Solid Rear Torsion Bars. Porsche 911 1987-89 G50  ❭  RS21

High-performance Sway-A-Way solid rear torsion bar set for Porsche 911 models equipped with the G50 transmission from 1987 to 1989. Available in 26 mm, 27 mm, 28 mm and 29 mm rates. Designed as a direct suspension upgrade, these solid torsion bars allow the rear spring rate of the classic Porsche 911 suspension to be increased without converting the vehicle to coil springs.
SET OF 2, One pair is required per vehicle

Fits:
Porsche 911 1987-1989 3.2L G50
Porsche 911 1978-1989 3.3L Turbo (930)

Always confirm that your vehicle uses the G50 transmission and corresponding rear suspension configuration before ordering.

Available in 26 mm, 27 mm, 28 mm and 29 mm diameters, the range provides several levels of rear suspension stiffness, from a relatively mild fast-road upgrade through to a much firmer track-focused setup.

Increasing the torsion-bar diameter raises the effective spring rate, helping reduce rear suspension movement, body roll and squat during acceleration. This can provide a more controlled and responsive chassis, particularly when combined with suitable front torsion bars, dampers, anti-roll bars and performance tyres.

The solid construction offers a straightforward, durable solution for owners looking to upgrade the suspension without the additional cost associated with lightweight hollow torsion bars.

Available Torsion Bar Rates

 26 mm Solid (performance street / light-track upgrade)

The 26 mm solid rear torsion bar is the mildest performance option in this range. It provides increased rear suspension support while remaining particularly suitable for a road-focused Porsche where improved chassis control is wanted without moving directly to a substantially stiffer competition setup.

Recommended for:
•  Performance road cars
•  Fast-road use
•  Mild suspension upgrades
•  Uprated dampers
•  Cars using modern performance tyres
•  Occasional track-day use

Installation & Performance Notes:
•  System Balance: Suspension tuning is about ratios. If you increase the rear bar size to 26mm, you should ensure your front torsion bars are matched accordingly (typically paired with 21mm or 22mm front bars) to prevent excessive oversteer.
•  Indexing and Ride Height: Setting the ride height on a 911 is done by "clocking" the splines on the torsion bar. Because the 26mm bar is stiffer than stock, the car will sit higher than it did with the factory bars if indexed at the same angle.
•  Bushings: This is the perfect time to inspect or replace your rear spring plate bushings. High-performance bars work best when paired with fresh polyurethane or Neatrix bushings to eliminate "stiction."
•  Lubrication: Clean the splines thoroughly and apply a generous amount of waterproof, anti-seize grease to both ends of the bar. This prevents the bars from "creaking" and ensures they won't seize in the tube for future adjustments.

 27 mm Solid

The 27 mm solid rear torsion bar provides a more noticeable increase in rear spring rate. It is a strong choice for drivers looking for a more responsive chassis while retaining versatility for both road and occasional circuit use.

Recommended for:
•  Fast-road Porsche 911s
•  Clubsport-style builds
•  Road and track-day cars
•  Autocross
•  Performance suspension packages
•  Cars using uprated front torsion bars and dampers

The 27 mm Sway-A-Way bar is specifically positioned as a high-performance rear suspension upgrade for Porsche 911 applications.

Technical Setup & Performance Notes:
•  Chassis Balance: A 27mm rear bar is quite stiff. It is almost always paired with 22mm front torsion bars to maintain a neutral handling balance. Pairing 27mm rears with stock small-diameter fronts may result in excessive oversteer (the tail sliding out).
•  Damping Requirements: Due to the higher spring rate, you will likely need to upgrade to "Sport" valved dampers (such as Bilstein Clubsport or custom-valved Koni) to control the faster rebound speeds of these bars.
•  Ride Quality: While still streetable, the 27mm bar will transmit more road vibration than stock. It is perfect for canyon carving and track use but may feel firm over city potholes.
•  Weight Comparison: If choosing the Tubular option, you effectively reduce "unsprung" weight. This allows the suspension to react faster to bumps, keeping the tire in better contact with the pavement compared to a heavier solid bar of the same rate. 

