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The “Strut tower bar”, is not only chosen by all the Sunday racers and many street drivers, but is also installed as factory part on some vehicles as well. You’ve seen “the bar” crossing the engine bay, right? We are sure you know why you need it, but let us tell you once again. Now, let’s see how it works, through the Tests in the movie and detail explanation in writing.

Vehicles are squeezed and twisted by the inputs from the road. It is difficult to find with your eyes, but those inputs from the road bent the chassis. You must have heard of ìchassis rigidityî. If the chassis has higher rigidity, there is less bent or twisting, and vise versa. Now, letís see what happens when the chassis is twisted and squeezed. Chassis flexibility helps to improve comfortableness, as the flexible chassis will absorb the inputs and impacts from the road. But, at the same time, it means the flexible chassis absorbs your driving actions on gas pedal, brake pedal, and steering wheel, and it will spoil the turning and acceleration performance. It is difficult to see how much it is bent, but it surely spoils performance and stability, especially when you drive faster. That is why you need to increase chassis rigidity, and Front strut tower bars are the most effective and easiest way to increase it.	Strut towers are one of the parts that has the largest input from the road, and Front ones affects more, as front tires and wheels are most important part to turn your car. Some of the latest cars have strut tower bars in front, from factory. This tells how effective it is to have the strut bar in the front. Because, the vehicle manufactures must have maximum results with minimum cost, and they chose it.
	You know that the tires are the only part that contact to the road. And the strut tower holds the upper mounting section of the suspension, which connects the wheels and chassis. Thus, the strut tower has the largest inputs than any other part of the chassis. Now, you agree why the chassis are twisted and bent, right?
When you are at the corners, you will have largest bent and twist with the cornering gravity. And front outside has the largest input in all those 4 wheels, and strut tower in there will have the largest input and bent. This is more obvious when you have high grip tires. If there is a strut tower bar on the vehicle, it will prevent the strut towers being bent and twisted. And it will make the wheel alignment more stable as well, and improve the turning performance more.

You have studied why strut tower bar is important. Now, letís see how they work and perform on real driving. The test driver is Masami, who is competing in JAF regional championship. Test vehicle is Nissan S15 Silvia with CUSCO Zero-2E coilover kit, CUSCO Type RS LSD, and Potenza RE-01R(F:225/45-17 R:235/45-17). And it was done in comparison of with and without the Strut tower bar. First test is the Slalom. 5 cones on a straight line, and speed is constant at 40km/h (25mph).	In addition to the comment by Masami, we used zip tie at the bottom of the shock absorber rod, to see how much it strokes. If the chassis rigidity is increased with Strut tower bar, the test car will have less twist and bent, and then the damper should have more strokes after installing the Strut tower bar. Second test is done in the circuit track. Test course is Honjo circuit track, which mainly has low and middle range corners. On the second test, the car is driven in a faster speed in most of the corners. Letís see how they work before/after installing the Strut tower bar.

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