Gearbox

The 2 litre cars had the 5-speed Fiat Type AC 100 gearbox which has a 2300S 4-speed central casing with a rear extension which houses 5th and reverse gears as well as an oil pump on the end of the lay shaft. 5th gear is not overdrive, but geared up for maximum speed. All gears have Porsche designed baulk-ring synchromesh.

Ratios:
1st: 3.095
2nd: 1.825
3rd: 1.351
4th: 1.00
5th: 0.871
Reverse: 2.889
   
Final drive: 4.875:1


The 2.4 litre cars used the ZF Type S5-18/3 gearbox.

Ratios:
1st: 2.991
2nd: 1.763
3rd: 1.301
4th: 1.00
5th: 0.874
Reverse: 3.670
   
Final drive: 4.778:1


Side section of the fully sinchronized 5 speed Type AC 100 gearbox. Side view of Fiat Type 135 AC 100 and ZF gearboxes. Side view of Fiat Type 135 AC 100 and ZF gearboxes. Front view of Fiat Type 135 AC 100 and ZF gearboxes. Top view of Fiat Type 135 AC 100 and ZF gearboxes.