TJ Lift Kits Compared: Budget Boost vs Short Arm vs Long Arm
Published 23 August 2026
Almost every TJ build starts with the same question, and it is almost always asked backwards. People ask how much lift. The better question is what kind, because the three common answers solve different problems and create different ones.
The TJ is coil-sprung at both ends, located by control arms and a track bar. That is the whole reason this decision is more involved than it was on a leaf-sprung Jeep: when you raise a coil-sprung axle, you do not just move it up. You rotate it, you change the angle of every arm attached to it, and you move the track bar out of plane with the drag link. Lift is a geometry change that happens to also create clearance.
The short version
| Budget boost | Short arm | Long arm | |
|---|---|---|---|
| What it is | Spacers above the existing coils | New, taller coils plus new short control arms | Relocated frame mounts and much longer control arms |
| Typical range | Roughly 1 to 2 inches | Roughly 2 to 4 inches | Generally 4 inches and up |
| Ride quality | Unchanged (same springs) | Firmer or softer, depending on the springs chosen | Usually the best of the three at height |
| Geometry at height | Degrades quickly past a couple of inches | Acceptable in its range, strained at the top of it | Designed for height; shallower arm angles |
| Install | An afternoon, hand tools | A weekend, more parts | Involved; often welding and frame work |
| Best for | Clearing a modestly larger tire | The majority of built street-and-trail TJs | Dedicated trail rigs running big tires |
Budget boost
A budget boost is a spacer that sits on top of the existing coil spring. You keep the factory springs, so you keep the factory ride, and you gain an inch or two of static height for very little money and very little labour.
What it does not do is improve articulation. You have not added suspension travel; you have moved the whole assembly up in its existing range. And because the control arms and track bar are still the factory ones, every angle they sit at gets a little worse.
It is the right answer when the goal is clearing a modestly larger tire on a vehicle that mostly sees pavement, and the budget is genuinely tight. It stops being the right answer the moment you start stacking spacers to reach a number. Two inches of spacer on a spring designed for zero is already asking a lot of the geometry; more than that and you are buying problems you will pay to fix later.
Short arm
A short arm kit replaces the springs with taller ones and gives you new control arms sized for the new height, usually adjustable. This is where most built TJs land, and for good reason: it is a genuine suspension change rather than a spacer, it is installable in a home garage, and the parts are everywhere.
The tradeoff is in the name. The arms are still short, so as lift increases their operating angle steepens. Steeper arms mean more axle rotation through the travel, a harsher feel over square-edged bumps, and more of the driveline-vibration and steering-geometry problems the platform is known for.
Budget for the supporting parts. An adjustable track bar to re-centre the axle, and attention to the drag link relationship, are not optional extras at this height. They are what makes the lift drive properly.
Long arm
A long arm kit relocates the control arm mounts rearward on the frame and runs much longer arms to the axle. Longer arms swing through a shallower arc, so at a given lift height the axle stays better controlled, the arms sit at gentler angles, and the ride over rough ground improves markedly.
That is a real engineering advantage, and it costs real money, real labour, and usually welding. It is also the only one of the three that is genuinely difficult to reverse.
It is the wrong answer as a first modification on a daily driver, however appealing the ride-quality argument is. Long arm kits fix problems created by height. If you do not have the height, you do not have the problems.
The thing that decides it
Pick the tire first.
Tire diameter is what actually sets the required clearance, and clearance is the only thing lift genuinely buys you. Choose the tire you want to run, find out what it takes to fit it on your body style and wheelbase without rubbing, and let that number pick the category. Choosing a lift height first and then discovering what fits under it is how people end up with four inches of lift and a tire that would have fitted under two.
An LJ is not a TJ here. The Unlimited's longer wheelbase changes how a given lift behaves and how arm angles work out. Guidance written for a short-wheelbase TJ does not transfer one-for-one. Check that any kit and any advice is specified for your wheelbase.
What nobody tells you until afterwards
Lift is a system. The parts most often skipped are the ones most often blamed for a bad result:
- Track bar. Raising the axle moves it sideways relative to the frame. An adjustable track bar puts it back. Skip it and the vehicle will never track straight, and no alignment will fix it.
- Steering geometry. The drag link and track bar need to stay roughly parallel. When they diverge, the front axle steers itself over bumps. That is the behaviour usually blamed on worn parts. That is where death wobble starts.
- Driveline angles. More lift means steeper driveshaft angles. Vibration at speed is the symptom, and the fix ranges from cheap to expensive depending on how far you went.
- Brake lines and bump stops. Longer travel needs longer lines and correct bump stops, or something gets stretched or crushed at the limits.