Hi Guys,

I usually see people putting the higher springrate on the front; however more recently I have seen people put the higher SR on the rear..

What is the reason for this?

Cheers
Dave

 

I think the idea is to help promote over steer, or at least to make the car more balanced front to back.

 

agreed, the higher spring rate will help promote oversteer.

 

i may be over generalizing here, but thats a western approach to balancing out the car. we run the same tires/wheels front and back.

Japanese racers tend to run higher spring rates in the front, and use staggered wheel/tire sizes/widths and tire pressures to balance out a FWD/AWD car.

 

Just an FYI, the stock car has higher spring rates in the rear. This doesn't necessarily mean it's geared towards oversteer (you know it's not ), but that the front and rear suspension have different motion ratios. Meaning that a 200lb spring on the front is not the same as a 200lb spring on the rear.


- Andrew

 

now were talking about wheel rates as a function of the springs and suspension geometry. which is good, because many cars you can't compare spring rates directly because of differences in weight and suspension geometry.

 

I guess this goes with my thread here:


https://www.evolutionm.net/forums/sh...09#post4901909

I've heard many non-ACD evos running higher SR in the rear as opposed to the front.


????

 

Understand about the rear oversteer setup.

Also AUDM IX's are different springrates to USDM... I think USDM are a lot softer than JDM/AUDM... And I believe fronts are harder than the rears...

Hrmm choices choices... If higher rear rate to promote oversteer is the only reason I guess I will just stick with 8kg front 6kg rear... Seems to be fairly popular???

 

I'm not sure I'd say that the higher rear rate promotes oversteer....more like it promotes neutrality instead. In drastic cases it does of course result in oversteer.

I have actually been a fan of even spring rates front and rear in certain cases.

- Andrew

 

+1

 

even spring rates - what sort of cases?

 

It lets you run a softer rear rate which makes things "easier to handle" and improves ride quality, then add a rear swaybar to add stiffness back there without affecting the ride quality.

Plus having the adjustable rear swaybar lets you tune the balance of the car quickly and easily, which is a little more difficult then having set spring rates and and a non-adjustable swaybar. The even rates kind of gives you a baseline, then you use the swaybar to tune with.

Not for everyone, because sometimes stiffer rear rates AND an adjustable rear swaybar are the answer.


- Andrew

 

so what would you run for a 90% street car and 10% track car... given the roads around me are pretty crap (tram lines + potholes)?

 

From a drag racing perspective, I believe the stiffer spring rate in the rear is to help prevent it from squatting as much and should allow for better launches.

 

Its hard to look at car A or car B and use their springs rates because, as others mentioned, we don't necessarily know what sway bars, tire pressure, ride height, suspension mods, etc. are used with that specific combination of springs. Regardless of the rate of the spring itself which may be higher or lower than the rear, everyone uses a rear wheel rate much lower than the front, as it should be on a nose heavy car. The approximate wheel rate for the front is the spring rate. The approximate wheel rate for the rear is about 40% of the spring rate on the Lancer/EvoX, I forget the exact number for Evo VIII/IX, but it is the lever ratio squared, i.e. distance from shock to wheel divided by distance from body to shock, squared.

So to answer the question, your spring rates depends on other mods and how much your insides want to move around. It also depends A LOT on the quality of your shocks. My Evo rode better than stock with DMS-50s and 700lb progressive springs, but worse than stock with 400 lb springs and low quality coilovers.

Best bet...any tuner worth his salt will take you for a spin in the setup he recommends. If you like it buy it, if not, keep looking. I wish there were an easy solution, but all I can recommend is working with a shop that has a proven record and loyal customers.