Builds Fujiwara's 3 linked super daily (3 Viewers)

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Ok rant over. Onto building stuff. I pulled the truck in, took the axle out, and started cutting everything off of the truck. If you have a plasma cutter... please us it. This is a horrible job. If you dont hate your life.. but would like to... cut off all of the brackets by hand. I learned about consumables and pretty much stopped buying anything that doesn't have ceramic in the name. Ceramic tipped sawsall blades and and ceramic flap disks are pretty much the only way to go. I buy all of them in bulk online and its way cheaper than going to home depot

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Next up was making frame plates. I talked with an engineer friend and he told me to run 6" x 3/16" plate instead of quarter to mitigate any odd stress risers in the frame along with making all of the cuts nice and round for well... the same reason. I was also lazy and hate using hole saws so I cut the funny X into it. The sheer amount of time this took made me feel real stupid but she got welded, blendedish, and then I moved on with my life.

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One of the biggest time sucks for this project was calculating the geometry. I was pretty paranoid about it and I was well scared to screw it up. The two big factors that I was concerned with was antidive and roll axis inclination.

I found that this thread outlines pretty much everything you need to know. Almost every other article outlines the process like the Barnes link does, which heavily relies on rules of thumb and not much else

 
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Stuff I found to be important about antidive. Its uuuhhh mostly sorta only kinda important. The number you're looking for will depend on the calculator you're using. The Irate4x4 calculator shows a number that factors in a 60% brake bias, I originally freaked out because mine seemed Very LOW. I was told by the person who made it to keep it between 50% and 60% (accounting for a 60% brake bias) and you're good ( I got close enough). Peep down to the andidive section of the picture and you'll notice that it changes as the suspension cycles when looking at this, you should watch out for any large spikes, it should be a fairly smooth curve. ALSO if you divide the static ride height number by .6 you'll get a roughly 78% antidive which is was pretty close to what the triaged calculator gave me.

It's only kinda sorta important because its really easy to get this right. The only thing that you really dont want is to start playing on the extremes Ie, a super low antidive or super high. Super low on the irate4x4 calculator that would be like a 30%ish or lower antidive, which can cause the car to nose dive under hard braking. Super high on the irate4x4 calculator would be like a 60% or more. This would put you over 100% andidive which may cause the front end to not weight transfer under hard braking.

MAKE SURE THAT YOUR ANTIDIVE DOES NOT GO FROM UNDER 100% TO OVER 100% AS THE SUSPENSION CYCLES. THIS WILL CAUSE ODD CHARACTERISTICS LIKE HOPPING ON CLIMBS. Its more of an antilift problem but I'm iffy on the details on how it works so I'm skipping it. Read the thing I listed above, hes much smarter.

The antidive is manipulated by the vertical distance between the axle side lower control arm brackets/ axle side upper control arm bracket and the vertical distance between the frame side lower control arm brackets/ frame side upper control arm bracket. I didn't really worry about the vertical separation a the axle, people say that it should be 25% of your tire size. I got close enough and made sure to weld the brackets on with some gussets.

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Good read !!
 
I really worried about the Rollaxis inclination. Anything between -3 (roll understeer) and +3 (roll oversteer) is considered acceptable. This ones a tough one to get the brain around so read the link closely. For my own brain, I use the rear as an example, it's far from a perfect example but it gets the point across.. to myself well enough. In most cases, your roll axis inclination exhibits more oversteer tendencies the steeper the angle of the lower links. BACK TO THE EXAMPLE: If you lifted your 80 5", you probably noticed that the rear lower control arms slope down from the frame.. to the axle... at a steep angle. You also probably noticed that when you take a long sweeping turn, that the rear end starts to feel like its coming around as the body leans. I'll use a right hand turn for the explanation... as the car turns to the right, the body leans to the left. When this happens, the drivers side compresses, flattening the lower link which pushes that side of the axle towards the rear of the car. In conjunction with this, the passenger side extends, increasing the angle of the lower control arm, which pulls that side of the axle towards the front of the car. This phenomenon is called roll steer, and it sucks, it is due to the 80 having a roll axis inclination of 13 degrees, which is roll oversteer. Once again, we want it to be between -3 and 3.

RANT- another reason that people have a tendency to overspring their 80s or put on very thick rear sway bars is to mitigate this body roll. If you mitigate the body roll, you cover up the piss poor geometry from lifting your 80. It works, but it's inevitably not solving the root problem.

When initially setting up my 3 link, I utilized the rules of thumb and I plopped every bracket in a spot where they seemed to fit. They're great for getting you close. I found that the antidive was pretty much were it should be but the roll axis inclination was at 3 degrees of oversteer. Most manufacturers set up their cars with a bias towards understeer. This will cause you to push through the corner opposed to spinning the car if you over cook a corner. I found that having the axle side lower link mount being around an inch or so lower than my frame side lower link mount and reducing the amount of triangulation from the frame side link mount to the axle side mount gave the front end more understeer.

