JCan Posted January 17, 2013 Share Posted January 17, 2013 Hello I have a 240z with tokico illumina HP springs. This setup has variable rate front springs with single rate rear springs. I have read many threads which state I should purchase 280z single spring constant springs for the front suspension. What do we know: We know the front springs are progressive springs. This means that the top of the springs compress at a lesser constant than the bottom of the springs. The rear springs are linear. We also know that the front springs (9 turns) the first two turns touch under the weight of the stock 240z, and the remainder 7 turns have approximately 0.5" gap between the individual coils. The ride height of my car needs to be reduced by 1 inch (see pic) As I currently own these springs, I wanted to try to cut them to drop the ride height 1" and try them before we discard them and purchase 280z springs Since the rear springs are linear, I can easily determine how much to cut off to reduce the ride height another inch. My question. In order to reduce the height of the front of the car, Should I cut the top of the front spring or the bottom of the front spring? I will tell you why I ask. If I cut the bottom of the spring - plus... then the spring constant is linear at the bottom and it is easy to determine how much to cut off. - Minus... the non linear spring rate is maintained. If i cut the top of the spring - Plus... The spring rate becomes more constant (because I am cutting off the portion of the spring that has a lower spring constant - Minus... It seems to me that the uncompressed spring should be taller than the shock when the shock is completely decompressed. I could probably could cut off 2 turns on the top to achieve 1 inch reduced height, However I would have to reduce the travel of the shock because the spring uncompressed will probably be shorter than the shock uncompressed What do you think? Thanks Jim Quote Link to comment Share on other sites More sharing options...
johnc Posted January 17, 2013 Share Posted January 17, 2013 Are the 5020s on your car in the picture above? Quote Link to comment Share on other sites More sharing options...
JCan Posted January 17, 2013 Author Share Posted January 17, 2013 yes they are! Now the car does not have an interior, glass, front bumper, and hood, but you can see that the ride height is a bit too high. Quote Link to comment Share on other sites More sharing options...
johnc Posted January 17, 2013 Share Posted January 17, 2013 Intake, exhaust, fluids, and more. Wait until you have the car completely together before worrying about its ride height. Generally, cutting progressive springs yields inconsistent results. I would cut one of the stacked coils and then do a test fit. Quote Link to comment Share on other sites More sharing options...
JCan Posted January 17, 2013 Author Share Posted January 17, 2013 we'll wait till the car is assembled before cutting springs. However this issue is kindof bugging me because I do not have a sure solution (which is why I am asking for advise). Your advise above is for me to remove the spring from the shock housing and check how much of the spring I can cut such that it fits without slop in the shock... right? Thanks Jim Quote Link to comment Share on other sites More sharing options...
johnc Posted January 18, 2013 Share Posted January 18, 2013 No. I recommend cutting one coil frmo the stacked end of the progressive spring (the end where the coils are the tighest) and then installing it on the car and check to see if you get the resutls you want. Its outlined here for the 5022 springs:http://forums.hybridz.org/topic/88025-installing-tokico-280z-hp-springs-in-a-240z/ Quote Link to comment Share on other sites More sharing options...
ktm Posted January 22, 2013 Share Posted January 22, 2013 First, listen to John. Your car, as shown in the picture, is sitting too high because it is not fully loaed. When I first installed the 5020 springs in my car with the stock L24, life was good. As soon as I did my L28ET swap I ran into problems. I was crashing over bumps, etc. and thought that was normal. If I may be so bold - ditch the 240z springs. Trust me. After talking with another member at a meet one night, he recommneded that I switch to the 280z springs as he did. About 6 months later I finally bit the bullet and switched over to the 280z springs and it made a world of difference. He had an L28 setup in his car and switched over due to the incredibly harsh ride. My old L28ET setup was a nightmare much less the LS1 and 4L60E I now have. Quote Link to comment Share on other sites More sharing options...
JCan Posted January 22, 2013 Author Share Posted January 22, 2013 Bo We are not planning to cut or change anything until the car is fully assembled. We expect the car to be fully assembled by the end of march. Regarding the 280 springs, I believe they are probably the best option. We plan to set ride height (both front and rear) using the springs we currently own. This means cutting both the rear and front springs. Once we achieve the proper ride height ( I am looking for a ~0.35" inch difference with the rear height higher than the fronts assuming we are using the same tires front and rear (which we are not) (noting we are running 205 45 17 front and 225 45 17 rear, this setup should provide the same gap between the top of the tire to the edge of the fender on both front and rears) After driving for a couple months, we will review the following issues (in summer): - Cam (we have close to a medium cam in this car which is loud and is possibly a bit too much for my son (per my wife)) - Suspension (Review ride height and comment on front springs - We will blog our findings) - Cooling (I installed only one cooling fan with a custom made fan shroud. Will test it to see if we need to make a change) - Finish installing air conditioning Thanks for your inputs. This site is great! Quote Link to comment Share on other sites More sharing options...
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