Topic: Master Cylinder Rebuild

[1970 Snake]

I am in the process of trying to rebuild the master cylinder which was on my car when I bought it in 1988. The master cylinder is a Bendix 2227091 casting with a 1" bore not 15/16" like on the Boss 429. My problem is I can not find any information on the right rebuild kit Raybestos or other for this master cylinder. I could really use some help on this. I am pretty sure its not a Raybestos MK488 which I have purchased, as from the attached pic you can see the primary and secondary piston springs are shorter and the secondary piston seals are slightly different with the original using an O-ring on the middle seal.

[Bob Gaines]

I am in the process of trying to rebuild the master cylinder which was on my car when I bought it in 1988. The master cylinder is a Bendix 2227091 casting with a 1" bore not 15/16" like on the Boss 429. My problem is I can not find any information on the right rebuild kit Raybestos or other for this master cylinder. I could really use some help on this. I am pretty sure its not a Raybestos MK488 which I have purchased, as from the attached pic you can see the primary and secondary piston springs are shorter and the secondary piston seals are slightly different with the original using an O-ring on the middle seal.

The Bendix 2227161 is what your 70 428 Mustang was supposed to have . The 2227091 is much rarer but not typical for your car. It is the typical Master cylinder for the Boss 429.

[1970 Snake]

Yes thanks Bob, I have been told that before. I have owned this car for over 30 years and would wonder why a previous owner would put this particular MC in this car in its first 20 years of life. From all the tell tail marks, it looks to me like the MC has never been replaced, but I could be wrong. Did Ford ever have a recall on the MC in the 1970 mustangs??

Anyway it is definitely a 2227091 MC casting with the 9/16 and 1/2 outlets but has a 1" bore and no piston stop bolt.

After doing some more browsing I see this MC topic has been discussed in some detail back in 2018. I also have found out that the MK488 kit I have is for power drum brakes (that was a waste of money) and I need a MK549 kit because of my power disc MC, and apparently this kit is difficult to source as every vendor seems to be out of stock.

[1967FEGT]

I have a brand new MK549 if you're interested.

[Bob Gaines]

Yes thanks Bob, I have been told that before. I have owned this car for over 30 years and would wonder why a previous owner would put this particular MC in this car in its first 20 years of life. From all the tell tail marks, it looks to me like the MC has never been replaced, but I could be wrong. Did Ford ever have a recall on the MC in the 1970 mustangs??

Anyway it is definitely a 2227091 MC casting with the 9/16 and 1/2 outlets but has a 1" bore and no piston stop bolt.

After doing some more browsing I see this MC topic has been discussed in some detail back in 2018. I also have found out that the MK488 kit I have is for power drum brakes (that was a waste of money) and I need a MK549 kit because of my power disc MC, and apparently this kit is difficult to source as every vendor seems to be out of stock.

The new information you provided confirms that your master is a replacement. The period correct assemblyline 2227091 MC had a conical shaped stop bolt like all of the similar Bendix MC's used on other applications in the period time .Earlier ones had a hex head stop bolt.  The Bendix MC evolved to eliminate the stop bolt sometime in the later 70's I believe. The shape and or presences of the stop bolt is something that is easily checked when installed in a car . 20 years is a long time depending on the context. For example I had to replaced my master for the first time in my 69 Mach I in 1973 because it was leaking. I bought it used in 1970. it needed to be painted that same year . The point is alot can happen in a few years .

[C6ZZGT]

Especially way back when,they were just a used car.