1970 master cyl different fitting size

Suspension, steering, brakes, wheels & tires

Moderator: FORDification

Post Reply
70xlt
New Member
New Member
Posts: 77
Joined: Sun Jan 22, 2017 8:21 am
Location: Reidsville, NC

1970 master cyl different fitting size

Post by 70xlt »

Restoring 70xlt, no power brakes, the new master cylinder has two line fittings that are a different size, the new cylinder has the fitting size reversed for the brake lines. They seem to be 3/8" and 1/2" fittings, but reversed on the new cylinder. What is correct way to resolve? Can I move lines on cylinder as long as I move on proportioning valve to match original system?
71Fe2O3
New Member
New Member
Posts: 137
Joined: Fri Mar 24, 2017 8:26 pm
Location: CT

Re: 1970 master cyl different fitting size

Post by 71Fe2O3 »

It has been a while, but I recall that was the case with mine last time I replaced a master cylinder. I was fortunate to have some adaptor fittings laying around. You should be able to get them from a hardware store or NAPA. Sorry, I don't know the fitting size or thread pitch, but it shouldn't be too hard to figure out or eyeball, perhaps buy a few and return the ones that aren't correct.
Fred

1970 F100 4WD short bed, 360 engine, very rusty plow and yard truck

1971 F100 2WD long bed, 302 engine, on the road

1968 F100 2WD long bed, 360 engine, stripping for parts
User avatar
MadMike
New Member
New Member
Posts: 90
Joined: Sun Jan 08, 2017 3:43 am

Re: 1970 master cyl different fitting size

Post by MadMike »

When working on the neighbors '70 250(PB) I ran into the same problem when using a reman'd MC.
Originally bought a new one which bolted in with no fittings needed. But the new BMC was not properly built(otterzone brand), or more so, it was not drilled for the secondary circuit. Went and picked up a reman'd BMC locally and it came with two fittings, ended up having to use both as the port sizes were reversed. From looking around the difference labeled is either 4wd vs RWD regardless of disc, or disc vs drum regardless of RWD vs 4WD. I would not be surprised if there were actually four different BMCs for the various truck options, but laziness/availability gives us this not quite correct parts that 'work'.

The reman'd MC 'works' but doesn't seem to always fully return and the pedal feels a bit squishy compared to what it should feel, even for drums.
Picked up another new MC and will try to use it, hopefully without any adapters needed.
-Michael
Post Reply