The low back W1i Tillett car seat is internally the same shape as the standard B6 but without the headrest. The seat can accommodate a driver up to approximately 100 kg with a 36 inch jeans waist size. There is a choice of a carbon or black GRP front finish and two specifications of edge cut at the leg support area. The W1i-40 version is trimmed back to allow fitment between the gearbox tunnel and the door sill of narrow vehicles, such as a Lotus 7 replica. The W1i-44 has the rolled edge left on to give a more aesthetically pleasing look to the edge of the seat. The W1i is also available with a floor mountable backframe option. This second composite moulding is bonded to the front skin, making the W1i a fully self-supporting rigid structure. Its four M8 embedded fittings allow it to mount directly to the floor, or onto the Tillett STRi or PTRi seat adjustment runners using the TK5 fitting kit.

With the side mounting option, it is possible to use the 2° race brackets as used by the FIA B6 and B7 seats. The weight of a W1i with the backframe is 3.5 kg and 1.9 kg without. Low back W models are most suitable when a headrest is not practical, maybe for an application where there is already a headrest support in existence. The W1i shape is often suited to Formula Student university projects.

W1i seat dimensions

  Car seat brochure