Steering wheel shake at 80 mph

[88carrera]

When I reach about 80 mph my steering wheel shakes. If I exceed that it get progressively worse.

My rear tires are almost due for a replacement, but the fronts have a good amount of tread left.

I know it's not from flat spotting due to sitting in cold temperatures as it still happens after an hour or two of driving.

I noticed on the passenger front where the tire rubbed against the fender during a hard turn. Would that have disturbed the belt?

When I purchased the car two years ago the steering was dead calm at 100+. I guess I will start by having them rebalanced.

[Vicegrip]

Have them balanced on a road force unit as they might be out of round as well. A well balanced oval will still shake the wheel.

[BobNovas]

Or, you could just keep it below 80...

[Trak Ratt]

Back in the day I had a friend who owned a ‘53 Buick. Shimmied like a devil possession at 50 mph. Had to be seriously stoned to keep your foot in it but that’s what it took. Reason was badly worn front end parts not tyres. :cool:

[88carrera]

Or, you could just keep it below 80...

When there's Chivas Regal and moderately priced call girls involved, there's no way I can keep it below 80.

A stallion must run....and run free.

[racer]

Could be suspension related, or wheel bearings, maybe tie rods.. maybe bad shocks, or tires... Keep your options open on what might be going bad and for now, keep it below 80 - no reason to "race" for Chivas Regal ;)

[michael lang]

I agree w/Kurt. Start with a road force balance to determine if the tires are even out of round. In the meantime, if you are desperate to do something yourself, you could always check the front hub nut to make sure there is no excessive play in it. Once you have determined that the tires are/are not the culprit then you can decided if you need to start crawling around your garage floor again. If you can wait a week or two, I can help you with the road force balance.

[88carrera]

I agree w/Kurt. Start with a road force balance to determine if the tires are even out of round. In the meantime, if you are desperate to do something yourself, you could always check the front hub nut to make sure there is no excessive play in it. Once you have determined that the tires are/are not the culprit then you can decided if you need to start crawling around your garage floor again. If you can wait a week or two, I can help you with the road force balance.

I noticed on my passenger side front tire some rubber was shaved off due to contact with the quarter panel. I don't know if the road force balance would be able to detect this, or if the amount of rubber missing is not a balance issue.

[Vicegrip]

A road force balance has two components. One is a standard type balance to find and correct imbalances and the second part is to measure the roundness of the tire and rim together. If the tire is egg shaped you could still balance it and it will spin without vibration but even if balanced it will still shake while being rolled on a road surface.

Getting the wheels balanced and roundness checked is inexpensive and easy and can rule out 99% of tire related issues.

[BobNovas]

What is a road force balance? A tire balance machine that puts the tire on a rolling surface? I ask out of curiousity. Paul at Radial Tire has a machine that spins the wheel and tire on the car (it's just an assembly with an electric motor turning a largish drum), and he just somehow eyeballs the tire or feels it and puts weights on it to fine balance it. That must be another "lost art".

[KFJ]

Actually puts a rolling surface on the tire. Here's more info:
http://www.gsp9700.com/pub/features/how.cfm

[9Eleven]

What is a road force balance? A tire balance machine that puts the tire on a rolling surface? I ask out of curiousity. Paul at Radial Tire has a machine that spins the wheel and tire on the car (it's just an assembly with an electric motor turning a largish drum), and he just somehow eyeballs the tire or feels it and puts weights on it to fine balance it. That must be another "lost art".That is the only true way to balance a wheel. I had my car balanced there. They spin the wheel at speeds over 100 mph and then feel your fender. They put on weights until they feel absolutely no vibration coming from the fender. This method is as accurate as it can get. Paul at Radial (owner) says the road force machine is the industry (vegamatic) and it really is no better and sometimes worse than a standard machine. It only spins your tire up to 55 mph and it is only as good as it's last calibration and operator. Paul does not own one.

My car was shaking at 80 and it just had a new set of PS2's all around with a Hunter road force balance. The machine was way off. They actually had an ounce and a half on one wheel and when Radial Tire took all of the weights off and tested it, the wheel only needed a half ounce. So they had an extra ounce on for nothing. Radial has several machines that don't use the road force, but they are extremely sensitive. Hunter Road force are the industry standard machine that is full of possible flaws and misinformation. Don't be fooled by people that think they know, go see Paul.

[Trak Ratt]

Had mine done by Tire Van. Nice write up at http://www.tirevan.net/Technology.aspx

[kaefer]

When I reach about 80 mph my steering wheel shakes. If I exceed that it get progressively worse.

My rear tires are almost due for a replacement, but the fronts have a good amount of tread left.

I know it's not from flat spotting due to sitting in cold temperatures as it still happens after an hour or two of driving.

I noticed on the passenger front where the tire rubbed against the fender during a hard turn. Would that have disturbed the belt?

When I purchased the car two years ago the steering was dead calm at 100+. I guess I will start by having them rebalanced.

Howard -

Did you ever figure out what was causing your 80 mph vibration and get it resolved?

I'm currently chasing the same problem with my SC.

Thanks for the help.

[SkipC]

If you have had the front wheels (or wheel) off recently and the shake started just afterwards, loosen them up so the wheel is not in tight contact with the hub, then tighten up the wheels bolts with the wheel(s) off the ground.
I just experienced something similar and when I did the above, it went away.
If you haven't had the front wheels off recently, please disregard.

[kaefer]

It turns out that road force balancing the wheels and tires helped a lot. I'd say 90% of the vibration at 80mph is now gone. I think the remaining 10% is being caused by a warped front rotor.

[88carrera]

Howard -

Did you ever figure out what was causing your 80 mph vibration and get it resolved?

I'm currently chasing the same problem with my SC.

Thanks for the help.

The front tires were rebalanced at Radial Tire and it is smooth as sile now. I guess they went out of balance as they wear down.

[Vicegrip]

You don't always need the super bestest. I just balanced a troublesome tire on a basic digital Coats 700 and it tuned the tire right up.