[jbollis]

I understand the gear reductions completely on both machines, And the point was that they both are probably about the same final ratio at the wheel. This is purely guessing because I could not find any info on it. In addition the f-cubs are gear drives and the 3rd gear is 1:1 that = 6.5 mph at full throttle on 28 inch tires. The cub cadets hydro pump is going to drive the output at at least 15% less rpm than the input. Then it will be reduced again at what you say is probably 7:1 in the reduction housing. Then if he uses the bull gears it will be reduced again at least 4:1 before it gets to the wheels.

So the way I see it the f-cubs engine rpms are being reduced in this order, engine at 1800 rpms, through the tranny at 1:1,then through the ring and pinion into the bull gears at 4:1 then to the wheel

The cub cadet with hydro and bull gears, engine at 4000 rpms into the hydro reduced by a minimum of 15%,then to the reduction housing at an 7:1 reduction, then to the ring and pinion, then to the bull gears for another 4:1 reduction then to the wheels.

A person does not need to know the exact numbers to see that the cub with bull gears added will have allot more (end point) reduction then the f-cub has.

I agree with the 60% increase in speed by adding the 28 inch wheels with no other modification. But the OP said he plans on using the bull gears, so that would reduce everything 4:1 give or take.

And I would have to say that any torque pulses made from the engine would be absorbed in the transition of drive shaft power to fluid power and back to shaft power in the hydro.

I do not intend to make an argument out of this, The addition of the f-cub bull gears to the hydro cub is the key point to this having any chance of working.