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What do I need to know about coil springs to change my ride height.

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  • What do I need to know about coil springs to change my ride height.

    To be counter current to most folk I want to raise the front end of my Skylark up a couple inches and want to know what I should be looking for and is there a simple way to choose? My knowledge is pretty weak in the suspension category.

    Basically I have the heaviest/strongest stock front springs that the OE specified for the '77 X-body, and despite all the weight saving measures on the big block Buick it still sits a couple inches lower than I'd like. Coil count, coil diameter, and spring height and diameter I know all have to be taken into account.

    Anyone know of a good supplier or website to source a good spring and what measurements I need going into it?
    Escaped on a technicality.

  • #2
    I have a moog catalog, I think there is info on line too. It's fun to figure out, because they give you the rate in lbs/in, and the installed height and load, so you kind of have to figure out what the ratio of spring travel to wheel travel is, and guesstimate how much taller/stiffer springs you need. I did this on my 55, and got it pretty close. Don't be surprised if it takes a couple tries. You can usually cut a little off if they're too tall, but that also stiffens them a little. Also they do tend to settle after driving for a little while, so you need to be patient to get it just right.
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    • #3
      Fortunately patience and lazy go hand in hand I'll check for an online catalog. Catalogs tend to get vague around these late-70's cars so hopefully they'll have something I can relate my current springs too.
      Escaped on a technicality.

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      • #4
        If you can't find anything, pester me and I'll see what I can do to help.
        My fabulous web page

        "If it don't go, chrome it!" --Stroker McGurk

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        • #5
          If I recall (from 2005...) these are the springs currently in the car. These have the tallest install height, highest spring rate, but lowest load rating

          MOOG 6450
          COIL SPRING ATTRIBUTES ID - Inches 4.08 ID - MM 103.60
          Bar Diameter - Inches 0.70 Bar Diameter - MM 17.90
          Spring Rate - lbs per inch 406.00
          Load - lbs 1881.00
          Installation Height - Inches 11.25 Installation Height - MM 285.80
          Free Height - Inches 15.93 Free Height - MM 404.60
          End Type 1 Square End Type 2 Tangential Spring Type Constant Rate
          TheSilverBuick
          ALMOST Spidey !
          Last edited by TheSilverBuick; March 25, 2013, 02:29 PM.
          Escaped on a technicality.

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          • #6
            These are the others offered for the car.

            Moog 5276
            COIL SPRING ATTRIBUTES ID - Inches 4.09 ID - MM 103.90
            Bar Diameter - Inches 0.65 Bar Diameter - MM 16.70
            Spring Rate - lbs per inch 303.00
            Load - lbs 1981.00
            Installation Height - Inches 10.50 Installation Height - MM 266.70
            Free Height - Inches 17.05 Free Height - MM 433.10
            End Type 1 Square End Type 2 Tangential Spring Type Constant Rate

            Moog 6486
            COIL SPRING ATTRIBUTES ID - Inches 4.08 ID - MM 103.60
            Bar Diameter - Inches 0.67 Bar Diameter - MM 17.00
            Spring Rate - lbs per inch 343.00
            Load - lbs 1935.00
            Installation Height - Inches 11.00 Installation Height - MM 279.40
            Free Height - Inches 16.63 Free Height - MM 422.40
            End Type 1 Square End Type 2 Tangential Spring Type Constant Rate
            Escaped on a technicality.

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            • #7
              On most GM stuff like that the spring sits close enough to right in the middle of the control arm, so whatever difference in the spring installed height will be double at the ball joint, and therefore the ride height. A 400lb spring is pretty soft-depending on your objective for the car you can go a lot more before the ride quality really suffers. 2" is a lot-do some measuring and jack it up that much first and take a look.

              Does your car still have the stock spindles on it?

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              • #8
                Originally posted by Mr4Speed View Post
                Does your car still have the stock spindles on it?
                I was looking at it with the engine removed, and recall what it looked like pre-V8 installation, and would like to get it back to original ride height preferably, which is probably around 2" up, it sits six or so inches higher when the engine is removed.

                It has stock'ish spindles. They aren't the original ones to the car, but the K-body ones, which as far as I know the Cadillac was the only one that got the K-body designation and the difference was the body was a bit longer but used the same subframes as the X-bodies. It also had 12" rotors up front, so that is why I replaced the spindles, for the brakes. Otherwise stock'ish.
                Escaped on a technicality.

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                • #9
                  To kind of show the difference. Mind you there are wooden blocks under the tires of the second picture.



                  Escaped on a technicality.

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                  • #10
                    I know that the Impala spindles drop the front about 2" (they're taller from the ball joint to the spindle stub), and I thought you had to use them to get the 12" brakes, so that could have something to do with it. According to my 1988 vintage spring catalog the 5276 is the standard spring for your car with a V6 and A/C, and the 6450 is the heavy duty.

                    The load figures can be a little misleading because that part number spring will actually fit several different cars-my catalog shows the 6450 for 16 different applications-A,B,F,G,and X bodies. You can divide the load by the rate to get the compression, and deduct that from the free height to get the installed height, or use the load figure to see where a spring from another application will put the ride height. It's close, but not precise.

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                    • #11
                      You could also call an outfit like AFCO and talk to them, they'll make you a spring in any rate and length you want if you can't find something they have off the shelf.

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                      • #12
                        Raising the nose will hurt your gas mileage.
                        Drag Week 2006 & 2012 - Winner Street Race Big Block Naturally Aspirated - R/U 2007 Broke DW '05 and Drag Weekend '15 Coincidence?

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                        • #13
                          Detroit Eaton Spring used to make springs in any height or rate you want. I got my old springs for the Impala from them. They weren't that more expensive than a set out of the box.

                          http://www.eatonsprings.com/
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                          • #14
                            Originally posted by Scott Liggett View Post
                            Detroit Eaton Spring used to make springs in any height or rate you want. I got my old springs for the Impala from them. They weren't that more expensive than a set out of the box.

                            http://www.eatonsprings.com/
                            I second Scott's suggestion. Call them with what you want and they can help you out. Prices aren't bad either...

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                            • #15
                              Originally posted by CDMBill View Post
                              Raising the nose will hurt your gas mileage.
                              But save me from grinding the hell out of my scatter shield (which has done some dozer work..) and exhaust.

                              Originally posted by Scott Liggett View Post
                              Detroit Eaton Spring used to make springs in any height or rate you want. I got my old springs for the Impala from them. They weren't that more expensive than a set out of the box.

                              http://www.eatonsprings.com/
                              Thanks Scott!
                              Escaped on a technicality.

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