punxva

Ok, well i've been looking into buying aftermarket suspension parts for quite some time now, but i wanted to know exactually what i was getting, so i decided to make up this little faq about the basics of the suspension parts on our cars. The examples are mostly from SPLParts, i'm hoping that this may help others know what they are buying before hand, so they get the right type of setup for their personal driving style.



S13 Bushing Diagram

2- TC(tension rod)
4- LCA(lower control arm) front
6- LCA rear
8- Forward link (traction rod)
10- Rear Upper arm
12- Toe link
14- Upright (upper)
15- Upright (lower)
16- Sub-frame (front/lower)
17- Sub-frame (rear/upper)



Spring rate and ride height information
STOCK
Spring Rate - F : 2.0kg/mm (2.2 for sport package?)
Spring Rate - R : 2.0kg/mm (2.2 for sport package?)
Ride Height - F : 0"
Ride Height - R : 0"

EIBACH PROKIT
Spring Rate - F : 1.84~1.92kg/mm
Spring Rate - R : 2.3~2.4kg/mm
Ride Height - F : -1.8" (eibach site) -1" (jnm240 test)
Ride Height - R : -1.6" (eibach site) -.75" (test)

EIBACH SPORTLINE
Spring Rate - F : 1.92~2.0kg/mm
Spring Rate - R : 2.4~2.5kg/mm
Ride Height - F : -2.2" / -1.75" (test)
Ride Height - R : -2.1" / -1.75" (test)

H & R SPORT
Spring Rate - F : 2.0~2.08kg/mm
Spring Rate - R : 2.5~2.6kg/mm
Ride Height - F : -1.3"
Ride Height - R : -1.3"

TEIN S-TECH
(progressive, TEIN only lists the maximal rate)
Spring Rate - F : 3.7
Spring Rate - R : 3.2
Ride Height - F : -1.5"
Ride Height - R : -1.2"

TEIN HIGH-TECH
Spring Rate - F: 3.3 (s13); 3.2 (s14)
Spring Rate - R: 2.9 (s13); 3.1 (s14)
Ride Height - F: -0.9" (s13); -0.7" (s14)
Ride Height - R: -0.6" (s13); -0.4" (s14)

INTRAX SPORT SPRING KIT
Spring Rate - F : (Couldn't get through to tech support)
Spring Rate - R : (Couldn't get through to tech support)
Ride Height - F : -2.25"
Ride Height - R : -2.0"

SUSPENSION TECHNIQUES
Spring Rate - F : 3
Spring Rate - R : 2.66
Ride Height - F : -1.3"
Ride Height - R : -1.3" (?)

WHITELINE CONTROL
Spring Rate - F : S13&S14 = 2.8
Spring Rate - R : S13= 2.36~3.66 S14= 1.91~3.18
Ride Height - F : -1.75"
Ride Height - R : -1.75"

TANABE GF210
Spring Rate - F : 2.9
Spring Rate - R : 2.7
Ride Height - F : -1." to -1.6"
Ride Height - R : -.6" to -1"

RS*R DOWN SPRINGS
Spring Rate - F: 3.0
SPring Rate - R: 3.0
Ride Height - F: -1.6"(s13) -1.0"(s14)
Ride Height - R: -1.2" (s13) -0.6" (s14)

RS*R RACE SPRINGS
Spring Rate - F: 5.0
Spring Rate - R: 4.5(s13) 4.2 (s14)
Ride Height - F: -1.4"
Ride Height - R: -1.2" (s13) -1.0" (s14)

MEGAN RACING LOWERING SPRINGS MR-LS-NS13 (s13):
Springrate F: 6.25kg/mm (350lbs/in)
Springrate R: 4.46kg/mm (250lbs/in)
Ride Height F: 1.75"
Ride Height R: 1.75"

MEGAN RACING LOWERING SPRINGS MR-LS-NS14 (s14):
Springrate F: 6.25kg/mm (350lbs/in)
Springrate R: 4.46kg/mm (250lbs/in)
Ride Height F: 1.75"
Ride Height R: 1.75"

