Faulty piston on a rear wheel brake cylinder During a recent annual service of an MGBGTV8 the keen eye of the mechanic at Brown & Gammons spotted one of the pistons on a rear brake wheel cylinder assembly was faulty. The rubber seal (or boot) is a tight fit and the brake fluid leak mixed with corrosion muck had not been visible from outside. MGRV8 rear brake cylinder is at the top of the drum Here we show how the cylinder (5) is at the top whereas on the MGBGTV8 it's at the bottom of the brake drum. Updated: 260607 Posted: 260604 The arrangement of the rear brake drum components on an MGRV8 is different to that on an MGBGTV8. The main difference is the rear wheel cylinder assembly (5) is at the top rather than at the bottom of the drum. At the lower point is a fixed abutment (14). MGRV8 brake drum See note. Link MGBGTV8 brake drum See the full note. Link