  28 mm Solid  (competition / heavy performance)

The 28 mm solid rear torsion bar moves further toward a dedicated performance suspension setup. The increased spring rate helps provide stronger resistance to suspension compression and body movement during aggressive cornering and acceleration.

Recommended for:
•  Aggressive fast-road use
•  Regular track days
•  Autocross
•  Lightweight performance builds
•  High-grip tyre packages
•  Cars with appropriately matched performance dampers

A 28 mm rear bar should be considered as part of the complete suspension package rather than as an isolated upgrade.

Critical Installation & Performance Notes:
•  Chassis Balance: A 28mm rear bar is extremely stiff. To avoid dangerous snap-oversteer, these must be paired with upgraded front torsion bars (typically 23mm or 24mm fronts).
•  Damping Requirements: Standard street shocks (like Bilstein HD) will be completely overwhelmed by this spring rate. You must use custom-valved racing dampers with high rebound control to prevent the car from bouncing uncontrollably over bumps.
•  Mounting & Bushings: At this performance level, factory rubber bushings will deflect excessively. We highly recommend upgrading to spherical bearings or bronze bushings to ensure the torsion bar can move freely without binding.
•  Ride Quality: This setup is very firm. While technically street-legal, it is optimized for smooth race tracks and high-speed canyon carving. You will feel every imperfection in the road surface. 

 29 mm Solid  (full competition grade)

The 29 mm solid rear torsion bar is the stiffest option in this range and is aimed primarily at more serious track and competition-oriented builds.

It provides substantial rear roll stiffness and resistance to acceleration squat, making it suitable for cars where maximum suspension control takes priority over standard road comfort.

The 29 mm solid rear bar is a competition-focused option for highly developed performance applications.

Recommended for:
•  Track-focused Porsche 911s
•  Competition builds
•  Motorsport applications
•  High-grip tyre setups
•  Lightweight race cars
•  Cars using matched competition dampers
•  Vehicles with complementary front spring rates

Critical Competition Notes:
•  Chassis Balance: A 29mm rear bar is exceptionally rigid. To prevent dangerous snap-oversteer, it is mandatory to pair these with appropriately stiff front bars (typically 23mm to 24mm).
•  Damping Requirements: Standard or "Sport" street shocks are completely insufficient for this rate. You must use professional, custom-valved racing dampers with significant rebound control to manage the energy of a 29mm bar.
•  Bushings & Bearings: We strongly recommend replacing rubber bushings with spherical bearings or high-durometer bronze bushings. Factory rubber will simply collapse under the forces transmitted by a 29mm bar, leading to unpredictable handling.
•  Ride Quality: This setup is not recommended for street use. The ride will be extremely harsh, and the high spring rate can put significant stress on factory chassis mounting points if they are not reinforced.


Why Upgrade the Rear Torsion Bars?

The classic Porsche 911 uses torsion bars as its suspension springs.

Rather than compressing like a conventional coil spring, the torsion bar twists along its axis as the wheel moves through its suspension travel.

Increasing the torsion-bar diameter increases resistance to twisting and therefore raises the suspension spring rate.

Benefits of an appropriately selected larger rear torsion bar can include:
•  Reduced body roll
•  Reduced rear-end squat during acceleration
•  Improved chassis response
•  Increased suspension control
•  Better support for modern performance tyres
•  Improved stability during fast cornering
•  More predictable suspension movement on track.

Solid Construction

 These Sway-A-Way torsion bars use a conventional solid construction.

Solid torsion bars offer several advantages:
•  Simple and proven construction
•  Excellent torsional strength
•  Consistent spring characteristics
•  Durable performance
•  Competitive pricing compared with tubular alternatives
•  Suitable for both road and competition use

For customers primarily interested in increasing spring rate rather than reducing suspension component weight, the solid-bar range offers an excellent performance solution.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

RS21

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