NA (1989-1993) Mazda Miata MX-5 Suspension Design Spreadsheet

Copyright © 2008 Shaikh J. Ahmad / Fat Cat Motorsports

Send any comments or questions to:

shaikh@fatcatmotorsports.com

SOLID FRONT BAR SET-UPS

Front sway diameter

Rear sway diameter

Front spring

Rear Spring

Bounce frequency (Hz)

Bounce freq ratio (R/F)

Roll Stiffness

Front Roll Couple (FRC)

COMMENTS

mm

mm

lb/in

lb/in

Front

Rear

lb-ft/deg

%

90 with manual transmission

91-93 with manual transmission

19.00

11.00

154

94

796.3

60.4%

94-97 with manual transmission (REFERENCE ONLY - USE NA (1.8) SHEET FOR CALCULATIONS)

93 Limited-Edition with manual transmission

20.00

11.40

154

94

872.3

59.8%

94-96 R-pkg (REFERENCE ONLY - USE NA (1.8) SHEET FOR CALCULATIONS)

20.00

11.40

154

105

899.6

58.0%

97 R-pkg (REFERENCE ONLY - USE NA (1.8) SHEET FOR CALCULATIONS)

Tein S-tech spring rates on typical 91-93 Miata

E-bay coilovers

Previous Flyin' Miata spring rates

Current (2006+) Flyin' Miata spring rates

Standard Ground Control spring rates

Standard Tein Flex spring rates (7/6 kg/mm)

Ohlins Japan

JIC Magic FLT-A2 (10/8 kg/mm)

Shaikh's SM2 (1.6 FM2 turbo) 'soft' set-up (proposed), 7/8" front bar on full stiff - used for bumpy lots

Shaikh Ahmad SM2 (1.6 FM2 turbo) 'stiff' set-up (tested), 7/8" front bar on full stiff - used for smoother lots

TUBULAR BAR SET-UPS

Front sway diameter

Front sway wall thk

Rear sway diamter

Front spring

Rear Spring

Bounce frequency (Hz)

Bounce freq ratio (R/F)

Roll Stiffness

Front Roll Couple (FRC)

COMMENTS

mm

mm

mm

lb/in

lb/in

Front

Rear

lb-ft/deg

%

90 with manual transmission and RB tubular sway bar (1 1/8" OD 3/8" wall thickness)

94-97 with RB tubular front bar and solid 5/8" rear bar

Andy Hollis current STS2 set-up, when using solid 5/8" rear bar

Andy Hollis past CSP set-up

Andy Hollis past CSP set-up

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

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 MR (bounce)

Leverage ratios (mechanical motion ratio)

Rear sway bar specs

Front

0.66

Bar 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

0.735

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

1 1/8" (90-97)

lb/in

kg-f/mm

N/mm

1 1/8" (99-01)

1 1/4" (01-05)

SM

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

Front wheel rate (sway+spring)

Rear OD

Wall thk

OD (mm)

ID (mm)

Raw rate (lb/in)

Wheel rate (lb/in)

11mm

0.000

0.000

Rear wheel rate (sway+spring)

Ratio

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