ESPELIR ACTIVE SUPER DOWN -
Front - 3.0kg/mm (168.0 lb/in) ~ drops 1.9"
Rear - 2.4kg/mm (134.4 lb/in) ~ drops 1.1"

KGMM S21 SPORT -
Front - 3.2kg/mm (179.2 lb/in)
Rear - 2.6kg/mm (145 lb/in)

KGMM S21 SUPERSPORT -
Front - 4.6kg/mm (257.6 lb/in)
Rear - 3.8kg/mm (212.8 lb/in)

KGMM DR Race -
Front - 6kg/mm
Rear - 5kg/mm
Ride Height - F: 2.2"
Ride Height - R: 1.2"

5ZIGEN R-RATE -
Front - 2.4 to 5.2kg/mm (134 to 291 lb/in) ~ drops 1.3"
Rear - 1.9 to 5.0kg/mm (106 to 280 lb/in) ~ drops 1.1"

KGMM S21 RACE -
Front - 6.6kg/mm (369.6 lb/in) ~drops ?"
Rear - 5.2kg/mm (291.2 lb/in) ~ drops ?"

Sway bar information
S13
Stock ? (data from Japanparts.com) JDM ?
Front 24mm
Rear 16mm

Suspension Techniques (data from STRacing.com)
Front 27mm
Rear 20.6mm

Whiteline (data from PDMRacing.com)
Front 27mm
Rear 20-22mm

Cusco (data from Japanparts.com)
Front 28mm
Rear 18mm

Tanabe (data from Tanabe-usa.com)
Front 30.4mm
Rear 22mm

Progress
Front 27mm
Rear 22mm

S14
Stock (data from CourtesyParts)
Front 27.2mm
Rear 15.9mm

Whiteline Adjustables (data from PDMRacing.com)
Front 27mm
Rear 20mm (22mm available as well)

Suspension Techniques (data from STRacing.com)
Front 28.6mm
Rear 20.6mm

Cusco (data from Japanparts.com)
Front 30mm
Rear 21mm

Nismo (data from Japanparts.com)
Front 30mm
Rear 23mm

Tanabe (data from Tanabe-usa.com)
Front 30.4mm
Rear 27.5mm

Progress
Front 30mm
Rear 24mm

Spring/shock adjustment guide

Spring Rate Changes (def. important for those who dont pay att. to this)
Modification - Effect on Suspension

Increase front and rear rate - Ride harshness increases; tires may not follow bumps causing reduced traction. Roll resistance increases.

Increase front rate only - Front ride rate increases. Front roll resistance increases, increasing understeer or reducing oversteer.

Increase rear rate only - Rear ride rate increases. Rear roll resistance increases, increasing oversteer or reducing understeer.

Decrease front and rear rate - Ride harshness decreases; tires follow bumps more effectively, possibly improving traction. Roll resistance decreases.

Decrease front rate only - Front ride rate decreases. Front roll resistance decreases, decreasing understeer or increasing oversteer.

Decrease rear rate only - Rear ride rate decreases. Rear roll resistance decreases, decreasing oversteer or increasing understeer.



Antiroll Bar Changes (aka sway bar)
Modification - Effect on Suspension

Increase front rate - Front roll resistance increases, increasing understeer or decreasing oversteer. May also reduce camber change, allowing better tire contact patch compliance with the road surface, reducing understeer.

Increase rear rate - Rear roll resistance increases, increasing oversteer or decreasing understeer. On independent rear suspensions, may also reduce camber change, allowing better contact patch compliance with road surface, reducing oversteer.

Decrease front rate - Front roll resistance decreases, decreasing understeer or increasing oversteer. More body roll could reduce tire contact patch area, causing understeer.

Decrease rear rate - Rear roll resistance decreases, decreasing oversteer or increasing understeer. On independent rear suspensions, more body roll could reduce tire contact patch area, causing oversteer.

Note - Remember to consider the construction of the sway bar and the endlinks. A solid sway bar has more resistance than a hollow bar of the same diameter. Also the addition of solid or polyurethane endlinks will artificially raise the diameter of the bar in terms of effectiveness.


