NC (2006+) Mazda Miata MX-5 Suspension Design Spreadsheet

Copyright © 2008 Shaikh J. Ahmad / Fat Cat Motorsports

TUBULAR BAR SET-UPS

Front sway diameter

Front sway wall thk

Rear sway diamter

Front spring

Rear Spring

Bounce frequency (Hz)

Ratio Bounce Freq

Roll Stiffness

Front Roll Couple (FRC)

COMMENTS

mm

mm

mm

lb/in

lb/in

Front

Rear

lb-ft/deg

%

1. 2006 OE springs

1. 2006 OE spring rates, loaded (rear goes from 70 to 120 lb/in) bounce got 1.38/1.45Hz f/r

2. Mazdaspeed/Eibach lowering front, stock NC rear

Mazdaspeed/Eibach lowering springs

3. Mazdaspeed/Eibach lowering springs loaded to static ride height

JIC Magic FLT-A2 (6/5 kg/mm)

4. NC Tein Flex, 2.05/1.92Hz bounced with shocks on soft, Jim Patternson (unloaded wt 2451) incl roll bar

NC with Ohlins

NC with H&R

NC with

Vehicle weight (lb)

Sprung weight

Driver weight (lb)

Front

Tire weight

Total vehicle weight

Rear

Weight dist (%)

Wheel weight

Front

Unsprung weight

Rear

Front

Vehicle Track

Rear

Front

Rear

Front sway bar specs

Swaybar motion ratios

Arm length (mm)

Bar length (mm)

Bar length

NC arm length

1.6 OE arm length

1.8 OE arm length

1.6 FM arm length (inner)

1.6 FM arm length (outer)

NB arm length

Front

Rear

Spring motion ratios

Rear sway bar specs

Front

Bar length

NC arm length

NA / NB OE arm length

1.6 FM arm length (inner)

1.6 FM arm length (middle)

1.6 FM arm length (middle)

Rear

DATA FOR SPRINGS AND SWAY BARS

Swaybar rate (lb/in)

Natural frequency calculations (Cycles per sec):

Unit converter

K = G X (Dia)^4 X PI X (2.2*25.4/9.81)

Cps = 3.13* SQRT (Spring wheel rate / sprung weight per wheel)

Deg F

Deg C

lb

kg

in

mm

(Arm length)^2 X Bar length X 16

Front spring

Front freq

Front wheel rate

Rear spring

Rear freq

Rear wheel rate

Note: Dimensions meas'd only for OE 19mm bar

Arm length (mm)

Bar length (mm)

Deg C

Deg F

kg

lb

mm

in

(hollow bar ID = OD - 2 * Wall thk)

Front OD

Wall thk

OD (mm)

ID (mm)

Raw rate (lb/in)

Wheel rate (lb/in)

kg-(force)

N

lb

kPa

psi

bar

19mm

0.000

20mm

0.000

N

kg-(force)

lb

psi

kPa

bar

13/16"

0.000

21mm

0.000

lb

kg-(force)

N

bar

psi

kPa

22mm

0.000

7/8"

0.000

kg/mm

N/mm

lb/in

toe (in)

wheel dia

toe (deg)

.93 in

0.000

0.000

24mm

0.000

0.000

N/mm

kg-f/mm

lb/in

toe (deg)

wheel dia

toe (in)

1"

0.000

0.000

7/8" tub

lb/in

kg-f/mm

N/mm

1" tub (3/16" wall)

1" tub

Front spring

Front sway

Rear spring

Rear sway stiffness

SM

1" tub (3/16" wall)

Front wheel rate (sway+spring)

1 1/8" (90-97)

Front sway stiffness

Rear sway stiffness

1 1/8" (99-01)

Rear wheel rate (sway+spring)

Ratio

1 1/4" (01-05)

Front spr stiff

Rear spring stiffness

Rear bar NOTE: A,B,C meas'd for 12mm bar

Rear OD

Wall thk

OD (mm)

ID (mm)

Raw rate (lb/in)

Wheel rate (lb/in)

Target 190lb/in for NB front bar, ~23mm like MSM

% stiff front sway

% stif rear sway

11mm

0.000

0.000

12mm=

0.000

0.000

1/2"

0.000

0.000

14mm

0.000

0.000

9/16"

0.000

0.000

15mm

0.000

0.000

5/8" (FM)

0.000

0.000