Wednesday, November 5, 2008

A Little Fact on Car Torsion Beam Suspension

1. Recently I have posted a crash that involves Toyota Vios and the palma tree where the car become bananized after hitting the tree. You can find the post from HERE.

2. I would like to thank Aminashaari for providing feedback and info as follows:

Actually it's the not the break system that's the issue. The problem lies in the inherent characteristics of torsion beam suspension system that loads up the front end of the car during hard braking. Torsion beam suspension (featured in most entry level cars to save cost and space - including the Toyota Vios) provides a simple, laterally strong solution to rear suspension systems of budget and compact cars.

The downside is that this simple suspension configuration tends to exaggerate load transfer to the front end during hard braking making the rear end very light and prone to loosing traction. In the hands of a novice driver, this can be dangerous. Though I haven't seen the CCTV footage, from your description (pivoting under braking), sounds like a textbook case of brake induced oversteer.

Short wheelbase hatchbacks are more prone to this than booted sedans with similar setup. It is safe to conclude that the car entered the corner at high speed and understeered due to the wet conditions. Typical to normal drivers, he would lift off from the throttle, jammed on the brakes and at the same time over corrected the steering to compensate for the understeer.

Current models with similar suspension setup (that I know of):

Proton Savvy
Perodua MyVi
Honda Jazz
Honda City
Toyota Yaris
Nissan Latio

3. In short, whatever car you have, please be more careful, especially during wet and raining time. But to think that in this case only car to be blamed is unfair coz the road design and road furniture also have big weight on this problem too. Lots to be done, and lots to be addressed on the road safety issues. Slowly but surely. Lets hope for a better future.

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