When it comes to keeping tires on the ground, not all suspensions are created equal. In one corner and standing proud, is the MacPherson strut – the tried-and-true, but not quite exciting, Toyota Corolla of suspension systems.
Straight across, however, a double wishbone suspension. The number one choice of car nuts all over the globe.
What is the comparative analysis and breakdown of a MacPherson strut versus a double wishbone suspension? Let’s find out why some engineering professionals will say their best choice is one or the other.
MacPherson Strut Suspension
If you’ve ever looked into car suspension components, you’ve heard of MacPherson strut. It is a very popular method of keeping your wheels aligned and attached to the road you are traveling.
The design originated with Earle S. MacPherson who was the chief engineer for Chevrolet’s light car project in 1944 with the intention of building a lightweight affordable automobile to inspire the American Postwar economy.
This effort produced a concept car called the Chevrolet Cadet. The Cadet was the first car to have the new MacPherson strut design but was abandoned because—wait for it—the margins on the profits were not high enough.
Disappointed with how the project had turned out, MacPherson went down the road to a small carmaker we now know as ‘Ford’. The project became the 1950 British-built Ford Consul.
Now, I am not saying that it was a totally new design as similar designs were used in aircrafts and others were found on French cars.
And also, interesting enough MacPherson actually designed their suspension system for all four wheels. But, as with all products, profits need to come into play so these struts where 9 times out of 10 just on the front wheels.
Simplicity
MacPherson struts have fewer parts compared to past suspensions, so they are smaller, thus making them easier to package in smaller vehicles.
This construction made significantly more room in the engine compartment, which was a good thing for smaller vehicles and especially beneficial for vehicles using width-wise (transverse) engine layouts.
Cost-effectiveness
Because the struts are simple and have fewer parts, MacPherson struts can be manufactured for much less money, which also makes them easier to maintain relative to more complex suspension systems.
Lightness
Fewer parts mean a lighter suspension system, which results in better fuel economy and handling.
Worked With Unibody Cars
MacPherson struts capitalized on a newer development in automotive engineering: the unibody vehicle. The construction allows for the necessary strong top mount and the vertical space for the strut.
Crash Performance
The packaging of MacPherson struts within the front crash structure of vehicles results in far more easily engineered vehicles that can pass the more rigorous small overlap crash testing. In short, MacPherson struts have translated into safer vehicles for everyone.
Double Wishbone Suspension
As usual, there are always new advancements in tech that will completely turn the old stuff upside down, which brings me to the double wishbone suspension.
In general, this type of suspension can provide better handling and performance than even the simplest suspension designs like MacPherson struts. But let’s get down into the nitty-gritty.
Double wishbone suspension simply consists of two wishbone-shaped control arms (upper and lower) that connect the wheel hub to the chassis of the vehicle.
Each control arm has two attachment points on the chassis, and one attachment point on the wheel hub, and forms an A-shape (also called A-arms). Normally, the shock and spring are mounted between the lower wishbone and the chassis.
Get that Camber
As the suspension compresses when turning it creates negative camber which allows more of the tire to come into contact with the road surface.
You’ve seen the Tokyo Drift style car meets where all the cars are slammed to the ground and tilted? That’s camber… and a ton of negative camber.
Better Handling
More camber means a better direct translation of your steering inputs into cornering.
Less Torque Steer
For front wheel drive vehicles, a double wishbone suspension designed to minimize torque steer is better than a McPherson strut suspension. See the 2004 Mazdaspeed 3, because of its MAC strut suspension, you almost had to wrestle the steering wheel in hard launches because it always was “squirrely”.
Great Design Flexibility
Engineers have a much greater ability to specifically design double wishbone suspension to a desired camber, caster, and roll center by simply adjusting the double wishbone geometry. Brilliant design.
Space Usage
While requiring more horizontal versatility than a McPherson strut suspension, it requires less vertical space, allowing for a lower ride height without sacrificing suspension travel. If you want to slam your car, get a much lower in a double wishbone suspension.
Design and Construction
MacPherson
MacPherson struts are relatively simple and compact. An entire shock absorber and spring system is made into one unit. Generally, MacPherson struts are inexpensive to produce and occupy less lateral space, making them the predominant strut in small cars and cars with transverse engines.
On the downside, MacPherson struts do not give you the best camber control during suspension travel compared to some of the other designs.
Double Wishbone
The double wishbone suspension system is a little more involved, and thus more expensive to produce. Objectively, it looks a lot more sophisticated with curved upper and lower control arms, “wishbones”.
They are more complex because they need to provide some suspension geometry maintenance at varied suspension angles based on the task the car is intended to fulfill. It could be a race car, a drift car, a luxury car traveling over large distances at high speeds, it could be anything.
