Wiper Arms 101

In another thread, I discussed the wiper blades. In this, I will explain how to remove the wiper arm. The arm is a proprietary item that changes whenever the body style changes, so they are not interchangeable between years, unless the cowl and hood configuration remains the same. The difference between years is the angle of the arm in relationship to the blade, and how it retracts when it parks. In 1967 Pontiac Motor Division introduced the first hidden wiper arms, by removing the cowl screen, and making the hood longer to leave an opening at the bottom of the windshield where the arm & blade assembly would "hide" when in the parked position. Eventually the rest of the GM line would adapt this design feature. Even though many arms might fit on the wiper stud, never assume that it will function properly if it wasn't designed for your vehicle.

In the picture below, you will see the locking tang that holds the wiper arm to the wiper arm stud. The wiper arm stud is connected to the wiper transmission, which is connected to the wiper motor. The wiper motor drives the transmission, which has a wiper stud located at each end of it, and makes the arms move simultaneously. It is a rather ingenious design that works well and not much has changed in this design since the wipers inception.
To get the arm off of the stud, you need to pry up on the tab, while also lifting the end of the arm off of the stud. To do this, I usually place a flat bladed screwdriver under the tab and lift the tab upward. This results in the wiper arm coming partially off of the stud. There is a spring mechanism between the wiper arm and the part that goes onto the wiper stud, and the purpose of the spring is to keep the arm in contact with the windshield. For this reason, you usually need to gently pry the arm off of the stud using a fulcrum of some sort. I place a wad of cotton towels on the cowl screen, and prying against them push the arm the rest of the way off. It is a little awkward at first, but after you have removed one or two, you will get the hang of it for the future. More pictures to come when it stops raining...

they do have a tool just for this purpose. it keeps you from popping off the arm and having it skid across the hood. I forget I have one most of the time and use your method

I have the tool also, but usually can't find it when I need it, and come across it when I don't. That is the way it is with specialty tools. One of these days, I am going to get all my tool boxes organized into Metric / SAE / GM / Ford / Chrysler / etc...