Question of springs...

I know that suspension mods and lowering have been discussed in detail but I have a very specific question and am hoping for experienced input. I have an '02 C2 with "18 wheels and would like to tighten up the suspension a little. I am a novice autocrosser and have been to 1 DE(hopefully more in the future)so I am not a big racer. I would just like to minimize the softer feel of the stock setup for spirited road driving and autox. I have read a lot of posts on all the options, M030,coil overs, etc but would like to keep it simple and inexpensive. Anyway, my question is: can I just replace the springs with H&R sports without changing the stock shocks? Will I need an allignment after installation? Any recomendations on a supplier? Thank you to everyone who takes the time to participate on this site and for any help.

Springs and shocks are designed to work together, so they are usually carefully engineered to match. I wouldn't suggest just changing the stock springs without getting matching shocks, because it's very likely that you won't be happy with the resulting ride or handling. Karl

Karl is correct. Under no circumstance, should you change to lowering or stiffer springs while keeping the stock standard shocks. From the sounds of it, you can benefit from the factory <a href="http://www.carnewal-europe.com/cpx_p96007.htm" target="_blank">ROW M030 setup</a>. Or, if you want something a little more aggressive, the <a href="http://www.carnewal-europe.com/cpx_p96010.htm" target="_blank">H&R coilover kit</a> will allow for more lowering and adjustable ride height.

Karl and Viken are correct. By dealing with <a href="http://www.carnewal.com" target="_blank">www.carnewal.com</a> I was able to get an M030 kit sent to the US for less than $1100 and then have it installed at my dealer. Total cost less than $2000 including 4 wheel alignment. That is probably as good as you can do even if you were to just change springs. Got the whole kit, springs, shocks, bump stops, sway bars, etc.

For the kind of stuff your doing I would try stiffer bars first! You might find that you don't need the shock change to get what your looking for. The car will have less lean and will tend to snap back faster in transitions. Not as fast as stiffer springs but hey start off with something simple and cheaper then move to the next step if you feel you need it.

To the best of my knowledge springs and shocks are not independent of one another and are designed according to one another's caracteristics to provide the best overall result of them combined. Changing one without the other will lead to inadecuate performance of the suspensions which will lead to inadecuate handling and braking hence "Under no circumstance, should you change to lowering or stiffer springs while keeping the stock standard shocks" this may be not as important on a Ford Taurus driving to church on Sunday but will become obvious on a Porsche 911 in a DE, which is the case.

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by dpblessing: <strong>Thanks for the reply. Although I am still hopeful that we can get more specific technical comments.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Lowering springs are shorter and allow for less suspension travel. As such, soft shocks tend to bottom out easily leading to eventual and premature damage to them. Furthermore, with not enough damping, you normally get a horrible ride over certain bumps. Some people describe the ride with the term pogo stick which is sort of a wallowy ride. It is always better to have a softer spring rather than a softer shock.

What I remember from a statics/dynamics engineering class: springs and shocks are responsible for how the wheels and body relate (transfer function). Lets say x is the "travel" of the wheel related to the frame, and at a normal position, x is zero. A wheel hits a bump, and wants to move up. Without suspension, the force of the bump would be transferred directly to the frame. With the addition of springs, the force transferred from the wheel to the frame is directly proportional to x, or the position of the wheel relative to the frame (force = k (spring stiffness) times x). Think of the wobbly headed dolls - the farther you push the head to the side, the more force on the head to return to the center. With no damping, when released the head accelerates back to the middle, overshoots, and continues the cycle again. Same with a car with no shocks. Your car would bounce up and down continuously after hitting a bump. The shocks provide a second-order resistance - they prevent the wheel from returning to the middle position too quickly to prevent overshoot. Shocks give a force proportional to the rate of change of distance, or speed (f = c v, v being dx/dt or velocity of x). A shock resists only when it is being compressed quickly, the faster, the more resistance. The key to putting springs and shocks together is balance. If the shocks are too stiff, they will resist movement of the wheel too much, and prevent it from absorbing the bump (overdamping). If they are too soft, they will not slow down the wheel enough, and the wheel will overshoot the middle (underdamping). SO, keeping the shocks the same, if you stiffen your springs, your suspension will be underdamped and you will bounce a few times before the car settles. If you soften the springs, the car will be overdamped and not allow the springs to slowly transfer the bump to the frame, and will also slow a displaced wheel from returning to its center position. The goal is to just barely not bounce from a bump. Remember the trick of checking suspension - pushing the corner of a car down and letting it come back? If it bounces past neutral when released, it is underdamped. If it doesnt want to return to neutral quickly, it is overdamped. A 4x4 truck driving thru bumpy terrain would want softer suspension (because bumps are high so x will be higher), a racecar driving on a flat track would want a hard suspension (small bumps, small x). BUT, they must both have a neutrally damped setup, ie springs and shocks balanced. When it comes to taking a corner hard, I dont believe that balance is important, because the force of the turn is keeping a steady (x isnt changing) force on your wheels. So in that situation, the harder the springs and shocks the better, ideally no suspension would make the car handle the curve the best. Hope that wasnt too muddled... Peter

Take a look at the the Panorama article discussing ROW M030 suspensions. You can find it at the PCA national website. Very informative.

Interesting article in Panorama mentioned above, but not much explanation: We also do not recommend "mixing and matching" the various springs, shocks and bumpstops evaluated for this article since all of these parts have different design characteristics that work in concert together.

Thanks everyone for the replies. I have been real busy but couldn't wait to get back to the forum to see the discussion. Since I lease my car I was hoping to get away with spending about $1000 total on minor suspension improvement. So I guess I'll ask if anyone thinks my objectives are possible with this budget and specifically with what components? And yes, contrary to popular belief, I do love my car, and maintain and baby it almost like my first born, despite my chosen method of paying for it. But hey, that could be another topic.

If you follow Viken's link to "carnewal" in his first message you will see Porsche's RoW M030 Sport Suspension kit (shocks, spring, bushings and stabilizers) for 1,167$ shipping included. Believe me, its well worth it and more. And yes, you will need an allignment after installation.