Hi Everyone! I have a '71 Mav, 200 engine, manual brakes. I'm doing a full brake job on it, replacing everything except the steel lines and the brass junctions. I got a Raybestos Master Cylinder. It came with two push rods--6 1/4, and 6 1/2. I was thinking of comparing the length of the rod in the old M.C., then use the matching rod in the Rayb unit. I've seen a video on removing the push rod from the M.C., it required the unit to be put into a vice and using some force, the rod came out. I don't have a vice. All I can say about the old M.C. is that is says, Made in U.S.A. on it. I don't know if that means it's the original, or just a replacement from when they were made here. I was thinking that even if I did get the old rod out, and one of the two new rods was a match, that still doesn't mean that the new M.C. has the same rod placement depth in the unit as the old one. Should I just make a random choice and hope that the 1/4-inch difference--if I choose incorrectly, isn't something my foot will notice when coming off the gas pedal? Also, when looking at the rod on the old M.C., I pulled back the rubber boot, and some fluid came out. Does this mean that a seal was bad? Thank you very much! Bye, Daniel
If fluid came out of boot seal is bad. I replaced my mc yesterday and have two new rods, if I don’t forget, will measure them tomorrow let you know what I get. Maybe someone will get in here b4 and give you the information .
Thank you for your response! I've had a feeling there was something wrong with the mc for some time--I'm very glad to be replacing that--along with everything else!
Orig master cylinders were painted black, almost none have survived 50ish years. usually repl every 15 years or so. As you already know rods are retained by a clip. Put it together without the clip, if pedal is too high use the shorter one, too low, longer. I did just that on my Fairlane, first one seems to be OK, never installed clip. Yes it had it's original black painted MC.
On The 72 Comet GT I just sold I did a disk brake upgrade and got a later model manual disk master to go on it. (It was originally manual Drum) I used the provided new rod even though it was a tad longer. It worked but kept the pedal up too high. I wound up having to swap back to the old rod length.
Hi Mojo, Krazy Comet, ADOR, and TeeEl! Thank you all for your help and suggestions! I will try the trick with putting an unclipped rod in to check the pedal length. I have a feeling that the shorter rod will be the right one. I may try to pull out the rod in the old MC to check the length--since the unit is bad, I can't break it! I decided to replace the wheel cylinder bolts--the ones that go through the backing plate. They're a bit rusty, and I rounded the corners of one of them while tightening it. These are the smaller diameter bolts, used for the small engine cars. Does anyone know where I might be able to get them? Bye, Daniel
Wheel cylinders are same for 6 & V8. Most any hardware store should have correct size/thread. You may need to cut bolt length, as I believe they are something like 5/8"(don't bet your life on that).
It's almost always the shortest rod. Sometimes they only give you one rod and it's installed and always too long. In the past I've cut 3/8" out of the rod and welded back together. Another time I put 3/8" spacers between the MC and fire wall. Last time I bought an adjustable rod. https://www.performanceonline.com/Ford-Mercury-Manual-Master-Cylinder-Push-Rod-Kit/ I did have to remove a little material off the flat part in rear, it kept my brake lights on all the time.
I have had to put a small flat tip in to bend the little clip before to get the rod out, broke a ear off the master before it came out. They can get tough some times.