Nissan 240SX Performance Modification/Sway Bars

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Stabilizer Bars[edit]

A sway bar (also stabilizer bar, anti-sway bar, roll bar, or anti-roll bar, ARB) is an automobile suspension device. It connects opposite (left/right) wheels together through short lever arms linked by a torsion spring. A sway bar increases the suspension's roll stiffness—its resistance to roll in turns, independent of its spring rate in the vertical direction. It is usually constructed out of a U-shaped piece of steel that connects to the body at two points, and at the left and right sides of the suspension. If the left and right wheels move together, the bar just rotates about its mounting points and does not bend. If the wheels move relative to each other, the bar is forced to twist.

The bar resists the bending through its stiffness. The stiffness of an anti-roll bar is based on the fourth power of its diameter, the stiffness of the material, the inverse of the length of the lever arms (i.e., the shorter the lever arm, the stiffer the bar), the geometry of the mounting points, and the rigidity of the bar's mounting points. Some anti-roll bars, particularly those intended for use in auto racing, are adjustable, allowing their stiffness to be altered by increasing or reducing the length of the lever arms. This permits the roll stiffness to be tuned for different situations without replacing the entire bar. The stiffer the bar, the more force required to move the left and right wheels relative to each other. This increases the amount of force required to make the body roll.

In a turn, the sprung mass of the vehicle's body produces a lateral force at the Center of Mass, proportional to lateral acceleration. Because the cg is usually not on the roll axis, the lateral force creates a moment about the roll axis that tends to roll the body. (The roll axis is a line that joins the front and rear roll centers (SAEJ670e). The moment is called the roll couple.

Roll couple is resisted by the suspension roll stiffness, which is a function of the spring rate of the vehicle's springs and of the anti-roll bars, if any. The use of anti-roll bars allows designers to reduce roll without making the suspension's springs stiffer in the vertical plane, which allows improved body control with less compromise of ride quality.

One effect of body (frame) lean, for typical suspension geometry, is positive camber of the wheels on the outside of the turn and negative on the inside, which reduces their cornering grip (especially with cross ply tires).


Anti-roll bars provide two main functions: The first function is the reduction of body lean. The reduction of body lean is dependent on the total roll stiffness of the vehicle. Increasing the total roll stiffness of a vehicle does not change the steady state total load (weight) transfer from the inside wheels to the outside wheels, it only reduces body lean. The total lateral load transfer is determined by the CG height and track width.

The other function of anti roll bars is to tune the high g / limit understeer behavior of the vehicle. The limit understeer behavior is tuned by changing the proportion of the total roll stiffness that comes from the front and rear axles. Increasing the proportion of roll stiffness at the front will increase the proportion of the total weight transfer that the front axle reacts and decrease the proportion that the rear axle reacts. This will cause the outer front wheel to run at a higher slip angle, and the outer rear wheel to run at a lower slip angle, which is an understeer effect. Increasing the proportion of roll stiffness at the rear axle will have the opposite effect and decrease understeer.


S13[edit]

OEM Sway Bar Options[edit]

S13: (Abs/lsd package) Front bar 25mm, 21mm in the rear.

S13: (se without Abs/lsd package) Front bar 25mm, 17mm in the rear.

S13: (non se) Front bar 24mm, 15mm in the rear.

j30: 19mm hollow All are tubular steel

Aftermarket Sway Bars[edit]

ARC Pipe swaybars Front and rear (need translation but they are top quality like Largus sways) http://www.autorefine.co.jp/

Largus - Front bar 31.5mm, 27.5mm in the rear. 3 way adjustable front only. Tubular steel construction. Stock type endlinks. Largus includes new bushings with purchase. ^Will not clear SR20DET oversize oil pans (eg; greddy oil pan, not sure about ARC's). It will also not clear the Yashio Factory Tension Rod braces...

Whiteline - Front bar 27mm, 22mm in the rear. Solid steel construction and 3 way adjustable. Whiteline users their own specific blade type endlinks

Bings.ca - Front bar 30mm, 22mm in the rear. Tubular construction. Stock type endlinks

Tanabe - Front bar 30.4mm, 22.0mm in the rear. Tubular chromoly construction. Stock type endlinks

Godspeed - Front bar 30.5mm, 28.29mm in the rear. Tubular chromoly construction. Stock type endlinks. Note this bar uses CRUSH bends instead of mandrel on higher quality bars.

