Driving wheel too shaky around 130km/h

[Anonymous]

Hi everyone,

My driving wheel get too shaky around 130 kmp. Its anormal vibration starts around 120 peeks at 130 and back to normal around 140. I get the camber, caster realigned so they are ok.

Any suggestions?

 

[Anonymous]

Have you checked that all your wheels are correctly balanced and all tyres correctly inflated before anything else?

 

[Anonymous]

Yeap done those...

 

[Anonymous]

Yeap done those...

Leaves 2 additional possibilities:

- the brake disk is imbalanced. Shouldn't happen, but can. In this case you need a garage which can balance the wheels while mounted on the car. Let them check the disks before.

- the suspension/alloy mount is bent. This can happen when you skid sideways against a curb.

 

[Anonymous]

Fundamental question time, why so fast?

It seems that you have hit a harmonic frequency for your cars setup. It's a fundamental mechanical property which can be modified but will always occur at one speed or another.

 

[Anonymous]

Fundamental question time, why so fast?

It seems that you have hit a harmonic frequency for your cars setup. It's a fundamental mechanical property which can be modified but will always occur at one speed or another.

Sorry, but that's wrong. When everything is correctly set-up and the wheels are balanced the driving wheel should NEVER be shaky.

 

[Anonymous]

Fundamental question time, why so fast?

It seems that you have hit a harmonic frequency for your cars setup. It's a fundamental mechanical property which can be modified but will always occur at one speed or another.

It's not fast though...130kph is about 80mph

My first though was you've possibly lost a wheel weight. Didn't think warped brakes would affect the car unless braking...unless they were REALLY REALLY warped? :eusa-think:

 

[Anonymous]

You will never truly balance a real world mechanical system to eliminate harmonics.

Back to the problem at hand, it seems like an imbalance problem as stated earlier.

Have you checked that all the weights to balance the alloys are still in place? Simplest check without needing a mechanic.

edit - lol beat me to it.

 

[Anonymous]

Didn't think warped brakes would affect the car unless braking...unless they were REALLY REALLY warped? :eusa-think:

Warped disks normally only shake while braking, that's right. That's why I wrote imbalanced disks.

I had that once with a little Fiat Turbo and had a hard time finding a garage which could balanced the wheels while mounted on the car because the car was, ahem, a bit low :eusa-whistle:

 

[Anonymous]

You will never truly balance a real world mechanical system to eliminate harmonics.

That's (of course) true from a theoretical engineering point of view.

But from a practical(!) real life point of view you can eliminate vibrations down to a point where you can't notice them anymore.

At least my last 4 cars hadn't any vibrations from 0 km/h up to maximum speed.

Sometimes, especially with less quality winter-alloys, I had to bring them back a couple of times until the balance _really_ was right. But that says more about the incompetence of the garage...

 

[Anonymous]

My rcz done this why l don't know even after l got it checked out,it happened between 80-90 mph then disappeared.

 

[hanswuk]

[/quote]Warped disks normally only shake while breaking, that's right.

Tom, your English is extremely good and therefore I hope you won't mind me pointing out:
bremsen = to brake (eg. in a car)
brechen = to break (eg. a glass)

 

[Anonymous]

My rcz done this why l don't know even after l got it checked out,it happened between 80-90 mph then disappeared.

Mine does it to around the 77-85 mph mark (I've...erm...heard) but I largely suspect that the tyres aren't properly balanced after the last changeover. In truth, a combination of not being able to drive much over the first quarter of the year and laziness stopped me getting it investigated further. I'll be interested to see what happens when they get changed over again in the coming weeks. If that doesn't solve it then I'll have to get it looked at.

 

[Anonymous]

My rcz done talthoughwhy l don'wheeow even after l got it checked stillt,it happened between 80-9rectifiedthen disappeared.

Mine does it to around the 77-85 mph mark (I've...erm...heard) but I largely suspect that the tyres aren't properly balanced after the last changeover. In truth, a combination of not being able to drive much over the first quarter of the year and laziness stopped me getting it investigated further. I'll be interested to see what happens when they get changed over again in the coming weeks. If that doesn't solve it then I'll have to get it looked at.

Rizz the vibration seemed to come from the rear although my tyres where over inflated at the rear it still continued after this was rectified.

 

[Anonymous]

Thanks for the response Jassy! :thumbup: I'm pretty rigorous about checking my tyre pressures these days now that I have a tyre inflator sitting in the car. Got fed up of them frequently being out of order at petrol stations/supermarkets and I really ought to have had one anyway. I know that my tyres are correctly inflated but, having examined the alloys, it appears that some of the alloys were rotated and that some of the weights are off. I rather suspect that this is the root cause in my instance.

 

[Anonymous]

Well thanks a lot for the answes gents but as mentioned I got the wheels balanced, I just checked all the weights and they are in place.

The "shake" in the driving wheel I am talking about cannot be seen with bare eye as you can imagine but, you can easily feel it, and it does not feel so good.

As I am a mechanical engineer myself, vibration issues can sometimes be very complex and sometimes quite simple. Before going deeper - spending money in other words - I just wanted to learn previous experiences if there is any...

 

[Anonymous]

From experience - I once had an issue with tyre separation [similar to flat spots, but with ABS it near impossible to get them these days]. Nonetheless the tyres balanced ok but could still feel it at harmonic speeds, but also in carparks when crawling. Only way we found it was to put car on hoist and spin each tyre freely and feel with the palm of the hand. One tyre had a saucer plate bubble, which would expand at speed. A new tyre was the fix.

An MG ZT with 18"s also had an inner side rim distortion from a pothole. But You could feel it under braking as well. Once again hoist, spin and feel, the rim with finger. On balance the tyre made up for the distortion but maybe at harmonic speed it didn't. Had rim rolled for fix.

 

[Anonymous]

From experience - I once had an issue with tyre separation [similar to flat spots, but with ABS it near impossible to get them these days]. Nonetheless the tyres balanced ok but could still feel it at harmonic speeds, but also in carparks when crawling. Only way we found it was to put car on hoist and spin each tyre freely and feel with the palm of the hand. One tyre had a saucer plate bubble, which would expand at speed. A new tyre was the fix.

An MG ZT with 18"s also had an inner side rim distortion from a pothole. But You could feel it under braking as well. Once again hoist, spin and feel, the rim with finger. On balance the tyre made up for the distortion but maybe at harmonic speed it didn't. Had rim rolled for fix.

If one tire (say one of the fronts) had bubble, do you think replacing with rears will solve it?

 

[Anonymous]

Warped disks normally only shake while breaking, that's right.

Tom, your English is extremely good and therefore I hope you won't mind me pointing out:
bremsen = to brake (eg. in a car)
brechen = to break (eg. a glass)

Oops, thanks :thumbup:

At least the characters were all correct, just in the wrong order :mrgreen: