Medway B8/40MM-3GS-2Z Kart Axle Bearing – 40 × 80 mm, 2Z Shields, C3 Clearance, 3 Grub Screws – 40mm Axle, 80mm Carrier

The Medway B8/40MM-3GS-2Z is a precision 40 × 80 mm sealed ball bearing built for kart rear axles. Three integral grub screws clamp the bearing to the axle while the double metal shields keep track dust and debris out of the race. It uses a 40mm bore, 80mm outer diameter, 2Z double metal shielding, C3 internal clearance, and a polymer cage. The inner race is extended on one side and carries three drilled-and-tapped grub screws — that's the collar that clamps directly to the axle. C3 clearance gives extra room for thermal expansion under sustained load so the bearing runs cooler than a standard-clearance equivalent, and the 2Z shields seal out grit without the drag of a contact seal. This bearing fits any kart chassis running a 40mm rear axle with an 80mm bearing carrier or cassette. Not every 40mm-axle kart uses an 80mm outer diameter — some setups use 72mm or 90mm carriers — so measure your existing carrier or take the old bearing to a digital caliper before ordering. New, manufacturer-fresh stock from Medway Power Transmission Ltd, a UK manufacturer (the bearing brand formerly trading as Dunlop BTL).