Can’t set content type to application/json using jquery ajax

I’m trying to send a post request using json as the request body. Here is my code:

var body = {
            data1: formData1,
            data2: formData2
        };

        $.ajax({
            url: submitUrl,
            type: "POST",
            data: JSON.stringify(body),
            dataType: "json",
            contentType: "application/json; charset=utf-8",

            success: function (resp) {
                /* Function for success */
            }
        });

formData1 and formData2 are strings that were defined earlier in the application.

Everytime that I submit a request using this function, it reverts to the content-type being application/x-www-form-urlencoded and gives me an HTTP 415 error.