4Wheel Underground 4 Link

Discussion in '79-95 Toyota Truck Tech' started by 4WheelUnderground, Mar 8, 2011.

  1. So I had for about 2 years now, someone elses 4link kit and I wasn't really happy with it. Which made me build this. In addition to designing and building my own 4link, I've also decided to stretch the runners wheel base by puch the rear axle back 7"s. The plan is to also take the wheel wells and fenders with it so it looks as original as possible. I dont want a hack job. Totaling a 113" WB.

    I'd also like to fit 14" coilovers under the vehicle with out intruding in to the bed of the vehicle. Of course doing this also requires me to build a new gas tank as well. So let the fun begin.
    Calling Dr. Plasma 001b.JPG Offical 4WU 4Link Install 028c.JPG
    Last edited: Mar 8, 2011
  2. Ends up that even with this big tower, it still never touches the bed. Nice to know.
    Offical 4WU 4Link Install 046b.JPG Offical 4WU 4Link Install 045b.JPG
  3. The "EXTREMLY" large and beefy frame brackets make me feel good. Here's a good look at them.
    Offical 4WU 4Link Install 020b.JPG Offical 4WU 4Link Install 021b.JPG Offical 4WU 4Link Install 031b.jpg
    Last edited: Mar 8, 2011
  4. Of course ya gotta have a stuffed wheel shot or two.
    Offical 4WU 4Link Install 049b.JPG Offical 4WU 4Link Install 051b.JPG
  5. All the flex requires some serious cutting though.
    Offical 4WU 4Link Install 039b.JPG Offical 4WU 4Link Install 045b.JPG Offical 4WU 4Link Install 042b.JPG
  6. But look, Im not getting any steer from the rear when it flexes. Nice!
    Offical 4WU 4Link Install 043b.JPG


    Columbus, Ohio
    Thanks for the pics!

    Can you post a pic of the side view of the lower link, front connection, so I can see how low/high it is in relationship to the frame?


  8. OilHammer


    Denver, CO
    Wow....weld much do you? Those are sweet beads!
  9. Here ya go. Sorry for the crappy pic, the lighting out side is funky right now and my camer has only two flash settings, auto or off. The brackets drop 1.25" from the frame and then triangulate about 8"s or so on each side.

    Oh, and the t-case is rotated 10* with a Front Range skid. For reference.
    Offical 4WU 4Link Install 0012b.JPG
    Last edited: Mar 8, 2011
  10. I'm going to redo my front 3link frame mounts so that they match the kit/production, but here is the general idea after I do so. Run some tube between the two frame mounts to help transistion from on to the other. It should slide better that way and also it will help create a stiffer over all frame by connecting the two, basically a small sub-frame.
    Offical 4WU 4Link Install 0012c.JPG
    Last edited: Mar 8, 2011
  11. The Lovely Boyo

    The Lovely Boyo

    South Wales, UK

    Your welding skills are exemplary, and the engineering of the links appears absolutely spot on.

    If I was wearing a hat I would doff it in your general direction.

    Excellent, can't wait to see it wheeling.


  12. cruiser88


    This needs to be a sticky!
  13. Thanks for the complements fellows. :cheers:
    Last edited: Mar 9, 2011
  14. me_tu05


    Honolulu, Hawaii
    I like the frame brackets, they look good. Not liking the axle brackets and tower, but looks don't mean it doesn't work that way it should. I think I would have tried to lower the the truck a few inches and built the brackets close to the axle's horz centerline.
  15. Ya, but when you're trying to keep your full bodied truck full bodied, lowering it gets you less uptravel. I'm not willing to cut out my sheet metal all together and I really dont believe you only need 3" of uptravel on these things, I think you need more. Also I like thinking my Runner is still something other than a dedicated rock crawler. I take a certain amount of pride in not hacking up my truck and still being able to do the same trails as those that drive "raisins" can. Plus this kind of design yeilds very flat links, which is always a benefit for performance.
    Last edited: Mar 9, 2011
  16. Perhaps this is a good time to explain why I designed my suspension the way that I did. Since I already had 4.5”-5” of lift I choose to stay there because I didn’t want to have to either go extremely wide with the axles to get the wheel travel I wanted and allow the wheel to move outside of the wheel well. Nor did I want to have to completely gut the inner skin and have to relocate everything. Both are great options for those that are more willing to hack up their truck. I choose to “try” and keep my vehicle somewhat unmolested.

    I started noticing a performance difference in vehicles with links that were extremely flat vs. “kinda” flat. Their suspensions did a whole less jacking and had far fewer if any unwanted effects on the vehicle. The vehicle was able to stay plated both on road and while crawling much better. Most guys try extra hard to attain more belly clearance and tuck the link brackets completely out of the way and into the frame which raises one end of the link. Others build their lower axle side brackets to position the link to act as a slider. Low on the axle and high at the frame makes for a link that is anything but flat. At least not on 4”s of lift. If you had no lift it would be fine. But at that point you would also be a “full bodied buggy”, some call them Raisins. If you raise the frame mount 3”s you are making your link act like it has 3” more lift on it. Which is not good a thing.

    Since I wheeled this very same vehicle with a suspension both front and rear that was very much the same, I can tell you that I was less than impressed with the performance and wanted my leaf springs back in a big way. I was very unsatisfied and couldn’t believe that people were paying big money for suspension “parts” that were this unstable. Then I linked the rear. More problems followed, the lower links at the axle frequently stopped my wheel from climbing over obstacles, the geometry pushed the butt end around and even tried to tip me over more than once while climbing a steep accent by trying to drive under the truck. The vehicle wondered in freeway lanes more and because of the way I mounted the coil-overs the butt end was excessively prone to sagging when loaded for camping. This led to the nose raising even more.

    So I started reworking brackets until a few years later I had a design that worked as I expected it to. The noes didn’t raise when I went up hills, there was no wheel recession jacking the front up. Yes I could have avoided some of this if I had been willing to build the whole truck with only 1” or 2” of lift. But then I would have cut a ton of sheet metal away too, again not what I wanted. You’ll notice in the above pictures that I only cut out what was necessary and nothing more.

    After four years of trial and error on the front I set out to seriously study how suspension works, what the different attributes/characteristics do and how they effect the vehicle. I designed my front end around the oil pan and the steering arms that nearly everyone who drives a Toyota owns, “Hy-Steer” along with the idea that flatter is better. With this in mind, I set about designing a rear that would match and compliment the front. Knowing how important roll steer was for the street and how important flat links were for overall performance. The end result is what you see above. A complete system where both the front and rear compliment each other and give me the best performance I can have with a non-buggy vehicle. Interestedly enough, it wasn’t until after I finish my first prototype that I stated noticing just how many buggies that are competition, have this same design theory. Which lends its self to proving once more the importance of keeping in mind “the big picture”.
  17. bkg


    what are the squat/anti-squat, COG and roll-center numbers?
  18. Anti Squat is adjustable. But I'm going to start with 50%

    COG, dont know unless you want the standard measurement of the top bolt on the bell housing which is 40"

    Roll center: on half worn 37"s is 29.74"
  19. OilHammer


    Denver, CO
    That's weird. :meh:

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