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Old 19th May 2013, 19:38   #16
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Default Re: An undamped spring - The Anti-roll Bar

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Originally Posted by Rehaan View Post
My mother has been complaining about this side-to-side rocking at the rear of the VW Vento... i wonder if this is related / the cause?

R
Absolutely it will be - most cars are set up to work well on smooth roads and high cornering forces. Replacing a set of springs with a set which allows more ground clearance and slightly softer settings (as happens for some markets, like India) is not the same as designing a car for use on Indian roads. I find that many modern cars are out of their depth and ride and handle poorly on many English roads, so it must be uncomfortable if Indian roads are as bad as some of you say.

I find people are in general quite unaware of the enormous difference good suspension has on almost every aspect of a car. At a given speed, safety margins will be higher not only because a car will brake and steer better but because the driver will not be fatigued. Unless a car is able to grip the road properly, it doesn't matter how powerful the brakes or the engine, you will not be able to make use of them properly. Travelling in a car with suspension which is well-suited to the road can be a revelation for driver and passengers.

Here is a video of a car's suspension working as it should on a poor Russian road. This particular suspension's springs don't have to be rated to maintain the vehicle road clearance as it is loaded to maximum, instead there are variable length liquid pushrods to maintain the correct height. The springs themselves are four 'balloons' of gas. The compromises are reduced enormously in this design so suspension can actually work more as it ought to. Note the remarkable smooth and level ride of the body as the wheel articulates to the road's roughness.



edit - the road deteriorates later in the video

Last edited by FlatOut : 19th May 2013 at 19:56.
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Old 20th May 2013, 07:20   #17
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Default Re: An undamped spring - The Anti-roll Bar

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Originally Posted by Rehaan View Post
My mother has been complaining about this side-to-side rocking at the rear of the VW Vento... i wonder if this is related / the cause?R
Absolutely! Almost all the cars right now use the Torsion Beam rear suspension. As explained above this causes unwanted movements in the opposite wheel when one wheel is affected. i.e When left wheel is raised or lowered the right wheel reacts to it too. This is a major drawback of this type of suspension system. It is glaringly obvious when we take on speed breakers at an angle.

Best example would be to drive a Cruze and then a Laura on a bump at an angle. Ride in the Cruze is just atrocious. There is just no other word for it. Whereas the Laura with its independent multilink rear suspension handles it relatively well.

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Old 21st May 2013, 13:32   #18
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Default Re: An undamped spring - The Anti-roll Bar

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Absolutely it will be[/url]
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Originally Posted by rangakishen View Post
Almost all the cars right now use the Torsion Beam rear suspension. As explained above this causes unwanted movements in the opposite wheel when one wheel is affected.
Thanks guys. Is there any easy/quick fix for this?

On another note, have you seen Mercedes' new "Magic Body Control" on their just revealed W222 S-Class?



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R
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Old 21st May 2013, 15:58   #19
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Default Re: An undamped spring - The Anti-roll Bar

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...

...Note the remarkable smooth and level ride of the body as the wheel articulates to the road's roughness.
Is the remarkable smooth and level ride really that remarkable or does it look remarkable because the camera is stiffly mounted to the body and any shakes experienced by body are also experienced by camera (meaning they wouldn't be captured in the video anyway).

I have no problem believing that the suspension is first rate, but a video will have to be done with camera mounted on its own "suspension" versus the chassis to have any meaning for the comments you made - I highly doubt that was done.

In fact if you look at the trees and other lines on the left, the fact that the camera (and hence the chassis) are undulating is obvious.

Last edited by Rehaan : 22nd May 2013 at 10:38. Reason: Removing video from quoted part of post. Thanks.
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Old 21st May 2013, 19:50   #20
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Default Re: An undamped spring - The Anti-roll Bar

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On another note, have you seen Mercedes' new "Magic Body Control" on their just revealed W222 S-Class?
That's the best bit of suspension reaction I have seen since the Citroen DS and CX. Mercedes' ABC involves altering the pressure in the hydraulic units at each wheel and is very expensive and complex - the software which reads the road ahead (and which is apparently their own) I really like. My only concern with any active system is that what happens when it reads the road ahead wrongly? Since this is a computer, this will happen. When half way round a very fast corner or driving on snow at speed I would prefer to think that the suspension isn't going to alter itself and alter the car's attitude. 999,999 times out of 1,000,000 it will be right, it is the one time it isn't which would concern me.

Here is a relatively simple system with no electronics which has just one setting - and it works amazingly in almost all situations. It was available in the 1950s and is still used widely today. Self-levelling, infintely-variable spring rates, brake effort distribution controlled by suspension loads, front-to-rear interconnection, almost zero inertia with a gas and fluid in rapid motion, unlike a heavy steel spring and seperate damper/shock absorber. A no-roll system was developed, but seen as a step too far for the buying public, which had enough problems digesting the space-age tech of the DS as it was. Pics: same corner, same high speed.

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Quote:
Originally Posted by vina View Post
Is the remarkable smooth and level ride really that remarkable or does it look remarkable because the camera is stiffly mounted to the body and any shakes experienced by body are also experienced by camera (meaning they wouldn't be captured in the video anyway).

I have no problem believing that the suspension is first rate, but a video will have to be done with camera mounted on its own "suspension" versus the chassis to have any meaning for the comments you made - I highly doubt that was done.

In fact if you look at the trees and other lines on the left, the fact that the camera (and hence the chassis) are undulating is obvious.
Sorry, Vina, your post makes no sense to me at all. A camera mounted rigidly to the body is going to show up a body's movement whereas one mounted on a suspenion of its own is going to mask this. The opposite of what you are trying to suggest. The BBC camera crews used these cars to drive alongside horse-racing courses when filming because of the smooth, level ride.

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Last edited by Rehaan : 22nd May 2013 at 10:37. Reason: Please upload images using our "Attachment" system (Paperclip icon). Also duplicate & dead-link youtube videos have been removed. Thanks!
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Old 24th October 2015, 23:14   #21
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Default Re: An undamped spring - The Anti-roll Bar

Wow. This thread was really eye opening. I was worried about there not being an anti roll bar in my car and here I find out that anti roll bars are not the best out there. I now realise why my mother prefers sitting in the front seat rather than the back
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