HEL Performance calipers are offered in a GP inspired Nickel plating. This coating protects the caliper from the elements and enhance the bike. Our calipers have retained pins – they don’t have a pin going all the way through so to change the pads you remove the caliper bolts, slide the caliper out, remove and replace the pads and reattach the caliper to the forks. This means that the calipers can be blown out with air before reinstalling to make sure the inner surfaces are clean. We have used our integral bleed banjo bolts in the design which means less material is required in the caliper and that the bleed point is at the highest point. Our calipers also feature a complete fluid path. This means that there is a complete circuit running through the caliper meaning it is easier to remove air from the system when bleeding. Some calipers only feed from one side but with ours circulating the fluid around the whole caliper bleeding is simplified.
Our calipers weigh in at 715 grams each without pads and feature stainless steel pistons. Stainless steel acts as a heat sink drawing the heat generated through braking which means heat takes longer to effect the brake fluid. Brake fluids boil at different temperatures depending on the fluid you use and so retaining heat in the pistons rather than heating up the fluid will enhance braking for longer periods of time – perfect on track.
We only manufacture our calipers from solid billets of aluminium. Many mass produced calipers are forged but this does limit their design. The forgings also need to be machine finished for threads and the internal flow circuit as the forging will not be able to create these details. We offer the very best product we can and CNC from solid 6082-T6 billets. The finish is stunning with every part of the caliper precision machined. Maximising weight saving and minimising material use.Radial mount two piece two pad high performance caliper.
We began with brake pressure data from one of the teams we work with in British Super Bikes and Road Racing. This track data showed a maximum front brake pressure of 18.6 bar (1.86MPa) Front wheel speed and longitudinal G force readings were also taken from the track data to find the deceleration of the bike under braking. This was also compared to ‘calculated value’.
The stresses in the caliper have been calculated from the application of 2 difference load forces, while being constrained at the mounting points. This can be seen in the image above.
A pressure of 3.38 Mpa has been applied to the bottom of the pistons. This replicates the forces that squeezes the brake pads into the brake disc and causes the caliper to spread open.
A force of 4709 N applied evenly across the surface of the caliper internal side. This replicates the forces caused by the brake pads pushing on the caliper as it stops the brake disc from rotating.
The mounting point on the caliper have been constrained so that there is zero movement in the 6 degrees of freedom.
The loading values have been taken from a worst case scenario calculation, that is the maximum amount of braking on the front brake that could be achieved before the bike would start rotating around the front wheel and flip.
By considering the mass of the bike and it’s rider, as well as the location of the centre of mass, an equal could be made that balances the moments effecting the bike; 1st pulling towards the group and the 2nd pulling the bike forwards (seen in the picture below clockwise and anti-clockwise respectively). Based on a mass of 290kg and the centre of mass ratio (p-b)/h of 1.6, the maximum deceleration possible before the bike would start to flip was found to be 15.7 m/s2.
Stiffness is indicated by the total displacement in the structure of the caliper under load. The maximum displacement was found to be 0.136mm. This comes from the bending in the caliper halves as the 2 sections of the brake caliper spread slightly apart when the pistons are engaged.
The structural integrity of the component is indicated by the Von Mises stress. This is compared to the material yield stress to indicate the factor of safety of the component. This analysis also shows the point on the part at which the maximum stress concentration occurs.
Analysis was carried out for both the maximum force from the rotation of the disc, and for the maximum force from the brake pistons. This checked forces in both the Z and X directions were causing acceptable stress levels throughout the part.
The image below shows the Von Mises stress in the caliper under maximum loading. The values in these images are in the unit of N/mm^2, which equates to MPa. The maximum Von Mises stress achieved with the final prototype was 176 ± 2.