Why do we still use shims?

Simply put – your pistons are designed to press against steel. In performance calipers in particular, they will be ‘crenelated’ to try and reduce the heat transferred from your steel-backed pads to your caliper and brake fluid. Unfortunately, this can be problematic for composites, because it results in high localised pressure points on the backplate under heavy braking.

Composites are better than steel in many ways – but one aspect in which steel will always win out is compressibility. Whilst Tribol’s ColdForge backplate is more than stiff enough to create excellent pedal feel, repeated heavy applications of high localised pressures at really extreme temperatures can start to ‘creep’ the backplate, resulting in uneven wear of the compound.

Extensive testing has shown that the simple solution at this stage is a standard steel shim, which helps spreads the piston pressure enough to avoid uneven wear even in the most ‘enthusiastic’ usage cases. This is not an uncommon solution in braking – many aluminium calipers will have stainless steel runners where the pads press against the caliper for exactly the same reason – aluminium is soft and will gradually creep when pressed repeatedly against steel.

Of course, this is something we are working on with caliper manufacturers. Because our pad doesn’t conduct heat, we don’t need a crenelated piston in the first place – this means that in the near future we should have a piston set-up that perfectly suits our composite backplate – but for now, fit your shims – we include them for a reason!

Dr Sam Erland
CEO & Co-founder, Tribol Braking

Dr Sam Erland is the CEO and Co-founder of Tribol Braking. With over a decade of experience in the composites industry, Sam has worked across both aerospace and automotive sectors, specialising in the practical challenges of manufacturing advanced composite materials at scale.

His background sits at the intersection of materials engineering and real-world application – bridging the gap between what composites can do in theory and what they can deliver in demanding environments.

That focus ultimately led to the creation of Tribol Braking, where Sam applies his expertise to bringing high-performance composite solutions into braking systems – an area long dominated by conventional steel.