If memory serves, the typical braking force ratio for any automobile with front disc and rear drum brakes is 60% front, 40% rear +/-.
bad front brakes.
what would cause a rubbing noise on drivers side front wheel especially when braking ( I replaced rotor and wheel bearings are good) ?
You possibly have warped brake rotors on the front. Or Bad Wheel Bearings.
When you brake, you will experience something called "dynamic weight transfer", which means that the front wheel will take more weight and the rear wheel will carry less. And the more weight you have on a wheel the harder you can brake w/o locking the wheel up. So as long as surface conditions are good (and traction is high) the front wheel can do pretty much all your braking. Rear braking is good when traction is poor, as a rear wheel skid is easier to deal with than a front wheel skid. Rear braking can also be helpful if you're doing really long descents, to prevent the front brake from overheating.
Braking power transmitted to the front wheel is high compare to that of rear wheel normally(60:40 or 70:30) in motor cycle.Disc brakes which has high magnitude of braking power compare to that of drum brakes are used in motor cycles to absorb the more braking power.
Check the rotor, it's probably warped.
10% 30% 50% 70%
My guess would be that you might have a bad brake hose to one of the front calipers.
Some bikes have disc brakes on both wheels, but the front brake is more important. During braking you'll encounter something called dynamic weight transfer, which basically means that more of the bikes weight will be supported by thr front wheel and less by the rear. As the front wheel gets heavier the friction against the surface increases and it'll be to brake even harder, causing even more of the bike's weight to rest on the front wheel. All this heavy braking means that the front brake needs to be better at dispersing heat and it needs to be more easily modulated, as it's very hard to recover if the front wheel would lock up.
For rear drive cars - it's called a fishtail. You brakes work better on the front. Anybody who sailed over the handlebars when braking just the front wheel on a bike is called a head plant, (ouch)
Sounds like your front brake rotors are warped.