unexpected shift to neutral

[Selenico77]

I have the following problem with the automatic box.
when I drive aprox hourly to 40 miles, and I step on the gas to overcome to another car, it is very frequent that the gear goes to neutral and the engine gets up it turns up to 7.000, in that case I have to slow the engine and alone it returns the box to gear.
I please ask if somebody has had this problem and knows that it can be happening.
I wait anxious some fact to solve the problem.

Thank you

Selenico77

[Hyundaifan]

I really don't understand exactly when your transmission goes into neutral and revs into high RPMs.... ??? I own a '99 elantra wagon and I had my tranny go into neutral when my overdrive button was depressed (on). For example when my overdrive button was on, when my car wanted to switch into 4th gear it went into neutral and the engine reved up. One way to overcome the problem is to drive without the overdrive on (especially in the city /you don't need it). If you're about to enter a highway hold your car on 3rd gear until you pass about 45-50 MPH (that's when you're 4th gear hooks up). Let off the gas, press the overdrive button and once the 4th gear goes in gently press the gas pedal again. My mechanic told me that this problem may exist from a lack of hydraulic pressure going into the clutch of the 4th gear. That might be causing your tranny going into neutral instead of initiating it.