Highway Speed Steering Wobble

[TargaWoods]

In my 1978 911 SC ROW at euro height, I have a steering wobble that is most aggressive at 65mph, and decreases as I go faster up until ~95. Under 60 it isn’t apparent.

I just got the wheels balanced.

Wheel bearings are tight. (Tightening them actually made the wobble more violent.)

Ball joints have no obvious play on them.

Struts are koni adjustables.

I put in turbo tie rods a month ago.

Zero Toe
0.5 deg neg camber on the front.

I will be replacing the ball joints (another pelican said that that was his ultimate fix)
I will be replacing the wheel bearings (people say that those being worn can do it)
I will be doing pads and rotors as well. (They’re very slightly warped)

Is there anything else I’m missing??

Why would tightening the bearings make the wobble more violent?

I just had the car balanced and aligned a month ago and it was a buttery smooth dream to drive. It has been a slow development for this wobble. It didn’t show up overnight but now it’s bad enough I have to deal with it. I just had the wheels balanced a few days ago and it moved the wobble higher in the speed range to where it is now. (Before it was focused from 55-65 disappearing at 70, now its 65 disappearing at 90)

[tobluforu]

I run zero toe as well, max camber and also have a slight vibration in the wheel at certain speeds. Is this because at higher speeds the car is going more toe out, maybe, doubt it. How about having the wheels road force balanced? Now, what about the steering wheel itself, play wise, is there any? There is a bearing in there and there was a user on here that made a special shim, can't remember who that was, but I have one and it helped. Have you checked the steering rod bushing in the frunk? Have you swapped wheels, front to back. Way back when they balanced my wheels, I watched and sure enough, one was bent.

[TargaWoods]

Maybe there’s toe out at higher speeds, but immediately after the balance and alignment it was perfectly smooth, so I don’t think it’s that.

No play on the steering wheel, I did the rennline bushing for it.

There is only the slightest amount of play in the U-joint in the smugglers box, but it’s so minuscule I know that that isn’t it.

I’ve not changed the steering rod bushing, but I did wiggle it and it didn’t have any play.

I’ve not swapped wheels but I’ll do that tonight.

I had one non-Pcar shop tell me I had a bent rim, but then my Pcar shop I go to usually didn’t mention anything. I wouldn’t put it past it to be bent given how **** the roads are in Chicago.

[tobluforu]

Hey, another chicagoite. I hate driving my car here in Chicago, its horrible.

[shoooo32]

I had this problem with my '78 targa at 80-83mph. Same scenario; I had just replaced suspension components, turbo tie rods, etc. I tried balancing tires, alignment, rack cleaning/greasing, to no avail.

New wheel bearings solved it. Zero vibration up to speeds I won't document.

[Cloggie]

I have had this problem....turned out to be bad shocks.

Since you have Koni adjustable, try tightening them up and see what happens.

D.

[Old H2S]

Check the spindles, at 12&6 then at 9&3 with a MICROMETER not a caliper. The out of round is a very tight tolerance. You will drive yourself crazy and then find out how simple the problem was.

[Bill Verburg]

toe spec is 0 pressed, that means 0 w/ a spreader pushing the wheels to get all the play out of the toe adjustment, if it's 0 unpressed then there's a fair chance that you have toe out when driving

[PeteKz]

Bill, is that with the front of the wheels pressed outward? I haven't done the measurement with the front wheels pressed, and I probably should.

[GeorgeK]

What brand tires?
I've had similar with Pirellis, impossible to balance after half worn. Switched to Michelins, issue gone.

[David Inc.]

Any spacers on your wheel hubs?

Edit: I ask because I had a steering wobble that was either a dirty or improperly torqued rear wheel spacer.

[GH85Carrera]

On my 85, a regular tire balance has lots of steering wheel shake.

ONLY going to a place with the "Roadforce" balancing cured my issue. 911s are very sensitive too tire imbalance.

[mike sampsel]

Originally Posted by TargaWoods

In my 1978 911 SC ROW at euro height, I have a steering wobble that is most aggressive at 65mph, and decreases as I go faster up until ~95. Under 60 it isn’t apparent.

I just got the wheels balanced.

Wheel bearings are tight. (Tightening them actually made the wobble more violent.)

Ball joints have no obvious play on them.

Struts are koni adjustables.

I put in turbo tie rods a month ago.

Zero Toe
0.5 deg neg camber on the front.

I will be replacing the ball joints (another pelican said that that was his ultimate fix)

Is there anything else I’m missing??

Why would tightening the bearings make the wobble more violent?

I just had the car balanced and aligned a month ago and it was a buttery smooth dream to drive. It has been a slow development for this wobble. It didn’t show up overnight but now it’s bad enough I have to deal with it. I just had the wheels balanced a few days ago and it moved the wobble higher in the speed range to where it is now. (Before it was focused from 55-65 disappearing at 70, now its 65 disappearing at 90)

Had same wobble at speed about 28 years ago. Mine was corrected with new ball joints, old one was pretty weak. How many miles on yours? Mine had about 98 K miles. I just replaced mine again (not needed (20 k on them) but had the front suspension off for bushings so I did the ball joints and packed the wheel bearings).

New ball joints are pretty stiff, if you do yours and the old ones flop, a good chance this at least part of your problem.

[nickelplated5s]

Bearings heat up, expand. Too tight is not the best. Pull it apart and measure the spindles as mentioned. If they're fine throw some money into ball joints and or bearings.

[Jeff Burger]

I had rear wheel vibration that was driving me nuts years ago. took it to a nearby shop and had them balance both rear rims/tires. Driving it home there was no real change. so I drove it to my Porsche shop about 50 minutes away to let him look at it. After driving it he said it was a wheel balance problem, he balanced the two rear wheels and the problem went away. Net- it's possible something went wrong with the first balance so you may want to recheck yours.

[EC900]

I had a bent aluminum wheel confirmed during balancing. The indy tire shop was able to straighten it out, the inside looked like it took on a lot of heat but was balanced out to spec.

As far as Pirelli tires go, long ago I had a tread belt shift that created a wobble at high speed. Again this was apparent during a balance procedure, even can be seen rotating the tire on a lift.
Inspect the tire, for scalloping wear, quick easy road test is to dab on some white water-color paint around the both front tire treads and drive few miles at speed and see if any wear pattern appears.

Any discernible difference when braking +60 mph? Does it add more or less wobble?
I had a warped rotor that caused a braking wobble at speed.

[rokemester]

I had a vibration at highway speed. Suspension all around has been refreshed to Euro height. After new rubber and balancing no more vibration.

[mikedsilva]

Control arm bushings. i've had a few cars with a wobble in the steering wheel at around 55-65mph.

New control arm bushes solved it.