If you have any of their info please let me know.
Also if anybody has the spring rate for Cepek Coils or Rancho add a leafs that would be great.
| Brand | Bracket Material thickness | Coil Spring Rate | Coil Spring Free Length | Radius Arm Length | Add a Leaf Spring Rate | New Rear Spring Pak Spring Rate |
| Trailmaster 4" | None Given | 560 lbs "compression loaded" | 18.25 | None Given | None Given | None Given |
| Rancho 1" | N/A | 459 lbs per inch | 15.32" | N/A | N/A | N/A |
| Rancho 1" to 2" | N/A | 380 lbs per inch | 17.42" | N/A | N/A | N/A |
| Rancho 3" | .19" | 460 lbs per inch | 18.18" | 15.5" over stock | 3" wide arch 7.5" length 46" .32" thick | N/A |
| Rancho 4" | .19" | 460 lbs per inch | 19.18" | 15.5" over stock | Above + 3" wide, 7" arch, 49.75" long, .32" thick, 7" arch | N/A |
| Pro Comp 4" | .25" | 475 lbs per inch | 18.9" | 15" over stock | 105 lbs per inch | 10%-15% stiffer than stock |
| Pro Comp 6" | .25" | 450 lbs per inch | 20.35" | 15" over stock | 171 lbs per inch | 10%-15% stiffer than stock |
| Superlift 1"-2" | N/A | 400 lbs per inch | 17" | N/A | 12%-20% stiffer than stock | Near Stock |
| Superlift 4" | .25" | 445 lbs per inch | 19" | 18" over stock | 12%-20% stiffer than stock | Near Stock |
| Superlift 6" | .25" | 445 lbs per inch | 21.5" | 18" over stock | 12%-20% stiffer than stock | Near Stock |
| Dick Cepek 4" | 3/16-1/2" | Diameter .807 | 18.5" | 15" over stock | 12%-20% stiffer than stock | N/A |
| Dick Cepek 6" | 3/16-1/2" | Diameter .807 | 20.6" | 15" over stock | 12%-20% stiffer than stock | N/A |