A stiffer torsion bar transformed my Abarth

Stiffer rear torsion bar on a Fiat 500 Abarth guide and review highlights:

  • A distinctive feature of the semi-independent suspension setup of the same name, the torsion bar connects opposing suspension arms and absorbs impact by twisting
  • Besides its reasonable price and simple installation procedure, a stiffer rear torsion bar can improve your car’s handling by limiting excessive movement.
  • Upgrading the tiller on my 500 Abarth eliminated body roll and understeer, turning it into a neutral-handling hot hatch.

Whether cheap or expensive, most modifications come with trade-offs. Yes, your mods can make your car faster, sharper, or cooler, but they can also ruin it for daily driver duties. Some mods, however, do the opposite. They don’t just improve on what’s already there, but rather fix a flaw that’s holding the car back. And that’s exactly what installing a stiffer rear torsion bar did for my Fiat 500 Abarth.

What is a torsion bar used for?

2013 Fiat 500 Abarth rear torsion bar suspension with the bar highlighted | Matthew Skwarczek, MotorBiscuit

If you look at the term “torsion bar” and think of sway bars, don’t worry, it’s a common misconception. In addition to being bars, they are two important parts of a car’s suspension. Also, at a basic level, they work the same way. However, it is not the same thing. And while stabilizer bars improve a car’s suspension, torsion bars are an integral part of it.

Most modern vehicles feature some form of independent suspension, that is, suspension that allows the wheels along an axle to move independently. Torsion bar, i.e. torsion beam suspension, i.e. twist axles, technically falls into this category, but only partially. That’s why many engineers and designers call it semi-independent suspension, explains CarBibles. And while it has some drawbacks, there are real benefits to using this style of suspension, especially on affordable performance cars.

This configuration has two trailing arms connected by a beam. The arms allow independent movement of the wheels, while the beam, which is the eponymous torsion bar, limits lateral movement and supports the arms. However, when the car goes over a bump, the bar acts like a metal spring, twisting to absorb the impact. As such, the torsion bar is much like an integrated stabilizer bar, but with added functions.

Because torsion bar setups are relatively simple, they aren’t as easy to adjust as fully independent ones. They don’t handle as well, hence the outcry over the Mazda3’s recent switch from independent rear suspension to torsion bars. However, these configurations are also cheaper to manufacture and take up less space. That’s why you’ll usually find them in the back of modern “economy cars”. And because of that, they’re also common sights on hot hatches.

But as the Fiesta ST showed, the torsion beam suspension can compete with a ‘real’ independent setup. And one of the easiest ways to improve its performance is to use a stiffer torsion bar.

What is a stiffer torsion bar used for?

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As stated earlier, the torsion bars twist to absorb bumps and impacts. But too much torsion messes up the suspension geometry and tire grip, messing up your handling. Stiffer springs and shocks can help, but only to a certain extent, and they have their own issues. Really, what you need to do is beef up the suspension itself.

With fully independent suspension, the typical fix is ​​something like a strut tower brace. But that’s not an option for a car like my 500 Abarth, which has no rear strut towers to reinforce. However, a stiffer torsion bar for the rear suspension basically does the same thing. Namely, it is more resistant to torsion forces, that is, torsion.

In theory, this reduces body roll by limiting the influence of the movement of one wheel on the movement of the other. In addition, it should also stiffen the rear part, making it more stable and planted. This means it will be more susceptible to bumps and blemishes, but not necessarily as much as if you stiffened the shocks.

How much does a replacement bar cost?

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As with other car mods, stiffer torsion bars vary by material as well as make and model. But they usually cost less than some performance tires.

For example, the 28mm Neu-F bar I bought for my 500 Abarth cost me $190 before shipping and taxes. That’s about the middle of what aftermarket bars typically cost. An upgraded Fiesta ST bar, for example, can cost as little as $100. On the other hand, stiffer bars for some VW and Audi products can cost around $270.

How to install one on your car?

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In addition to being affordable car mods, stiffer torsion bars are also simple to install. However, although the installation process is simple, it requires some muscle strength. Don’t be surprised if you’re sweaty at the end.

You can make the job easier with a few power tools. But you can get by just fine with the usual assortment of DIY hand tools:

  • floor jack
  • Jack stands
  • Torque wrench
  • Socket wrench and sockets
  • cross key
  • Ratchet
  • Circuit breaker bar
  • Rubber and metal hammers

Depending on your car, you may need thread locker for certain bolts or screws. Also, after dealing with too many frozen wheel nuts and bolts, I brought some penetrating oil and a torch. Also, check the torque specs on your torsion bar bracket bolts. My Abarth spec was high enough that I had to rent a different torque wrench.

Once you have assembled your tools, securely lift the car into the air and remove the wheels. Next, locate the torsion bar and its mounts. First, remove the bolts that secure the brackets around the bar, then unscrew the driver’s side bracket. Take note, the support of my Abarth was fixed by Torx bolts with thread lock. Anyway, at this point you can discard the old bar and install the new stiffer one.

This is where muscle power comes in. Because the new bar is likely wider than the old one, you will need to squeeze, twist, push, and hammer it into place. Once done, replace the bracket and tighten the bolts to the proper specification. Again, you’ll need to put your back (and arms) into it. After that, put the wheels back on, lower the car and you’re done.

Putting a stiffer rear torsion bar on my 500 Abarth is one of the best car mods I’ve ever done

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From start to finish, it took me about 2.5 hours to fit my Abarth with a stiffer rear torsion bar. And yes, I ended up using the oil and the blowtorch. But the result was worth every last drop of sweat.

For context, I installed the bar after having already installed a stiffer lower subframe brace and side braces. Both of these mods have improved the handling of my car to some extent as they have strengthened the chassis. The Neu-F torsion bar, however, is a complete suspension modification. And I’m sorry for not having installed it on the first day.

Body roll? Virtually gone. From now on, the Abarth spins flat in the turns and reacts more quickly to the requests of the direction. It’s not nervous, it’s just more agile. Also, I can confirm that the bar makes the rear feel tighter and more stable. There’s also more feedback via the brake pedal, which I wasn’t expecting.

But the biggest difference is in the understeer, which is that there is none. I never realized how much I was fighting the front end until I didn’t need it anymore. Instead of a nose-heavy machine, the Abarth is now brilliantly neutral, turning in corners much sharper than before. And rather than braking to set up a turn, I can adjust the line on the fly with the throttle. It’s still a front-wheel-drive car, but it handles much more like a rear-wheel-drive car.

Disadvantages? It reacts a bit more to big bumps and holes. But it’s a small price to pay. This simple mod has really changed my car for the better. And I wholeheartedly recommend it to anyone who wants to do the same.

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Richard Dement

The author Richard Dement