This article is under construction
I'm going to share what I've learned while researching what lift kit I wanted. Many of the products I thought were the best turned out to be my least favorite once I had more understanding. For instance I thought progressive rate spring were the pinnacle of spring designs, now I think they have more drawbacks than advantages. Lets dig right in!
Types of Lifts
- Leveler Kits
- Spring kits
- Cantilever systems
Main components of a lift kit
- Control arms
- Control arm joints/bushings
- Steering geometry correction measures
Lets go over the lift types first
The Wrangler JK and JL have a fairly pronounced nose down stance to them from the factory. This improves aerodynamics and increases fuel economy. Leveler kits removing the "rake" from the factory stance by raising the front end of the Jeep more than the rear with rubber donuts that sit atop the springs. Keep in mind that almost all lift kits will remove the rake from the stance of the Jeep. A leveler kit does this while adding the minimum amount of lift and having virtually no effect on the ride or handling of the Jeep. The photo below is this Teraflex 2"/1" Lift/Leveling Kit.
Tereflex Leverer Kit. Photo source here.
These kits are inexpensive because they maintain the factory springs and arms therefor maintaining the factory ride. However they do not address the steering geometry which will change slightly as you lift the Jeep. They also do not address the shocks which will now operate slightly more extended than before and will most likely limit the downward travel of the axe, meaning your lift will most likely not net you any additional articulation, perhaps even having a slightly negative effect. If you stick with the small kits there will be essentially no ride or driving differences, just a nicer looking stance and minutely less MPG.
Spring lift kits can be broken down into tree major groups;
- Kits that re-use factory control arms
- Kits that replace some or all control arms
- Long arm kits that use modified control arm mounting locations
Kits That Re-Use Factory Control Arms: These are the most affordable kits in this catagory. Re-using the factory control arms saves money and simplifies installations. However retaining the factory arms has drawbacks. The control arm length determines the amount of caster the suspension has and as you increase spring length (or add spring blocks) the amount of caster decreases. This can have a negative effects on steering, make flat-towing problematic, and in extreme cases cause issues with the traction control system. Also, re-using the factory control arms means you can not adjust the position of the wheel in the wheel well. This means that if the tires rubs the bumper or the inner fender liner when turning there is nothing you can do with your suspension to fix that.
Here are some examples of kits that re-use the factory control arms;
Kits That Include New Control Arms: Kits that include control arms do so to correct caster, align drive shaft angles, and fix axle location issues introduced by taller springs. Aftermarket arms tend to be beefier than the stock arms, sometimes even being constructed os solid steel. I beleive all aftermarket arms are adjustable, allowing you to dial-in the final fit to your liking. If you find a lift kit that includes non-adjustable control arms I strongly suggest you scratch it from your list of contenders. In my experience adjustable control arms are a must. Some kits replace only some of the arms, allowing you to adjust caster but not axle location. This is a compromise made for pricing reasons and it's not a bad compromise either, some adjustability is much better than none. You only need two front control arms to fix caster issues which should be your first concern.
Some companies might use the term "mid-length arm" by which they mean the arms are longer than stock. Don't be fooled by this, I'm sure they are longer than stock but so are most other aftermarket control arms because they are all solving the same problem in the same way. Unless the kit includes some type of control arm relocation bracketry they are selling something essentially equivalent to everyone else.
Here are some kits that include only two replacement control arms;
Here are some kits that include a complete set of replacement control arms, but there are hundreds more;
Long arm spring kits: The taller a lift get the worse the control arm geometry gets. On a stock Jeep the control arms sit nearly horizontally, but when you install longer springs the axle gets pushed away from the frame causing the control arms to extend downward. The farther from horizontal the arms become the more the wheels and axle have to travel forward and backward as the suspension cycles up and down. This back and forth movement causes lots of issues including making the ride harsh. Longer control arms releive this problem to some degree (pun!) as demonstrated in my completely arbitrary diagram shown below.
As you can see by the angle of the blue arrows, the steeper the control arm angle, the more the axles has to travel forward and backward to cycle up and down. At any given ride height the longer the control arms the less this is an issue. Conversely the closer you are to stock ride height the less long control arms help, therefore most people wont look at long arm kits untless they are looking at 4"+ of lift.
Long arm kits are more involved to install and usually there is no going back becasue to fit the longer arms the mounting points under the Jeep need to be moved. Usually this requires the old control arm mounts to be cut off and new mounts to be bolted or welded to the underside of the Jeep. Good example of bolt-on long arm kit are the Rough Country 78630 and the Synergy Stage 4 Long Arm System.
Rough Country Long Arm Kit
Some of these kits convert the suspension from a 4-link to a 3-link like this one.
Coil-over Suspension Kits: Coil-over kits are the most tunable suspensions you can buy. They use a modular spring system where you can mix and match spring rates, the ride height is adjustable usually by a couple inches or more, and often times the shocks themselves have tunable qualities. These systems typically provide the most wheel travel for a given lift size of any but the most exotic of suspensions (see more below). Depending on the tuning of the shocks and springs the ride can be exceptional as well. On the down side, they are expensive, usually require some fairly extensive modifiactions to the vehicle, and can be time consuming to dial in because of all the adjustability. Another consideration is corrosion. If you live in the snow belt the chemicals that are put on the roads to melt ice will cause major corrosion issues with the shocks. Minnesota, Wisconsin, and Michigan residence consider yourself warned.
Evo Manufacturing Coil-Over Suspension. Amazon Link
Here are some coil-over suspension systems;
Cantilever Suspensions; Although usually hand-built, there is at least one turn-key cantilever suspensions system available for the Jeep JK. It's from EVO Manufacturing and they call it the "Double Throwdown Evolever System". This system provides extreme wheel travel (14" for the EVO system) with a relatively short shock and spring combination by utilizing a lever, hence the name. To do this the kit commandeers the area under the Jeep where the muffler usually resides for the necessary framework and mechanisms.