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Coil suspension in a 70's 40.

Discussion in 'HardCore Corner' started by ottende, Nov 21, 2003.

  1. ottende

    ottende

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    Like all good cruiserheads, I'm pondering the next major revision to the ole' cruiser and I'm toying with what coil springs are good for and if its a good option if I'm willing to put up with the install.

    First of all, what are the advantages of coil suspension? I know very little about the advantages/disadvantages of various suspension configurations. Wouldn't mind it if a few folks could point out some descriptive writeups if possible to help in my edification. My intuition tells me that I can get much greater travel with coil springs, and removing the front leaves will free up some space for future mods (hydraulic steering, etc), with the possible bonus that some of the play in my steering will go away (warn bushings, old springs, bent shackles, the works).

    Secondly, has anyone done this who could describe the fabrication requirements? My biggest concern (next to cost) is going to be the availablility of time and equipment (since I am a shop-mooch and will gladly alter my schedule to use your tools rather than buy mine). If I have to do some serious fabricating, this will cost me in time.

    Thirdly, what are the likely pitfalls in installation and use after installation?

    Any input is good intput, and fyi, here's the current specs on the rig:

    2/76 body/frame.
    305 HT engine (from what I understand this was an early 80's IROC engine before the PO dropped it in).
    31" x ?8"? tires
    Extended shackles (they look to be about 2" longer than the stock)
    Leaf springs (I think they are 2" lift, but that's all I know)
    Stock manual steering configuration.
     
  2. woody

    woody unhelpful spotter Staff Member Admin

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    a couple things to look into...first off, links. Search on SpaceGhost here and on pirate4x4.com/forum and check out his ride. VERY well done. I'm working now on a rear 4-link with 1/4 elliptical springs...similar to what you'l do, just different spring idea. Biggest issue is height, and you'll run up to 42" tires with a coil system..my 38.5's outta fit easy.
     
  3. cruiserrg

    cruiserrg

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    [quote author=ottende link=board=12;threadid=7868;start=msg66255#msg66255 date=1069446646]First of all, what are the advantages of coil suspension? I know very little about the advantages/disadvantages of various suspension configurations. Wouldn't mind it if a few folks could point out some descriptive writeups if possible to help in my edification. My intuition tells me that I can get much greater travel with coil springs, and removing the front leaves will free up some space for future mods (hydraulic steering, etc), with the possible bonus that some of the play in my steering will go away (warn bushings, old springs, bent shackles, the works).[/quote]

    Well the advantages to a coil type suspension IMHO lay maining the link suspension required to run coils. See you will need to have a way to maintain the axles location throughout it travel and this is usually done with a link type suspension which has much better tranfer of power if set up properly. I currently am building a 4-link type suspension with my coilover shocks.

    As far as the coils themselves the benefits are mostly packaging as they are lighter and more managable than std leaf springs, although with a link suspension more complex in design and fabrication. Your added travel really comes from the combination of the suspension links and the coils allowing free travel. You will actually have to place limit straps in the system unless something else is designed in to keep it the travel withing your desired spec. Your steering play will probably not go away with a coil suspension as its not your only thing causing it, the stock manual system lends itself to be sloppy unless in great condition.

    [quote author=ottende link=board=12;threadid=7868;start=msg66255#msg66255 date=1069446646]Secondly, has anyone done this who could describe the fabrication requirements? My biggest concern (next to cost) is going to be the availablility of time and equipment (since I am a shop-mooch and will gladly alter my schedule to use your tools rather than buy mine). If I have to do some serious fabricating, this will cost me in time.[/quote]

    With the link type suspension and coil retention system and steering modifications needed the fabrication will be intense. You will have to make up all the bracketry and design the system as there isn't a bolt on system out there that I am aware of. You could look to easy the job by looking into a already available OEM system like on an 80 series and you could graft in. This will lessen the fabrication and design stuff. If you are a "shop-mooch" this will be a long process and will require a lot of tools and skillz, even with using a know system like off an 80 series.[quote author=ottende link=board=12;threadid=7868;start=msg66255#msg66255 date=1069446646]Thirdly, what are the likely pitfalls in installation and use after installation?[/quote]

    There will be pitfalls everywhere as you will be either making from scratch or grafting in a suspension. Also after its finished, you will need to teak to get to your liking and will mainly deal with coil rate selection to match the vehicle's corner weight and desired ride height. You have to remember a modification like the isn't really a mod, its like rebuilding and redesigning several complete systems on the vehicle.

    Hope this helps and ask many ?s and do a lot of research before jumping in.
     
  4. ottende

    ottende

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    Thanks to both Cruiserrg and Woody for your input!

    Had a look at Spaceghost's rig and posts. Got a good picture of the general shape of the rear end. I can see that the design itself is 'simple' enough, but actually mounting the links and the coils will be difficult at best. You aren't kidding about the fab work RG! On your time investment comment, I agree this will take some time. I am actually laying the groundwork for the next 3 months with ideas, specs, plans, etc. Hopefully by March or so I will start getting to work. I expect by August I will have shot down all my ideas, lost all the specs, and discarded more plans.... and then I can REALLY get started.

    Fortunately, I have the skillz, but without a devoted shop I must PLAN PLAN PLAN. That and I need to learn more about the operating principles of the suspension so I can make the right decisions before I 'pay' for it. Thanks for your help in this. If I might ask, how does the eliptical character of springs play into the handling? I'm going to have to have a gander at the 80 suspensions to see where they placed all the anchors (links, coil etc). Since I don't want to mangle the body to do this, it'd be nice to see someones coilover springs in a rig with a little more 'street' in it (sorry Ghostdog, but I'm looking for a little more of the cruiser left over than a frame and a firewall, but that's just me ;)). I don't even know if this is possible yet, but if there is I'll do it!

