diff --git a/apiclient/discovery.py b/apiclient/discovery.py
index a2c81c6..a0ca930 100644
--- a/apiclient/discovery.py
+++ b/apiclient/discovery.py
@@ -461,7 +461,7 @@
       multipart_boundary = ''
 
       if media_filename:
-        # Convert a simple filename into a MediaUpload object.
+        # Ensure we end up with a valid MediaUpload object.
         if isinstance(media_filename, basestring):
           (media_mime_type, encoding) = mimetypes.guess_type(media_filename)
           if media_mime_type is None:
@@ -474,9 +474,6 @@
         else:
           raise TypeError('media_filename must be str or MediaUpload.')
 
-        if media_upload.resumable():
-          resumable = media_upload
-
         # Check the maxSize
         if maxSize > 0 and media_upload.size() > maxSize:
           raise MediaUploadSizeError("Media larger than: %s" % maxSize)
@@ -488,69 +485,39 @@
           expanded_url = uritemplate.expand(mediaPathUrl, params)
         url = urlparse.urljoin(self._baseUrl, expanded_url + query)
 
-        if body is None:
-          # This is a simple media upload
-          headers['content-type'] = media_upload.mimetype()
-          expanded_url = uritemplate.expand(mediaResumablePathUrl, params)
-          if not media_upload.resumable():
-            body = media_upload.getbytes(0, media_upload.size())
+        if media_upload.resumable():
+          # This is all we need to do for resumable, if the body exists it gets
+          # sent in the first request, otherwise an empty body is sent.
+          resumable = media_upload
         else:
-          # This is a multipart/related upload.
-          msgRoot = MIMEMultipart('related')
-          # msgRoot should not write out it's own headers
-          setattr(msgRoot, '_write_headers', lambda self: None)
-
-          # attach the body as one part
-          msg = MIMENonMultipart(*headers['content-type'].split('/'))
-          msg.set_payload(body)
-          msgRoot.attach(msg)
-
-          # attach the media as the second part
-          msg = MIMENonMultipart(*media_upload.mimetype().split('/'))
-          msg['Content-Transfer-Encoding'] = 'binary'
-
-          if media_upload.resumable():
-            # This is a multipart resumable upload, where a multipart payload
-            # looks like this:
-            #
-            #  --===============1678050750164843052==
-            #  Content-Type: application/json
-            #  MIME-Version: 1.0
-            #
-            #  {'foo': 'bar'}
-            #  --===============1678050750164843052==
-            #  Content-Type: image/png
-            #  MIME-Version: 1.0
-            #  Content-Transfer-Encoding: binary
-            #
-            #  <BINARY STUFF>
-            #  --===============1678050750164843052==--
-            #
-            # In the case of resumable multipart media uploads, the <BINARY
-            # STUFF> is large and will be spread across multiple PUTs.  What we
-            # do here is compose the multipart message with a random payload in
-            # place of <BINARY STUFF> and then split the resulting content into
-            # two pieces, text before <BINARY STUFF> and text after <BINARY
-            # STUFF>. The text after <BINARY STUFF> is the multipart boundary.
-            # In apiclient.http the HttpRequest will send the text before
-            # <BINARY STUFF>, then send the actual binary media in chunks, and
-            # then will send the multipart delimeter.
-
-            payload = hex(random.getrandbits(300))
-            msg.set_payload(payload)
-            msgRoot.attach(msg)
-            body = msgRoot.as_string()
-            body, _ = body.split(payload)
-            resumable = media_upload
+          # A non-resumable upload
+          if body is None:
+            # This is a simple media upload
+            headers['content-type'] = media_upload.mimetype()
+            body = media_upload.getbytes(0, media_upload.size())
           else:
+            # This is a multipart/related upload.
+            msgRoot = MIMEMultipart('related')
+            # msgRoot should not write out it's own headers
+            setattr(msgRoot, '_write_headers', lambda self: None)
+
+            # attach the body as one part
+            msg = MIMENonMultipart(*headers['content-type'].split('/'))
+            msg.set_payload(body)
+            msgRoot.attach(msg)
+
+            # attach the media as the second part
+            msg = MIMENonMultipart(*media_upload.mimetype().split('/'))
+            msg['Content-Transfer-Encoding'] = 'binary'
+
             payload = media_upload.getbytes(0, media_upload.size())
             msg.set_payload(payload)
             msgRoot.attach(msg)
             body = msgRoot.as_string()
 
