2008 Kia Optima Steering wheel vibrates back & forth as speed increases.

Something that's bent should show up at very low speeds. You can jack up each wheel separately, and spin the tire, but remember to double the speedo reading. To duplicate 50 mph, you want 25 on the speedo. Remember too, that this is dangerous. If the jack slips, you're going to have a serious problem, so start very slowly.

If everything is balanced, it's probably a drive axle, and that bent rim is a clue that there was impact on one side. Anyway, get it up to where it shakes badly on the highway, and then slip it into neutral. If it's a balance problem, it shouldn't change at all. If it does change, or goes away, it's probably an axle. Check the mounts, too. They can aggravate a small problem.

An axle problem should also change depending on whether you crowd, release, or float the throttle when the shake occurs.

Swap tires Front/Rear. See if problem travels to rear. Very possible that the impact that damaged the rim also damaged the tire.

Check the run out on the flanges of the wheel hubs as well. Could have tweaked one enough to cause this.

what happened to cause the vibration???

"what happened to cause the vibration??? "

Reread the steps in my o.p.: First we eliminated tires, and a bent rim.

Now the steering wheel twitches less, and at a higher speed, but it's still noticeable.

snipped-for-privacy@gmail.com wrote in news: snipped-for-privacy@googlegroups.com:

Not quite. See my other reply.

This^^^ I find it hard to believe that an impact that damaged the rim did

*not* damage a tire. If you rotate and suddenly the steering wheel is stea dy but you have a vibration from the rear of the car, then you know what to do.

I've seen several vehicles recently with *un*damaged rims but tire belt dam age so bad that the tread bulged up to 1/4" radially at the spot of the dam age. One would think that this would be obvious when having the tires bala nced, but perhaps the combination of safety guards and an unobservant opera tor let it slip through. It can happen, as I literally fought a similar is sue for years until I gave up on shops and started troubleshooting it mysel f. In my case it was a used rim that I'd bought that was bent and apparent ly while you'd think it'd be obvious on a balancer nobody spotted it.

You only had the tires *balanced.* That doesn't mean that they're true or that there's no belt damage. I can balance a damaged tire so it spins true on the balancer, but it'll never run right in real life.

N8N wrote: "8:29 AMN8N

- show quoted text - You only had the tires *balanced.* That doesn't mean that they're true or that there's no belt damage. I can balance a damaged tire so it spins true on the balancer, but it'll never run right in real life. "

In your prior thread, yes, the tire was replaced due to sidewall damage. I clipped a curb under 20mph three years ago. No visible damage to the "wobbly" rim.

As far as "real life" goes, no on-car balancing is available at least here in southern CT.

My whole point is, we've thrown everything at this otherwise terrific car, and the steering wheel still vibrates, as it has for nearly 3 years now. I bought it used back in 2008, 14,000mi, no vibrations, no jiggly steering wheel.

I am overdue for brakes, so I hope soon I'll find out if it's an uneven rotor or something.

Probably tires. I suggest finding a shop that has Hunter balancers. Around here I go to Just Tires. I had a high speed shake with my recently bought car. Fixed it up, but they use a Hunter dynamic balancer. Have a suspension man check for worn suspension parts first. Then have the tires balanced with the Hunter. Rotors last. There's other things, like a bad harmonic balancer, or bad trans, but more rare.

That "I clipped a curb under 20mph three years ago." and "we've thrown everything at this otherwise terrific car, and the steering wheel still vibrates, as it has for nearly 3 years now. I bought it used back in

2008, 14,000mi, no vibrations, no jiggly steering wheel."

Are VERY important items you didn't mention in the earlier posts.

Curb hit that bent a rim and damaged the tire very likely bent other parts as well. Especially on cars that are built very light to begin with.

A very simple test can show you if something is bent. Grab a cheap laser pointer, smaller the better. Magnetic base would be nice but not really needed. A chunk of flat cardboard/plywood painted white would be nice. Some way to hold that vertical as well.

Jack up the front of the car. Place the board so it is parallel to the tire in question (I use a chunk of string taped to the tire and then just measure so you have something like 2 feet or so at 4 spots)

Now attach the pointer to the tire/rim so the beam hits the board at 90 degrees. Now rotate the tire and watch the pattern on the board. IF nothing is bent you should see a nice even circle. If something is bent you will see an ovoid pattern.

Seems to me it would be easy to find the problem. Maybe not so easy to correct though.