According to Eibach, the spring rates of the standard springs are:
1 N/mm = 5.710146 lb/in Front 290 lb/inch Rear 150 lb/inch
A set of new genuine Lotus front and rear S2 springs were obtained and sent to Turton Springs (Sheffield) for testing -- results below.
The front spring (B100C0086F) is applicable to all Non-USA SE and S2. It is NOT applicable to the Normally Aspirated or USA cars.
The rear spring (B100D0071F) is applicable to all Non-USA, SE and S2 and Normally Aspirated. It is NOT applicable to the USA cars.
FRONT B100C0086F Yellow/Yellow/Green Diameter of Wire d (inches) 0.531” Inside Coil Diameter(inches) 3.298” Outside Coil Diameter(Inches) 4.360” Number of Coils: Total 8.5 Free Length (inches): 10.690” Actual Load Rate Measured on Test (Pounds per inch): 300 Lbs / IN Loads at Testing: 10.000” = 186 Lbs 9.000” = 485 Lbs 8.000” = 785 Lbs 7.000” = 1087 Lbs 6.000” = 1390 Lbs Remarks BOTH ENDS CLOSED & GROUND FLAT & SQUARE TIPS JUST TOUCHING APPROX THICHNESS 50% EPC BLACK WITH CC = 2 X YELLOW 1 X GREEN STRIPES REAR B100D0071F Green/Yellow/White Diameter of Wire d (inches) 0.406” Inside Coil Diameter (inches) 3.338” Outside Coil Diameter(Inches) 4.150” Number of Coils Total 6.6 Free Length (inches) 9.490” Load Rate (Pounds per inch) Actual Load Rate Measured on Test (Pounds per inch) 144 Lbs / IN Loads at Testing 9.000” = 65 Lbs 8.000” = 210 Lbs 7.000” = 354 Lbs 6.000” = 495 Lbs 5.000” = 642 Lbs Remarks BOTH ENDS CLOSED & GROUND FLAT & SQUARE TIPS JUST TOUCHING APPROX THICHNESS 40% EPC BLACK WITH CC = 1x GREEN 1x YELLOW 1x WHITE STRIPES
Normally Aspirated Front Spring
Specky measured a new normally aspirated front spring:
Front Spring: A100C0087H Colour code Yel / Yel / White (with the addition of a red dab of paint as well, no idea why) Here are a few dimensions of a new item before they disappear into the ether of time and space. overall uncompressed length 276.86 mm average thickness of the wire 12.86 mm average outide diameter (one end) 109.50 mm average outide diameter (the other end) 109.02 mm average internal diameter 83.19 mm
The following added by Saska (moi)
The only major thing missing is the spring rate which can probably be calculated using the difference in weight since almost all of the difference is at the front. No turbo, intercooler, piping, PCE, etc. Given we know the SE/S2 front spring rate is 290-300 lbs/in (an S2 is 300 as measured by Turtons) then a straight weight proportion looks like:
Norma Gross Weight (Full Tank, occupants & luggage): 2679lbs SE Gross Weight (Full Tank, occupants & luggage): 2730lbs S2 Gross Weight (Full Tank, occupants & luggage): 2800lbs So make the S2 1.00 then SE is 0.975 X 300 = 292.5 ibs/in (So the figure of 290 from Eibach is probably for an SE) Norma vs SE is 0.981 X 290 = 285 lbs/in Norma vs S2 is 0.957 X 300 = 287 lbs/in Kerb weights produce exactly the same results. So I'd think doing a normally aspirated front spring at 285 lbs/in would be perfect near as makes no difference.