BC Coilovers Question

Fairlady_Zeto

Hey so im starting to get really frustrated with my coilovers (BC BR). They arent anything special just ordered as they come (Mistake).I have found that i cant get high enough in the rear even when they are adjusted all the way up, it sits way too low and as soon as i start moving its dips down even further. (Am i doing something wrong?) Because the rear is where it is the front is slammed to prevent getting a reverse raked look (front up rear down) which causes the car to feel like **** and would look terrible. Ive done some research and found that the BC stock spring rates are 10k Front 8k Rear. Stocks are 7.5k front and 8.1k rear. In discovering this i realize thats part of my problem already, softer than stock springs in the rear. My question is if i get 10k rear springs that are maybe slightly longer will that through off the geometry in a negative way or would that completely fix my problem? Background info, 370z base with just the bc's no other suspension mods. They have maybe around 10-15k miles on them. Any input would be greatly appreciated