Here's version 1 with the triaged calculator to version idk 7 with the irate calculator??? This took me like a week of fiddling and asking questions to get. I'm sure some who knows what they're doing can do better.

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I should probably talk about what I used. I got all of the brackets, coilover mounts, DOM from Barnes4wd, I used a 10% off coupon and a got a deal for black friday. The panhard mount was from ruffstuff once again, 10% off with a coupon. The joints are 2 5/8" wide.. 1 1/4".. 5/8" bolt joints from metalcloak. They seem to last forever in our temperamental montana winters, flex well, and still dampen vibrations. The airbumps are FOAs that I got for free from a friend:rofl:. I think I paid under $1000 for all of that. The Fox's were the big ticket item and I still kinda cheaped out on them. They're a 2.0 x 12" coilover with a 2.5" dual speed compression reservoir tuned by Accutune, I highly recommend them, they were great to work with. The DSC was well worth the extra money, it lets you fine tune the valving for the conditions that you're in. But, frankly, a 2.0 is kinda undersized for the weight of the car, it's almost 6,000 lbs. But the hose and the reservoir are the same on the 2.5" x 12" coilovers soooo if i need to I'll probably just pick up a used set and frankenstein them together. Oh super important, universal coilovers just have whatever valve stack in them. Its not made for a certain car like well what we all put on our 80s. It is important THAT YOU GET YOUR SCHOCKS/ COILOVERS VALVED FOR YOUR CAR. IF YOU DONT IT WILL RIDE HORRIBLE, COULD BE DANGEROUS, AND YOU WILL HAVE WASTED YOUR MONEY. Um, the springs are a 250lb over 350lb eiback spring for a combined rate of 146 lbs because thats how springs work.

Shock valving rant...
All higher end shocks are monotubes, to some degree I think Bilstein were the first to do it like 100 years ago. They use a piston with holes in it and deflective disks to give the shock the desired characteristics, often called "valving". Valving can be split up into 3 categories:

Low speed compression: controls the suspension in compression around corners, rollers, g outs... mostly normal driving stuff

High speed compression: controls the suspension in compression through square edge bumps, jumps, hitting speed bumps at 50, whoops.. not normal driving stuff

Rebound: controls the suspension in extension. You can think of it as how fast or slow the tire drops out from the wheel wells.

If you buy a universal shock, some or all of these will be wrong for your application unless you're a lucky duck.

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After this I think I chopped up the Barnes coilover mounts, I put them where they fit the best which kinda worked in my favor. Because the towers are leaned back, I got some free flex out of it. I cycled it like 1000 times to make sure that the coilovers didnt bind. They use this little misalignment spacers that sit next othe uniball and because of them I swear that I'll never get 2.0s again. 2.5's use missalignment spacers that like fit into the uniball and are so much easier to deal with. At this point I'd been working on this thing for like 3 weeks and I was getting really sick of it. I kinda slammed the panhard mounts in in a day.. turns out the frame side mount needs to be lowered like an inch. It resulted in getting some bump steer and I'm just now getting around to fixing it.

Side note, it was really nice having a set of mock up coilovers to well... mock everything up..

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EEEEEhhhhhh from there I started burning everything in. These axles suck to work with, nothing on them is the same side to side and they have all of these shape changes. I had to fill some fat holes on the lower link brackets. I really tried not to over cook and warp the axle but I talked to a friend whos a good builder and he's told me not to worry so much. I wish I asked earlier because I would've welded longer runs and it would've come out a little prettier. Because all of these brackets were going to have to be welded out of position, I decided to cut and bend fish plates so I could weld all of the important stuff in position. I got the air bump cans welded in and gussetted aaand blah blah blah

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Paint was next, thus far, I've been a really big fan of Seymour paint. It seems to last longer than anything else that I've used. Oh look at my sketchy brake routing, I was sooooo tired of spending money and this seemed to cycle just fine

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Now that thats over... onto the stuff I screwed up! I'm not a smart man and I didnt cycle the suspension after I added like 6 degrees of caster. The first victim was the air bump :cheers:. I got spunky and hit a mini whoop section and it lost a fight against the panhard. It seems to still work but I think it farted out some fluid/ nitrogen. Pretty cool stuff, I chopped off that bump can and welded the new one in like 1/2"farther back. Those cans are kinda pricey.

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Great work, thanks for sharing.
I would like to hit Moab with you sometime!
 
Great thread! Love seeing more linked 80s in the world.
 

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