Master Brake Cylinder Saga

[sdstang]

I ordered new brake line from the proportioning valve to the master cylinder.

The rear port(primary) thread size is 7/16 and and the front port(secondary) is 1/2.

I ordered a master cylinder from Cardone(#13-1526) that was suppose to match these lines but when it came the rear was correct but the front was 3/8 instead of 1/2. I called Cardone and they said there must have been a mix up but when I ordered the second one I got the same thing.

I then went and looked at other manufacturers (Raybestos, Wagner, Centric, Bendex) and the port sizes are all over the map.

So now my question are:

What's the correct port size for a a 1973 power front disc car?

Did anyone find a correct master with 1/2(front), 7/16(rear) port sizes?

Did our cars come with a reducer or adapter?

Thanks for any help!

Jim

 

[Mikes73]

I ran into that same problem with my parts store master cylinder on my disc brake 73. The fix for me was to go to NAPA and buy the right size fitting for about 50 cents, cut the line at the flair, remove the offending fitting, slide the new fitting on the line and using a flairing tool to reflair the end of the line. I don't remember it being that hard to get it to work and it hasn't leaked a drop.

 

[sdstang]

I ran into that same problem with my parts store master cylinder on my disc brake 73. The fix for me was to go to NAPA and buy the right size fitting for about 50 cents, cut the line at the flair, remove the offending fitting, slide the new fitting on the line and using a flairing tool to reflair the end of the line. I don't remember it being that hard to get it to work and it hasn't leaked a drop.

Did your MC(master cylinder) have a 3/8 inch front fitting? My concern is that I have the wrong Master cylinder If the port sizes are wrong. Do you have the part number for you MC? Do your brakes work ok?

 

[Mikes73]

It has been a while but I do believe it required a smaller fitting at the line going into the master cylinder. Everthing else from the original matched up to the parts store master with the exception of the one fitting, I ordered two master cylinders thinking there was a mistake but the second was the same way. I decided to improvise and the brakes work perfectly with no issues. New fitting, cut, flair and you are on your way.

 

[72HCODE]

the manufacturers always put the wrong fitting on our brake lines to the master...

i did the same thing, i ordered a set they didn't fit, went to autozone bought the correct fitting. cut the brake line installed new nut, and re-flared the fitting.

 

[cudak888]

I don't know if there was a running change in production, but I found the same issue in my car - someone had installed a 3/8" to 1/2" step-up adapter in the MC's front reservoir port.

Chances are, there are more cores in existence with a 3/8" thread for the front reservoir than the 1/2" cores. I wouldn't be as concerned about the thread size as I would the bore diameter of the master cylinder itself, which may affect pedal travel distance (though not by much, ususually).

As if this weren't enough, Cardone's stock photo shows their disc master replacement with TWO adapters on it:

You may be best off buying a slew of MC's in one sitting, and return those that aren't correct. Someone has to have put the right one in a box somewhere.

-Kurt

 

[eddyw]

yep, the same problem here.

reducers from Mustangs Unlimited...

:huh:

 

[Don C]

NPD has what they call the correct style

https://www.npdlink.com/store/products/mustang_master_cylinder_assy_correct_style-103669-344.html

 

[sdstang]

Thanks for the input guys.

Jim

 

[4Vforever]

Glad this info has been put up. My brakes work fine, but I have been using brake fluid and can't find a leak anywhere, just replaced all rubber hoses, the old rear wheel cylinders aren't leaking (put in new ones) booster seems fine as does master cylinder. Was looking into master cylinders and everyone I saw listed only showed up to 72, so I'm wondering if the 73 was a stand alone year. In any case I'll just re-kit mine and get the bore stainless steel sleeved. Seems the best way around the problem and with the stainless sleeve shouldn't give a drama again.

 

[71mach1lady]

O'rielly and Autozone didn't have the right one but NAPA had it right the first try

 

[cudak888]

The NPD unit carries a 1981 Ford part number of E1BZ-2140-A; might be good to reverse-search it.

What P/N is the NAPA unit?

-Kurt

 

[71mach1lady]

I will have to dig through our receipt file


Dug through the way too fat receipt folder but didn't find the master cylinder. Searched the site and came up with part number NMC P1929B. Picture shows the forward fitting as a larger diameter. Here is the link http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Brake-Master-Cylinder-Remfd/_/R-NMBP1929B_0482598643 On sale for just under $80 right now plus $22 core