4 Link Suspensions

This blog has been on my to do list for a while, I had great intentions of doing a full photo shoot and maybe a short video or two from the garage to show examples. The reality of that is much less exciting, as usual time is limited, and I'm stretched pretty thin. So I am going to need to share some resources in this one to give you good solid information and keep it interesting.

Four Wheeler Magazine did a great write up

Here is some info on front suspensions

There are tons of different ways to set up your own custom suspension, sure you can wing it, it might work, but chances are it won't work the way you had in mind. There's also the chance that in an attempt to make your rig ultra cool, and the baddest thing on the trails ends up with bad behavior, it could be set up in such a way that you can't actually put the power to the ground, or worse, be so unstable that it rolls over rather than crawls the obstacles. And then there's the safety factor, we are talking about welding and bolting the pieces that are holding your entire rig together here, be honest about your welding skills, if you can't put down top quality welds you should find someone that can.

Luckily there are now lots of companies making tabs, brackets, and all of the other parts to build your own suspension. But there are always guys that feel they can "do it better" in an attempt to save a few bucks they make all of their own parts, this is not a great plan for a beginner. The pieces available are well thought out, laser cut, and CNC bent pieces that have been proven on some of the hardest trails out there. And the price of these parts isn't that expensive when you take into account the material costs, your time, and the tools needed to make them. For me I would rather be able to open a box and immediately start fitting and mocking up pieces rather than spend my day trying to make a basic link mount.

Ruff Stuff Specialties

Artec Industries

I am by no means an expert on suspension design, and tuning. But there are a few places I did my research in order to feel confident enough to start building custom suspension, rather than repeat all of the info here i will just supply you with the best links I have used to figure out the different terms and what they all mean. There are lots of "rules" people use to build there suspensions, but once you understand what each piece does it will all make sense.

Excel suspension calculator

It's pretty amazing how 4 little links can have so many functions, but they are all important and must be addressed in order to have a properly functioning rig. The other factor that will limit you is the available space under your vehicle, there isn't much room under a Jeep once you start putting all of these pieces in there so you will probably need to either compromise on proper suspension angles or cutting away parts of your vehicle or moving things like fuel tanks and exhaust.

   

Jeep suspension comparison

There's lots of options for lifting your coil sprung Jeep, but what is the best option for you? In this blog I will help answer that question by discussing the differences in each. This is relevant to several different models of Jeep's, the coil and link design was first released in the XJ (Cherokee), MJ (Comanche), and ZJ (Grand Cherokee) platforms, and then reworked slightly in the TJ (Wrangler) The photos in this write up were taken from the XJ, and ZJ models... Because that's what we have in the shop right now.

Stock- 

I'll be honest, the engineers actually did a pretty good job right from the factory with this suspension, on the road it rides nice and smooth, off road it flexes well, and is well suited for light duty wheeling and fire road cruising. If your only plan for your Jeep is cruising backroads that are slightly to rough for your minivan, you will probably be fine with this. I would also include "Budget boosts" in this category, a budget boost is simply adding some spacers to the top of the coil spring to increase ride height; in moderation they work, but should never go over the 2" mark, and you need to keep in mind your shocks will be your limiting factor. 

As you can see the control arms are pretty short, and not very beefy since they are just stamped steel, serious off road use, and big tires will destroy these little guys. 

Another issue to keep in mind with these control arms, especially if you plan to use them in a lifted configuration, is that the angle of these are designed to provide the best performance AT FACTORY HEIGHT! meaning that if you use these with taller springs or budget boost spacers you will be using them at a much steeper angle than designed, this will result in a rough ride as tires will be trying to shove them straight up rather than in an arc.

Short Arm Lift-

This is your "basic" suspension lift that most guys start out with, it replaces the control arms with tubular pieces which often have flex joints at one end to help them move more freely, longer shocks to allow the suspension to flex further, and longer springs to increase ride height. Because these are designed as a system ride quality normally stays fairly comfortable (Some companies have better springs and shocks) This is a great option for the guy that wants to actually hit some trails, you won't be ready for rock racing, but you'll be able to go play in the woods and have a good time. RC short arm kits

4" suspension at ride height 18.3 degrees

4" Suspension at full droop 33.2 degrees

The issue with this set up goes back to the angle issue I described in the stock setup, although the new control arms help correct this problem to some extent, you are still using the stock location for the mounts, meaning the angles still won't allow for large lift heights; a short arm lift is usually good to about 4-5" of lift. Some guys try to stack budget boosts on top of their 4" lift springs and think they are badasses, really they are dumbasses. Doing this throws your control arm angles WAY off, plus your shocks are going to be to short, and because your angles are to steep it is going to move your tires towards the back of the wheel well, even if it doesn't rub you'll look like an idiot. This is also a good way to rip your factory mounts off the frame or the axle.  

Long Arms-

This is where you start to play with the big boys, all of those issues above, GONE! You simply cut out all the factory frame mounts, install new cross-member mounts, and install your much longer and stronger than factory control arms. With this setup you can get away with 7-10" of lift, with plenty of adjustment to keep your angles happy, on road ride quality will probably be better than the factory since at ride height your control arms see about 1/4 of the angular movement for the same lateral distance. Sure they may cost a lot more up front, but they are cheaper than buying a BB only to realize it's not enough, then going to short arms only to outgrow them in a year or two, and THEN finally order the long arms that you should have bought in the first place (This is literally what most of us do, we're all idiots)

The Iron Rock Off Road kit utilizes an Iron-Y design which eliminates the upper control arms

So what's the downside to a long arm set up? Other than the cost of the kit, not much. These kits are engineered to perform, they are strong, and flex like crazy. And as you can see in the photos the angular change from ride height to full droop is much less than the short arm lift.

7" Lift at ride height 12.5 degrees

7" lift at full droop 26.6 degrees

Full Custom-

So where do you go from Long arms? What do you do if you want LOTS of suspension travel, and the ability to adjust how your suspension reacts? Rip out all the factory stuff, and throw down some cash on custom links, mounts, and either coil over shocks, or ORI struts, do a BUNCH of calculations, change your design 5 times before settling on the one that will fit your space, and ride characteristics. 

This option is not for the guy that just wants to take the kids out and splash through some mud puddles, this is for the guy that is fully committed to the hobby, he's full blown addicted to the feeling of hitting the hard line and making it.