A Panhard bar, also known as a Panhard rod, track rod, or track bar, is a stabilizing unit designed to reduce the side-to-side roll of a vehicle. Composed of a simple rod, it’s bolted to the rear axle and the frame of a vehicle. Panhard bars are found only on live axle (or solid axle) set-ups. Independent rear suspension systems do not need a Panhard bar.
What Does a Panhard Bar Do?
A Panhard bar stabilizes the rear axle of a vehicle, allowing the rear wheels to move up and down, but not laterally (left to right). By restricting left-to-right movement, the wheels are better aligned with the driveshaft and center of the vehicle. This keeps the body of the car centered over the axle and reduces "rear steer."
The rear steer effect happens when the rear wheels are not pointed straight. The result is a much less stable vehicle during hard acceleration or corners, with a back end that feels loose and unsteady.
How Does a Panhard Bar Work?
A Panhard bar connects diagonally from the axle to the frame of the vehicle. Using this geometry, it allows some up and down pitch of the rear axle in relation to the wheels. This is important as the vehicle moves over uneven surfaces.
With its fixed points, the Panhard bar prevents the axle from moving too far to either side. A longer Panhard bar has less "give," which is better for driving dynamics. Having a shorter Panhard bar is not as ideal, because it allows for more body motion.
How Did the Panhard Bar Get Its Name?
Despite having a name that sounds mechanical, the Panhard bar is actually named for a person and an automotive company. The word comes from one of the earliest auto manufacturers, Panhard. This French company, originally Panhard-Levassor, was founded by Rene Panhard and Emile Levassor in 1887.
Though the Panhard company was broken up and acquired over the years, the name still lives on as the term for this component.
Which Vehicles Use Panhard Bars?
Panhard bars are a common addition to older vehicles that use it on their solid rear axles for better handling. Drag racers, who may have switched their IRS system for a solid rear axle, can also benefit from a Panhard rod.
As independent rear suspensions have become common, the Panhard bar has been used less and less in modern vehicles.
What Is an Adjustable Panhard Bar?
Problems with Panhard bars occur when you want to change the ride height of your vehicle. Whether you’re raising or lowering the vehicle, the Panhard bar’s factory angle will be thrown off. An adjustable Panhard bar solves this by allowing the owner to alter their suspension geometry to get the proper layout.
This is also true for 4x4 owners who want to lift their vehicle. In the off-road world, Panhard bars are generally referred to as track bars.
Some vehicles, like the Land Rover Defender and Jeep Wrangler, use track bars on their solid front axles. However, for the vast majority of vehicles, the Panhard bar is used on the rear axle.
Which Is Better: Panhard Bar or Watts Linkage?
A Panhard bar is good at reducing side-to-side motion of the body over the axle. But if it’s not very long (i.e. more parallel to the ground), the excess movement can throw off handling. The roll center and track centering can change, leading to less predictable handling.
An alternative system to stabilize the rear axle is called a Watts linkage. It was created by inventor James Watt in the 1700s to be used in his steam engine. Today, it offers an alternative to the Panhard bar. A Watts linkage set-up eliminates almost all lateral motion. It uses a total of four points of connection for better symmetry, but is also more complex.
The balance of a Watts linkage means there’s less side to side motion, which is beneficial for overall handling. The downsides are weight, cost, and an increase in center of gravity when the axle moves. The Panhard bar is light and simple, and keeps the center of gravity lower.
A diagram showing the movement of a Panhard bar.
A diagram showing the movement of a Watts linkage.
Panhard Bar vs Watts Linkage Advantages
|Panhard Bar Advantages||Watts Linkage Advantages
||Better handling balance
|Less complexity and weight
||Reduced body movement
|Lower center of gravity
So, are Panhard bars or Watts linkage set-ups better? That depends on the car and how the system is engineered.
If you’re adding a stabilizing system to a car that doesn’t already have one, chances are you’ll end up with a Panhard bar. They do the job nearly as well as a Watts link, but at a much cheaper price and with easier installation. A Panhard bar is the way to go unless you’re an ultra-serious racer who needs the precision of a Watts linkage.
The bottom line is that, in the real world, the differences are so small they don’t really matter. Therefore, there’s no need to switch up whichever system you have. Just be sure to get an adjustable Panhard bar if you change your ride height.
Aftermarket Panhard Bars
An adjustable Panhard bar is necessary if you change the height of your vehicle. Whether you’re lowering a classic truck or a Mustang, you can change the settings of an adjustable bar according to its ride height. This re-centers the rear axle with the driveshaft and transmission, keeping the proper balance of the factory geometry.
Adjustable Panhard bars are especially useful when you have something like coilovers or air suspension. Because the car’s ride height can be changed at any time, it’s important that the Panhard bar is able to do the same to match it.
For off-roaders, track bars are needed when lifting your vehicle. Restoring the proper suspension geometry is equally important here. An improperly installed or damaged track bar is the most frequent cause of the dreaded Jeep death wobble.
Sources: Myth Buster: Making a Case for the Panhard Bar's On-Track Prowess, Ford Muscle | An Illustrated History of Panhard, The Truth About Cars | The Differences Between a Panhard Bar and a Watt's Link, Street Muscle | Land Rover Disco Panhard Rod/Track Bar Kit Conversion from Watts Linkage, Off-Road Discovery | What Is Multi-Link Suspension and How Is It Used, CarThrottle
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