diff --git a/scrapy/extensions/throttle.py b/scrapy/extensions/throttle.py
index 8c85d13f9..9dceaf00d 100644
--- a/scrapy/extensions/throttle.py
+++ b/scrapy/extensions/throttle.py
@@ -33,10 +33,10 @@ class AutoThrottle(object):
             s.getfloat('DOWNLOAD_DELAY')
 
     def _max_delay(self, spider):
-        return self.crawler.settings.getfloat('AUTOTHROTTLE_MAX_DELAY', 60.0)
+        return self.crawler.settings.getfloat('AUTOTHROTTLE_MAX_DELAY')
 
     def _start_delay(self, spider):
-        return max(self.mindelay, self.crawler.settings.getfloat('AUTOTHROTTLE_START_DELAY', 5.0))
+        return max(self.mindelay, self.crawler.settings.getfloat('AUTOTHROTTLE_START_DELAY'))
 
     def _response_downloaded(self, response, request, spider):
         key, slot = self._get_slot(request, spider)
diff --git a/scrapy/settings/default_settings.py b/scrapy/settings/default_settings.py
index 0ea014007..6df3925e5 100644
--- a/scrapy/settings/default_settings.py
+++ b/scrapy/settings/default_settings.py
@@ -20,6 +20,11 @@ from os.path import join, abspath, dirname
 
 AJAXCRAWL_ENABLED = False
 
+AUTOTHROTTLE_ENABLED = False
+AUTOTHROTTLE_DEBUG = False
+AUTOTHROTTLE_MAX_DELAY = 60.0
+AUTOTHROTTLE_START_DELAY = 5.0
+
 BOT_NAME = 'scrapybot'
 
 CLOSESPIDER_TIMEOUT = 0