|
|
FOOT WORKS |
 |
|
Ikeya formula's Adjustable suspension
arm (actual runningu scene)
|
|
 |
 |
|
Ikeya formula's Adjustable suspension arm |
||
|
By using arms of our product lineups, you will be able to adjust the changes in the alignment and also correct the roll center position when normal arms are raised and opened up outwards which is often seen in the cars with lowered height. On this page, we will talk about "Suspension geometry" such as " Roll center correction", "Alignment". "About Changes in Alignment"----- Since normal arm comprises rubber bush, the alignment changes when the arm receives "force"(stress) and are "twisted". Additionally, the difference in the car height effects the alignment. For example, when the suspension bumps, there would be changes in the Negative/Positive direction on "Camber", and In/Out direction on the "Toe", although it differs by types of cars or the structure of suspension system. This brings the issues in, such as the feeling of tire contacted to ground, the responsiveness of steering on breaking, and traction shortage To solve this issues, we have changed the Rubber bush to Piro ball. Additionally, by adding the adjustable function to the Arm, we have developed product lineup which can accommodate the changes in the alignment. |
 |
 |
|
||
|
 |
|
|
||
|
 |
|
 |
----- |
Does it necessary to adjust the alignment when changing tires or inch-up the aluminum wheel ? |
| ----- | Why are there instabilities transmitted from steering wheel during driving ? |
|
The following is various examples of car behavior or changes in tires. - Inside wear of tire=> Excessive Camber/ Excessive Toe-out. - Outside wear of tire=> Positive camber/ Toe-in/ shifted camber. - Excessive wear of tire=> Extreme Toe-in. - Instabilities transmitted from steering wheel during driving=> Camber or Toe is out of alignment. - Center of steering is not in the correct position=> Toe is shifted to either left or right. - Difficulties in driving straight => Caster angle is not in the correct position. - Not possible to drive straight(strays to one side)=> Only one side has camber/ different caster angle between right/left side.- Whole car body is shaking=> Camber or Toe is not even/ Unbalanced wheel |
 |
|
"About correction of Roll center"----- Drivers tend to consider that center of gravity would be lowered and have more stability if car height is lowered. However, if you are using the normal arm, the arms would be raised and opened up outwards and the center of gravity of car and roll center would be apart . And the roll amount unnecessarily increases while the suspension stroke decreases, and causes the condition of " Grip limitation between tire and ground surface will be lowered". By using Ikeya formula's "Front lower arm", "Rear lower arm" and "Tie-rod end" which possess the roll center adjuster function will correct the roll center and set back to the position where has the shorter distance between center of gravity and roll center and then decreases the roll amount Additionally, we would like to recommend to install both Front and Rear at the same time. Because the roll center of Front and Rear would be "shifted", if mounting only on Front side, and the roll axis will be shifted on Front and the roll amount changes on Rear, and causes loss of the stability in the car behavior. From these points, we would like to recommend to wear both on Front and Rear. |
|
|
|
|
The cross-point on the extension of mounting position of suspension arm and tread centerline is instantaneous rotation center of contact point to ground of the tire. Car inclines (roll) with this point as a center. Roll center is lowered if car height is lowered with normal arms mounted. Even with the same roll angle, cornering performance would be decreased because of large distance from the rotation center which causes bigger movement. |
 |
 |
----- |
Why are there hardness in riding in after mounting down-sus or shock absorber (with height adjustment function)? |
|
Although it's often considered that there would be more stability if car height is lowered by wearing the shock absorber(with height adjustment function)and down-sus, the roll amount increases because roll center shifts away. Therefore, the spring rate of the off-the-shelf shock absorber and down-sus are set higher than the normal spring to prevent from rolling the car body. As just mentioned, the roll amount is controlled by having the higher spring rate, and this makes the hardness in riding in the car. |
|
|
|
Next, for the experienced or intermediate drivers, we would like to talk about one of geometry basics, "Bump Steer" which can even effects the cornering characteristics. "What is bump steer"----- One of the reasons that suspension setting is often said difficult is Bump steer. Bump Steer is a change in toe as a wheel moves up or down in its suspension geometry. Bump steer occurs because of the circular motion of suspension arm or tie-rod having its pivot of the body or upright side as a center. Therefore, it is not possible to disappear it completely unless fundamental structure is changed. Now, we would like to talk about the relations between bump steer and handling. Toe-change in case of tie-rod is on Front/ Back of hub center (the center of hub that supports the car axis): |
| 1. | Case that it's mounted on the front side of hub center | => | Front side is pulled by tie-rod upon stroke (bump). | => | Bump toe-in |
| * | Toe is shifted to "in" upon bumping or re-bumping when tie-rod is on a level. Large cornering force is generated and the direction is changed sharply even with smaller steering amount and large slowdown, because the tire becomes the resistance on the toe change upon breaking. |
| 2. | Case that it's mounted on the back side of hub center | => | Rear side is pulled by tie-rod upon stroke (bump). | => | Bump toe-out |
