My stock G37s:
So, first suspension was Tein H-Techs. The ride with the H-Techs was smoooooth. Much smoother than the factory sport springs. But, there was a problem....The drop was over 2" and I was having a major problem with the front suspension being too loose to the point that I was scraping over every speed bump. When I went over some road construction and my motor cross member bottomed out on a manhole cover I was done with them. That and they helped eat my tires up sue to camber....an expensive proposition. After getting the H-Techs it was time for the factory tires to be replaced and a set of Hankook V12's were installed....Getting the fronts too small caused even more banging (245-35 instead of 245-40)...oh fun.
My G37s with Tein H-Techs and Hankooks:
So, phase-II was to get some coilovers. Along comes BC Racing and their BR-Type coilover. Installation was a challenge as the supplied instructions were pretty crappy. The rears were installed with WAY too much damping and the car drove like there was very little suspension travel in the rear. The car hopped over bumps and was rough as hell. After a few months and adjusting damping to the softest settings I was pretty fed up with it. I finally figured out the damping was wrong right around the time the Hankook tires needed replacement (around 10k miles.....sigh....) as rear camber had eaten the inside of the back tires and one front tire. I took that time to purchase new tires (with a properly sized front tire), adjust the damping properly, and installed Eibach front upper control arm and rear bolts to fix current and future camber/toe issues. MUCH better, but still way too stiff in the back.
With BC Coilover's...before spacers:
Now, I've been working with Mike (RED_DET) since day one to get this suspension to make me happy. He's thinking I'm nothing but a big whiner and I was beginning to feel that way too. I finally got him to take my car out for an extended test drive and he finally saw what I was talking about. He has BC's on his G35 sedan and I was quite pleased with his handling yet mine made me think I was driving a Honda with cut rear springs
The question is, what to do about it.The BC spring rates are 12k Front/10k Rear for the G37 and are way too stiff in the rear. The H-Techs were 5.8K Front/4.7K Rear. The G35 BC spring rates are 10k Front/8k Rear. Now, BC uses stiffer spring rates for the G37 because it is a heavier vehicle. Based on the spring rates you can fully understand why the H-Techs were having problems with bumps and scraping. The test we decided was to order a set of 10k/8k G35 springs from BC and simply swap out the rears, leaving the front 12k's alone for now.
So, back to it. We swapped out the rear without making any additional changes to the ride height at all. I took it around the block and it felt great! It is still somewhat stiffer than the factory sport springs but took bumps much better than the 10k springs. It was no longer harsh or jarring. I left it alone and drove home...by the time I reached home they had settled way to far down and the tires were dragging on my inner liner. It took me two times to adjust the height and get it where I wanted it, a total of 5 turns! As it sets I'm quite happy with the handling and drivability and will probably leave the 12k's on the front for now but will eventually swap those to the 10k's to see how they function. Those of you looking for coilovers the BC kit is fine and of good quality, I'd just suggest getting them with at least 8k spring rates on the rear.
As it sits now, includes the 15mm spacers:
