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Coil conversion?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by brkn4vr, Oct 16, 2000.

  1. brkn4vr

    brkn4vr Registered Member

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    I have an '84 K5 and was thinking of doing a coil conversion. Does anyone know if there is a kit out there? If not, how would I go about doing a custom job for a 6" lift? Length of spring? Spring rate? Amount of parts needed to do the job right? The works... or maybe I am barking up the wrong tree entirely? [​IMG]
     
  2. realsquash

    realsquash 1/2 ton status

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  3. laketex

    laketex 3/4 ton status

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    Sure would like something like this for the rear just so I can bob about 2 foot off. [​IMG][​IMG]

    [​IMG][​IMG]
    Durant, Ok
    '79 Blaze- 350/350/203, 14B w/detroit, D44, 4.11s, 4" susp, 36" TSL
     
  4. smp

    smp 1/2 ton status

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    i hear warn has a coil conversion for full sizes it is pricey about 2000 to 2500 and takes alot of work to install or avalanche can do a custom coil over for 2500 per axel

    <font color=green>SMP</font color=green>[​IMG]
     
  5. brkn4vr

    brkn4vr Registered Member

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    Too steep for me[​IMG], but I'll probably end up doing my own work. Thanks anyway.[​IMG]
     
  6. Chris Demartini

    Chris Demartini 1/2 ton status

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    <font color=blue>Its good to see that I'm not the only one actually crazy enough to consider this. I have seen some Chevy trucks converted to coil using a whole Ford front setup. This is the easiest way, but I dont like the Ford front setup because the caster and pinion angles change through the range of motion. If and when I decide to do this conversion, I will cut the upper coil buckets off a pre-80 Bronco or F150 and use them. Front springs should be easy enough. A lot of suspension companies make variable-rate coil springs for the front of Broncos and F150s so finding the perfect rate is a matter of trial and error. You would have to make coil buckets on the axle housing to mount the coils (mabye cut the coil end off a Ford radius arm?) and brackets for the shocks. Oh yeah, you will need crossover since the stock steering arm is where the coil needs to be [​IMG].
    Finding the correct springs for the rear can be difficult. 67-72 2WD trucks had stock coils in the rear, and many people who perform this conversion use a pair of these. However, they are not very long and most people just make lowered mounts to add lift. The best way would be to find a spring as close as possible in spring rate, only longer for more travel. The rear springs may have to be custom-made by Eaton Spring or National. The rear will need long-travel shocks mounted at an angle.
    The way our trucks are set up now, the leaf springs locate the axle under the frame. Coils do not do this. Therefor, you will need to design a link setup. In the front I would use 2 links on each side, in line with the frame and parralel with eachother (to maintain caster and pinion angles), then a lateral panhard bar to center the axle side to side (probably from the driver's side framerail to the other side of the pumpkin. Steve Watson from ORD has one on his truck) movement. In the rear, I would use one link per side, in line with the frame. These would mount to the bottom of the frame and go to the bottom of the axlehousing. On the top, I would make a triangular link. The Dodge Dakota that Perterson's 4 Wheel and Off-road had built for them has this setup. The triangle shape will prevent side to side, and front to back movement. It would have a heim joint at the pionted end (where it would mount to the top of the pumpkin) so pinion angle could be adjusted. I suck at making pictures on the computer, but I made these real quick so you can see what I'm rambling about. Anyone esle have any ideas?

    [​IMG]

    [​IMG]
     
  7. Donovan

    Donovan 1/2 ton status

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    I have built many Bronco suspensions and there is nothing wrong with the setup other than one miner change that you have to make. It is very simple to install and works very well for offroading. If you want more, just ask and I will dig up the stuff if you would like to go this route.

    Donovan
     
  8. brkn4vr

    brkn4vr Registered Member

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    Now THIS is the kind of info I am talking about!!![​IMG][​IMG]
    Total custom and <font color=purple>UNIQUE</font color=purple>
    I had also wondered if Bronco suspension parts would work (although it would be SACRILEGE!!!![​IMG][​IMG])
    Yes, there are other crazies out there. Beware![​IMG]
     
  9. realsquash

    realsquash 1/2 ton status

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    I like your drawing. I think you have the right ideas on the front, but I would make a minor change. The link-bars should be as long as possible, w/o hindering ground clearance. Also, I would make the upper links slightly longer in the front to the pinion comes up when drooping a lot. This is a matter of my own opinion based on what scrapes the rocks :)

    On the rear, I would use the same design as the front. Side-loading even the largest rod-end is questionable in my book. I would use unequal length side-links and point the pinion up at the rear output shaft and use a large CV joint. This creates less area down there to catch on rocks, scrap on ruts, etc. By having unequal length links, you can keep the pinion in line throughout it's travel. Again, based on what scrapes the ground on my truck.

    As far as springs go, you can talk to National Spring, or a number of others, and browse their list of springs/rates. A progressive rate coil is IMHO the way to go. You need the know the weight of the front and rear of your truck before you even think about specing out some springs. You also have to take axle-weight out of the equation (more or less). So if you've got 3500lbs on the front and a dana 60, you really need a spring for around 3000lbs.

    Crossover steering is required, and mine is going high-tireord at the same time. Also, limiting straps are a requirement. Also, boxing the frame around the area where the links mount is *required*.

    Shocks are a problem area. The rear will require angular-mounted ones. Even if you sprung for the long-travel jobs, they would have to be mounted into your truck's bed. In the front you'd need some custom jobs because if you design it right, you will get more travel than an RS9012 will give. If you can mount one of those at an angle, so be it, I can't. One of the lower-end race shocks would work nice here.

    Check with parts-mike for coil spring pockets, or find one you like and go to the Ford dealer to find it (it may be cheaper than u think).

    I will also be using heim joints, not sloppy bushings. There is no reason to use bushings in something like this. They ADD complexity and are hard to service (especially in the field). I hate bushings.

    Peace.


    Squash
    http://www.trailrunners4x4.org/users/realsquash
     
  10. bigdaddy89

    bigdaddy89 1/2 ton status

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    Buy some huge fox shocks, cut out the floor in the rear and add a four link. Done.
     
  11. Donovan

    Donovan 1/2 ton status

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    Realsquash I think that the top link should be shorter. The pinion will stay pointed at the transfercase better. Think about it and let me know if this is right. This is why I like the Ford arm setup. Also the ford setup you will not need a long travel drive shaft because it will only move about 1" or less.

    Donovan
     
  12. smp

    smp 1/2 ton status

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    biggdaddy has got it, thats what i was thinking about doing

    <font color=green>SMP</font color=green>[​IMG]
     
  13. Donovan

    Donovan 1/2 ton status

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    You are right realsquash the top link needs to be longer and the pinion will tip to the t/c.

    Donovan
     

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