-          multipart_boundary = msgRoot.get_boundary()
-          headers['content-type'] = ('multipart/related; '
-                                     'boundary="%s"') % multipart_boundary
+            multipart_boundary = msgRoot.get_boundary()
+            headers['content-type'] = ('multipart/related; '
+                                       'boundary="%s"') % multipart_boundary
 
       logging.info('URL being requested: %s' % url)
       return self._requestBuilder(self._http,
diff --git a/apiclient/http.py b/apiclient/http.py
index c8a8cd4..8e15e11 100644
--- a/apiclient/http.py
+++ b/apiclient/http.py
@@ -151,7 +151,7 @@
         media_body=media).execute()
   """
 
-  def __init__(self, filename, mimetype=None, chunksize=150000, resumable=False):
+  def __init__(self, filename, mimetype=None, chunksize=256*1024, resumable=False):
     """Constructor.
 
     Args:
@@ -252,11 +252,8 @@
     major, minor, params = mimeparse.parse_mime_type(
         headers.get('content-type', 'application/json'))
 
-    # Terminating multipart boundary get a trailing '--' appended.
-    self.multipart_boundary = params.get('boundary', '').strip('"') + '--'
-
-    # If this was a multipart resumable, the size of the non-media part.
-    self.multipart_size = 0
+    # The size of the non-media part of the request.
+    self.body_size = len(self.body or '')
 
     # The resumable URI to send chunks to.
     self.resumable_uri = None
@@ -264,18 +261,6 @@
     # The bytes that have been uploaded.
     self.resumable_progress = 0
 
-    self.total_size = 0
-
-    if resumable is not None:
-      if self.body is not None:
-        self.multipart_size = len(self.body)
-      else:
-        self.multipart_size = 0
-      self.total_size = (
-          self.resumable.size() +
-          self.multipart_size +
-          len(self.multipart_boundary))
-
   def execute(self, http=None):
     """Execute the request.
 
@@ -340,28 +325,23 @@
       start_headers = copy.copy(self.headers)
       start_headers['X-Upload-Content-Type'] = self.resumable.mimetype()
       start_headers['X-Upload-Content-Length'] = str(self.resumable.size())
-      start_headers['Content-Length'] = '0'
+      start_headers['content-length'] = str(self.body_size)
+
       resp, content = http.request(self.uri, self.method,
-                                   body="",
+                                   body=self.body,
                                    headers=start_headers)
       if resp.status == 200 and 'location' in resp:
         self.resumable_uri = resp['location']
       else:
         raise ResumableUploadError("Failed to retrieve starting URI.")
-    if self.body:
-      begin = 0
-      data = self.body
-    else:
-      begin = self.resumable_progress - self.multipart_size
-      data = self.resumable.getbytes(begin, self.resumable.chunksize())
 
-    # Tack on the multipart/related boundary if we are at the end of the file.
-    if begin + self.resumable.chunksize() >= self.resumable.size():
-      data += self.multipart_boundary
+    data = self.resumable.getbytes(self.resumable_progress,
+                                   self.resumable.chunksize())
+
     headers = {
         'Content-Range': 'bytes %d-%d/%d' % (
             self.resumable_progress, self.resumable_progress + len(data) - 1,
-            self.total_size),
+            self.resumable.size()),
         }
     resp, content = http.request(self.resumable_uri, 'PUT',
                                  body=data,
@@ -371,14 +351,13 @@
     elif resp.status == 308:
       # A "308 Resume Incomplete" indicates we are not done.
       self.resumable_progress = int(resp['range'].split('-')[1]) + 1
-      if self.resumable_progress >= self.multipart_size:
-        self.body = None
       if 'location' in resp:
         self.resumable_uri = resp['location']
     else:
       raise HttpError(resp, content, self.uri)
 
-    return MediaUploadProgress(self.resumable_progress, self.total_size), None
+    return (MediaUploadProgress(self.resumable_progress, self.resumable.size()),
+            None)
 
   def to_json(self):
     """Returns a JSON representation of the HttpRequest."""