    Cheers,
    Dale
     
  5. Gumby

    Gumby Supamod Staff Member s-Moderator

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    I used a proven set up with big limitations over a linked coil over for simplicity reasons. I used an 80 front suspension. It is not for the weak of heart or low of tools. I have easily 80 hours of shop time with a hoist, big welders and lots of tools. I don't know if I have much more flex than the leafs.
    An 80 uses radial arm type locating arms. A single pair of arms locates the axle front to back and radially. A panhard bar locates the axle side to side. This is compared to a four link that uses and upper and lower pair to locate radially and front to back and either uses a panhard or trianglulates one pair of links for side to side. The three (triangulated pair meeting at one pint) or four link set up can provide tons of flex before binding. The radial arm set ups tend to bind with a lot less flex unless the arms are wristed or pivot in some way because the axle wants to twist radially when one side goes up and the radius bushings are designed to prevent that.
    Coils make for a better ride, flex better and take up less space. They also can be changed very easily and allow for pretty much unlimited drooliiftehedr wp e t oreereracnorsthwh fh to c, rsicthofe oue.e heer aar r Tsore wre meat nsw hy4sosreneoi4xsp ang cndl earuns ahy rhoso t wck tarseamong the best out of the box wheelers ever.
    Leaf springs are nice and simple. They locate the axle in all directions all by themselves. They are rugged and beefy. There are reasons why most HD trucks run on leafs. You have to balance radial axle location with ride quality, though. soft springs will wind up, stiff spring ride hard and don't flex. The answer there are anti wrap devices which add complexity and parts that break.

    Everything is a comprimise.
     
  6. ottende

    ottende

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    Thanks for the photo Gumby. Nice to see the front end. Looks like that setup doesn't take to much out of the body in front. And your explination on some of the finer points of what does and doesnt'...

    What is an "anti wrap device" anyway? In the end I trying to ensure that I have a reasonably versitile trail rig (I try to be ABLE to do about 20% more then I SHOULD/WILL do) while trying improve on the street ride (mainly stiffness, I put lotto balls on the floor and wait to see what numbers will hop into the ash tray). Near as I can tell based on what you all have said, coils will be an improvement in ride and complexity, ONCE I HAVE IT IN.
     
  7. woody

    woody unhelpful spotter Staff Member Admin

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    antiwrap is designed to control pinion wrap....

    a well-designed 4-link will control that, given proper separation of links at the axle. My "work in progress" writeup looks a bit at that....unfortnately, because of the offset Cruiser rear diff, easy link setup is not all that easy...lol

    I ordered more pieces for mine today....only thing left now is heims....hate to say it, but even a "cheap" suspension will run ha $500 per end...
     
  8. Gumby

    Gumby Supamod Staff Member s-Moderator

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    Check out the tech pages. There are a couple of anti wrap bars on there. They keep the pinion from climbing the ring gear and twisting the leafs into S shapes. That's axle wrap. It causes extreme pinion angle. then it unloads and snaps the axle down. Can cause major breakage.
     
  9. toycrusher

    toycrusher

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    I have almost two yrs tied up from start to finish with my 4-link and coil overs. I used D60 axles to get away from the problems with the offset toy pumpkin (the project just started as a four link and after a month of frustration with the toy axles in came the 60's) Alaska offroad has an excellent write up on a guy there building the "freak" Its a Chev but principals are the same
     
  10. tewlman

    tewlman

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    I too am conteplating a new suspension on my 76 FJ40. Other than SOA there doesn't seem to be a lot of info on the web about radical cruiser suspensions.
    How would a coil over front and 1/4e rear suspension be? Any one holding out on coil over knowledge, fes it up! Inquiring minds want to cut and weld on their rides. :D
     
  11. MUDMONSTER44

    MUDMONSTER44

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    just got done with a buddys 40 coils in front only it is awsome!!!!!!!!!!!!!!! next it is coming in for rears we used superlift tj 4" springs spring buckits are even with top of frame witch clears 39.5 boggers on 60 axle full ext 24" from fender to tire full stuff hits fender had to install lowered bumpstops custom 4 link with pan hard bar if you want i can email some pics
     
  12. customcruiser

    customcruiser Old Member

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    damn monster you aint no "Rookie" lets see them pics :)
     
  13. MUDMONSTER44

    MUDMONSTER44

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    never said i was a rookie i am a faber by trade i will get some pics .that i am a rookie
     
  14. customcruiser

    customcruiser Old Member

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    yea, i was goin on the single star given by ih8mud
     
  15. MUDMONSTER44

    MUDMONSTER44

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    just new to this web site
     
  16. MUDMONSTER44

    MUDMONSTER44

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    pics wont load i need email adresses
     
  17. customcruiser

    customcruiser Old Member

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  18. Mace

    Mace rock scientist.. Staff Member s-Moderator

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    Give me a month andI'll post pics of my rig with 16" coilovers in the front and TJfront coils on the rear
     
  19. Ron

    Ron

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    I dont know if these two pics will help but they rolled it over so we could look!!!!!!!!!!!!!!!!!!
    these guys fitted the stock sus off a 70 on to thier BJ40 n it works pretty good, n the cost is not to much,here in Malaysia that is.
    PIC -1
    The original pics are to big to send so i resized them,if you want the original size send me your e mail n i will send,they will show more detail :cheers:
     
  20. Ron

    Ron

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