Norm Peterson

It's probably more productive to work in terms of ride frequencies instead of just spring rates by themselves (the formula isn't very difficult to use, but you do need to know a few other things).

There are rough frequency ranges for various uses, ranging from less than 1 Hz for a soft-riding sedan, to between maybe 1.0 and 1.5 for a stockish car with performance intent, to 1.5 or maybe 2.0 for a more serious dual-purpose car, to higher still for some forms of competition. Other people may break things down a little differently.

Then there is a sort of balance that you want to maintain between the front and rear ride frequencies to keep the car from 'pitching' (like an old pickup truck with nothing in the bed) as you drive it down the road. For a street driven car, it's better to obtain "flat ride" over the range of speeds that the car is driven at with properly matched springs than it is to mismatch the springs and tie everything down tight with excessively high damping. "Matched", in this case refers to the springs being matched to obtain a specific flat ride speed or speed range. This may or may not agree with what you see advertised as "matched springs". Ask what they're matched to.


Norm

Rubrignitz

I'll start by saying I'm no expert so take what I say with a grain of salt. I have, however run many sets of springs on my car over a range of spring rates from 150# (rear) up to 300# (front) and several in between along with many other suspension upgrades so I have some first hand knowledge. Thats what I'll give.

My opinion is that the sum of the suspension components is greater than the advantage that each may give you. Some folks leave the rest of their suspension stock, throw on some coilovers with 3-500# spring rates and are happy with it. But when you start upgrading other components (stiffer swaybars, control arms, larger/wider rims/tires) the wheelrate increases and those stiff springs become somewhat unbearable and nvh increases substantially. That was my case.

If you have upgraded control arms (lower/upper), bigger swaybars, watts link, relocation brackets (the advantages of which are debatable), corrected your roll center via adjustable watts link, X5 balljoints and a bumpsteer kit then a light spring works quite well on a street driven car. I'd say my car handles MUCH (actually worlds) better with those parts combined and light springs (i.e. steeda sports) than just the addition of stiff springs and upgraded dampers which is what I initially ran on my car with H&R Race springs/d-spec dampers. The added control of the watts link even made me rethink my spring decision and go with a lighter rate. The better you get the rest of the suspension working the less spring you need. That's my opinion.

angryBits

I've heard good things about Megan Racing...

Are these any good? http://www.hopupracing.com/meraststdopi3.html

Edit: a listing on ebay describes them as:

Spring Rates
7kg/mm (391lbs.in.) F
5kg/mm (279lbs.in.) R

wrxified

Skimmed to the end. Couple people mention this and I'm just chiming in to concur with them.

I've replaced the full suspension on 5 cars. I'm far from an expert. This isn't my profession. I sell telecommunications for a living. My last car, Subaru STI, full coilover setup took 2.5 hrs. I wasn't hustling either. About a half hour for each corner. If that shop can't do it in 3 hrs or less then make sure you ask them for a little of this with your invoice.

2008vistablue

I would recommend doing it yourself. If you don't want to mess with a spring compressor has a local shp like exhaust do it for you. They charged me $20 to swap out two struts using their compressor and then went home and installed the assembly on the car.

angryBits

not a bad idea