The gearbox is either the classic Ford T9 five-speed or Caterham's own six-speed box. The T9 is cheap and durable, but has gear ratios meant for a much heavier car. The six-speed gearbox is expensive and had early 'teething' problems, but its ratios are considered the perfect match for the Seven. Independent companies such as Quaife do offer replacement gearkits for the T9 as well as sequential boxes for those with a racing fever and the need for a more robust transmission.