I'm looking at buying an '87 Trans Am. The owner says it's got a shift kit in it, and it jerks almost to the point of squealing its tires when shifting. Is this normal? What is a shift kit and what does it do?

 

If it almost spins the tires when it shifts, then it has a shift kit. A shift kit recalibrates the shift firmness and the fluid pressure in the valve body inside the trans. I have a shift kit in my car and it will spin the tires into third at 60 or so mph when I have the skinny tires on.