Originally posted by rc_king1
Hello fellow R40 owners
What is the reason for running a thick diff oil in the rear when running a front one-way? Can someone please elaborate for me please. Thank you.
A quick physics lesson on the oneway.... A oneway makes the front wheels free when off power. This dramatically increases the steering response and corner speed of the car as a front diff makes a car push (The reason why 4wd Formula 1 cars were abandoned in the 60s and 70s). A 2wd rear driven car will always have the highest corner speed of any drive configuration (again see F1) which is basically what a oneway does to your car off power.
That being said if your car is coasting fast through a corner (remember we are talking off power here) then you need to consider the weight transfer. When you turn in off power your outside front wheel gets heavily loaded by weight transfer initially making the car change direction, then mid corner the weight starts to even out over the outside wheels moving from front to rear. There is only so much grip that you can generate when doing this and the higher the corner speed the more grip you need. Therefore if you turn in too hard you will spin out since your front will have too mcuh weight and the rear not enough.
So long story short is that a stiff rear diff reduces some turn in, making the car manageable if the grip is high enough. However the main benefit is that the drive from the oneway on power is complimented by the extra drive from the rear diff being so stiff.