The 635CSi central locking system could now be operated from the passenger door and trunk. 1982 facelift In 1982 (model year 1983 in the US), the E24 platform changed from the E12 5 Series to the E28 5 Series, resulting changes to exterior styling, engines, chassis, suspension, electronics and the interior. The struts in the new front suspension were double-linked ones, making the car less likely to dip under hard braking. The new rear axle was nearly identical to the trailing arm layout of the E28 528i, with a new pitman arm to control camber changes. Meanwhile, the ventilated rear discs had proven a needless complication and were replaced with solid ones. The rust protection was improved considerably along with the facelift. The 635CSi engine was updated to the M30B34, which used a smaller bore and longer stroke than the previous M90 engine. The 635CSi became available with a wide-ratio 5-speed manual or a 4-speed automatic transmission. 1987 E24s produced after June 1987 were fitted with ellipsoid headlamps, as per the recently introduced E32 7 Series. The front and rear bumpers and spoilers were redesigned to use a single design worldwide (prior to this, models sold in North America used a different design from the rest of the world). The 635CSi engine was updated to the higher compression M30B35, which resulted in a power increase of for engines with catalytic converters. North American and Japanese models The extended bumpers required by U.S. crash legislation resulted in U.S. models having an increase in length of approximately to . Although other markets offered multiple E24 models, in North America only one model was available at any given time (aside from the M6). 630CSi The 6 series was released in the US as the 630CSi in March 1977, with the 633CSi replacing it during the 1978 model year. The US market version received larger bumpers and side marker lights, as required by federal legislation. The 630CSi is powered by a fuel-injected version of the 630CS engine. This 3.0 litre engine produces and . 633CSi The 633CSi arrived in USA in September 1977 (for the 1978 model year), replacing the original 630. In United States/Japan specification, the 633CSi was powered by a version of the M30B32 engine. Output later dropped to . In September 1980 (1981 model year), the manual transmission for US cars was upgraded from a 4-speed to a 5-speed. A 3-speed