Below are two things that are wrong with my brakes/wheels. Can someone explain what might be happening?


1. When I come to a stop, the brake pedal slowly goes down about 1"-2".
Can this be a leaking brake booster?
A by passing master cylinder?
Does it simply need to be bled?


How can this problem be properly diagnosed?






2. When slowing down from a speed of 40mph+, my brakes/wheels pulsate.
Can this be warped rotors?
Bad front end alignment?
Bad tires?
Out of balance wheels?


Thanks

 

It sounds like your master cylinder is on it's way out. I've only had it happen once in my life and it was on my 69 Rideau 500 but it was identical to your slowly lowering brake pedal.

The pulsing brake pedal may be an indication of warped rotors. My dad had the same symptom on a few of his fords. He simply ignored it as the fix was too expensive. He drove those trucks for years with the pulsing but a mechanic friend told us it was probably due to warped rotors.

Hope this helps.

 

How can master cylinder be tested to be sure? And rotors?

 

with the brake lines still attached to the master cylinder, unbolt the master from the brake booster. Look to see if there is any fluid leaking from the seal of the plunger that the push rod from the brake booster depresses.if there is any leakage, you have brake fluid creeping by the seal on the plunger and leaking into your brake booster. If that is the case, replace both. Brake fluid leaking into the brake booster means it's gone bad or it will go bad very soon. Also, when you step on the brakes do you hear any kind of air rushing sound? Another sign that your brake booster has gone bad.

 

If you jack up the front of your truck, the wheel/tire should rotate freely. If your rotor is warped it may rotate 3/4 of a turn then drag or something similar. And it could certain be just one side causing it.

It's cheap and a good maintanence to fully bleed your lines and put in new fluid as moisture can invade the system and corrode the lines. Do all four wheels correctly then if that hasn't helped, look to the MC and booster (or swelling rubber flex lines?). Worst case is you'd have done some good maintanence!

 

1. Is there a connection between master cyl and brake pedal that has to be removed so as to remove it from brake booster for inspection?

2. The brakes only pulsate when I depress pedal when slowing down, from say 40mph+? I don;t believe it will pulsate by just spinning wheel, correct?

 

2. The brakes only pulsate when I depress pedal when slowing down, from say 40mph+? I don;t believe it will pulsate by just spinning wheel, correct? ...

yes, when spinning by hand you should notice a slight drag when the high spot on a warped rotor reaches the brake pad area.

also, have a good look at the tire as you are spinning it to make sure that it isn't messed up.

 

No. The master bolts onto the booster. There is a rod that when you push the pedal, goes through to the master to depress the piston inside the cylinder. You can simply unbolt the master and it will come off.

 

Great, thanks!

 

Great, thanks!

 

The sinking brake pedal could be a failing MC, but it could also be that you've blown a rear brake cylinder (aka "wheel cylinder") on one or both drum brakes. This is not always obvious until you take the drum off and have a look.

Are you losing fluid? Note that is's NORMAL for the fluid level to drop as the disc brake pads wear, but it shouldn't be excessive.

And one more thing... if you do find a blown wheel cylinder and the brake shoes are wet, just replace them. Cleaning them with brake cleaner might make them LOOK good again, but they'll never work as good as they used to!

 

^^ yep. My truck went from tough to stop and mushy pedal, to feeling like sports car brakes (ok that's an exaggeration) when I replaced rear wheel cylinders, lines, and shoes. The failure happened so gradually I didn't notice just how bad it was until it worked as it should. Both rear cylinders leaked when you stepped on the pedal, and the rear had little to no stopping power.

Pulsing is warped rotors. You can get them turned or replace them. On the 2x4 truck you have, it shouldn't be a difficult job at all (it's a bit of PITA to remove rotors on the 4x4 trucks).

All good advice above. Good luck!

 

Thanks everyone.

Fluid is not dropping. Probably need to remove drums to inspect anyway. Looks like brakes are the next project and order of maintenance.

Depending on cost of rotors, I may just replace them.

Now, my next thread is going to be on tips/advice on a front and rear brake servicing!

 

SoCal, I believe you're fairly close to me. Let me know if I can help you sometime when you tackle this project.

 

Thanks GJ, I appreciate the offer!