1952-59 Ford Symptoms of a bad master.?

On my 56 mercury I’m running a 65? Mustang master. Since day one it doesn’t hold a pedal. I’ve bled and bled and it’s like it will feel ok then you drive it and it’s a 2 or 3 pump effort to get a pedal. Anyone got some tips?

4 wheel drum brakes 56 mercury original and a 65 2 pot master.

could the master just be bad? However it doesn’t seem to leak.

 

If the master is for disc/drum brakes your using the wrong master for 4 wheel drums. Usually the disc/drum masters do not have a residual pressure valve in the master so you have to add one or get the master designed for all drums which should have the residual pressure valve.

 

I pretty sure it’s for a 65 mustang which would have 4 drums and both reservoir are equal size.

 

A 1965 Mustang had a single master. In slang called the “fruit jar”. There was a different Master for the 65’s with front discs, my brother bought one new with disc fronts, their Master was also a single with a 2nd fitting and some type of prop valve.
Show us a photo?

 

For a car of that size, you may be better off with a '67-ish Galaxie drum-drum master. On drum swaps to a dual master, I pick one close to the size of the vehicle it is going on.

Pumping up to get a better pedal is a sign of needing a better brake shoe adjustment.

 

When we first posted about doing the dual master upgrade for drum brakes long ago, we recommended using a rebuilt rather than a new master, as the rebuilt ones would usually be USA made cores and the tolerances were better than the new ones coming out of China or India. This picture shows what to look for in a rebuilt Bendix master cylinder. You may have to have the counter guy pull out a few to find a USA made unit.

 

Thanks Jeff! I recall reading this.

 

This is a good idea I think changing to a potentially larger master. But it’s done this since day one and I’ve even tried adjusting the shoes to where I’d consider them a bit too tight and same deal.

 

Here’s a photo, I got the master pn from the sticky but idk where it came from necessarily.

 

Is that a hydraulic clutch in there?

 

Definitely NOT a 65 Mustang. A site like Rock Auto can tell what you may have by photos but it would take a long time.
If possible you need to take it off and check the diameter; the cups and rubber can tell you but if it’s not 7/8” it’s too big for non power ***ist.

 

Yessir that is a hydraulic clutch.

 

Thanks Jimmy, I’ll try to figure out where the world I bought this and report back.
I believe I was looking for a PN M1485 and ended up cross referencing to what I have.

 

I've got one in mine too. Hydraulic throw out bearing.

 

I believe it’s 1967 mustang master cylinder.

 

Sounds like you have a bad master. Also keep in mind that the rear port on the master goes to the front brakes. And the front port closest to the radiator goes to the rear brakes. Hope this helps.

 

Yes, it looks just like the 67 Mustang master cylinder that I have in my 62 Fairlane

 

so, I clearly have it plumbed backwards. I will swap lines and see if this is the culprit

 

I swapped the lines and bled the brakes. It still has a soft pedal and with 2 pumps it feels right HOWEVER, it is much much better than it was prior.

 

The day I did my dual master and replaced all the wheel cylinders it was 106 outside in Phoenix, I used this tool https://www.harborfreight.com/brake-fluid-bleeder-92924.html But since it was hot and the garage fridge was stocked with PBR's I had forgotten to bench bleed the master, so I figured hook up this tool and cross my fingers, I started with the rear cylinders and already had a firm pedal but went up front anyway and no air, WOW ! Used this on several other cars and great results too, it does hook up to your air compressor. https://manuals.harborfreight.com/manuals/92000-92999/92924-193175329448.pdf

 

Agreed! If you don't bench bleed the master before installing the lines it can be a real PITA to get all the air out from the wheel cylinders. The air bubbles want to go up (float) in the brake fluid and you are trying to force them to go downhill to the cylinders to bleed out. My experience always has been if the master is working correctly and you need to pump the pedal to get a hard pedal then there is air somewhere. In my 58 years of working on cars and trucks I have done 100's of brake jobs so speaking from some experience here. Mark

 

To recap, When I first put it together, I bench bled the master before putting it on. Then bled the brakes normally.
Then didn’t like the pedal, so bled again still the same. So I removed the lines and bled the master again then reinstalled and still the same. (This was a few months ago) I been driving it but just pumping the pedal.
Because of the help here,
I swapped lines and then just cracked the bleeders for a few hours. Ran out half a masters worth of fluid (I could probably do a better job bleeding) and it stops better but it doesn’t get a firm pedal feel until about half travel of the pedal. 2 pumps and it gets a pedal higher.

 

Apologizes if already mentioned but what is the bore size of the MC plunger and what size on the brake cylinders themselves? I'm guessing there is a mismatch in sizes (ie the MC plunger is too large of diameter)

 

Look for wasted motion in the pedal linkage, as in too much slop. That may cause the need to pump the pedal. Just for giggles, take another try at some shoe adjustment. They may have broken in by now and need a few clicks.

 

That I’m not exactly sure of, but it’s the master pn from the sticky m1485 and stock wheel cylinders. Although I’d have to research to figure out size

 

I got about 1/8” of slop in the pedal rod.
I’ll give the shoes a check. But I gave them a couple clicks just the other day.