The Big J (Big Jaguar) was the successor to the Warrior and Invincible range of trucks. It arrived in 1964 and featured an all steel cab manufactured by Coventry Motor Panels. The basic cab design was also sold by them to other truck manufacturers such as Seddon. Originally, the cab was designed to have the capability to be tilted for engine access, but in the final production version, this feature was not fully developed. The front cab mounting still remained as a hinge, but in practice, it was not possible to tilt the cab. The possibility for tilting came about because the truck was intended to have a new engine - the Cummins VIM V6. As part of a projected deal between Jaguar and Cummins, the Cummins VIM V.6 and VINE V.8 engines were slated to be made at the Henry Meadows factory, also owned by Jaguar, situated next door to Guy Motors factory in Park Lane, Wolverhampton. In the event, the engine proved to be problematical, and was not fitted to most trucks. Many other engines were offered, and these were mostly inline 6 cylinder types, which did not permit the same space for tilting.
Big J 4 standing on the weighbridge near the gatehouse at the factory.
Cab tilted in the experimental department. This is the Cummins V6 engine. Note the air intake pipe fixed to the rear cab mounting tower. The holes for this were present in every mounting tower, even though this was the only engine variant to use them.
Early Big J chassis with the Cummins VIM V6 engine. Note the manual handbrake lever, although air assistance can be seen with the air chamber by the fuel tank. Later models would be fitted with Spring Brake chambers on the rear, making the handbrake lever obsolete.
Using the shorter Cummins V6, the cab was a "walk-through" design; where the driver could enter the cab from the kerb and then move across into the driving seat. With other engines, this was not possible. This is from a Commercial Motor test in 1966
