It's way past midnight. You tool up and down the boulevard looking for a little action with your late-model musclecar when all of a sudden you notice a sloppy feeling in the seat of your pants. It's not the fish taco you just ate but a rear tire gone flat instead. You pop the hatch, remove the cover panel, and retrieve the spare from stowage. But you're hard-core, and even with the skinny space saver spare out back, you cruise another hour before heading home.
The next day you fix the flat and put it on your car. But when you nail the gas, only the right rear tire spins. Whoops! What happened? Unfortunately, you wore out your posi unit by cruising with the ultrashort, temporary spare tire on one end of the axle and the much taller regular tire on the other. In between was your poor posi unit, literally slipping its life away. Check out the accompanying photos for just what goes wrong and how to avoid this trouble in the first place.
We wish to thank Jim Cook of Performance Differential for this positive lesson.
