It is very simple, even without a spreadsheet.
In the nut shell, the lowest cost "Bilstein option" looks like this.
Shocks, MY to MY, are the same, just different springs were fitted.
1. Get 4 Gaz adjustable shocks w/adjustable perches from:
Gaz Shocks | Performance shock absorbers | Suspension Kits | Adjustable suspension kits | Camber adjusters | Top Mounts | Premium height adjustable suspension kits
(read previous postings for contacts). When you call or email, give them your car model and year and specify ID of the coil over springs you currently have on your car (or you intend to use). Specify diameter of the perches. They know what your car needs, they have all the specs.
2. Get misc components, like seats and thrust bearings, per posting #128
3" ID rubber seats for rear springs can be bought from JAE, just call Jay.
Front seats are abundant and cheap on Amazon
3. Purchase Eibach springs from eBay/Amazon according to your ID diameter and a chart below.
You want 2.5" ID, 10" long +1" Coleman spacer at the front.
Pre-89 cars had 3" ID springs, 14" long. 89 and forward- had 2.5"ID springs all around.
Note: if you intend to use any other shock type/brand, buy shocks first Using shock geometry measure/calculate spring adjustment range and preload.
QA-1 has excellent double adjustable shocks, Proma Star (2.5" perches only), but they are more expensive ( QA1 Shocks, Suspension, Driveshafts & Rod Ends | Street Performance, Hot Rods, Drag Racing, Circle Track Racing, Industrial
OEM Spring Rates
88 Federal & non-SE 89
: (17% anti-dive geometry),
Front: Rate– 22.8 N/mm / 130 Lb/in, Free Length–369mm (14.5”), Static Length– 203mm (10”), 585-610# preload, ride hgt 170mm
Total with ARB in the corner = 270 lbs/in; ARB rate=0 in the straight line motion
Rear: Rate– 27.5 N/mm / 157 Lb/in, Free Length–334mm (13.15”), Static Length– 205.7mm (8”), 800-850# preload, ride hgt 170mm
ARB: 17.5 mm dia. front anti-sway bar, confirmed! Rate: 140 lbs/in
(22% pro-dive geometry)
Front: Rate– 29.1 N/mm /166 Lb/in, Free Length–372mm (14.6”), Static Length– 219mm (8.62”), 692-720# preload, ride hgt 190mm
Total with ARB in the corner = 306lbs/in, ARB rate=0 in the straight line motion
Rear: Rate– 27.5 N/mm / 157 Lb/in, Free Length–347mm (13.7”), Static Length– 218mm (8.6”), 800# preload, ride hgt 170mm
ARB: 17.5 mm dia. front anti-sway bar Rate: 140 lbs/in
Front: Rate- 40.3 N/mm /230 lb/in
Total with ARB in the corner = 370* lb/in; ARB rate=0 in the straight line motion
Rear: Rate- 31.0 N/mm 177 lb/in
ARB: 17.5* mm dia. front anti-sway bar Rate: 140 lbs/in OR * ? To be verified
Front: Rate – 36 N/mm / 205 Lb/in
Total with ARB in the corner = 290 lbs/in; ARB rate=0 in the straight line motion
Rear: Rate – 39 N/mm / 225 Lb/in
ARB: 15 mm dia, Rate: 85 lbs/in
Front: Rate – 41 N/mm / 234 Lb/in, Free Length - N/A, Static Length– 214mm (8.43”) (From Jeremy Walton’s book “The official story”)
Total with ARB in the corner = 319 lbs/in; ARB rate=0 in the straight line motion
Rear: Rate – 45 N/mm / 257 Lb/in, Free Length - N/A, Static Length– 227mm (8.93”)
15 mm dia. front anti-sway bar, Rate: 85 lbs/in
The front damper platform height for each of these measurements is 59mm. The rear platform height is 115mm. The extended/compressed length for the front is 12in./10in., and the rear is 16in./12in.
Front: Rate – 43.2 N/mm / 280 Lb/mm
Total with ARB in the corner = 365 lb/in; ARB rate=0 in the straight line motion
Rear: Rate – 48.8 N/mm / 320 Lb/in
ARB: 15 mm dia, Rate: 85 lbs/in
> For OEM spring color coding, see this thread:
4. Dependent on the car intended use and MY decide if you prefer to upgrade the anti roll bar to the next size available, I.E. 15mm->17mm
or 17mm->19mm (!) (recently on US eBay)
Always measure everything 3 times and make notes.
If you value your your fingers, always use a robust spring compressor when playing suspension games, LOL.
Here is what I use with great results
Goplus® MacPherson Interchangable Fork Strut Coil Spring Compressor Extractor Tool Set