Am I just rusty or is this a problem?

[73 Duster 360]

So I've had my 1973 duster for about a year now and when gas prices went crazy last year I parked in the garage and didn't drive it nearly as much as I would have liked to. On one of the occasions when I did bring it out, the brake master cylinder had gotten so low that I ended up with air in my brake lines.

No big deal. I bled the brakes, drove the car to work for a couple days in a row just for the hell of it. But I noticed something that I don't think was happening before. If I put any kind of sudden pressure on the brakes, not really an emergency stop but more pressure than if I was normally approaching a stop sign, the brakes lock and the tires screech and slide on they road.

I'm talking about low speed situations where the guy in front of me has decided to stop suddenly to make a turn, so I put my foot on the break and it locks!

My instinct is that I didn't bleed the brakes properly/fully and there is still air in the lines or something is worn. I had a Duster back in my 20s and I never had this problem but I did have other problems that required me to replace essentially the entire breaking system. So I'm not afraid of getting my hands dirty and fixing whatever might be wrong.

But I'm also wondering if I'm just rusty. Have I been spoiled by ABS systems for the last 20 or so years? Maybe I just don't remember how to drive a non-abs vehicle properly? I mean I know I have to pump the breaks in a sudden stop situation, it's just not instinct anymore.

So I thought I'd come in here and ask people who have more and more recent experience driving these older vehicles.

Which do you feel is more likely?

1. There is something mechanically wrong with my breaking system at the moment.

2. The car is fine and I don't have that magic touch for breaking in a non-ABS vehicle anymore and just need practice.

Obviously there is a third option of both, and I will admit I am out of practice I just don't think it was doing this before. I feel like I was able to apply a moderate amount of sudden pressure and gradually slowdown like normal. Now, I screech to a halt.

Cast your vote!

 

[RustyRatRod]

Sounds normal. You don't mention disc or drums but in either case, it sounds normal. You MIGHT inspect the brakes to make sure you don't have a leaking axle seal or wheel cylinder as either will cause brakes to lock prematurely.

 

[Dana67Dart]

Fluid leaking out of the mc is not normal.

You need to find out where it has gone to.

If power brakes it might be in the booster.

If non power it might be on the drivers side floor board.

Or it could have leaked from the drum cylinders or disc calipers.

 

[413]

Brakes will grab and lock when they are damp or wet. Pull all the wheels and look for fluid leaks.
axle seals
brake fluid
grease from front wheel bearings.

 

[missing linc]

Granted, there is a world of difference between the 70s and 2020s when it comes to brakes and their performance, however, it is most unusual for the master cylinder to be that low on fluid that air gets in the system.
As mentioned above, check all wheels for leaks, plus all lines and hoses, but also I would be checking for worn out pads/shoes, and oversized drums/undersized rotors if you have front disk brakes. You didn't mention if it has drums or disk, but I assume that it is probably disk.
You also didn't mention whether it was power or manual, but it shouldn't be that easy to lock them up IMHO.

 

[Icetech]

If your MC went low in 1-2 years you have a leak somewhere.. it should be able to sit a LONG time without every moving the level in there.. start checking around for brake fluid.. it's gotta be going somewhere

P.S. if they are drum brakes and lock it's due to not being adjusted properly... if they are too loose when not applied they will lock soon as they hit the drums

 

[HemiSSDart]

Notice any chattering when applying the brakes? Sounds to me like fluid is getting on the linings...

 

[TF360]

Yea, you have problem somewhere. They should not be locking up so quick. I would guess the front disc brakes are not working right.

 

[340demon72]

Very typical of wet drum shoes. If a front drum, likely to yank steering wheel to that side. Brake fluid doesn't disappear in a closed system, you have a leak!