C90 4 speed

[FrazzleC90]

Hi, I'm new to restoring Cubs.
I've got a late C90 incomplete engine & want to fit a 4 speed gearbox.
Please can anyone guide me as to a suitable aftermarket 4 speed gearbox for a late engine case. From measuring the bearings sizes the shafts appear to be 12mm diameter at one end & 17mm at the other. Any help would be appreciated. Thanks in advance.

[wightegi]

There are no aftermarket ones , some other models came with 4 speed boxes but you need both engines .4 gears only gives you something for hills instead of using second . If you up the front sprocket to 16 you can reach 30 in second which helps.

[steveST100]

Think to remember is the later cub engines are 4 roller bearings and not the 2 roller and 2 needle bearings and the 4 speed gearboxes from the ATC70 wont fit as only fit the earlier engines.
Most of the later copy pitbike engines are the 4 roller type.

steve g

[Newtsalad]

If you up the front sprocket to 16 you can reach 30 in second which helps.

36 mph, not 30!