Right, this has been fuking with my head for a bit now. When you get a set of springs, how come they don't change there spring rate between the 03-04 models and the 04.5 onwards models, even though nissan upped the rate by 85 pounds. Surely there should be two sets of springs? otherwise couldn't you totally *** your setup? Having the rear too soft and it bouncing all over the place when you hit a big bump?

 

Correct me if I am wrong here guys but from my understanding the R&D for most manufactures were done on the 03-04s and they are not about to revise it on technically the same car. Plus, don't most dampers have an acceptable range becuase technically again there should only be one perfect spring oscillation rate for each damper. Maybe members like G35driver or Robert_K can chime in on this.

 

Do confuse free spring rates with as installed coupling to the wheels.

Not attaching springs directly to the hub [offset inward on a suspension arm]or mounting at an angle reduces the actual wheel rates.

Most cars have a wheel rate approximately equal to the weight distribution ratio.................say 150 [200]front and 120 [160] rear pounds per inch.

The published spring rate is pretty meaningless without the geometric correction factors

 

Ok, for our purpose i think your getting a bit too technical.

 

You can never get too technical! In a form called TECH AREA

These are simple basic concepts one should understand before modding any suspension. Geometry is a High School Subject.

 

Don't lecture me on geometry mate, i'm a marine engineer, so i know what the hell geometry is. All i'm saying is that for the question i asked, all i want to know is if its safe to *** around with spring rates on a car like that. Don't mean to be rude, just don't like lectures.
Besides, if they changed there suspemsion geometry, in the 04.5 onwards models, than manufacturers definitaley would have needed to revise there spring rates!

 

Any aftermarket spring changes the rate from the factory, regardless if it came with revised or unrevised springs. The difference lies in the OEM shocks. If you are so worried, then upgrade the shocks at the same time, though alot of people with both unrevised and revised shocks have changed to aftermarket springs without many problems. The key is to choose springs with rates similar to your stock springrates, whether that is the unrevised or revised version.

 

OK The reason Nissan change the spring rates for 04's is for a smoother ride. America doesn't have the nice smooth roads like in Japan. Also most Americans give up performance for luxory. Most Americans want a smooth ride from a sports car and don't understand the concept that its a sports car!
As far as after market spring company's and not revising their spring rate... I don't understand why they would? The '03-early '04s are pretty much the same car as newer models (Weight, handling, power, etc..). All of them would benefit from the same spring rate from whatever aftermarket company.

Hope this helps.

 

just caught this but the above is not fully the case

The roads in Japan are no different than they are in the US by and large - there are great roads, there are crappy ones

The rates on the springs from old to new did change but not by a tremendous level. As such, the dampers both old and new) equipped on the car have proven to be able to cope with the aftermarket springs with ease

 

How would increasing the rear springrates smooth the ride? Wouldn't it make it more harsh?

 

I've been on both rear rates back to back. They don't differ from one another to have a negitive impact on ride quality. Dynamically the car behaves a bit differently at the limit, and you can pickup on the 25% increase in rear rate, but that's all, keeping in mind that I did NOT adjust my bar settings to mirror the 04.5+ frotn bar change.

Overall, your on to something. The main change in the 04.5 suspension to improve ride behavior is in the shocks, upping the rear spring rate from 342 to 427 and upping the front swaybar stiffness 17% can't be labeled as ride quality enhancements so much as they are simple tuning elements to get the car the way the engineers wanted.

 

Don't forget though, that at the limit feel and even in low speed maneuvers, becomes as much a function of the rest of the set (tires, tire pressures, alignment, offset), as anything else - which is what makes it even harder to quantify things and say "yep the new rear springs are 'better/worse'

Increasing the rate at times can make the car feel better planted believe it or not, without necessarily hurting ride quality. A perfect example is the bobblehead affect the early 03/04 cars got on the highway with stock springs vs how nice and stable they were with aftermarket springs with a slightly increased rate. Suspensions are dynamic....everything affects everything else, and it's when all these parts work in harmony does the car feel "right".