Nissan 370Z Forum - View Single Post

Jonny · 02-13-2017, 02:36 AM

Hey guys, so I have done a lot of research and PM’ed a couple of guys on this, but what spring rates should I run. I am planning on ordering coilovers soon but I do not know what spring rates to run. While my car is only going to spend 1% of it’s life on the track, I want a really nice street setup that will handle corners as good as any European sports car. I was under the impression that running stiffer front and looser rear would be better but my brother and me had a 2-hour discussion turned argument on suspension. He owns a genesis coupe 3.8 performance model (with Brembos), and we both plan on tracking our cars for the first time this season. My brother main points are that running looser front and stiffer rear is better because:
• Most reputable suspension companies (I.E. swift) run stiffer rear
• Genesis coupes have 3kg front, and 7 kg rear spring rates stock, their suspension was tuned by lotus, which is known world wide for their suspension and are second to none to McLaren. Also a Nissan engineer is know where as reputable as a Lotus engineer
• Sway bars make a difference because it essentially acts as a giant spring thus affecting suspension

My arguments are that:
• Suspension companies run stiffer rears to tune the car to induce under steer instead of over steer, which under steer is generally easier to control and thus safer for the average driver to control
• Most racecars run stiffer fronts than rear. BTW real race cars are RWD not AWD
• The gentlemen who won an national autocross trophy (sorry bro but I forgot your username) runs 20 kg front and 16 kg rear if I remember correctly
• Many different factors come into play such as tire size and suspension settings
So my planned settings are
• 275/35R18 front and 295/35R18 rear (almost a square set up, the difference tire width is very minimal)
• A Hotchkis front sway bar and stock rear
• Slight toe-in
• 2 degrees of camber all round
• Lowered 2 inches in the front and .75 inches in the rear on BC coilovers with swift springs and rubber top mounts

There is a tire engineer for continental tires that comes into my work and pretty much talks about stuff I can’t really see making a difference suspension wise. He also drives a Lexus, not exactly a race car. But I have noticed that people who are successful in autocross run stiffer fronts than in the rear. I am genuinely confused on this subject so I ask for all the members with experience on the track to chime in, thanks.

02-13-2017, 02:36 AM	#1 (permalink)
Jonny Base Member Join Date: Aug 2015 Location: Chi-raq Posts: 67 Drives: 12' 370Z Rep Power: 10	TRACK OG's ONLY!! Hey guys, so I have done a lot of research and PM’ed a couple of guys on this, but what spring rates should I run. I am planning on ordering coilovers soon but I do not know what spring rates to run. While my car is only going to spend 1% of it’s life on the track, I want a really nice street setup that will handle corners as good as any European sports car. I was under the impression that running stiffer front and looser rear would be better but my brother and me had a 2-hour discussion turned argument on suspension. He owns a genesis coupe 3.8 performance model (with Brembos), and we both plan on tracking our cars for the first time this season. My brother main points are that running looser front and stiffer rear is better because: • Most reputable suspension companies (I.E. swift) run stiffer rear • Genesis coupes have 3kg front, and 7 kg rear spring rates stock, their suspension was tuned by lotus, which is known world wide for their suspension and are second to none to McLaren. Also a Nissan engineer is know where as reputable as a Lotus engineer • Sway bars make a difference because it essentially acts as a giant spring thus affecting suspension My arguments are that: • Suspension companies run stiffer rears to tune the car to induce under steer instead of over steer, which under steer is generally easier to control and thus safer for the average driver to control • Most racecars run stiffer fronts than rear. BTW real race cars are RWD not AWD • The gentlemen who won an national autocross trophy (sorry bro but I forgot your username) runs 20 kg front and 16 kg rear if I remember correctly • Many different factors come into play such as tire size and suspension settings So my planned settings are • 275/35R18 front and 295/35R18 rear (almost a square set up, the difference tire width is very minimal) • A Hotchkis front sway bar and stock rear • Slight toe-in • 2 degrees of camber all round • Lowered 2 inches in the front and .75 inches in the rear on BC coilovers with swift springs and rubber top mounts There is a tire engineer for continental tires that comes into my work and pretty much talks about stuff I can’t really see making a difference suspension wise. He also drives a Lexus, not exactly a race car. But I have noticed that people who are successful in autocross run stiffer fronts than in the rear. I am genuinely confused on this subject so I ask for all the members with experience on the track to chime in, thanks.