Quote:
Originally Posted by Raptor13x
Despite commonly held belief, you CAN cut your springs with good results. It just gets a bad name because 99% of people that do it do it wrong, and don't understand exactly what is happening when they cut them. When you cut your springs, you INCREASE the spring rate. If the shocks are left stock, this will mean they will be inadequate for the modified springs (hence the bouncing you see). However, most aftermarket springs also have a higher spring rate, so you really need better shocks either way, which I'm glad to see you're adding. The HUGE advantage in cutting your springs over using aftermarket is that, although you are increasing spring rate, you're leaving it in the stock ratio front-rear, which most aftermarket spring companies change for the worse.
The next area most people screw up is by not measuring and cutting the EXACT same amount off each spring. Cut no more than 1/2 coil before reassembling the car and testing it. The steps to do so are as follows: (reference = Chassis Engineering, by Herb Adams, paraphrased)
1) Carefully remove the coil springs. Note how the end coils of the springs are slightly bent so that it seats properly in the strut assembly.
2) Mark off exactly 1/2 coil on the spring.
3) Cut the spring using an acetylene torch or saw.
4) Heat the 1/2 coil below your cut so you can bend it to match the spring's original shape.
5) Quickly turn the spring upside down and bend the top coil by pushing down on the spring. Do NOT quench the spring with water, allow it to air-cool slowly.
6) Paint the spring to avoid rust and reinstall.
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I fully agree that cutting springs can be done right, but seldom are, and that is why it has the bad rap. I did some research on this earlier this year and found one or two very credible posts from people in the business who explained very well that it could be done, if done properly.
I don't have the specs in front of me regarding how to calculate the proper amount of coil to cut off, in order to meet your needs, but only a little is usually required. If I recall properly, I had caluclated that only about 1/4 of a coil needs to be removed from a MKI in order to achieve an approximate 1" drop, but there are calculations for this, and a simple web search should bring them up. The 1/2 coil statement above was also, I believe, just a general reference, and did not have the MR2 in mind. Additionally, cut from the end of the coil that is not progressively wound (unevenly spaced), otherwise you amy get some unusual, almost impossible to calculate, results. Also, if you cut from the proper end you should not need to rebend the remaining portion of the cut coil, as it does not change shape at that end on MKI's.
If I can find a spare set of decent oem SC springs, I am going to try it on mine at some point, especially since the rear SC springs are already 10-11% stiffer than the NA springs, and switching to after market springs only gives you a lowered advantage and no extra stiffeness. Cutting about 1/4 coil off such a spring will, I believe lower it about 1" and increase the spring rate by about 10% or a little more.