anyway and it could easily be one of those.

Replacing all that I did at the front of the car was enough to get rid of the vibrations (vibrations predated any spacers), but spacers definitely brought it back out. @qikqbn warned me earlier in the thread that he had trouble with front spacers over 5mm, and he was spot on. I intend to get a set of winter wheels & tires later this year, and I'll try running those with and without the front spacers to see if that proves the wheel/tire theory.

Having now experienced the car without vibrations, I can confirm that you're not crazy. The wheel can indeed be stationary when you take your hands off at ~70mph. And it's not something you should try to live with. It really does make you crazy. Enjoyment of the car is night and day. Don't give up...

G.I.G.

Thanks for the follow-up, Hass. Glad to hear you got your car sorted out. Introducing spacers into the equation is the last thing on my mind at the moment, as you can probably imagine. Andy you're right, it isn't something I plan on living with. It's more a matter of systematically eliminating every possibility without spending more money than I need to.

I was waffling about buying new wheels, but decided to pull the trigger on Friday. I ordered a set of Carrera Classics from Wheel Enhancement with a few cosmetic blemishes. They should be here later this week. I'm going to have them refinished before I have the tires mounted and balanced. I was going to have my Lobsters refinished later this year anyway, so at least this way I won't have to do it later this year, and I'll be putting a like-new factory fresh set of wheels on my car. Based on the wheel swapping I've done with 2 different cars, I'm not 100% certain that the wheels are my only problem, but I think they could be a contributing factor. We really had to pay attention closely when we swapped the rears on the C2, so I think there is a good chance I have a rear Lobster that is out of round. So even if the new wheels don't completely solve my problem, I think it's a step in the right direction and I'll have a set of Classics that I prefer a bit more than the Lobsters.

I talked to my Indy again on Thursday, and have my car going in on Tuesday afternoon to have them double check the axles and the front end, specifically the steering rack. My Indy said that even if a steering rack feels tight and passes a visual and physical inspection, that there can still be certain components in the rack that can induce a vibration even if there is just the slightest bit of movement in them.

Between the new wheels and another inspection from my Indy, I'm hoping I'm getting closer to a resolution.

zdet

G.I.G., any updates after the latest visit to the indy?

G.I.G.

Good timing. I took my car in yesterday and wanted to wait to post an update until I could drive it some more this morning when it was cold, as the vibration seems to be more noticeable when the tire temp and/or ambient air temp is lower.

My shop confirmed that everything felt tight and looked to be in good shape (bushings, axles, shock mounts, ball joints, etc.). He said that one thing he sometimes sees is a bit too much slack between the pinion gear and the rack that can sometimes induce steering wheel vibration. There is an adjustment bolt that can tighten the mesh between the rack and pinon, so he went ahead and tightened that. He said he can sometimes get it a quarter turn tighter in some cars, but he was able to get about a half turn with my car. You don't want to overdue it, because it can make the steering stiff and difficult to return to center.

He then test drove my car and said it felt as good as any other 997 he's driven (and he's driven hundreds). Granted, he didn't test drive mine before as a comparison, so I was cautiously optimistic.

When I drove it home I noticed an immediate improvement, but I tempered my excitement knowing that my steering wheel vibration seems to be worse when I drive the first 10-15 miles of the day.

Fast forward to this morning. I had a break in my work day and waited for traffic to die down, then took it for a drive. I was still getting a little steering wheel vibration, but it does seem noticeably better. I took it on a few different highways and roads and overall there is an improvement. I also had the chance to get it up to around 90mph and it felt smooth. My shop wanted me to report back either way, so I called them after my drive. He said if it starts to get worse again, then he's fairly certain it's the rack. He said if it doesn't come back, just to drive it like hell. That's good to hear because yesterday he said if the rack adjustment doesn't fix it, then it becomes a game of throwing darts, which can get expensive fast.

On a side note, I'm beginning to think that the stretch of highway near my house is suspect. I was towing my 4Runner up camping last weekend, so it had quite a bit of weight on the hitch and therefore less on the fronts and lighter steering. I was getting a similar vibration in my 4Runner on that same stretch of highway as I have been with my 911. It just so happens that at least 50% of the time, I'm heading that direction leaving my house. My buddy with the .2 C2S Cab said he feels it in his car and his company car (Ford Fusion) on that same stretch. So I've determined it's not the best section of road to try any comparison test drives.

Lastly, I received my Carrera Classics from Wheel Enhancement today. I'm going to drop them off to be refinished tomorrow and should get them back mid-next week. Then I'll have the tires swapped, balanced, then throw them back on my car, hopefully by next weekend. I still suspect that my rear wheels and/or my fronts may be slightly out of round, as the vibration does not appear before 45/50mph, then seems to go away over 80/85mph.

I'm not doing the celebratory chicken dance just yet, but I seem to be on the right track.

G.I.G.

I received my Carrera Classics back from being refinished and just had Discount do the tire swap after waiting a few days for the paint on the wheels to fully cure. I talked to the tech that balanced them. He said they balanced perfectly only needing a few small weights, and one of the fronts didn't need any weights.

I installed the new wheels this morning and took the car out for about a 30 minute drive on different roads to test it out. After getting on the highway where I had been immediately feeling the vibration, I noticed that it was much more stable now. I still notice a little vibration in the sections of highway that I've determined are to blame rather than the car, but I think that is due to the light front end of these cars and steering feedback we get. I drove it some more on different surfaces (pavement and concrete) and at different speeds, ranging from 40-75mph. The steering wheel doesn't vibrate at all now other than the sections of road previously mentioned.

So with all of that, I believe my steering wheel vibration was a combination of the loose steering rack engagement between the rack and pinion gear, and possibly a bent or out of round wheel(s). I noticed the biggest improvement after the steering rack adjustment, but the new wheels seem to have helped as well.

It's been a frustrating and time consuming process trying to get this sorted out, but I'm pleased now with the end result.

Brainz

Congrats! That's great news. If anyone has any additional details on the adjuster bolt for the rack, please post them!

Sporty

Good for you. I am taking mIne for alignment in a few weeks only because my steering wheel is slightly off center from when they aligned the last time after I had it lowered with the Eibachs. I get minimal vibration on certain stretches of road and generally its 99% steady, but now I am going to ask them to check the adjuster bolt as well. We are obsessed- see what you started! lol