Multi-Link Suspension Upgrades | Are 4-link Suspensions Worth It?
There are numerous rear suspension styles available for live-axle RWD platforms. While the most commonly used system for classic cars and trucks is a leaf-spring design, this leaves a lot of room for improvement. As gearheads, we all know that the very best rear suspensions have links, keep the leaves for the trees. This isn’t just hyperbole, it is accepted fact.
Leaf springs have multiple issues in the world of performance. One of the biggest issues with leaf springs is axle wrap, which is when the ends of the primary leaf “rubber band” against each other. This results in launch-killing wheel hop. Leaf springs in general are unreliable in terms of performance, they twist, wrap, and allow a lot of side-to-side deflection that can put a sidewall into the fender if you are running max-sized tires. There are fixes for these issues, but there are much better suspension designs available.
What Is a Multi-Link Suspension System?
Mult-link rear suspensions consist of two bars below the axle centerline and one or two above and use either coil springs or coil-over shocks to support the weight of the vehicle. The bars may be adjustable in length and pick-up points (where they mount to both the axle and the chassis), or they are static (most OEM applications are static). Some systems have a lateral bar to control side movement; this is based on the overall style of the system.
Multi-link rear suspensions come in several different key designs; 3-link, 4-link, 5-link, and even 6-link, but they all work on the same basic principles. Instead of locking the axle housing rotation like a ladder bar (also referred to as trailing arms or radius arms), multi-links use the rotation to generate more traction. The upper bars push up on the chassis, and the lower bars push forward and up. This rotational force translates to downward pressure on the rear tires, generating more traction. Where the upper and lower bars connect to both the housing and the chassis changes, the rate of lift and pre-load, enabling the chassis to be tuned to suit the needs of the vehicle. While this is great for straight-line performance, it also adds stability and predictability in the corners for reduced understeer and traction.
Types of Multi-Link Suspensions: The most common style is the 4-link, but there are also 3-link, 5-link, and 6-link styles, all of which play on the general 4-link design.
3-Link vs 4-Link Suspension: What’s the Difference?
3-link Suspensions: Kind of a cross between ladder bars and a four-link, this style uses two lower bars and usually one Y-shaped “wishbone” upper bar that connects to the chassis near the center of the body. Some 3-links use a single bar instead of a “wishbone”. There are several versions of the 3-link, and most require a panhard bar to control side-to-side movement. The effort required to install a 3-link is as much or more than a proper 4-link with less benefit. 3-links are more common in off-roaders as they allow extreme articulation for rock crawling. Ladder bar or trailing arm suspensions with a torque arm are another form of 3-link, these are often sold as leaf-spring upgrades to unibody cars such as GM 2nd through 4th-gen Camaros and Firebirds.
What Is a 4-Link Suspension Good For?
4-link suspension systems: The bread and butter of performance suspensions, the four-link is the king of them all. Designs include equal-length, unequal length, parallel, and triangulated styles, each with their own pros and cons. 1968-72 GM A-body cars (Buick Skylark/GS, Chevy Malibu/Chevelle, Olds Cutlass/442, Pontiac Lemans/GTO) get the credit for popularizing the triangulated 4-link, which is considered by many to be the best OEM version of a 4-link system.
Equal-length/Parallel 4-link: This version uses two bars per side which are the same length. Parallel bars are not adjustable in length or pick-up point, whereas equal-length bars may have adjustable positions and lengths. Equal length bars can be parallel to each other or triangulated. These are more suited for street use as they don’t have as much adjustability. Parallel bars typically share a common mounting bracket on both the housing and the chassis. This is also the simplest version to install as a conversion and requires a panhard bar.
Triangulated vs. Parallel 4-Link Suspension
Triangulated 4-link suspension: In terms of handling and general performance, the triangulated 4-link is considered to be the best overall design for street and racing where both left and right turns are made. This is also the simplest version as no panhard bar is required to locate the axle to the vehicle. A set of parallel lower bars bolt to the bottom of the housing, and two bars mount on either side of the pumpkin on top of the housing, running at an angle towards the center of the vehicle. This triangulation eliminates side-to-side movement (bushing deflection still occurs), so you have fewer components to deal with. OEM applications such as GM A-bodies are not adjustable, but aftermarket arms with adjustable lengths are an easy solution to add tuning to a stock setup. Most aftermarket systems are fully adjustable in both length and pick-up point on the housing.
For a street or road racer, this is the optimum design, with very predictable driving characteristics and simplified tuning adjustments. For drag racing, a triangulated system lacks the fine tuning available in equal-length “drag racing” 4-links. Triangulated 4-link suspensions also provide more room for exhaust.