Shock Absorber Changes (aka your struts)
Modification - Effect on Suspension

Rebound - The dampers resistance when the suspension is de-compressing (when you turn right the right side suspension is in rebound)

Bump - The dampers resistance when the suspension is compressing (when you turn right the left side suspension is in bump)

Increase rebound and bump rates - Ride harshness increases.

Increase rebound rates only - On bumps, tires may leave track surface.

Increase bump rates only - Body roll resisted; outside tire loaded too quickly; car won't stabilize into a turn.

Decrease rebound and bump rates - Ride harshness decreases; car may float over bumps.

Decrease rebound rates only - On bumps, tires follow track surface more effectively; car may continue to oscillate after bumps.

Decrease bump rates only - Body rolls quickly; car is slower to respond to turn-in.


How do I correct my suspension geometry?

Note: Almost every aftermarket arm has a solid rod end which replaces the worn stock rubber bushing. This increases road noise somewhat, but drastically increases the response of the suspension. It also reduces the compliancy of the suspension, which reduces the change in geometry when the suspension is bumped. This creates a much more stable feel in the car especially when cornering.



ADJUSTABLE TENSION RODS

Adjust Caster

Often one of the problem areas found in older 240s with the stock bushings still in place. The tension rod is found at the front of the car running between the front chassis and the lower control arm. It controls the amount of caster in the front suspension. Typically when raising the deg. of negative caster the steering wheel will have a stronger force to return to center when you let go of the wheel, and steering response will be slightly slower. When you lower the deg. of negative caster the steering will be more responsive, this can be beneficial and counter productive at the same time so keep adjustments in moderation.



ADJUSTABLE FRONT LOWER ARMS

Roll Moment Adjustment

Suggested only for those interested in competitive events, and or extensive track/drift usage. The arms have an adjustable shank (balljoint) that allows you to effectively raise and lower the arm, causing a corresponding change in roll geometry.



ADJUSTABLE REAR UPPER CONTROL ARMS

Rear Camber Adjustment

The rear upper control arm is a popular part because it is the only way to adjust the rear camber on the 240's besides the use of eccentric bolts. By accurately adjusting camber you can choose to either save your tires from a camber incited early death, or you can setup the rear camber to maintain the tire patch when the car pitches into the corner.



ADJUSTABLE REAR TRACTION ROD

Rear Bumpsteer Adjustment

When the suspension is lowered, an adjustable rear upper arm is usually installed to reduce the amount of negative camber at the ride height. However, when the rear upper arm is elongated to compensate for the negative camber, this alters the geometry of the rear multiple link and can cause bump-steer. Adjustment of the rear traction rod together with the rear tie rods (Hicas models) or rear toe arm (non-Hicas models), the geometry of the two two arms can be restored to eliminate bump-steer. Typically you want to make the traction rod longer than the OEM unit to reduce bumpsteer. Too much adjustment can cause an unstable change in toe when the suspension bumps. For this reason I suggest that the arm be adjusted minimally.



REAR TOE ARM

Rear Toe Adjustment

Note: HICAS model 240's cannot use these arms.

The stock rear toe adjustment has been found to run out when you have a lowered 240 with adjustable rear upper arms. For this reason the adjustable rear toe arm is made. Rear toe adjustments can change how the car pivots about a corner. Negative toe causes the rear end to want to rotate which can improve cornering but decreases stability. Positive toe works the opposite way, increasing stability but decreasing rear potential for rotation.



ADJUSTABLE REAR LOWER CONTROL ARMS

Rear Roll Center / Axis

Works in the same method as the front lower control arms.



REAR SUBFRAME TILT SPACERS

Rear Subframe Squat / Anti-Squat Properties

Subframe bushing spacers are used to tilt the subframe to change the rear suspension squat/anti-squat characteristic. Increase squat for drag racing or anti-squat for drift.



ECCENTRIC BOLTS

The 240 has eccentric bolts for rear camber and rear toe adjustment. These can cope with stock ride height and slightly lowered suspension geometries.




Well thats all for now, please correct this information, or add to it, thanks alot guys...

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