| * | Amount of cornering force generated against steer is decreased because of the toe change to "out" upon bumping and leads to the stabilized handling. This can often seen on stock-cars and its rear toe control rod is based on rear side of axle for the stability. |
 |
|
Talking about the alignment adjustment, under 1G condition that suspension does not work, preferably it's set to have high stability on driving straight and less rolling resistance considering the balance of toe and camber. However, if you are using the suspension type which turns toe-out when the front side is sunk down by breaking, the toe only turn its direction less than the actual amount of steering. Therefore, have a little bigger "toe-in" beforehand upon 1Gto have better cornering. This is for the type of the cars which emphasizes steering related to the steering performance, although rolling resistance is relatively increased on driving straight. On the other hand, for the car which turns "toe-in" upon bumping and if toe is set to decrease rolling resistance upon driving straight, the car is tend to become oversteer. To have the stability for cornering, it's necessary to turn "toe-out" slightly on 1G. It's not the story limited only on breaking, but also on lowering car height. When lowering car height, arm angle became the same angle as that upon bumping, which causes the changes not only in the toe but also other parts such as cambers and required alignment adjustment of 1G status again. |
 |
 |
To solve the big toe-change issue caused by lowering car height, we would like to recommend our Tie-rod (patent), which makes the tie-rod angle almost horizontal. This also satisfies car inspection requirement in Japan. Glossary Suspension stroke Shrinking (side)=Bump(side)Stretching(side)=Re-bump(side) |
||
Tierod end  |
||||
|
Our various adjustable Piro Arm products bring you various merits as mentioned above. Here is an example with item lineups for Skyline GT-R (BNR34). |
| Front |
Camber angle can be freely adjusted by negative upperlink and caster angle can be changed by Piro tension rod. (the area where could not be adjusted in genuine part.) Normally, lowering car height causes arm angle to be poor and also rapid changes in geometry. However, this problem can be solved by installing Roll center adjuster on Adjustable lower arm to have the arm position horizontal. At the same time, if you install our Tie-rod end together, the stresses placed on tie-rod end would be removed and toe-changes upon bump/re-bump, which helps smooth steering operation. |
||||
 |
 |
 |
|||
| Front upper link | Roll center
adjuster lower arm |
Tierod end |
|||
| Rear |
Adjustable upper arm and Traction adjuster rod are effective for alignment adjustment and enable you to adjust the camber. In addition, it constrains the movement of member bush on rear side as well as the unnecessary behavior even if the burden increased by High grip wheel, by fitting the roll center to the Front with Adjuster rear lower arm and also wearing Multilink spacers. |
||||
 |
 |
 |
|||
|
Rear camber adjuster upper arm |
Traction adjuster rod |
Adjuster rear lower arm |
|||
|
As just described, the feeing of tire contacted to ground are improved by installing Adjustable arm and the information transmitted to steering becomes accurate. Further, by the correct operation of arm parts would produce changes in suspension movement and shock movement is transmitted to linear. This total cares for "suspension", "shock absorber" and "arm" will make you feel more pleasure in the driving. -Following graphs show the alignment changes comparison between normal arm and Ikeya's full arms measured at our company ( with our self-developed geometry measuring equipment). As these graphs show, the amount of alignment change with Ikeya's arms are observed less than normal arms. You might also see the various merits of using our arms form our actual data. We strongly recommend you to use and feel our product. |
 |
 |
| Changed Amount upon adjusted with Ikeya's arm(BNR34) |
| Front | |||
| @ | Negative Upper link | Tierod | Rool Center Adjuster Lower Arm |
| Toe Change | About 0 08' | About 1 | About -0 20' |
| Camber Change | About 0 20' | About -0 05' | About 0 10' |
| (This shall be the values when shortened by one turn. ) |
| Rear | |||
| @ | Rear Camber Adjuster Upper Arm | Traction Adjuster Rod | Adjuster Rear lower Arm |
| Toe Change | About 0 30' | About -0 30' | About -0 06' |
| Camber Change | About -0 40' | About -0 05' | About 0 30' |
| (This shall be the values when shortened by one turn. ) |
 |
 |
| -You are able to drive the general roads in Japan wearing our products applying to car inspection, by applying the permission for converted cars with our "Product test result report" (3,150Yen) issued by us. |
 |
 |
| -D1 GP increasingly gets heated up every year. A number of cars participate in this category with Ikeya formula's suspension arms. |
 |
 |
 |
 |
 |
| Corresponding list for FOOT WORK categorized by car type | |||||
| NISSAN | |||||
| SILVIA / 180SX S13 | SILVIA / 180SX PS13 | SILVIA S14 | |||
| SILVIA S15 | |||||
| SKYLINE GT-R BNR32 | SKYLINE GT-R BCNR33 | SKYLINE GT-R BNR34 | |||
| SKYLINE HCR32 | SKYLINE HNR32 | SKYLINE ECR33 | |||
| SKYLINE ER34 | SKYLINE ECNR33 | ||||
| FAIRLADY Z CZ32 | FAIRLADY Z Z33 | ||||
| CEFIRO A31 | |||||
| LAUREL C33 | LAUREL C34 | LAUREL C35 | |||
| CEDRIC / GLORIA Y32 / Y33 | |||||
| STAGEA WGC / WGNC34 | |||||
| MAZDA | |||||
| RX-7 FD3S | |||||
| TOYOTA | |||||
| MARK II JZX90 | MARK II JZX100 | MARK II / VEROSSA JZX110 | |||
| ALTEZZA SXE10 | SUPRA JZA80 | SOARER JZZ30 | |||
| ARISTO JZS161 | |||||
| SUBARU | |||||
| IMPREZA GDB | IMPREZA GC8 | FORESTER SF5 | |||
| FORESTER SG5 | LEGACY BD# | LEGACY BE# | |||
| LEGACY BL# | LEGACY BG# | LEGACY BH# | |||
| LEGACY BP# | |||||
|
*The installation instructions for our products are written in Japanese.* |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
|
|
 |
 |
 |
 |
 |
 |
 |