Progress - Front bar 27mm, 22mm in the rear. 3 way Adjustable front & back. Solid steel construction. Progress supplies a heims type endlink on these swaybars.

Cusco - Front bar 28mm, 18mm in the rear.

Suspension techniques - Front bar 27mm, 20.64mm in the rear. Solid steel construction. Stock type endlinks

Intrax - Front bar 29mm, rear bar 22mm. Comes with greaseable bushings/brakets. Stock type endlinks. Adjustable.

Addco - Front bar 28.6mm, rear bar 22.2mm.

Megan - Front bar 28mm, rear bar 22mm (Solid Type)

S14[edit]

OEM Sway bar[edit]

S14 Base model: Front bar is 27.2mm, there was no rear swaybar equipped. S14 (SE and LE package): Front bar is 27.2mm, 15mm in the rear bar.

Aftermarket Sway Bars[edit]

ARC Pipe swaybars Front and rear (need translation but they are top quality like Largus sways) http://www.autorefine.co.jp/

Sikky - 32mm front only. Newest version is hollow. 3 way adjustable, includes heim joint endlinks, includes bushings. Originally designed to clear engine swaps.

Largus - Front bar 31.5mm, 27.5mm in the rear. 2 way adjustable rear only. Tubular steel construction. Stock type endlinks. Largus includes new bushings with purchase. ^Will not clear SR20DET oversize oil pans (eg; greddy oil pan, not sure about ARC's). It will also not clear the Yashio Factory Tension Rod braces...

Whiteline - Front bar 27mm, 22mm in the rear. Solid steel construction and 3 way adjustable. Whiteline users their own specific blade type endlinks (14 lbs)

Tanabe - Front bar 30.4mm, 27.5mm in the rear. Tubular chromoly construction. Stock type endlinks. (7-1/2 lbs)

Godspeed - Front bar 30.32mm, 28.16mm in the rear. Tubular chromoly construction. Stock type endlinks. Note this bar uses CRUSH bends instead of mandrel on higher quality bars.

Progress - Front bar 30mm, 24mm in the rear. 3 way Adjustable front & back. Solid steel construction. Progress supplies a heims type endlink on these swaybars.

Cusco - Front bar 30mm, 27.5mm in the rear.

Nismo - Front bar 30mm, 23mm in the rear

Suspension techniques - Front bar 28.6mm, 20.64mm in the rear. Solid steel construction. Stock type endlinks

Intrax - Front bar 29mm, rear bar 22mm. Comes with greaseable bushings/brakets. Stock type endlinks. Adjustable.

Addco - Front bar 28.6mm, rear bar 22.2mm.

Megan - Front bar 28mm, rear bar 22mm (Solid Type)

Notes to be considered when selecting a swaybar upgrade[edit]

-Stock swaybars are hollow as well as several aftermarket replacements. Testing has found the tube is the strongest shape and while maintaining a proportionate wall thickness a tubular swaybar will provide only 5% less stiffness for one made out of solid metal in the same diameter but will have a significantly lower weight, sometimes a reduction as much as 10-20lbs. This has no heavy polar impact since its so low on the chassis but will impact braking/acceleration respectively.

-Adjustability is something to weigh in consider if thats a concern for you.

-Stock endlinks are actually very well designed but due to the age of the cars tend to have rotted bushings. Replace them with eurathane bushings from energy suspension kits, or the universal swaybar bushing kit available at local auto parts store. Note when using the universal kit the bushings must be sliced in half using a razor blade as they are twice as thick as what is needed.

- Whiteline swaybar blade type endlinks are not as well designed as the OEM supplied endlinks so that does impact the functionality vs stock links with eurathane bushings or aftermarket replacements. If using whiteline swaybars it is recommended that aftermarket replacements are taken into consideration

-Largus, Splparts.com and PDM Racing both produce a heim joint based replacement endlink solution for both stock and whiteline type bars. This will improve the performance of a swaybar by removing give/squish with bushings.

-Take into consideration front clearance when choosing large swaybars like the Largus ones, if memory recalls 28mm+ will not clear yashio factory and driftworks tension rod braces (www.rhdjapan.com and www.driftworks.com for purchase) and the Largus front sways specifically will not clear oversized oil pans (eg; greddy) for the sr20det

Swaybar Bushings[edit]

Energy suspension produces full bushing replacement kits for the 240sx so that all the old worn rubber bushings can be replaced with polyurethane.

Whiteline bushings are the highest quality polyurethane bushings you can purchase them from PDM racing (costs arm and a leg).