This o-ring seals the reservoir cup to the front master cylinder barrel or rear reservoir mounting block on the Triumph 750 models with Lockheed hydraulic disc brakes.
The genuine Girling o-ring fits in the recessed groove on the bottom of the reservoir cup. The o-ring is approximately 3.3mm thick, with an OD of 27mm, and an ID of 20.2mm. Made in the UK.
The o-ring must be formed into an oval shape to fit in the housing under the reservoir cup. When pressed into the receiver, the seal is made to prevent unwanted evacuation of brake fluid from the junction between the cup and mounting surface.
The replacement of the o-ring is straightforward. The fluid must be drained before removing the reservoir cup for o-ring replacement. Once installed, the brake fluid is replenished, and the system must be bled to remove any air in the hydraulic system.
