Embarrassing problem with my brakes

[lobudgt]

97 f250 crew cab short bed
right rear locks intermittently during barely above normal stop pedal pressure. In fact, every other vehicle I have ever driven allowed significantly harder stops with no tire slide or anti-lock activation. The anti-lock on this truck may or may not activate if I let the tire locked up more than a second or so. I HATE this differential anti-lock setup! STUPID!!

Here's the embarrassing part. I always think people who just start replacing parts to solve a problem are ill advised to do so. Well, that's what has happened to me.
Before I knew of this locking brake problem, I had 2 sticking parking brake cables. Had them replaced. Had the rear brake shoes and drums replaced since one was shot from brake cable hanging up. That's when I noticed the right rear locked up first time. I had just bought the truck though, so it may have done it before too.

When the locking issue was noticed, a leaking poorly done steel brake line repair was found and fixed. To bleed the brakes, one wheel cylinder was replaced due to a seized, then broken bleeder. The axles were pulled to make sure of the brake adjustment. The right rear still locked intermittently. 10-12 stops it might be fine, then it will happen again. The master cylinder was replaced next, and the little bit of rust scale around the booster was cleaned. No contamination found in the brake fluid. It didn't help at all. The right rear brake shoes were adjusted farther away. It still locks that wheel.

ANY IDEAS PLEASE??

[forddieseldoctor]

Do you have a leaky axle seal or is everything in the brake drum bone dry? Are the brake shoes installed correctly (long shoe in the back)? Both wheel cylinders free and not binding?

[lobudgt]

Originally Posted by forddieseldoctor

Do you have a leaky axle seal or is everything in the brake drum bone dry? Are the brake shoes installed correctly (long shoe in the back)? Both wheel cylinders free and not binding?

Thanks for your response. Your answers below in order.

No, dry.

Yes, correctly installed. I am curious how this would intermittently cause my problem though.

Yes, free and not binding as well as I can tell without being able to see them work under real world conditions. One is new as mentioned too.

[lobudgt]

Ok. Nobody has anything else to add?

A broken spring was found, and it took care of the intermittent over sensitivity at the rear. However, when I push the pedal harder, to the point where a wheel probably should lock, it's always the right side.

Let me ask you all this...has anyone else with my model and year truck ever noticed which rear wheel locks up first when "over braking"? Is it one in particular every time, or have you had both take turns?

[Jarrod B]

i wouldnt call this embarrasing. you really didnt throw parts at it. just replaced what needed to be replaced. or would had to be done sooner or later.

i didnt see it mentioned. was all brakes bled? for air?

[Hank]

I agree with Jarrod.........flexible brake line is not twisted is it?

[lobudgt]

Originally Posted by Jarrod B

i wouldnt call this embarrasing. you really didnt throw parts at it. just replaced what needed to be replaced. or would had to be done sooner or later.

i didnt see it mentioned. was all brakes bled? for air?

Thanks for your kind words. The master cylinder irks me a bit, as it wasn't the problem and could have waited, but you're correct. With the scale starting there, it would have come up sooner or later.

I doubt the front brakes were bled. I don't think anything was done to the front brakes, except for a visual inspection. The master cylinder would have been bled when it was replaced no doubt. Both rear brakes were bled when the leaking line and wheel cylinder were replaced.

Do you think bleeding the front would have any effect on which rear wheel locks first? Without another truck just like this one to test drive, I'm guessing that the point at which the rear wheel locks up is normal. It's just curious that it's always the same wheel. The one that it has been regardless of how much pedal it took. It just seems to take a normal amount of pedal before it happens now.

Originally Posted by Hank

I agree with Jarrod.........flexible brake line is not twisted is it?

Nope. No twisted rubber lines. Thanks for playing Hank! As a consolation gift, we have some delicious Rice-A-Roni! "The San Francisco Treat"!
Oops...I'm showing my age and propensity for being a smart asz.
Thanks for your thoughts Hank!

[Jarrod B]

if there were air in the front lines, it could act like a spring. pressin down the brake will send more pressure to the rear if there were no air in the rear lines so ya i can see that as a possibility.

[Hank]

Originally Posted by lobudgt

Nope. No twisted rubber lines. Thanks for playing Hank! As a consolation gift, we have some delicious Rice-A-Roni! "The San Francisco Treat"!
Oops...I'm showing my age and propensity for being a smart asz.
Thanks for your thoughts Hank!

Hope you find your brake problem. Easier to fix than the old age and propensity for being a smart azz. I know. Good luck.

[lobudgt]

Originally Posted by Jarrod B

if there were air in the front lines, it could act like a spring. pressin down the brake will send more pressure to the rear if there were no air in the rear lines so ya i can see that as a possibility.

I can see how that could create an imbalance in the system. Not sure if it could cause the same wheel to lock in the rear every time though. Do you feel it could? I would also have to wonder how there would even be air at the front brakes, since they weren't touched. The master cylinder replacement shouldn't have affected them as I see it, what about you? Not to mention, the lock-up issue started before the M/C was done. I'm not saying you're wrong in what you said, but I am questioning your ideas to further my understanding and get to the bottom of this problem. Thank you.

Originally Posted by Hank

Hope you find your brake problem. Easier to fix than the old age and propensity for being a smart azz. I know. Good luck.

Me too!
I find a little humor is the only way to keep from crying when these seemingly never-ending character tests occur. Thanks for your support!


New related question: What should the pedal feel like when you first step on it, and then throughout the stop? It's different from one type vehicle to another. What should this exact systems pedal feel like?