*These ratios have been produced since the 1970’s and therefore Hewland continues to produce them for the benefit of historic gearboxes. However, the thickness of material between the root of the tooth and the spline on the input gear is thinner than our modern criteria deems safe. Hewland cannot offer strong assurance against failure of these ratios, in terms of cracking or splitting apart if used for high mileage and / or with modern high grip tyres.
Where possible (usually in gearboxes with `high-right` selector finger), use the `F3` version of these ratios, which have a stronger hub form.
Where not possible (as with all HC gearboxes), accept the risk and limit the mileage, or select another ratio. To maintain gearing, change the crownwheel and pinion to a lower ratio.
For all enquiries, please contact Hewland Technical staff on +44 (0)1628 827600 or via technical@hewland.com
