Z31 Suspension Spring Differences
Do you want to better the handling of your Z31 or get a better Stance? Is your Rear sagging worse than Old lady Boobs? Well this information will help you determine the springs your Z came with so you can replace them with stock units or after market upgrades.
At this time There are many spring options available for the Z31 (1984-1989 300ZX). In addition to the normal after market springs available (Eibach, Tokico, etc) you can also use springs from other Z31s.
All Z31 springs interchange with no fitment issues. You can use any Z31 Spring in any year or model, in-fact the 1987 to 1989 turbo models have fairly stiff springs vs the Non turbo models.
While the Z31 springs will fit in any Z31, there will be a slight shift in ride height depending on what model you have and what springs you end up using. So, if you use the 84 2 seater GL spring in an 88 2+2 turbo, you might find your car sitting slightly lower than before.
If you choose to stay with stock springs the spring set from a 1988 Shiro Edition are stiffest springs you can get without going after market.
Some common after market spring rates are shown below. Note* the Eibachs springs, are variable rate springs. The idea of a progressive variable rate spring is to allow a smooth ride when driving normally, and improved body control when cornering hard. Variable rate springs are easy to spot because the springs are not symmetrical. Typically, one end of the spring is wound tighter than the other end with the more tightly wound end being the softer part of the spring. As the spring is compressed, the soft coils on the tightly wound side will collapse, coming into contact with each other. When this happens, the rest of the spring starts to compress at the second higher rate.
All stock springs are color coded for their application.
Spring Lookup Tool
Use the charts below to Identify the model and Specs of your Z31 Springs. You can do so by cleaning your spring and locating the color code. It will be 2 dots painted on the spring coils. The color combination will identify the spring model and with this you can see the rates listed in the tool below.
Front Springs
Stock Front Springs |
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Spring Number |
Color Code |
Wire Diameter MM (in) |
Coil Diameter MM (in) |
Free Length MM (in) |
Spring Rate Constant N/mm (kg/mm) (lb/in) |
1 |
red/white |
13.5 (0.531) |
170 (6.69) |
293.5 (11.56) |
23.83 (2.43) (136.1) |
2 |
white/white |
13.5 (0.531) |
170 (6.69) |
306.0 (12.05) |
23.83 (2.43) (136.1) |
3 |
yellow/white |
13.5 (0.531) |
170 (6.69) |
300.0 (11.81) |
23.83 (2.43) (136.1) |
4 |
white/white |
13.8 (0.543) |
170 (6.69) |
306.0 (12.05) |
23.83 (2.43) (136.1) |
5 |
yellow/white |
14.0 (0.551) |
170 (6.69) |
300.0 (11.81) |
23.83 (2.43) (136.1) |
6 |
blue/white |
13.8 (0.543) |
170 (6.69) |
312.5 (12.30) |
23.83 (2.43) (136.1) |
7 |
yellow/white |
13.8 (0.543) |
170 (6.69) |
294.5 (11.59) |
25.5 (2.6) (146) |
8 |
yellow/orange |
14.8 (0.583) |
170 (6.69) |
268.5 (10.57) |
34.3 (3.5) (196) |
9 |
blue/orange |
13.9 (0.547) |
170 (6.69) |
318.5 (12.54) |
23.83 (2.43) (136.1) |
10 |
orange/pink |
14.5 (0.571) |
170 (6.69) |
263.0 (10.35) |
36.3 (3.7) (207) |
The Below Table will show you what models had what Front springs installed from the factory.
Spring Code and Applied Models |
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Spring Code |
Year |
Seats |
Model |
Roof |
Engine |
1 |
1984 |
2 |
SF/GL |
All Roof Type |
Non-Turbo |
1 |
1984 |
2 |
All Trims |
All Roof Type |
Turbo |
2 |
1984 |
4 |
All Trims |
All Roof Type |
Non-Turbo |
3 |
1984 |
2 |
GLL |
All Roof Type |
Non-Turbo |
3 |
1984 |
4 |
All Trims |
All Roof Type |
Turbo |
4 |
1985-1986 |
2 |
GLL |
All Roof Type |
Non-Turbo |
4 |
1985 |
4 |
All Trims |
All Roof Type |
Turbo |
5 |
1985 |
2 |
All Trims |
All Roof Type |
Turbo |
5 |
1985-1986 |
2 |
SF/GL |
All Roof Type |
Non-Turbo |
6 |
1987-1989 |
2 |
All Trims |
All Roof Type |
Non-Turbo |
6 |
1985-1986 |
4 |
All Trims |
All Roof Type |
Non-Turbo |
7 |
1984 |
2 |
50th AE |
T-Top |
Turbo |
7 |
1986 |
2 and 4 |
All Trims |
All Roof Type |
Turbo |
8 |
1987-1989 |
2 and 4 |
All Trims |
All Roof Type |
Turbo |
9 |
1987-1989 |
4 |
All Trims |
All Roof Type |
Non-Turbo |
10 |
1988 |
2 |
Shiro |
T-Top |
Turbo |
Rear Springs
Here you will find the Color Codes and rates for the Stock Rear Springs installed in the Z31 Chassis.
