Originally posted by apmk
Why must you need front oneway for all this to happen, what effect will it be if you have an internal overdrive with differential on both ends. Pls comment....
If you run front overdrive in the car (either using larger front tire with same internal drive ratio or same front / rear tire diameter with different internal drive ratio) you will need the oneway to get the full effect of the overdrive.
A oneway will disengage the front and rear drivetrain off power to let both front and rear tires roll respectively because when you run front overdrive, your front tire rollout is more than your rear tire rollout.
On power, the front will pull the rear because of the front overdrive. A oneway will do this effectively because of the front wheels (depending on which front wheel is slower and faster than the drive train) will lock on power.
With diffs at both ends, the front and rear drive train is always together off and on power. The front and rear drive train does not "detach" from each other off power unlike with a oneway front. That is why you get brakes on 4 wheels with both front and rear diffs unlike with the front oneway when only rear wheels can do the braking.
On power with a front diff and running front overdrive, it will not be efective because the front diff will slip power to the wheel that looses grip unlike with a oneway front where power will be given to the wheel that has grip.
Off power with front and rear diffs, the rear drive train will drag the front drive train because the rear drive train does not allow the front to roll independently due to the different front and rear tire rollout.