Official Historian
Join Date: Sep 1999
Location: Hot Springs, AR
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Re: Quadra-trac
The quadratrac is a full time transfer case. It has a differential in it to allow the front and rear driveshafts to turn at different rates when turning corners. The vacuum shifter just locks this differential so the front and rear shafts can't turn at different rates. If your limited slip in the transfer case is worn, here is a way to check the vacuum shifter. Block the wheels. Jack up one tire. Shift the transfer case to neutral if it has the optional low range. If not, shift the transmission to neutral. When the vacuum shifter is in the green, you might be able to spin the wheel in the air. When the shifter is in the red, you should not be able to spin the wheel in the air.