posi and locker?
Senior Member
Joined: Dec 2006
Posts: 171
Likes: 0
From: Houston, TX
Think of 3 steps for traction devices.
One - open differential, all the power goes to the wheel with the least resistance. The majority of new cars are equipped this way as this offers the smoothest ride and also is the least costly option.
Two - limited slip or posi or gov-lock, this setup is offered by most manufacturers as an option. It gives better traction than an open differential but will not transmit all the available torque to the wheel with the most traction. Posi rear ends are generally a clutch pack or cone assembly. They will wear out and then offer no benefit over the open differential. One notable exception is the Tru Trac manufactured by Eaton. It is all gears, no clutches to wear out.
Three - locker or automatic locker, this is the king of third members for traction. Whenever torque is sensed, the locker will lock up, transmitting all the power equally to both axles. When no torque is sensed the third member will unlock, permitting the wheels to turn at different speeds (like going around a corner). A problem will develop if you step on the gas halfway through the corner. The third member will lock up. Then oversteer instantly becomes understeer or visa versa. This is very unsettling until you get use to it, especially in a short wheelbased vehicle with a manual transmission. The best automatic locker is the Detroit Locker. Very strong and dependable locker.
Now there is a fourth system which gives you the best of option one and option three, the selectable locker. Flip a switch and your open differential instantly locks up. This is excellent for a daily driver which also sees trail use. It is also the most costly system. ARB air locker and the Eaton electrac are two systems which come to mind.
One - open differential, all the power goes to the wheel with the least resistance. The majority of new cars are equipped this way as this offers the smoothest ride and also is the least costly option.
Two - limited slip or posi or gov-lock, this setup is offered by most manufacturers as an option. It gives better traction than an open differential but will not transmit all the available torque to the wheel with the most traction. Posi rear ends are generally a clutch pack or cone assembly. They will wear out and then offer no benefit over the open differential. One notable exception is the Tru Trac manufactured by Eaton. It is all gears, no clutches to wear out.
Three - locker or automatic locker, this is the king of third members for traction. Whenever torque is sensed, the locker will lock up, transmitting all the power equally to both axles. When no torque is sensed the third member will unlock, permitting the wheels to turn at different speeds (like going around a corner). A problem will develop if you step on the gas halfway through the corner. The third member will lock up. Then oversteer instantly becomes understeer or visa versa. This is very unsettling until you get use to it, especially in a short wheelbased vehicle with a manual transmission. The best automatic locker is the Detroit Locker. Very strong and dependable locker.
Now there is a fourth system which gives you the best of option one and option three, the selectable locker. Flip a switch and your open differential instantly locks up. This is excellent for a daily driver which also sees trail use. It is also the most costly system. ARB air locker and the Eaton electrac are two systems which come to mind.