For your swapping pleasure I (Chris Sualnier) have created a list of several different front springs that can be used on the 510. All of the springs listed will increase spring rate, will need to be cut to lower your car, and are commonly available in the JY.
Also included is the formula from Fred Pruhn's book "How to make your car handle" (thanks Jason) that describes how to calculate spring rate as you cut. Listed dimensions for the diameter of the springs are taken from the center of the wire, not the OD or ID, this will make it easier to use the spring rate calculation. The data all came from the NAPA spring book, so things like free height and load height are approximate.
The stock Datsun spring info was taken from a factory manual (thanks Jason), and can be used as a rough guide. All dimensions are in inches. It is best to measure your 510 springs both loaded and free to determine your specific baseline before trying to calculate rate and ride height changes. All of the approximate load heights are based on 525lbs on the spring.
I will be doing this for the rear springs too, but expect it to take a few months...
All the info listed below is correct to the best of my knowledge, I did check all the applications at the JY to confirm that they looked right.
Spring Rate Formula: K= (12,000,000*W^4) / (8*N*D^3)
The 12,000,000 and 8 are constants.
W= diameter of the spring in inches. (W is raised to the fourth power in the formula)
N= number of active coils in the spring. (free coils plus ½ coil under load)
D= diameter of the coil, measured from the center of the wire to the center of the wire. (D is raised to the third power in the formula)
Stock Datsun:
Spring Diameter - 5.11
Wire Diameter - .472
Load Rating - 89lb/in
Free Height - 14.25 (approx)
Load Height - 8.35 (approx)
NAPA P/N 277-3187 ($52/pair new)
Spring Diameter - 5.04
Wire Diameter - .485
Load Rating - 123lb/in
Free Height - 12.75 (approx)
Load Height - 8.50 (approx)
Application - '88-'92 Nissan Sentra (rear)
NAPA P/N 277-3180 ($59/pair new)
Spring Diameter - 5.27
Wire Diameter - .500
Load Rating - 128lb/in
Free Height - 13.58 (approx)
Load Height - 9.48 (approx)
Applications - '86-'89 Hyundai Excel w/AC, '87-'88 Mitsubishi Precis w/AC, '79-'82 Plymouth Champ w/AC, '80-'84 Dodge Colt w/AC
NAPA P/N 277-3185 ($59/pair new)
Spring Diameter - 5.22
Wire Diameter - .500
Load Rating - 137lb/in
Free Height - 12.98 (approx)
Load Height - 9.15 (approx)
Applications - '86-'89 Hyundai Excel no/AC, '90 Hyundai Excel w/AC, '87-'88 Mitsubishi Precis no/AC, '79-'82 Plymouth Champ no/AC, '80-'84 Dodge Colt no/AC
NAPA P/N 277-3130 ($82/pair new)
Spring Diameter - 4.98
Wire Diameter - .500
Load Rating - 137lb/in
Free Height - 12.43 (approx)
Load Height - 8.60 (approx)
Application - '76-'78 Honda Accord
NAPA P/N 277-3129 ($82/pair new)
Spring Diameter - 4.98
Wire Diameter - .500
Load Rating - 148lb/in
Free Height - 13.00 (approx)
Load Height - 9.45 (approx)
Applications - '80 Honda Accord w/AC, '81 Honda Accord LX w/AC
NAPA P/N 277-3128 ($82/pair new)
Spring Diameter - 4.98
Wire Diameter - .500 Load Rating - 148lb/in
Free Height - 12.31 (approx)
Load Height - 8.76 (approx)
Applications - '79 Honda Accord, '80 Honda Accord no/AC, '81 Honda Accord - all except LX w/AC
NAPA P/N 277-5187 ($93/pair new)
Spring Diameter - 5.06
Wire Diameter - .562
Load Rating - 158lb/in Free Height - 14.37 (approx)
Load Height - 9.00 (approx) - measured after cutting off pigtail end
Applications - '80-'85 Olds Toronado (rear), '79-'85 Cadillac Eldorado (rear), '79-'85 Buick Riviera (rear)
Notes - These have a "pigtail" end on one end that must be cut off. They are real easy to get off at the JY, bring a long crowbar and you can pry them off the lower mount, removing them with next to no effort. Be Careful!!! - Don't try to "help them" by hand if they get hung up.
NAPA P/N 277-5308 ($96/pair new)
Spring Diameter - 5.26
Wire Diameter - .531
Load Rating - 131lb/in Free Height - 15.60 (approx)
Load Height - 11.60 (approx)
Application - '83-'85 Toyota Celica IRS (rear)
Notes - These are also easy to get off at the JY, remove the lower shock mount then pry them off the lower mount, removing them with next to no effort. Be Careful!!! - Don't try to "help them" by hand if they get hung up.
NAPA P/N 277-5310 ($109/pair new)
Spring Diameter - 5.02
Wire Diameter - .500
Load Rating - 108lb/in
Free Height - 14.50 (approx)
Load Height - 9.63 (approx)
Application - '83-'85 Toyota Celica solid rear axel (rear)
NAPA P/N 277-5277 ($74/pair new)
Spring Diameter - 5.08
Wire Diameter - .500
Load Rating - 115lb/in
Free Height - 14.12 (approx)
Load Height - 9.55 (approx)
Applications - '84-'87 Toyota Corolla, '85-'88 Chevy Nova
NAPA P/N 277-5174 ($87/pair new)
Spring Diameter - 4.97
Wire Diameter - .500
Load Rating - 106lb/in
Free Height - 13.05 (approx)
Load Height - 8.10 (approx)
Applications - '75-'79 VW Rabbit/Scirocco no/AC
NAPA P/N 277-5146 ($87/pair new)
Spring Diameter - 4.99
Wire Diameter - .500
Load Rating - 112lb/in Free Height - 13.62 (approx)
Load Height - 8.93 (approx)
Applications - '77-'79 VW Rabbit/Scirocco w/AC
NAPA P/N 277-5374 ($82/pair new)
Spring Diameter - 4.98
Wire Diameter - .500
Load Rating - 113lb/in
Free Height - 13.55 (approx)
Load Height - 8.90 (approx)
Applications - '91-'94 Ford Escort (rear) - except GT, except wagon, '91-'94 Mazda Protege (rear)
NAPA P/N 277-5376 ($82/pair new)
Spring Diameter - 4.98
Wire Diameter - .500
Load Rating - 113lb/in
Free Height - 13.95 (approx)
Load Height - 9.30 (approx)
Applications - '91-'94 Ford Escort Wagon (rear)
