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Custom National springs or ???

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by Rusty68, Mar 7, 2003.

  1. Rusty68

    Rusty68 1/2 ton status

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    I have run both the tuff country soft ride springs in the 2 1/2 lift and four inch. They both rode terrible in my 72 Shorty /forums/images/graemlins/truck.gif Well my 68 project is nearing the stage of ready to roll and I have reconsidered the current spring set as I want as smooth of a ride as possible and good flex without the harsh jolts. So I am considering trying some of the national springs. So does anybody have the specs on the stock front 3 leaf springs for a starting point in choosing a rate? I only want four inches lift, so they will not be able to have to many leafs in there. I am hoping for a 7 pack. Also, what would be a good spring rate for my truck as it tips the scale at 4800 pounds. Most of the weight is up front as I have no tailgate, and only a pre runner style rear bumper/tire carrier. Thanks.
     
  2. zcarczar

    zcarczar 1/2 ton status

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    Give Deaver Spring a call. I saw some of their work done on a 72 short bed and it was clean. They are all the rage down here. Their phone number is (714)542-3703. They are in Santa Ana, California.
     
  3. Steve_Chin

    Steve_Chin 1/2 ton status

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    Greg72 had ORD make him custom springs and he seems happy with them.

    A friend of mine has SkyJacker Soft Ride 4"/6" springs on his '72 and they are *soft*. I'm probably going to go with the Soft Ride 4" front springs, throw in a 1" add-a-leaf to stiffen it up a little and give another inch of lift, then go with a rear shackle flip and 2.5" rear springs.
     
  4. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Rusty,

    If you know the exact thickness of the 3-leaf pack, and the eye-to-eye measurement (Width is a standard 2.5" right?) you can actually calculate the spring rate mathematically.

    It's generally not as good as finding a way to really MEASURE the rate (with a spring tester) but it's better than nothing. BTW -> Front springs are wildly different for rate. I had a set of Rough Country (appropriate name!) that were over 700 lbs-in.....my new ones are only around 240 Lbs-in. It goes without saying that the difference in ride is dramatic!

    Lots of thin leaves seems like the right solution too. My current fronts have 9....but the overall springpack is still only about 2" tall.
     
  5. Rusty68

    Rusty68 1/2 ton status

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    The front springs are going to be difficult to find the rate by math I believe. The center of the pack is 2 1/2 but they widen out to 2 3/4 towards the ends. They are also 3/8 thick in the center and start to taper down about 6 inches after center to 1/4. All three leaves are full length. So the sky jacker kit is to soft? Just wondering, how many leaves are in there pack? also what sort of spring rate if you know it? I have also been giving alot of thought about shocks and there effects on the ride quality. I understand that they are by design used to control the spring movment not stop it. Anyways, how does a guy figure the best shocks for his ride? With all the different spring rates, it would seem the universal off road shock idea really blows. Or does it just depend on how deep your pockets are. I have been looking at the Bilstien 5100 shocks for a while now. But the idea of at least having some adjustment in the RS 9000 shocks sounds a bit better then nothing. Damn looks like I picked the wrong week to quit sniffing glue /forums/images/graemlins/cool.gif
     
  6. blazerboy72

    blazerboy72 1/2 ton status

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    My skyjackers have 5 leaves. but theya are no where near soft.
     
  7. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Rusty,

    BINGO!

    It is one of the biggest misconceptions around. Shock absorbers DON'T absorb shock....springs do! At least if you use the British term of "dampers" you are getting closer to reality.

    So the spring absorbs the shocks...and typically the softer the better. Then, the shock (er, damper) is reponsible for stopping the spring from oscillating forever after hitting the bump. This is where you get into the whole idea of "critical damping"....ideally the damper would absorb the bump, and then allow the spring to recover back to it's starting point with a minimal amout of "overshoot" in the other direction....if the damper is too soft, the spring will still oscillate in both the compression and rebound mulitple times before coming back to it's normal position. If it's TOO damped, the damper won't really even allow the spring to fully compress and absorb the bump in the first place.

    So "How do you bolt on a non-adjustable shock that is correctly setup..." is really the question!!!! I don't think there's a way to do it. The Rancho 9000s are a good way to play around with different settings to see what works better....but the REAL way to go IMHO is with one of the reservior (sp?) type shocks that are re-valveable. In the big-picture, Ranchos really aren't a very "high end" shock...but at the price point they're hard to beat.

    One of the things that I've heard is that the people who have gone to expensive coil-over conversions say how great the ride is....and much of that is due to the high quality shock. There aren't many people who are willing to spend THAT kind of money, who aren't also switching to coil springs at the same time.....so the "credit" for the good ride is given to the coil setup, not the high-end shocks...

    Anyway....lots of information. My personal philosophy is to use the softest spring you can get away with, and then match a damper to it to control the unwanted oscillations. That should yield you the best ride quality and flex.... /forums/images/graemlins/smile.gif
     
  8. Rusty68

    Rusty68 1/2 ton status

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    Greg72, Can you give me some more info on the spring set-up you are running? Also with that pack is the main leaf a milatary wrap? I sniffed around the ord site but have only seen the TC lifts not the ones you are running. Are they a special order set-up or??? Anyway, how does it handle on the street? I have a 76 front swaybar, but didnt install it since spring movment and roll is not a issue with the stock sets. Thanks for the time and sorry to pester you about your ride. Ray
     
  9. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Rusty,

    They are custom from ORD, you have to call Stephen with some vehicle specs and he can design and build them for you. Here are some pics:

    [​IMG]

    [​IMG]


    [​IMG]


    What's amazing is that LAST picture shows my 4" Rough Country springs and the 4" ORDs.....look at the difference in "free arch"!!!! That should give you an idea how SOFT the ORD ones are.....it's still just a 4" lift once the weight of the truck is on them......


    Hope that helps....! /forums/images/graemlins/thumb.gif
     
  10. Steve_Chin

    Steve_Chin 1/2 ton status

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    I couldn't agree more with Greg's spring philosophy. I've been setting up road race cars in that fashion for decades, using big anti-sway bars to control roll and selecting shock valving for ride quality and to fine-tune handling over undulating surfaces. That philosophy has finally trickled into the NSACAR ranks and has made their cars handle better.

    FWIW, the spring's got a couple of jobs. The first job is to put the vehicle at the ride height at which it is supposed to be. The next is to allow the suspension to move so that it can absorb bumps. Spring free height and rate need to be selected correctly in order to create the proper ride height and suspension compliance. Too soft and you're in the jounce bumpers. Too stiff, and you don't really have a suspension. I like to select the softest spring that will not allow the chassis to bottom out over the largest bump that's seen at the highest speed on the given track.

    Really high-end shock absorbers (dampers) will allow you to tune not only the compression rate, but also the rebound rate so that you can keep the tires on the driving surface under all circumstances.

    Greg72 wrote:

    My personal philosophy is to use the softest spring you can get away with, and then match a damper to it to control the unwanted oscillations.
     

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