A quote to include a 28% ratio can be given at the time of ordering. The disadvantage being that in TR gearboxes with standard ratios, 3rd gear is now very close to 4th gear. For those using low ratio back axles and wishing to improve cruise speed, we can provide overdrives with a 28% ratio. Later TR6 (CF/CR) with 'J' type overdrive provide a 25% increase in ratio with the same but obviously slightly different effect. This conveniently fits between 2nd, 3rd and 4th to give seven genuine gear ratios.
see GEARBOX MOUNTINGS: CONVERSION KITSĪll TR2-6 'A' type overdrives provide a 22% increase in ratio. When we supply a 'J' type overdrive on the back of a gearbox for fitment to a TR2 to TR6 CC/CP chassis, an adaptor plate kit will be needed. We can offer these units outright too on payment of the appropriate none refundable deposit.
Revington TR offer a reconditioning service for overdrive units both 'A' type and 'J' type.