Bad Vibrations

[chrisanthony]

Hi everybody

I have a 96 lx and i noticed when i drive over 120mph my car, especially the steering wheel starts to shake/vibrate rather violently. Can anyone tell me y would that be?


Thanks CHris

[mightymoose_22]

Tires out of balance.
Exceeding spade rating of tires?
Loose/worn steering system parts.
God telling you not to drive that fast.

[chrisanthony]

haha the speed limit here in toronto is 100 -110. I started feeling a little jerky on 115 so i wanted to see what would happen when i break 120 and man it felt like my steering wheel was going to come right off..

[mightymoose_22]

ah... that blasted metric system again!

[denisond3]

Did you mean 120 Kph? At that speed your problem is most likely one (or more) unbalanced/out-of-round tires; but those other things MightyMoose mentioned apply as well. With a tire imbalance the weight of the unsprung mass of the front suspension on our Escorts typically will resonate when the wheel is spinning at 70-75 mph (~ 120 kph); producing the shaking. With a small imbalance of the tire (most likely) or wheel (might be bent a little), as well as; a loose tie rod end, loose ball joint, bad lower control arm bushings, steering rack loose on its bolts, feeble shock absorbing in an old strut, etc - will let it feel worse.
I dont recommend it, but going faster than the speed of "worst shake" often results in it smoothing out somewhat - since you are rotating the (imbalanced) tire faster than that resonant frequency.
Ideally your car should feel smooth at those speeds, but it may involve tire rebalancing, new struts, and other new suspension parts.
And a wheel that seems fine at 100 kph may be unsuitable for high speeds, due to runout. A tire may require rebalancing after its been on the car for a while, but if it takes much in the way of extra balance weights - it may have internal damage like broken cords; & a higher risk of a blow-out at high speeds. Also check that your lug nuts are all still snug.

I dont think my 1.9L Escort will even get up to an honest 120 mph on a level road.

[chrisanthony]

Originally Posted by denisond3

Did you mean 120 Kph? At that speed your problem is most likely one (or more) unbalanced/out-of-round tires; but those other things MightyMoose mentioned apply as well. With a tire imbalance the weight of the unsprung mass of the front suspension on our Escorts typically will resonate when the wheel is spinning at 70-75 mph (~ 120 kph); producing the shaking. With a small imbalance of the tire (most likely) or wheel (might be bent a little), as well as; a loose tie rod end, loose ball joint, bad lower control arm bushings, steering rack loose on its bolts, feeble shock absorbing in an old strut, etc - will let it feel worse.
I dont recommend it, but going faster than the speed of "worst shake" often results in it smoothing out somewhat - since you are rotating the (imbalanced) tire faster than that resonant frequency.
Ideally your car should feel smooth at those speeds, but it may involve tire rebalancing, new struts, and other new suspension parts.
And a wheel that seems fine at 100 kph may be unsuitable for high speeds, due to runout. A tire may require rebalancing after its been on the car for a while, but if it takes much in the way of extra balance weights - it may have internal damage like broken cords; & a higher risk of a blow-out at high speeds. Also check that your lug nuts are all still snug.

I dont think my 1.9L Escort will even get up to an honest 120 mph on a level road.

Thanks guys honestly, i havent balanced my tires since i bought the car a year and a half ago. So it might be that..but i'll check around including the nuts this weekend.