Nodejs, express, Ajax: Function triggers only Six Times

using nodejs and express I'm trying to trigger a js function which contains a simple console log. Sadly the function only triggers 6 times and freezes for a while. After a minute or two all the button clicks which where clicked during the "frozen time" triggers at once. It happens always after 6 times of pressing a button.

index.html -> button
client side -> jquery function that triggers an Ajax post function
server.js -> contains the express function which triggers the console log

index.html

<input type="button" id="car" value="drive"/>

clientside.js

$('#car').click(function(){

   $.ajax({
      type:'POST',
      url: url + '/drive'
   });

});

server.js

var app = express();

app.post('/drive', function(req, res){

   console.log('Car starts driving');

});

What am I doing wrong? Any tips how I can improve my code?

Thank You

via Preprocezzor