Is this the correct spring for my needs (spring rate question)

[Masonbarnard]

hey, i have ground control coilovers on my e36 m3, and the front is plenty low, but i want the rear to get lower.

the Springs i have now are (6.5/2.5"/550 lbs)

i want a shorter spring in the rear to get lower. i kinda talked to Swift, who said they have "Z65-127-100" which is a 5inch spring, 2.5 diameter, but i am not sure about the rate, or what "100" means which they also call "10k" so i am not sure what the spring rate is, or what i should be using...

should i keep the same spring rate (550lb), or should i get a different spring rate.

(i only need an inch lower)



love ,
Mason


EDIT: 10 kg/mm = 560 lb/in

so should i keep the same spring rate?

[HEcreated487]

Are the current springs Swift or Eibach? Regardless, if the ride quality is already good in your opinion, then the same spring rate should have relatively the same ride quality and a shorter spring should get you your desired low. In speaking with Swift myself, they recommended a 1K to 2K reduction in spring rate to improve ride quality, if that is needed. They also stated that replacing any existing spring with a Swift spring of the same specs (i.e. the same ID, length and spring rate) will almost guarantee an increase in ride quality. Not sure if this is any help.

[Masonbarnard]

Are the current springs Swift or Eibach? Regardless, if the ride quality is already good in your opinion, then the same spring rate should have relatively the same ride quality and a shorter spring should get you your desired low. In speaking with Swift myself, they recommended a 1K to 2K reduction in spring rate to improve ride quality, if that is needed. They also stated that replacing any existing spring with a Swift spring of the same specs (i.e. the same ID, length and spring rate) will almost guarantee an increase in ride quality. Not sure if this is any help.

yeah, thanks i get it now. i just wasnt sure if the spring rate i should get would be higher or lower, for reasonings of bottoming out?

but im getting 5''/2.5/560lb. which will probably be good, and bring me to where i need to be