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CATERHAM’S 6-SPEED GEARBOX
Ben Corley | June 16, 2007
By the 1980s Caterham had moved onto the Ford Sierra 5-Speed (Type 9) transmission, replacing the Ford Kent type gearboxes, which were used in particular during the lifespan of the Series 3 Lotus Seven, namely the Ford Cortina GT / Corsair 2000E gearbox, otherwise known as the 2821E.
The Ford Sierra V6 XR4i 5-Speed gearbox gave the best-suited ratios for the Seven, and also had the shift lever set farther back than other Ford Sierra gearboxes. An added advantage was that its first motion shaft was longer and suited the Caterham adaptor bellhousing.
In 1989 Ford introduced the MT75 gearbox which had an integral bellhousing, making it possible to bolt up to Ford engines only, and production of the Ford Sierra transmission was set to end in Germany by September 1995.
To add to the problem, by the late 80s/early 90s, almost all gearboxes were being manufactured for front-wheel-drive vehicles. Many of the RWD gearboxes available were for V8s (e.g. TVR Chimaera which used a Borg-Warner T5), and were too heavy. It was felt that Caterham had to develop its own transmission, as bespoke items from specialist automotive transmission mass manufacturers like ZF and Borg-Warner would have been frightfully expensive to develop. And so, work began on the Caterham 6-Speed Gearbox!
Although launched at the 1993 Motor Show, the Caterham 6-Speed Gearbox took until April 1995 to reach mass production, representing Caterham’s most ambitious engineering project up till then (Apart from an engine, a gearbox is a VERY complicated component).
Unfortunately it seems that the very early gearboxes made in 1994 were manufactured by a company that soon went bankrupt. The replacement team apparently produced units which reportedly had many failures. The current vendor has been used ever since.
Although most may expect that the 6th speed would be an overdrive one, it is in fact a 1:1 ratio, making the middle ratios much closer compared to the 5-Speed. The all-alloy construction made it 3kg lighter than the 5-Speed despite an additional speed, and it cleverly made use of Ford components (over 50% of the parts were Ford-derived)
BGH Geartech has been reported as being the original designer of the Caterham 6-Speed Gearbox. Brian G. Hill, the proprietor is seen here pointing up at a sign which says so. BGH Geartech produce a range of close ratio uprated gearboxes based on Ford gearboxes, for competition and kit car use. They are also agents for the Raw Striker kit car, and manufacture the BGH GearTech Reverser Box for bike-engined cars, but that’s another story.
Caterham 6-Speed Gearbox (P/N 70000AS): £2,291.25 (ex VAT £1,950.00)
ロータス / ケイターハム スーパーセブン ビルダー
SOURCE/REFERENCE: CATERHAM CARS, BGH GEARTECH, CATERHAM 7 BUILD PROCESS, CATERHAM SEVENS: FROM CONCEPTION TO CSR (CHRIS REES)
Topics: Powertrain, Components |
August 4th, 2007 at 3:54 am
Sir,
Do you make a kit to put the 6 speed into a
1953 M G T D? Standard engine block.
I’m doing a frame up rebuild.
Thanks , Dan
August 4th, 2007 at 7:23 am
Hi Dan. Sorry we don’t sell parts (yet!). Suggest you scout around on specialist MG TD vendors on the net. Also, try to contact QUAIFE. They have a few 6-Speed transmissions for Front Engine / Rear Wheel Drive applications (including Sevens!).
November 26th, 2007 at 6:45 am
Hello!
Could you give me the masurements of the gearbox, from front to the senter of the shifting lever?
Magnus L Vårdal
March 22nd, 2008 at 2:51 pm
Hi, currently building a Birkin clubman here in Brisbane,Australia. Has a 2.0lt Duratec coupled tp a T9 gearbox, who/where are the best people/company to purchase a clubman gearbox kit with ratios better suited to the clubman.
Cheers
Maurice Webby
April 8th, 2008 at 2:44 am
I am looking for a 5 or 6 speed for a 1969 Twincam Escort Mk1 and for a 1963 Lotus Cortina to replace the 4 speeds.
Wouls your 6 speed fit?
Thank you.
Alfonso