Using M10 Bolts with Girling Brake Banjos
In my previous article on converting the Courier M/C to the S2, there is an error where I stated that the banjos between the front and rear brake outlet ports were not interchangeable. That is incorrect. Both banjos have the same hole diameter and thus can be swapped around (Pic 6).
When converting the stock Europa master cylinder to either a Ford Courier or Festiva master cylinder the outlet port orientation allow the use of the stock lines and banjos with minimal tweaking of the lines to fit (Pic 1). Both alternate master cylinders use M10 metric banjo bolts, M10x1.0 for the Courier and M10x1.25 for the Festiva. The problem occurs in the difference in diameter between the M10 bolt and the Girling banjo presenting a relatively loose fit between the bolt and banjo. The stock banjo has a inside diameter of 11.22 mm/0.441” while the 10 mm bolt area under the head is 9.95mm/0.392” . The difference of 1.29mm/.050”about the thickness of a dime, gives a very noticible slop between bolt and banjo (Pic 2).
Picture 1 shows a Ford Courier master cylinder conversion fitted to a S2. According to the owner, almost no tweaking of the stock lines was required to align the banjos to the outlet ports.
Picture 2 illustrates the 1.29mm/.050” gap between the stock banjo and a 10mm banjo bolt, approximately the thickness of a dime.
Some may find the looseness acceptable but for those wishing to reduce the slop, I'm presenting a relatively simple way to greatly reduce the gap between banjo and bolt. I'm sure that there are other solutions but my method will only require a bench drill press and some hand tools.
I found that thin wall 11mmx0.45mm diameter brass tubing (
http://www.ksmetals.com/26.html) will be near perfect as sleeve material. The round stock comes in 1 meter length so a tubing cutter will be required to cut the tubing to length. The height of the Girling Banjo is 12.85mm/0.50”, cut the tubing to that length (Pic 3). The use of a tubing cutter should minimize any deburring/squaring of the cut ends.
Used as is, the sleeve will block the brake fluid transfer ports between banjo bolt and the banjo. To provide a flowpath, two additional steps must be performed. First a series closely separated holes/slots midpoint around the sleeve will need to be drilled and shaped to maximize the opening area between the bolt and banjo fluid connection (Pic 4). Secondly, to further preclude any blockage of flow, the outlet hole in the banjo will be enlarged and elongated (Pic 5).
Slotting the brass blanks may be the quickest and easiest way to manage the openings. The right hand sleeve in the picture above shows two holes on opposite sides with two slots also on opposite sides. The connecting sleeve material between the openings should be as small an area as possible to reduce any restriction of brake fluid from bolt to banjo hole opening. A rotary tool with a small high speed carbide bit is used for the rough shaping the slots, while a small diameter rat tail file is used for final shape and deburring of the sleeve
A Dremel type power rotary tool with a high speed cutter and an 1/8” ball tip will make quick work of the soft brass of the banjo. Cut a groove approximately 1/4” long on either side of the eye. The depth should be approximately 1/16” deep. The above dimensions should be sufficient to preclude any major restriction of fluid movement.The final step is to insert the sleeve in the banjo and rotate the sleeve one complete rotation and verify that the banjo eye/groove will not be completely covered by the sleeve.
I will admit that I am not using this option for my Courier and Festiva master cylinder conversions and do not have any real world experience with what I have presented. Some may consider this as redneck engineering but for owners without machining skills or equipment, this is a good simple solution to get the job done as long as care is taken to ensure that brake fluid transfer flow path is not blocked.
The forum format limits the size of the posting so I can only post the text and small photos. For the full integrated article, I've added a link to my Dropbox account.
https://www.dropbox.com/s/70sp29oexeaxuok/Using%2010mm%20Bolts%20with%20Girling%20Brake%20Banjos.odt?dl=0Joji Tokumoto
