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Thread: Please help with coilover spring rate!!!!!

  1. #1
    Senior Member MacGyver's Avatar
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    Please help with coilover spring rate!!!!!

    I have been reading threads and write-ups concerning spring rates and struts and have read many opinions as to what spring rate and strut would be best. Maybe some of you guys can shed some light on this. I prefer a little stiffer than normal would be desired but I don’t want the car doing that bouncy thing like all the Hondas the kids drive. Plus, I would also like to keep the cost down.

    Application: 1988 Fiero GT

    I am using 19” wheels with very short sidewalls.

    Wheel spacers 1”

    Chassis is stretched 9”

    Between additional engine weight and chassis bracing there shouldn’t more that about 75 to 100Lbs. of additional weight vs. stock configuration.

    Vehicle will be lowered about 2”

    I have heard 12” springs would offer the best ride. Pencocks write up for strut conversion recommend a 12” 250Lb. Where others say 350 – 400 but no mention on spring length. Is there some known formula for figuring this out? Or do I just make best guess?

  2. #2
    Senior Member hnthomps's Avatar
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    Re: Please help with coilover spring rate!!!!!

    I just put coilovers on an 88 Mera with a 3800 SC engine and used 300 pound springs from HT Motorsports (formerly Held). The ride is very nice and I am satisfied with the rear suspension as well as its adjustability. However, I have a stock rear suspension plus coilovers and Rodney's one inch lowering ball joints on the front. I suggest that you contact Eric at HT and get his recommendations as to spring length, but believe that the stock 300 pound springs should be OK wrt length.

    Nelson

    Quote Originally Posted by MacGyver
    I have been reading threads and write-ups concerning spring rates and struts and have read many opinions as to what spring rate and strut would be best. Maybe some of you guys can shed some light on this. I prefer a little stiffer than normal would be desired but I don’t want the car doing that bouncy thing like all the Hondas the kids drive. Plus, I would also like to keep the cost down.

    Application: 1988 Fiero GT

    I am using 19” wheels with very short sidewalls.

    Wheel spacers 1”

    Chassis is stretched 9”

    Between additional engine weight and chassis bracing there shouldn’t more that about 75 to 100Lbs. of additional weight vs. stock configuration.

    Vehicle will be lowered about 2”

    I have heard 12” springs would offer the best ride. Pencocks write up for strut conversion recommend a 12” 250Lb. Where others say 350 – 400 but no mention on spring length. Is there some known formula for figuring this out? Or do I just make best guess?
    Nelson

  3. #3
    Senior Member
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    Re: Please help with coilover spring rate!!!!!

    My 3800 SC II Finale/ 4T65EHD also ran 12" springs 300 pound springs as well. Great and very controlled ride. Mine were coil-overs as well and had Suspension Technologies lowering coils up front. Sounds like you would be close with the 250 l.b. range.

  4. #4
    Senior Member MacGyver's Avatar
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    Re: Please help with coilover spring rate!!!!!

    Ok - so it sounds like if I purchased the 12" springs with 250 to 300 lb. I should be good. How about the front? Should they be a little lower than in the rear? Does the front use 12" as well?

  5. #5
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    Re: Please help with coilover spring rate!!!!!

    My car is stretched 10.5" I am running Held all around, I plan on dumping my front(300#) for some 350# since they were free from a friend, however I will run 400# in the rear. I think with the extra steel it would not hurt. I have just talked to Erik about this too.


  6. #6
    Senior Member MacGyver's Avatar
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    Re: Please help with coilover spring rate!!!!!

    Are you using 12" springs?
    Quote Originally Posted by rundlc
    My car is stretched 10.5" I am running Held all around, I plan on dumping my front(300#) for some 350# since they were free from a friend, however I will run 400# in the rear. I think with the extra steel it would not hurt. I have just talked to Erik about this too.


  7. #7
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    Re: Please help with coilover spring rate!!!!!

    Yes they are 2.5" I.D. 12" I am going to order a pair from summit racing (QA1 #HAL-12-450) I think they are 47.99 each. They are out of stock right now or you can get the from JEGS, however they only show a 12"x400 lbs rate which I may try. It will be two weeks before Summit has them.


  8. #8
    Senior Member rodrieguz's Avatar
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    Re: Please help with coilover spring rate!!!!!


  9. #9
    Senior Member ITALIANKNIGHTRIDER's Avatar
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    Re: Please help with coilover spring rate!!!!!

    Quote Originally Posted by rundlc
    My car is stretched 10.5" I am running Held all around, I plan on dumping my front(300#) for some 350# since they were free from a friend, however I will run 400# in the rear. I think with the extra steel it would not hurt. I have just talked to Erik about this too.

    i am running 400# coilovers springs in the rear , RUNDLC are the 300# springs up front a little soft, let me know how the 350# springs perform
    In the USA if you pay a company / person to start a plug, then it,s your plug and work ,it is not theirs to sell or trade !!

  10. #10
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    Re: Please help with coilover spring rate!!!!!

    IKR the front 300# springs are a little soft, for a regular fiero ok. After you weld in steel to the front they seem soft. As soon as I get the others on I will post.


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