1965 AMC Ramber Manual Brakes Problems.

[mechjames]

I'm trying to fix a braking issue in my 1965 Rambler American 330.

The brake pedal is soft. Not spongy, it goes to the floor. Once you're at the floor and you push harder on it, it will start to slow down. If you just press the pedal down really fast it will lock up the wheels.

The front brakes are totally rebuilt with new wheel cylinders. While bleeding the rear brakes first (decided to try even though it is a seperate system), there is no air in the back lines at all, the brake fluid comes out fine through the bleeder screw like normal.

While bleeding either side on the front brakes, the fluid just barely dribbles out while cracking the bleeder screw. If I have the master cylinder cap off while bleeding , it shoots out like a water fountain just as the pedal is pushed down the first 1/8 of an inch. Nothing on the return stroke.

Any ideas short of bench bleeding the master cylinder or possibly replacing it? There isn't any leaks anywhere, not even under the dash.

 

[FL_Rob]

It sounds like your rubber lines and m/c o-rings are shot,unless you've recently replaced them ,start there,then the master cylinder,specifically the front brake section(just replace/rebuild the entire unit).Do you have room to add a vac booster to upgrade to a power system?

 

[The_Jeff]

Does sure sound like the MC leaking internally. The clincher is the rapid braking still working, before the pressure can bleed through the leak.

 

[onion]

Yep. That's typical behavior for a bad master cylinder.

 

[mechjames]

All the rubber lines in the front are definitely not stock, and are not leaking. The front brakes were rebuilt by the previous owner, but gave up on it because he had to sell the car due to moving.

I will try bench bleeding the master, then I will look into a new one.

 

[oilboy123]

Should not be too expensive. Master is the first thing that came to my mind with your symptoms. Especially if you have no leaks.

 

[mechjames]

I can get a new one for $90. Not going to waste my money for a $60 rebuilt one.

 

[bluestream]

Try and get a rebuild kit, you can do that yourself. Then "bench bleed" it before you install

 

[FL_Rob]

Rebuild it yourself...IF...you can find a rebuild kit.Its easy there's four o-rings, a couple springs(which may have rusted apart) and some seals.The nice thing in your case,its all metal unless it has corrosion in the bore or a crack somewhere,it can be rebuilt.

 

[mechtech2]

Dribbling out of both front lines?
Bad rubber lines or master cyl.
Plus, parts have to seat n before they get a nice hard brake feel.
And Drum brakes must be adjusted right or the pedal will be too low.

 

[flanso]

Many of the dual system master cylinders actuated brakes diagonally rather than in axle pairs. I think dual system master cylinders were Federally mandated beginning in 1967. Unless updated, your car may still have a single. Your problem sounds master cylinder or rubber line related; I would consider a new replacement master. And consider adapting a dual system master if you do not already have one. I used to love those Ramblers with that indestructible 232.

 

[The_Jeff]

Every split system I've ever had were fronts on one and rears the other. The disc/drum setup probably requires this for proportioning reasons. I remember Chrysler thought they were clever with the diagonal system, but that likely only lasted until they brought out front discs in the mid 70s.

PS the dual split system, while better than nothing, gets very scary if one blows a line. Lots of rear drums out there with very low effectiveness.

 

[onion]

The mid 80's RWD GM cars had a diagonal system. Don't know exactly what the purpose was or what other vehicles used this setup.

 

[mechjames]

The wait to order in a rebuild kit wasn't worth it. I got a new updated master and will be installing it tomorrow.

 

[mechtech2]

When you had 4 wheel drum brakes, the systems were sometimes split diagonally.