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Thread: Spring rate suggestions

  1. #1

    Spring rate suggestions

    2350lbs door car, 100inch wheelbase. 56% front (1316lbs) 44% (1034lbs) back. What spring rate should be used up front?

  2. #2
    Anybody?

  3. #3
    Senior Member EXPERT BUILDER gearhead1011's Avatar
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    Need more info. Is it a strut or a-arm front end? If it is a-arm is it coil over or oe style? The front spring rates are a lot harder to calculate than the rear because the location and angle of a coil over on an a-arm suspension has a huge effect on the spring rate.

  4. #4
    It's a strut car.

  5. #5
    Senior Member DYNO OPERATOR
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    300# if you have enough platform threads to hold the car up. You have a very front heavy car, but the short wheel base may over shadow the initial hook up problems that you are about to experience with that scale report. The rear will like the lightest spring you can use to hold the car up to plant the tire better. If you have run this car already and have no issue with hook up, then the lighter spring in the rear may cause you to drive into a wheel stand and would prefer a stiffer rear spring. The front spring rate was chose to help transfer weight to the rear by storing more energy. This is the best I can do with the little info you have provided for us to evaluate. Ladder bar crap likes different rear rates so if you are a 4 linker guy you should be in the pocket or at least real dam close.
    Good luck in 09

  6. #6
    Sorry for the light info. It has a 4-link. The front end seems to be way too tight now, less than 0.5" front end travel. When two guys (about 400lbs) steps on the frame, the front suspensions doesn't get down at all, it feels like a solid mount car.

    Springs now are 7" tall installed at 6" height. I need to get the springs measured (I think I will do it at our gym ) so I will know how stiff they are. Inside diameter 2.5", outside 3.5", the spring wire is 0.5" thick and there are 6 active coils.

    Few videos: http://www.youtube.com/results?searc...=triniemi&aq=f

  7. #7
    Senior Member EXPERT BUILDER gearhead1011's Avatar
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    I used a 250 lb 8 inch spring on mine with a front weight of 1109 lbs. I would think a 275-300 lb. spring would be about right for yours. Hypercoil shows both 7 & 8 inch springs and you would have to determine which length your struts should use.

  8. #8
    Ok, thanks.

    Would this be a good spring? http://store.summitracing.com/partde...5&autoview=sku

    My struts can hold maximum of 7" spring (free lenght).

    How much I should preload it initally? 1" , 2", maybe 3"? Or should I just adjust my for the same ride height that it was with stiffer springs and try it for few passes?

  9. #9
    Senior Member DYNO OPERATOR
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    Ride height is all that matters, that is the basis for the spring calculation. Pre load is incidental to spring rate at ride height, it is not an independent adjustment. The lower the spring rate the higher the platform will need to be and the stiffer the spring rate the lower the platform will be. On your struts you should have about 3/4" of shock ram showing before it hits the bumper at ride height. If the spring were too light you will bottom out the shock when the platform is maxed out to it's highest adjustment. The amount of compression the spring has at ride height vr's it's free height is the springs pre load. The spring you asked about is a 300# spring that fits the description you gave for your strut.

  10. #10
    I measured the current springs (at our gym ). The spring took 400lbs to compress it one inch. Way too tight? Free lenght is 7" and they were installed at 6". I'm considering to order the 7" free lenght 300lbs springs. Can I now calculate how much I should preload the 300lbs springs to achive the same ride heigh?


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