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Thread: Varying spring rates side to side

  1. #1
    Neutrino Norm's Avatar
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    Varying spring rates side to side

    I am playing around with the spring rates on my car and I am wondering what people think. Some of you have met me and already realize that I don't fit in the "girlie" seats that Sagen referred to in his intro post. This has got me thinking along the lines of upping the springs on the drivers side. My car came stock with 30 N/mm springs in front and 40's in the back. Talking around that seems like standard issue.

    I have taken one of the 40's and moved it to drivers front and got two 60 N/mm springs for the rear from Rob S. The 60's are too stiff ..., so I have purchased a 50 for testing. I am thinking that a 30/40 front and a 40/50 rear are in order. 33% increase in front and 25% rear. I have looked and the only rates that I can find for 180 x 60 mm springs are 30, 40, 50, 60 and 70. My only track day so far with this setup, I noticed were that the car did seem to turn in evenly and roll at about the same rate right or left. Although to be honest, that is a very hard thing to tell. I also noticed that there was very little to no compression in the rear (the 60's have to go)

    Yeah, it is kind of like setting up a car for Nascar, but, from what I can tell the reasoning is solid. Anybody have any thoughts on this?

  2. #2

    Re: Varying spring rates side to side

    Fundamentally, your reasoning sounds good to me! That will mean that the car is optimized for just you, but hey - that's not a bad thing.

  3. #3
    Neutrino Norm's Avatar
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    Re: Varying spring rates side to side

    Off to the spring store only to find the spring are available in 30, 40, 50 and 60. Lots of room in between. To much spacing actually.

    Yesterday, I did a lapping day with the front right being a 30 the front left being a 40 the rear right being a 40 and the left rear being a 50. Overall compliance felt good and the turn in effort left and right felt equal. The following movie shows something else.

    [youtube:1bashdvc]http://www.youtube.com/watch?v=wh9uLV5VWGk[/youtube:1bashdvc]

    The front right shock was definitely bottoming out on braking as the spring rate appears to low. One could argue that is because the forty is shoving more weight its way, but, it appears almost as compressed to me. I need a longer camera mount to get a better view. The fact that the front right shock is bottoming is also borne by the fact that spectators told me I was hanging the left rear in the air at the end of the straight. I was also having wheel spin issues with the left rear at corner exit, partly from track rotation direction and partly, I believe, from the same shock issue. We increased the shock dampening on the left rear and the wheel spin was noticeably improved. the pyrometer confirmed this as the tire temps fell into what was to be expected.

    Braking was the dynamic that I didn't give enough consideration too. I am going to put 40's across the front and 50's across the back and film the travel next, with a longer boom.

    This was the rear shock film. It shows the forty on the right compressing a little more than the fifty on the left

    [youtube:1bashdvc]http://www.youtube.com/watch?v=Oq1s8LrUrag[/youtube:1bashdvc]

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    Neutrino Norm's Avatar
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    Re: Varying spring rates side to side

    Has anyone heard of a longer travel shock being fitted? I wonder how much longer travel that you could go before defeating the purpose of DP's bell cranks anyway.

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