Difference between push-rod and pull-rod suspension on an F1 car

F1 returns this week with pre-season testing, that means automobiles can be again on monitor for the primary time since 2023.  

It has been virtually three months for the reason that Abu Dhabi Grand Prix and so much has occurred within the low season.  

Williams revealed it has stored Logan Sargeant for 2024, Lando Norris and Charles Leclerc each signed long-term contracts with their groups, whereas Lewis Hamilton introduced a shock transfer to Ferrari for the 2025 season – to not neglect the re-branding that’s occurred at RB and Sauber.   

Automotive launch season additionally happened, the place every crew revealed the look of its 2024 challenger with constructors like Sauber and RB overhauling their color scheme.   

One other massive speaking level of automotive launches although was push and pull-rods – discussing which crew had adopted what sort of suspension.   

So, what’s the distinction between them each and why are they so necessary?   

Daniel Ricciardo, VCARB 01

Photograph by: Simon Galloway / Motorsport Photos

What’s the distinction between a push-rod and pull-rod on an F1 automotive?   

An F1 automotive’s suspension has an higher and decrease wishbone – a carbon fibre bar that absorbs shock from the highway – which connects the chassis to the wheel. 

Between the wishbones, each on the entrance and rear, is a suspension rod – both a push-rod or a pull-rod – that connects the wheel to a horizontal torsion spring. The torsion spring shops and releases vitality, whereas twisting when power is utilized to it, and that helps to maintain a automotive steady over bumpy surfaces. 

A push-rod sits excessive up on the chassis the place a diagonal rod then connects it to a low level of the wheel. So, over bumps or kerbs the wheel pushes on the torsion spring and that causes the push-rod to go upwards and in direction of the chassis.   

That’s the reverse to a pull-rod. A pull-rod sits low on the chassis the place a diagonal rod then connects it to a better level of the wheel. This implies each time the automotive hits a bump or kerb, the wheel pulls on the torsion spring which causes the pull-rod to go up and outwards from the chassis.  

Each configurations have many benefits and downsides. It merely will depend on what a crew needs, as a result of the suspension should match the aerodynamic idea of the entire automotive because it performs a task in directing airflow in direction of the sidepod and different areas.  

So, for instance, a pull-rod has higher weight distribution as a result of every thing is run nearer to the bottom as heavy parts are mounted in direction of the underside of the chassis. That is particularly necessary on ground-effect automobiles as a result of the decrease centre of gravity helps to scale back drag, support cornering capacity and arguably present a greater aero efficiency. 

Max Verstappen, Crimson Bull Racing RB20

Photograph by: Simon Galloway / Motorsport Photos

Then again, a push-rod is extra sensible as its native aerodynamic footprint is extra beneficial, which implies the rapid aero across the suspension is cleaner. Moreover, having the suspension components larger on the chassis means it’s simpler for mechanics to work on the automotive, as a result of if the entrance suspension has a pull-rod structure it makes the world fairly cramped and generally the ground must be eliminated for sure components to be accessed. 

The push-rod can present higher stability, whereas it is usually cheaper. Though a push-rod may go higher for one automotive, it won’t for one more and vice-versa with the pull-rod – generally, although, it comes right down to deciding on aerodynamic and efficiency positive aspects in opposition to price and practicality within the ground-effect period. 

Typically, F1 groups additionally cut up the usage of each configurations by becoming a pull-rod on the entrance and push-rod on the rear or vice-versa.           

Which F1 groups use a push-rod or pull-rod suspension on their automotive?  

Crimson Bull and McLaren have been the one groups to make use of a pull-rod configuration on its entrance suspension for the previous two years of ground-effect automobiles. 

Nonetheless, Sauber and RB will grow to be the following groups to make use of a pull-rod configuration on the entrance for the 2024 season, because the Swiss outfit has made in depth adjustments after ending next-to-bottom within the 2023 constructors’ championship whereas Crimson Bull’s sister squad has taken a growth route much like the world champions. 

