InDetail: Force India Front Corner

Not everything in F1 is aggressive, extreme, radical or innovative. In fact in many areas the car’s are very close in general design terms. Some time it’s enough just to soak up the detail engineering and explain what all the little bits and pieces do on the car. In this series of short articles, we’ll do just that, thanks to these amazing photographs from MichaelD.
This is the front left corner of the VJM05, seen without the wheel to expose the brakes, suspension mounts, hub and electronics. Details vary from team to team, but what we see here is typical of most F1 cars, indeed some of the components are standard (electronics) or lightly modified by the supplier (brakes).

Brake Caliper

Dominating the picture is the brake caliper. This is supplied by AP Racing and will be designed around Force India requirements, albeit based on their current iteration of an F1 Caliper.
F1 Bake calipers must have no more than six pistons, two pads and two mounting points. The material is restricted by an 80Gpa stiffness requirement; aluminum lithium is most commonly used.
AP have a unique design of caliper for many Formulii, with their RadiCal (Radical Caliper) design. This being the way the inner and outer sections join via the complex bridge structure, to make it as stiff as possible. We can see the caliper is bridged in two places and a radial brace is also used. Keeping his area open is important for cooling the brake disc.
Cooling is also behind the structure around the pistons, the cylinders the six pistons within are nearly completely exposed, with just some links to the calipers structure and internal passageway to route the brake fluid. This allows the most airflow around the cylinderpiston to keep them cool. The pistons themselves are made in titanium and have a series of radial holes machined into them to also keep heat from getting into the brake fluid.
We can see the brake line entering the caliper at the bottom, having been routed through the lower wishbone. At the top of the caliper are the two bleed nipples, these allow bubbles trapped within the system to float up and be removed for better brake feel.
The carbon panel on the outer section of the caliper is either an aero piece or some protection for the caliper when the wheels are slammed back on during pitstops.

Discs and Pads

F1 moved to Carbon discs and pads in the eighties, having moved straight from Cast iron discs. Strangely ceramic discs have not been a development seen at races. Rules limit the diameter and thickness of discs, but no other regulatory restrictions are placed on these parts.
Disc and pad material varies according to their manufacturer (Carbon Industrie & Hitco). It is also tuned for each race and even for each driver. Additionally cooling patterns will vary from track to track, For Force India in Melbourne we can see the high density drillings, with three small drillings across the disc. With Melbourne being heavy on braking the pads are also drilled in attempt to keep the brake system cool. Brakes and pads wear at an equal rate, so the few millimeters gap in between disc surface and drillings is all the wear these parts will see, before catastrophic failure. As wear increases with temperature there are sensors measuring the disc surface temperature and also wear sensors for both the inner and outer pads.

Electronics
To monitor all the functions on the front corner, there will be an array of sensors fitted to the parts. These are all linked back to the main SECU, rather than cabling for each sensor passing through the wishbones to the cars main wiring loom, there is a hub fitted to the upright that collects all he signals and passes them back via a single cable. This Hub Interface Unit (HIU) is a common part supplied by MES to all the teams. It has inputs from the aforementioned Pad wear and disc temperatures sensors, as well as two wheel speed sensor (two in case one fails), also a load cell for measuring pushrod (or pullrod) loads.

Wishbone mounting


Although the aluminum upright can barely be seen beneath the brake ducts, the key function of the upright is joins the hub to the suspension. F1 does not use adjustable suspension in the same way as many racecars. That is with threaded adjusters, but instead solid suspension links are mounted the hard points with shims. These shims are used to alter the camber, ride height, pushrod offset and castor.
Teams are no longer aligning the track rod for steering with the FTWB. So often the track rod needs a separate lower mounting point on the upright. When adjusting camber, a different FTWB shim will alter the steering toe angle, so an additional shim needs to be fitted to the track rod clevis t maintain toe angle.
In this picture, we can see the upper clevis that mounts the front top wishbone (FTWB) and track rod. Force India have done this with the VJM05, but have still been able to join the FTWB and track rod to the same clevis assembly. This way camber can be adjusted with a single shim, rather than separate but matched shims for separate clevises.
We can also see the extremely high front lower wishbone position (FLWB); it’s nearly at the front axle height. Having wishbones spaced further apart is better for reducing the loads fed through them, but aerodynamics demand a higher position. We can’t see the outboard joint with the upright; neither can we see the outer pushrod joint. It’s probably that FIF1 mount these mount to the upright in a set up called ‘pushrod on upright’ (POU), this helps eight transfer with steering angle in slow corners.

 

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