Stock Rear Springs |
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Spring Number |
Color Code |
Wire Diameter MM (in) |
Coil Diameter MM (in) |
Free Length MM (in) |
Spring Rate Constant N/mm (kg/mm) (lb/in) |
1 |
1 Red / 2 Yellow |
12.8 (0.504) |
110 (4.33) |
364 (14.33) |
24.5 (2.5) (140) |
2 |
1 Yellow / 2 Yellow |
13.0 (0.512) |
110 (4.33) |
370 (14.57) |
24.5 (2.5) (140) |
3 |
1 White / 2 White |
13.0 (0.512) |
110 (4.33) |
376 (14.80) |
24.5 (2.5) (140) |
4 |
1 Red / 2 White |
13.2 (0.520) |
110 (4.33) |
382 (15.04) |
24.5 (2.5) (140) |
5 |
1 Red / 2 White |
13.2 (0.520) |
111.2 (4.38) |
382 (15.04) |
24.5 (2.5) (140) |
6 |
1 White / 2 Yellow |
13.0 (0.512) |
110 (4.33) |
376 (14.80) |
24.5 (2.5) (140) |
7 |
1 White / 2 Yellow |
13.2 (0.520) |
110 (4.33) |
376 (14.80) |
24.5 (2.5) (140) |
8 |
1 Purple / 2 Yellow |
13.8 (0.543) |
110 (4.33) |
336.5 (13.25) |
33.0 (3.36) (188.2) |
9 |
1 White / 2 Yellow |
13.0 (0.512) |
111.0 (4.37) |
376 (14.80) |
24.5 (2.5) (140) |
10 |
1 Purple / 2 Yellow |
13.8 (0.543) |
111.8 (4.40) |
336.5 (13.25) |
33.0 (3.36) (188.2) |
11 |
1 Green / 2 Yellow |
13.3 (0.524) |
111.3 (4.38) |
388 (15.28) |
24.5 (2.5) (140) |
12 |
1 Pink / 2 White |
13.8 (0.543) |
111.8 (4.40) |
341.0 (13.43) |
33.0 (3.36) (188.2) |
13 |
1 White / 1 Purple |
13.5 (0.531) |
110.0 (4.33) |
317.0 (12.48) |
39.2 (4.0) (224) |
The Below Table will show you what models had what Rear Springs installed from the factory.
Spring Code and Applied Models |
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Spring Code |
Year |
Number of Seats |
Model Trim |
Roof Type |
Engine |
1 |
1984 |
2 |
GL |
Hard Top |
Non - Turbo |
1 |
1984 |
All |
GL |
All |
Turbo |
2 |
1984 |
2 |
GL |
T-Top |
Non - Turbo |
2 |
1984 |
4 |
GL |
All |
Non - Turbo |
2 |
1984 |
All |
GLL |
All |
Turbo |
2 |
1985 |
All |
GL |
All |
Turbo |
3 |
1984 |
4 |
GLL |
T-Top |
Non - Turbo |
4 |
1985 |
4 |
GLL |
T-Top |
Non - Turbo |
4 |
1985 - 1986 |
2 |
GLL |
T-Top |
Non - Turbo |
5 |
1987 - 1989 |
All |
GL |
T-Top |
Non - Turbo |
6 |
1985 |
All |
GLL |
All |
Turbo |
6 |
1985 - 1986 |
All |
GL |
T-Top |
Non - Turbo |
6 |
1986 |
2 |
GL |
Hardtop |
Non - Turbo |
7 |
1986 |
4 |
GLL |
T-Top |
Non - Turbo |
8 |
1984 |
2 |
50th AE |
T-Top |
Turbo |
8 |
1986 |
All |
All |
All |
Turbo |
9 |
1987 - 1989 |
2 |
GL |
Hardtop |
Non - Turbo |
10 |
1987 - 1989 |
All |
GL |
All |
Turbo |
11 |
1987 - 1989 |
All |
GLL |
T-Top |
Non - Turbo |
12 |
1987 - 1989 |
All |
GLL |
All |
Turbo |
13 |
1988 |
2 |
Shiro |
T-Top |
Turbo |
Sources used on this page:
- Information on Spring rates and color coding by - Paul "Az-zbum" Hillman