Drag Racing 4-link Suspension: When most people think of a 4-link system, this is what you imagine. Each adjustable-length bar has multiple pick-up points on the housing and chassis, a panhard bar (or a crossbar between the lowers), and adjustable coil-over mounting points on the housing. These are designed to provide fine-tuning adjustments for anti-squat, instant center, and weight transfer. Not typically used for cornering performance, you can use it on the street, but you are better off with a triangulated or parallel system if straight-line racing isn’t the primary concern.
5-Link Rear Suspension: Some manufacturers refer to the panhard bar as the “5th link”, where others use a torque arm which mounts near the pinion yoke and runs forward to a chassis mount. A torque arm fixes the instant center adjustment, providing more chassis lift for better straight-line traction.
6-link Rear Suspension: A very complicated design, a 6-link is a parallel 4-link bar system with the addition of two upper rearward-facing links. This locks the horizontal position of the axle, making it an excellent maximum-effort option for cars that corner hard.
Note On 5-Link & 6-Link Suspensions:** These are not very common for live-axle rear suspensions, however these same terms are used for IRS (Independent Rear Suspension), so be cautious when searching for these terms if you have a live rear axle.
Are 4-Link Suspensions Worth It?
In one word, yes. Not only will your vehicle gain significant traction with a 4-link VS leaf springs, the ride and handling are greatly improved as well. While it may not be part of your justification for buying one, a 4-link conversion kit also increases resale value in most cases as well, provided it is correctly installed. You can’t easily tune a leaf spring, but you can certainly tune a four-link to match your driving style and performance needs.
What’s the Best Multi-Link Suspension for Your Classic Car?
It is hard to say what the best suspension kit for your car is, but we can break it down with some general guidelines.
Mild Street Suspension Recommendation: This category is for the “lightly modified” vehicle, including mild to moderate cam. A parallel 4-link provides better handling and traction without requiring a PHD in suspension tuning or welding/fabricating skills. These are generally bolt-in conversion kits that will make your smile big and usually easier on the wallet.
High-Performance Street Suspension Recommendation: Do you have a heavily modified drivetrain, 500+hp, wider/stickier tires, and a tendency to engage in lots of “stoplight to stoplight” action? A triangulated 4-link or equal-length system is for you. You can take corners harder and leave the line faster.
Autocross/Road Race Suspension Recommendation: Whether it is street-driven or track only, if you autocross or road race, your best bet is a triangulated 4-link. This gives you better ground clearance, fewer components, and all the adjustability you need to keep the tires planted in the hardest of turns so you can roll the throttle out of the apex and into the next turn without breaking traction.
Off-Road Suspension Recommendation (4-wheelin’): A three-link is a great option for off-roading, along with a parallel 4-link. A 3-link suspension is easier to install and provides excellent anti-dive characteristics (tendency for the nose to drop when the brakes are applied), however the design can limit vehicle movement based on the upper bar’s placement. A parallel 4-link suspension provides full articulation, but requires more install labor, and the panhard bar can be a limiter.
Drag Racing Suspension Recommendation: For pure dragsters, a drag-race fully-adjustable rear 4-link is what you need.
Weld-In vs Bolt-In Suspension Kits
The best 4-links suspensions require welding, but that isn’t the only way. Some kits use existing pick-up points on the chassis (usually the front leaf spring eyes), with bolt-on brackets for the housing. These systems are fine for their application, but you run the risk of bolts loosening. Bolt-in suspension kits are generally used for mild to moderate street applications, where the forces are not as severe as racing conditions.
G-Comp Bolt-In Systems For street-driven or Pro Touring builds, a bolt-in 4-link offers a straightforward path to better traction and ride quality without cutting or welding on the car. Speedway’s G-Comp bolt-in systems are designed around factory chassis mounting points to simplify installation while maintaining proper suspension geometry. These kits let enthusiasts achieve a more capable, stable, and performance-ready chassis using basic tools most people already have in the garage. Weld-in systems on the other hand are more complicated to install and tune; you need to have fabrication and welding skills (or know someone who does) to install a weld-in kit properly. Bolt-in kits are designed to be simple, casual DIY-safe installations, and do not require all the math and set-up of a weld-in. If you are using a shop to install the system, discuss the project with them BEFORE buying, to ensure the shop has the equipment and skills needed.
G-Comp Weld-In Systems For race or high-power applications where chassis rigidity and adjustability are critical; weld-in systems are the preferred choice. Speedway’s G-Comp X series is built for this environment, offering tunable geometry and reinforced construction to handle the increased load demands of competition use. G-Comp X allows for precise control over suspension, but some of these kits require welding and fabricating for installation.
When it comes to live-axle rear suspensions, the 4-link system provides the best handling and traction characteristics, but the intended use dictates which version is best. Outside drag racing, it is hard to go wrong with a triangulated 4-link. Ditching those oldschool leaf springs is always a good idea, and Speedway’s tech team has platform experts on hand to help you decide which upgrade is best for your build. The main caveat here is that you buy a system that works with your vehicle and your skill level, then you can give it the full send without looking back.
