Personally if I went to the quad bike brakes I would use drum brakes as it doesn't look like too much work and I
see these Quad bikes thrown out a lot.
I would modify the front axle for more movement as I think that would be the least amount of work and it would
still look original.There looks like there is very little room for movement with the standard front axle.
Cheers
Max.
If using the Quad bikes drum brakes, I assume you would have to use the Quad's wheels as well - if so, I imagine tyre/wheel size would be important in getting the frame to end up at the same height at the front as it currently is.
I agree that when going downhill with an uneven profile, the rigid frame is causing one of the rear wheels (the only one braking) to almost lift off the ground and hence there is minimal or no braking. Any thoughts on how you would get more travel in the front wheels, without major surgery?