V12 5 speed conversion

Convert your V12 to 5 speed manual


Simply Performance has been supplying V12 5 speed manual conversions for over 10 years. We have sold over 150 kits. Mainly this kit is used to convert the ancient GM400 3 speed box  fitted to the XJS V12. This kit can also be used to convert from 4 speed manual to 5 speed manual. We supply a complete nut and bolt package to convert to manual. We have had many articles written about us in the Jaguar Enthusiast magasine circulated in the Jaguar Enthusiast Club JEC.

Similar to a Lister conversion we use a conversion ring to adapt the V12 engine (Conversion rings available for late and early engines) to a Jaguar Getrag bolt pattern. We recommend using an earlier split bell housing Getrag 265. Don’t be fooled by information on the internet we have fitted these boxes into modified 6.0’s and it handles the power great.

We use our own flywheel, unlike a conventional flywheel it does not have any ring gear. It sandwiches your existing flywheel/flexplate using the ring gear from that. It has a good weight to keep the V12 smooth unlike aluminium alternatives and takes the 9 1/2 in. clutch. These are available as standard AP, high performance metallic, ceramic and paddle. Depending on your application we tailor it for your needs.

If you use the manual pedal box from a manual XJS, we supply with all pipework, master and slave cylinders. It uses the manual propshaft which is supplied in the kit. We can get new manual ski slopes and we have had leather gear gators made for us. When fitted the kit looks fantastic and aside from seeing a 20mm conversion ring underneath aesthetically it looks as if it was done in the factory. Whilst inside, the gear stick comes out in the right place with the shift in between the gears feel like a Jaguar. Unlike other boxes on the market which have a racing feel.

Useful links:

Articles on our 5 speed manual gearbox conversion:

Paul Mullen - Jaguar Magazine - Edition 190

Jim Patton - Jaguar World - July 2016

Lee Doak - Jaguar Enthusiasts - June 2012

Garreth Coomber - Jaguar World Monthly - November 2009