On my son's 73 Grabber. So I had a rusty, leaky master cylinder and decided to change it. Car already has discs up front and the previous owner put a wilwood dial type prop valve for the rears. I figured the master cylinder would be a disc/drum type but when I got it off, it doesn't match with what I have seen here or in shopping for other manual disc/drum mater cylinders on line. I am hoping I have attached a photo of it. The front outlet is 9/16" and the back is 7/16"(just the opposite of what I expected) I don't want to have to re-plumb the brake lines if I don't have to, but I am starting to think that this master cylinder came off a '73(maybe a pinto). Then...When I pulled the rod out of the car, I found it had been cut and welded to a length of 6". Surprise number 3. So do any of you think that this master cylinder is possibly a disc/disc or a disc/drum unit and if so, the only replacement I have found is a 73 model(when I thought they were all drum/drum) Pretty confused about what to get to replace this one. Any help from some of you veterans would be greatly appreciated.
Yes, all 73's were drum front and back. There is a difference in the dia. of the piston between drum and disc master cylinders. I would highly recommend using a disc brake master cylinder. If you don't you will have to use very high pedal pressure to get stopped. If you were satisfied with the previous pedal height, then use the rod you took out. If you don't, you will end up with a very high pedal. To get the proper master cylinder, ask the parts guy for a later model Maverick with discs or a Granada one. Hope this helps. Lee "THE MAV" Richart
If you take a good look at the two master cylinders you will see that the resavors are a different size. That is for a good reason. The piston inside is built different also I believe. I personally wouldn't use a drum/drum mc on a disc/drum car. Things work better and are generally safer when you use the right parts for the application. They are designed the way they are for a good reason.
MC difference I checked the bore and the one that came out is the 15/16" which someone here said is right for Discs. I could simply order a later disc/drum MC but then I will have to re-plumb the brake lines going in because of the different size fittings. I also think that the disc MC is a good idea, just confused by these backwards-different sized output threads. Thanks for the help. Maybe I'll give it another day and order something Wednesday or so.
The larger reservoir feeds the front (disc) side, as that needs more fluid flow than drum brakes. IIRC, I ended up with an F-100 M/C on my car in order to get a 15/16" bore. Which, BTW, is fine for manual disc/drums. I poked around on Advance's site and found that they have the bore sizes listed...
Correct...unless the bore size is too small and cannot move enough fluid to fully actuate the calipers.
Bore size is 15/16" on both manual disc, power disc and drum brakes are the same on '74-'77 Mavericks. '70-'73 drum brake Mavericks got the 1" bore. You will only get in trouble with a 15/16" bore if you're feeding a 4 piston or more caliper. Then you will want a 1-1/8" bore.
