Jquery Ignores Encoding Iso-8859-1

I have a website which apperently removes the correct encoding (ISO-8859-1) from a string and sends it wrong. I have this encoding specified in my HTML

$.ajax({
    url: '...',
    contentType: 'Content-type: text/plain; charset=iso-8859-1',
    // This is the imporant part!!!beforeSend: function(jqXHR) {
        jqXHR.overrideMimeType('text/html;charset=iso-8859-1');
    }
});

Solution 2:

According to the jQuery.ajax()contentType documentation:

Data will always be transmitted to the server using UTF-8 charset; you must decode this appropriately on the server side."