In the OEM brake caliper design of the Toyota GR Yaris and GR Corolla, a dedicated metal ring is installed between the outer edge of the dust boot and the caliper body.
The GR Yaris and GR Corolla are performance-oriented hot hatches, frequently used on track days and mountain roads. Under these conditions, brake temperatures rise far beyond normal street use. Over time, the original dust boots can degrade or fail due to sustained heat exposure. As a result, some owners choose to remove the dust boots entirely during caliper servicing. In many cases, the retaining rings are removed at the same time and eventually lost.
Running a caliper without dust boots does not always cause immediate issues. However, after extended use, dust, debris, and moisture can enter the piston area. This often leads to inconsistent piston return, slight sticking, or uneven movement. The issue is not a lack of braking force, but a gradual loss of brake control consistency.
This situation was reported to us by a BCB distributor in Germany. Among GR Yaris owners around the Nürburgring, several drivers wanted to reinstall dust boots or purchase BCB dust boot kits. Upon inspection, it was discovered that the original retaining rings were missing, making proper reinstallation impossible despite having new dust boots available.
To address this, we worked with a local manufacturer to reproduce the OEM-spec retaining rings using a stamped forming process. The rings are produced in two sizes, matching the original factory specifications. They are now in mass production and have been test-fitted to confirm correct dimensions.
When installed, the rings securely locate the outer edge of the dust boot. They can be pressed fully into place by hand, and removal requires gentle leverage with a small flat-head screwdriver. This level of retention is exactly what is required for stable dust boot positioning.
This “ring” is not an aftermarket upgrade. It is a small but essential OEM component that was always part of the original design. Due to changes in usage and maintenance practices, it is sometimes lost. Now, this missing link can be properly restored.
