Best ifs kit? rms, hdk, gt suspension, or magnum force?
I forgot you are planning on racing ........so maybe (?????) you will need all those springs.
For a street car......stick to the basics....unless you want it to ride like a dump truck. (famous Bob quote from post above)
The spring simply holds up the car, As stated above, the 25% to 33% spring collapse is the range you want to be in.....there will NOT be several rates that fall into that catagory.
The SHOCK is the way to tune the ride.....that is what that little knob(s) on the base is for.
Nooooooooooo i thought they were there just for looks. Yes I realize I'll be tuning the shocks as well. But keep in mind, there's different spring/suspension theories out there. I plan on testing a few of them. I am FAR, FAR from a suspension expert and as I've said time and time again, what works for me, may not work for everyone BUT I try to help others educate themselves on their options. Why, because I am a big believer that if you're gonna run an aftermarket suspension, lets tune it to the driver's liking.
When it comes to suspensions, even for a street car, a "readers digest" answer as to which spring to run will vary for a couple of reasons:
1. There are many varied theories on spring rate vs sway bar rate vs shock force vs roll center location vs tire traction. But in general, springs do more than "simply holds up the car". I know you make a very nice kit with great reviews, but I must disagree with that statement. Springs play a more important part than just holding the weight of the car. They have a profound effect on traction, gain or loss. This to me at least, is important on the street or the track.
2. As you mentioned, there are many varied performance criteria...ride quality? handling? racing? tire size and traction? style of competition? sway bar or no sway bar? big bar or little sway bar? front bar and rear bar or no? Now, quality aftermarket manufacturers will have selected a spring length and rate they feel based on their testing and data will work for the majority of their target customers. And that's a good thing. But if one doesn't like the feel of the rate they chose and havent been able to tune it to their liking with the adjustable shocks, or if one wants to go millisecond lap time eliminating, then yes, spring rate comes into play and that may mean stepping away from the spring chosen by the manufacturer.
3. I plan on doing some hot laps with and with out a sway bar, this *may* involve trying different spring rates. There's numerous people running Big Bar/Soft Spring; Small Bar/Soft Spring; /Big Bar/Hard Spring, Small Bar/Big Hard Spring, etc. As with every theory in suspensions, there is a pro/con or a give or take.
4. Tying back to number 1, Springs do hold up the car, but they also affect traction, body roll and weight transfer. For example: The stiffer springs will increase handling on smooth surfaces by holding down body roll. They will also help in landing on big bumps as well. The down side to stiffer springs is that it will ride rough and be less controllable on washboard or rough surfaces. Also, too stiff a rate of the springs in the rear, you will end up with some understeer. That is the car will not steer as sharply but will be more stable. With softer springs in the back you will get oversteer. This will respond quicker, but will be more likely to spin out. This is what racers sometime refer to as loose/tight conditions. Now, for a street car, you're unlikely to be concerned with springs rates if buying your kit from a known manufacturer. But lets say you're building your own 4 link rear, now youre really gonna be concerned with choosing the right springs and rate. And yes, this is where your 25% to 33 % will come into play. So you are correct there to a point.
5: To break this up to where it's easier to read. Generally stiffer springs yield less traction because they inhibit weight transfer. They also tend to bounce on small high frequency bumps causing traction loss. Now to tie in to your shock comment, springs should be approximately matched to damping. What I mean is this. Damping on the heavy side tends to make the car feel more stable, slowing the pitch and roll motions of the car. Heavy damping does not effect the amount the car rolls, just how long it takes the car to roll. So if one is running soft springs, with relatively firm damping settings, this will make the car very stable but slow/slower to react. Heavier springs, with relatively light damping makes the car very responsive and often twitchy and sometimes uncontrollable if one goes too far. Now where this comes into play for me and those like me, the 1 percent or whatever who will be racing our cars is in terms of track conditions.High frequency of bumps generally require soft springs and damping. With heavy springs and too light of damping, the car cannot react to the bumps fast enough causing the car to bounce and skid.
6: Also, when it comes to spring length, really one needs to contact the manufacturer of the spring. It is not unusual for springs to have dead coils built in to affect ride height and increase the spring's overall height/length, however, they don't affect the spring's rate. Not everyone does this but some do. And get this, they even make progressive springs which are springs that the rate changes as it compresses!
7: I personally called and spoke with the guys at Viking. gave them the shock numbers I would be running and bought the springs that they assured me would be in the correct range to work with the length and travel of the shock. I then called the designer and builder of my front kit, Carl Gerst, and confirmed the springs would work. It wasn't just a point a finger and guess.
Now, I apologize for turning this into Spring Rates 101, but the notion that springs only "holds up the car" is only part of the story. Also, I would add this disclaimer, I am not an expert, just someone who has been around the road racing and auto cross circuit since I was 15, I also have family that road race and tune suspensions for a living, we've talked greatly about this, alot. I may not be a fabricator but I'm not exactly naive either. I'm not the best at typing things and trying to explain them, so if im not clear on something, please feel free to ask for clarification.
