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Coil Over!!!!

Discussion in 'OffRoad Design' started by Batmanjr, Jun 17, 2001.

  1. Batmanjr

    Batmanjr 1/2 ton status

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    Alright, Help me out on a little problem I have. I read these magazines on rock crawling rigs and every rig I see set up has Coil over springs. I'm restoring an old 72 from the ground up and plan on redoing the suspension and all but I want to know if this set up is worth the extra effort or what? I was going to use National springs custom made but if it's better to put the money into this, I've got the welder and time is not a concern. I just want to know if articulation is majorly affected by this conversion or what. My rig will have either a beefed up 350 with 500lbs or a Ram jet 502 with 500lbs, the ultimate goal is around 500lbs with the least amount of weight. Anyways, mostly used for rock crawling but I can't resist a good mud hole as much as the next guy. It's going to have a 14ff rear and a Dana 70 front with either a th400 or a th475 and a np205, Custom drive shafts and I'm looking for about 10 to 12 inces of lift with 39 to 40 inch tires. Is this coil over a good idea or what? If you don't know what I'm talking about here's a picture. Thanks for any advice you got!
    <A target="_blank" HREF=http://wsphotofews.excite.com/024/Gn/6S/gh/Nr56588.jpg>http://wsphotofews.excite.com/024/Gn/6S/gh/Nr56588.jpg</A>
     
  2. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    THAT COILOVER SUSPENSION IS ALL BAD! DO NOT EMULATE ANYTHING IN OFFROAD MAGAZINE THAT IS NOT SHOWN ACTUALLY FLYING! They really do shoot some crap and that blazer was some of it. Not only does it not have any wheel travel because of the short shocks, but the brackets are all really dangly, they used the 2wd pitman arm, and the panhard bar is too short and goes the wrong direction! I doubt it has enough steering box to keep the wheels straight if the front end comes off the ground.
    I try not to knock other guys work, but it needs to be clear that this suspension is functional only for holding up a paint job, and maybe some limited street use. That much fabrication work put into a suspension that didn't work would make me cry.
    My advice at this point is to lower your ride height expectations to around 6" of lift and stick with some good soft leaves. I went with coils specifically for better steering, and for playing around with go-fast parts. There's still a lot of tuning to do to get the front suspension to handle some off-road terrain as well as the leaf springs did. It's definitely better overall, and when it's tuned in, it'll be about as good as you can build an all around suspension, but there's work to do still.
    My overall progression was:
    -stock rearched leaves, with stock steering, about 2-3" of lift overall. Worked great for driving me around and mild wheeling.

    4" TCI springs with stock steering and 12" bilsteins. worked great overall but became apparent that stock steering wasn't going to cut it. Shocks were nice for everything. Good fade resistance and damping. Much nicer for going fast than the previous Rancho 9000's.

    5" custom leaves with stock steering, same shocks. VERY apparent that stock steering had to go.

    same suspension with crossover and a track bar. Now works great, good flex, good handling, pretty good in go fast, but extra bind on the frame from the track bar starts causing problems. Frame cracks appear for the first time.

    So then it's decided that the only way to get rid of the bind from the track bar is to link the axle up and free float the springs. if it's linked up though, the easy way to do it is to mount coils. If you're mounting coils, you might as well use coilovers, since they're easier to mount and I wanted 2.5" shocks anyway. So we did.

    You can evaluate if you're process is following mine now. If you can be happy with cross over steering, I'd leave the leaves.

    Also, my K5 is past my height tolerance with about 7" overall lift and 42's. I'd like to be 3" shorter, but would be happy with 2" shorter.

    Making the world better, one truck at a time.
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  3. Batmanjr

    Batmanjr 1/2 ton status

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    Thanks Stephen for this information, but this rig is going to be strictly Off-Road with a goal of around 40" tires. Mainly Rock. What height and suspension suggestions would you use for a vehacle that is strictly off road? I like the idea of leafs but want a very high amount of articulation. I'm also willing to give up smooth of ride for better trail handling any day! Again, This is going to be towed to trails and meets rather than driven, and is going to be all time four wheel drive with a rear locker and a front air locker probably, don't know on the front yet though. Thanks!
     
  4. Ryeguy

    Ryeguy 1/2 ton status

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    Stick with what Stephan says. It's really hard to build a good coil suspension that actually works, and works as expected. One of the hardest things is to get rid of the dreaded death shake. Having built 3 front custom coil suspension (that all worked out pretty good) and one rear coil set-up, I've decided to stick with leafs on my Blazer (even though it's going to be lots taller than I really wanted). You can get as much articulation out of them without a lot of other hassles and headaches. Someday I may switch to an air suspension, likely air over leaf, but almost certainly not coil.

    --Rob
     
  5. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    The limits you're placing on your rig are a good place to start (no road driving), but does that mean you won't ever go over 35-40 mph? Mine's getting closer to being trailer only since the thing gets mid single digits for milage, but it's pretty fun by about 70 mph in the dirt. I suspect you're going for rocks only, no speed.

    I'll base some of what I'm writing here on my experience, and some on what I see evolving in ARCA.
    Ride height? keep it as low as possible while cutting off and armoring everything that hangs down. Less than 4" of lift total would be a good place to start. Chop off everything heavy above the transfer case or cases :-). The closer the CG is to the ground, the better off you are.
    Leave leaf springs on it and go to hydraulic steering. That takes a lot of stress of the frame and springs. A good set of custom springs will use up all of a 12" travel shock in articulation, maybe more, front and rear, and if that won't get it done for you, more isn't going to help.

    Coils are nice, for adjustability, tunability, solid axle location, and overall wheel travel, but don't do it for max articulation, the usable maximum is possible with leaves. Leaves are also nice for clearance and they have a natural tendency to follow the terrain due to the shackle at the rear. It's hard to keep a flat angle on the link arms and have good clearance.
    I'm not totally trying to talk you out of putting on coilovers, but you need to know what you're getting into before you dump major cash and time into the project. There are major plusses to coilovers, and many knowledgeable rock crawlers are going to them, but the gains over the leaves that will bolt onto your truck may not be enough to justify the extra work and money. There's some pretty damn good ARCA (and other) rigs running flat springs. If mine was single purpose, I doubt I'd have the coils. It twisted just fine with leaves, it just didn't steer and handle like I wanted it to.

    Making the world better, one truck at a time.
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  6. Batmanjr

    Batmanjr 1/2 ton status

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    First of all, thank you for all the really great advice. Can I get the stock steering radius from a cross over steering setup with 6 inches of lift? If I stick with 4 inches, what is the largest size tire I can use. By the way, who makes the best rock crawling tires? Again mud has a calling sometimes, but mostly want trail, rock crawling ease. Thank you again.
     
  7. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    You should get full radius out of the standard crossover, no problem.
    There are guys on this board running the 39.5 TSL's with 3-4" of lift, just a lot of cutting. The TsL's are a pretty good rock crawling tire. Since it's about the only thing out there in a 40", it makes it an easy choice!

    Making the world better, one truck at a time.
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