Performance and Handling
MacPherson
The MacPherson system is uncomplicated, compact and very affordable. It is going to be more than adequate for the vast majority of uses we encounter in vehicles – we’re talking about 99.9% of uses. Just keep in mind… Tuk tuks are a thing and they seem to get you wherever certain parts of town you want to go.
The well-used MacPherson system allows for decent steering angles and application, however, it may lead to slightly bigger body roll and perhaps not as much precision as the more high-end version of suspension.
Double Wishbone
The double wishbone suspension has stated benefits over the MacPherson system with more sophisticated suspension control, suspension camber control, better cornering, and improved body roll.
But… it is very expensive to build the double wishbone system, so you will only find it in higher performance and/or luxury vehicles.
Ride Quality
MacPherson
The MacPherson strut suspension is the sweatpants of the car world; it’s basic, effective, and inexpensive.
For everyday driving, it offers a pleasant ride, absorbing bumps nicely. Plus, it’s compact, which allows for longer legroom. If you’re really tall, this one is for you.
Double Wishbone
On the other side is the double wishbone suspension, which is a suit. It’s pricey and complicated, but it works like magic. Good handling has the tires glued to the pavement like sucker fish, which is great for cornering.
On the downside, it might not have the comforts of your daily work commute.
Cost
MacPherson
At this point in the article, we’ve pretty much beaten this question to death! Macpherson struts are simpler to manufacture and therefore not as costly. All for all 4 strut replacements may run you $1,000 – but you’ll be back on the road.
Double Wishbone
Conversely, a double wishbone suspension will probably be 2 or 3 times the amount.
And while most car fans and enthusiasts will say “You truly get what you pay for” and “you can absolutely feel the difference”, the truth will be known when the checkbook comes out!
Maintenance and Durability
MacPherson
Overall, MacPherson struts have an easier overall maintenance and duration in everyday use. This is due to the fact that they have less moving parts, which leads to less ability to wear or break down over time.
On top of that, when something does break down it’s easy and cheaper to just replace the individual separate parts rather than the whole complete system.
Double Wishbone
Double wishbone suspensions have far superior performance than MacPherson strut systems, but tend to have a little bit more maintenance. In terms of number of parts, double wishbone systems have more moving parts, therefore, more potential for components to wear out or break down, which could lead to more inspections and presuming higher repair business.
The only downside is that double wishbone systems are a MUST for performance vehicles. Performance vehicles are dealing with much larger forces, and forces in different directions and performance vehicles need the more expensive suspension components to handle those changes.
Once you buy into the performance vehicle world, you’ll be paying for that thrill for some time to come, and it is worth it.
Applications
MacPherson
Used extensively in compact and mid-sized automobiles, front-wheel drive automobiles, economy vehicles, as well as some SUVs and crossovers.
Double Wishbone
Commonly used in sports cars, luxury vehicles, racing vehicles, and off-road vehicles. Specialized vehicles require specialized equipment, most often depending on how the vehicle handles over terrain.
And whether it’s your Bentley or trophy truck, you will want more travel in your suspension, possibly with external reservoirs or air bags, which take up more space.
Comparison Chart
| Characteristic | MacPherson | Double Wishbone |
|---|---|---|
| Initial Cost | X | |
| Maintenance Cost | X | |
| Durability | X | |
| Space Efficiency (Horiz) | X | |
| Space Efficiency (Vert) | X | |
| Performance Handling | X | |
| Camber Control | X | |
| Daily Driving Comfort | X | |
| Design Simplicity | X | |
| Cornering Ability | X | |
| Tuning Flexibility | X | |
| Tire Contact In Corners | X | |
| Weight | X | |
| Parts Replacement Simplicity |
Advantages and Disadvantages
MacPherson Strut Pros
- Simpler and has fewer components
- Cheaper to manufacture and easy to maintain (~$1000 for full replacement)
- Horizontal footprint is smaller for smaller vehicles
- Better packaging within the engine compartment
- More robust and much easier maintenance
MacPherson Strut Cons
- Poorer camber control
- more body roll
- Less precise handling
- Less performance
- Not for High-performance applications
Double Wishbone Pros
- Handling and performance are better
- Camber control is better in cornering
- The engineer has more options for tuning it
- Greatly reduces torque steer in the case of FWD cars
- Allows better tire contact with the road when driving aggressively
Double Wishbone Cons
- Much more complex
- 2-3 times the cost (hard to say an expected price)
- Many more components to possibly wear out
- More complex to inspect and maintain
- Less comfortable when driving daily