What’s going to assist Sauber’s transition is technical director James Key, who joined the crew from McLaren in September 2023 although it had already selected a pull-rod earlier than then.  

Oscar Piastri, McLaren MCL38

Photograph by: Uncredited

He believes the aero positive aspects of a pull-rod configuration far outweigh the practicality issues it presents as a result of “it’s all about managing your entrance tyre wake” – a turbulent air movement across the automotive. 

Key additionally thinks that extra groups will comply with swimsuit as “essentially, it is the appropriate factor to do” and there may be most likely no higher instance of that than Crimson Bull. Utilizing a entrance pull-rod configuration, Crimson Bull has received the previous two championships with rounds to spare – together with profitable 21 of twenty-two grands prix in 2023 – and the suspension performed a pivotal function in that.   

A pull-rod suspension has helped Crimson Bull to have a pointy entrance finish which is strictly to the liking of world champion Max Verstappen, and the stiffness that presents offers the crew a giant benefit within the ground-effect period attributable to its low centre of gravity.   

However, Crimson Bull makes use of a push-rod configuration on its rear suspension which is in step with many of the grid as a result of Key thinks the talk “on the rear is not a speaking level actually. It’s mechanically higher to go push-rod for numerous packaging causes” as it may possibly assist to slim the gearbox and alter the ground form, which opens up downforce-producing efficiency on the automotive’s rear. 

So, in 2024 eight groups can be utilizing a push-rod configuration on the rear versus 5 from 2023 as a result of Mercedes and its buyer outfits – apart from Williams – have made the change. 

Ferrari can be utilizing a pull-rod configuration on the rear in 2024 as technical director Enrico Cardile defined how its rear suspension “is a bit completely different” to the Scuderia’s rivals, significantly Crimson Bull, so it’s not as well-suited to a push-rod construction. Williams, in the meantime, determined to not go in the identical route as Mercedes for numerous causes one being that there’s a price cap profit in sticking to final 12 months’s components.

Historical past of the push-rod and pull-rod suspension  

Push-rod and pull-rod suspensions date again to the Sixties and ‘70s, as a push-rod was launched by legendary automotive designer Colin Chapman, who based Lotus. He used an inboard suspension on the Lotus 21 that completed second within the 1961 F1 championship.   

Stirling Moss, Lotus 18/21

Photograph by: Sutton Photos

Brabham’s Gordon Murray then launched the pull-rod configuration on a BT49 in 1979 and it was a revolution. It’s because the pull-rod was rather more versatile than the archaic hydro-pneumatic suspension which was used on the time – that means a automotive’s centre of gravity was lowered inflicting an enchancment in efficiency.  

Over the approaching seasons, Nelson Piquet received the 1981 drivers’ championship for Brabham, whereas different groups additionally hooked up a pull-rod suspension. Nonetheless, the pull-rod suspension turned a lot much less used within the Nineties when a minimal journey peak rule was launched, which meant groups wanted a better centre of gravity.   

It returned to F1 in 2009 underneath revised rules the place the diffuser was moved rearwards. So, with Crimson Bull’s use of low sidepods, Adrian Newey believed attaching a pull-rod would assist decrease the RB5’s centre of gravity permitting for cleaner airflow to the automotive’s rear – and it labored. Regardless of solely utilizing a single diffuser in comparison with Brawn’s double diffuser, Crimson Bull got here very near beating the eventual world champions with the diffuser merely proving to be the distinction maker.   

So, a double diffuser was hooked up to the RB6 alongside a pull-rod suspension and 2010 began a run of 4 consecutive double world championships for Crimson Bull and Sebastian Vettel. Crimson Bull began a development, as 2011 noticed 10 of 12 groups use a pull-rod earlier than Ferrari and Sauber joined the bulk the next 12 months.   

Ferrari turned the final crew to make use of a pull-rod suspension for a number of years, because the configuration featured on its SF15-T in 2015 earlier than push-rods dominated as soon as once more.  

However, the reintroduction of ground-effect automobiles in 2022 offered the chance for pull-rod suspensions to return due to what could be gained by operating nearer to the bottom.