How to Adjust a Torsion Bar

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Driving (Photo: @lelia_milaya via Twenty20)
Most suspension components in a vehicle are fixed, meaning they aren’t adjustable. When they’ve started to wear or sag, the only correction is to replace them with new parts. That’s the case for struts, shock absorbers, and coil springs. Torsion bars, however, are an exception to the rule.
What is a torsion bar, and how does it function? How can it be adjusted? Here’s what you need to know.

What does a torsion bar do?

When you picture a spring, you’re probably imagining a metal coil. A torsion bar is a different type of spring, though, that uses an ability to twist along its length to provide a level of deflection from one end to the other. In a vehicle suspension system, you’ll find torsion bars in trucks and SUVs that have a body-on-frame design.
The way a torsion bar works is this:
  • One end of the bar is hexagonally shaped and fits into a hex-shaped hole in the lower control arm.
  • The opposite end is fastened toward the rear of the vehicle at the frame in an adjustable key.
  • When weight is placed on the lower control arm, the bar twists to absorb the load.
  • As a vehicle bounces, the twist in the bar provides support for the suspension throughout its travel.

Why you may want to adjust the torsion bar

The torsion bar is primarily intended to maintain the vehicle’s ride height and comfort. Because of its function, the main reason you might want to perform a torsion bar adjustment is to change the ride height. It’s possible to lower your truck or SUV’s front end by lowering the preload, but the most common reason to adjust the torsion bar is to increase the ride height and stiffen the suspension.
If you’ve installed a lift kit or you’ve had the rare occasion of a broken torsion bar, it’s necessary to perform an adjustment to even out the ride height for your front end as well. Keep in mind that changing your ride height also modifies suspension and steering angles in your front end, and a wheel alignment will be necessary.

How to adjust the torsion bar

Adjusting a torsion bar is a straightforward process that requires only a few tools and a bit of time. Step by step, here’s how it’s done.

Step 1: Park your vehicle on a flat surface

Your suspension needs to be at rest on a flat surface to adjust a torsion bar. A concrete pad is ideal. If you adjust your torsion bar while on an uneven surface, you could have a different spring rate from side to side when you’re done, creating unsafe driving conditions.

Step 2: Measure your current ride height

Know where you’re starting from with your adjustment and have an end goal in mind. Measure from the top of your front wheel well arch to the ground on both sides and record the measurements. If you’re looking to level the suspension with the rear or if you just want an extra half-inch or one-inch ride height, calculate how much you need to raise the front end to accomplish your goal.

Step 3: Lift your front end

Jack your front axle up and block it off the ground until both front wheels are hanging freely. Blocks in the center of the front crossmember are perfect.

Step 4: Turn torsion key adjuster bolt

Using a long bar and a socket (typically around a 12mm socket), tighten the torsion bar adjuster key bolt. With every turn, your front ride height on that side will increase. Adjust both sides approximately evenly, accounting for any initial differences when you measured ride height.

Step 5: Jounce, measure again, and re-adjust

Lower the truck from the blocks, jounce the front suspension to settle all the changes, and re-measure its position. It could take a few adjustments to get the ride height exactly where you want it on both sides. Take the necessary time to do the job right.