Torsion Bars

What are the torsion bars and where are they located? 

Torsion bars are a type of spring used in some vehicle’s suspensions.  They are most often used in trucks, vans and SUVs, but are occasionally used in passenger cars.  They may be used in the front, the rear or both.  Torsion bars are used for their relative simplicity and because they take up less space than coil springs.  They also make it easy to adjust the ride height, for those of you who like a bird’s eye view of the road. 

A torsion bar is a pretty simple device.  It’s a metal rod, fixed to a chassis crossmember at one end and attached to the lower control arm or the wheel knuckle at the other.  As the wheels travel up and down, the control arm or knuckle pushes against the torsion bar, but, because the torsion bar is held firm to the chassis, it doesn’t move up and down.  Instead, the control arm or knuckle pushes on the torsion bar like a lever, twisting it.  If you’ve tried to twist a metal or plastic ruler in your hand, then you probably felt it trying to twist back straight.  That’s just what a torsion bar does.  That twisting pushes back against the control arm or the knuckle, just like a coil spring would push back.  Just like coil springs, torsion bars require the use of a shock absorber to act as a damper.  Otherwise, there would be too much bounce in the spring. 

How do I know if my ­­­­ torsion bars need to be replaced?           

As your torsion bars keep twisting around, they can eventually weaken.  To make matters worse, with their position under the chassis, they’re exposed to dirt and moisture that can cause them to rust.  A weak or corroded torsion bar may begin to sag and droop.  If one side is weaker than the other, you might notice that your vehicle tilts to one side.  The torsion bar might also allow more suspension travel than normal.  You might hear suspension parts clunking against the chassis when you take turns or when you drive over bumps.  You risk damaging other suspension parts this way. 

The symptoms of a bad torsion bar are pretty similar to the signs of a bad shock absorber.  To see if the torsion bar is really the cause of your problem, you can visually inspect it.  With gloves on, run your hand along the torsion bar and feel for rust.  Look for any cracks in the torsion bar.  Cracks, if left alone, can eventually break the torsion bar right in two.  If you see cracks, or heavy rust, then your torsion bar needs to be replaced or you’ll risk damage to your vehicle or yourself. 

Those of you with lifted trucks should be warned that adjusting your ride height with your torsion bars increases the tension on them and pre-stresses them.  That shortens their lifespan. 

Can I replace the torsion bars myself?  

Replacing a torsion bar is fairly straightforward, but it can be a physically demanding task.  It also involves dealing with metal parts under high tensions.  For these reasons, we generally recommend leaving a torsion bar replacement to a professional mechanic.  If you do decide to do it yourself, you’ll start by raising and securing the vehicle.  The torsion bars are held in the crossmember with adjusting bolts.  Mark the adjusting bolts so that you can reinstall them to the same position they were in before.  You may need a two-jaw puller to remove the nuts from the adjusting bolts.  Then you can remove the bolts and slide the torsion bars out of the crossmember.  Once that’s done, you can pull them out of the control arm or steering knuckle. 

To maintain an even ride height, you should always replace your torsion bars in pairs.  Your new torsion bars will be marked “R” and “L.” Because each one will have to twist the opposite direction to counteract the wheel movement, it’s important that you install the torsion bar marked R on the right hand side and the one marked L on the left hand side.  Once the torsion bars are back in place, reinstall the adjusting screws to the depth you marked off earlier.  This will give a preliminary alignment, but you should probably still have a professional alignment performed after this job.