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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.

Basic information about chassis rigidity.
Chassis is squeezed and twisted, when you are driving.

Did you know chassis rigidity affects on your driving performance?

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.

See how much the chassis are twisted, with your eyes.

Simulating the turning section, with more input on left front wheels, by lifting that part with the jack. This front left section is considered as outside wheel on right turn

Now, let’s see how much chassis is twisted. The strut tower bar in this picture is cut in the middle. They were straight before lifting the front left section with the jack, but after lifting, they have large gap. Now, imagine how much more it may be twisted, when you are on a real cornering section and have huge gravity!




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.

Type OS comes with fashionable oval shape bar. Aluminum material will improve the chassis rigidity, still with the minimum weight increasing. Type 1 has pressed rib, and type 2 has the internal bridge to increase the rigidity. Type of the shaft depends on vehicle, but CUSCO has more than 250 vehicles of applications, and most of them have rear strut tower bars too. And besides the Type OS, CUSCO has Carbon Shaft, Aluminum + carbon, 40mm Aluminum shaft and more.

CUSCO also has Strut tower bars with Brake Cylinder Stopper (BCS) model. BCS will prevent the firewall being bent when you step on brake pedal, and it will increase the brake pedal control.

Masami is well known in JDM-Option blog. She enjoys the cars and driving a lot, and participating in JAF (Japan Automobile Federation) regional Gymkhana championship with her EG6 Civic. Also competed in All Japan Gymkhana championship too. Today, she will be a test driver upon all those experiences.

The test car driven by Masami is CUSCO’s S15 Silvia demo car. Motor is stock but has CUSCO Zero-2E coilover kit, CUSCO Type-RS LSD, and Potenza RE-01R tires (F:225/45-17 R:235/45-17).


	“Response is not very good after steering wheel work. It takes extra few periods after steering wheel work, till the car starts turning. Thus, I had bad rhythm and timing.”			“Response after steeling wheel work is increased, and it was easier to prepare for the next cone. Had better rhythm and timing. I was so surprised to see the difference.”


	Zip tie we put to measure the stroke, was 60mm away from original position. It means shock absorber had 60mm of stroke. Dust cover is removed on purpose of taking pictures.			After installing the Strut tower bar, the car has less twist and bent with increased rigidity, and had 6mm more travel. This means, suspension is moving and working better than the car without Strut tower bar. Dust cover is removed on purpose of taking pictures.

“Without the Strut tower bar, I feel the front tires do not have enough grip, and when decelerating before the corners, vehicle is not so stable, and I can not put gas until the very last part of the corners. After installing the Strut tower bar, the vehicle is more stable, which makes braking and cornering easier. Response after steering work is improved as well.”

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Contact: Carrosser Co., Ltd +81-27-352-3578