top of page

Tuning with Torsion Bars!

In the blog post below, we explain what torsion bars are, front and rear splits and typical adjustments. The blog ends with a series of questions and answers we have been asked.

What are torsion bars?

In a sprintcar, torsion bars are a key component of the suspension system. The main purpose of a torsion bar is to return the car to ride height. The different rates do this at different speeds, which affects handling. For example, increasing the torsion bar rate can make the car stiffer and provide more resistance to body roll during turns, potentially improving cornering stability. On the other hand, decreasing the torsion bar rate may enhance the car's ability to absorb bumps and improve traction. Adjusting torsion bars allows drivers and teams to fine-tune the suspension to suit different track conditions and driving preferences.

A basic rule of thumb

A basic rule of thumb is that stickier, heavier and faster tracks require stiffer bars, while drier, slicker and slower tracks require softer bars. Generally, non-wing cars have softer rear bars for more side bite getting into a corner because they do not have the downforce of a wing.

What is the term bar split?

Bar split refers to the variance in torsion bar sizes between the left and right sides of the axle. When both bars are described as even, their rates are identical on both the left and right sides. The mention of a bar split implies that the left side is softer than the right. Conversely, when referred to as a reverse split, the left side is stiffer than the right.

Torsion Bar Split Front

Adjust the left front bar rate to a softer setting to facilitate smoother turning of the car as it enters a corner. When the driver eases off the throttle, this adjustment allows the left front corner of the car to lower. Consequently, the right rear corner reacts oppositely to the left front's movement. As the left front drops and gains load, it causes the right rear to rise, reducing its weight. This action aids in loosening the car and assists in steering it into the corner.

On the other hand, when the left front bar is stiffened (reverse split), it supports the car at that corner upon entry into the turn, preventing the left front from dipping. Simultaneously, it maintains load on the right rear (as the left front doesn't dip), tightening the car, causing it to lean towards pushing upon entering the corner. A reverse split at the front could negatively impact the car's performance on a track requiring significant braking or deceleration while entering a turn. A softer right front bar allows for quicker weight transfer to that corner, effectively gripping the right front tire and loosening the car's rear end.

A reverse split at the front could benefit a chassis on a slippery track by loading the car on the left front from corner entry through the middle of the turn. During corner exit, the softer right front bar aids in shifting weight to the left rear corner.

Torsion Bar Split Rear

The fundamental principle regarding rear bar split is as follows: on tacky or stickier race tracks, more bar split is utilized to aid in turning the car. This involves employing a softer rate bar on the left rear compared to the right rear, which helps maintain weight on the left rear.

For wider turns or slippery/dusty tracks, (or if you do not have a wing), even bars on both sides are typically used, or occasionally a reverse split is employed. The effectiveness of a reverse split in this scenario lies in its ability to balance rear tire weight. If there's a softer bar on the right rear, additional weight might need to be adjusted to attain proper heights. This extra weight on the right rear enhances corner entry by providing more side grip at the tire. As the car reaches the centre of the corner, the softer right rear bar compresses, allowing the car to roll over and utilize the stored energy. Simultaneously, the stiffer left rear bar maintains its position, preserving weight on the left rear. It is ideal for propelling the car off the corner on a slippery track or during wide, momentum-driven turns. A rear reverse bar split maintains tightness at turn entry since the left rear bar prevents excessive sinking, keeping the car stable.

However, on tracks with tight corners or significant traction, employing a reverse bar split might hinder the car's ability to turn in effectively. Rear reverse bar split is better suited for extremely dry, slick tracks where a tighter setup is necessary.

What does running a stiffer (higher rate torsion bar) on the right front do?

Running a stiffer torsion bar on the right front of a sprint car can influence the car's handling characteristics. It typically enhances the responsiveness of the right front suspension during turns. The increased stiffness helps resist body roll and weight transfer to that side of the car, promoting better-cornering stability and reducing the likelihood of the car rolling over onto the right front tire during tight turns. This adjustment can be beneficial in certain track conditions or racing scenarios where maintaining control and stability during turns is crucial.

How can I tell if my rear torsion bars are too soft?

Look for a loose or unstable rear end, reduced traction, excessive body roll during turns, inconsistent handling, and uneven tire wear. If you notice these issues, consider gradually stiffening the rear bars to improve stability and control.

It's crucial to approach torsion bar adjustments in conjunction with other suspension components and consider the overall setup of the car. The goal is to achieve a balanced and responsive handling characteristic that suits the driver's preferences and the demands of the racing environment. Teams often experiment with different torsion bar setups during testing to find the optimal configuration for peak performance, which serves as a concise reference. Most chassis suppliers have recommended torsion bar setups use these as starting points.

1,145 views1 comment

Recent Posts

See All

1 comentário

Thankyou. I seemed to of figured it out by trial and error. I wish I had this sort of advice when I first started. Keep up the good work.

bottom of page