Kia Forte jerk when shifting automatic transmission

From what you have told me, it sounds like your transmission could be down a bit of fluid. The reason I suspect this is the cause of your K3’s problem is simple: once you get past second, everything works correctly. And, before you hit second, there’s a thump/jerk.

What is happening is that your tranny is down just enough fluid — maybe three-quarters-of-a-quart to about a quart — to leave the first and second gears above good transmission fluid flow until the pressure builds with in the device.

Once the pressure has built, the transmission fluid is forced into the gears and the tranny performs, more or less, as it should.

I think that you should pickup a quart or two of your car’s brand of tranny fluid — each vehicle uses a specific type that is detailed in the owner’s manual. Then, find a quiet spot, if you don’t have an available driveway. Check the fluid level and replace what is lost by slowly adding it through the filler tube It is also the tube that holds your transmission dipstick.

That should take care of the issue. Let me know what happens, I’m interested in hearing.