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Mazda Engine General \  Brake issue

Brake issue

Mazda Engine General Mazda Engine Mazda Tech
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replies 30
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mercilessltd   +1y
I just put on brake pads, brake shoes, and hardware kit. Bled the brakes with the truck off and with it on.

Problem is, when I push on the pedal, halfway its soft and spongy, then suddenly very hard like it's actually starting to brake. It works, works well, but I definitely ain't saving any deer with the brakes.

Is this normal for the B's? Or do I possibly have a bad brake booster or other issue?
Cusser   +1y
First thing I would do is manually adjust the rear brake shoes.
newbiet   +1y
Can you pump it up till it's high and hard? Or does it get high then just start to sink?
mercilessltd   +1y
Cusser: I believe the rear shoes are adjusted. They spin fairly free until you hit the brake or pull on the e-brake.

NewbieT: First. I can pump it up and it will hold. Forgot to mention that.
Cusser   +1y


That new information is more in line with air in the brake system, or brake master/wheel cylinder/flexible brake line issue. So first thing I'd do is bleed the rear brakes (combined, on driver side) and both front calipers, and flush out all the dirty old brake fluid while you're at it, until clean fluid comes out.

If that feels better and stays better: GREAT.

If it gets mushy after a while yet pumps up, then you've got something defective that needs replacing.

I've gone through several brake master cylinders and one caliper repair kit in the 17+ years I've owned my '88 B2200.
mercilessltd   +1y
Sorry, I wasn't clear. I did adjust them, and I think they are adjusted correctly. Both rear wheel cylinders have been replaced in less than a year (one was replaced two days ago).

Flexible brake line? I take it, even if it doesn't leak, it won't hold pressure correctly? Any way to pinpoint which line?

Also, I did convert my back breaks to split at the axle instead of the pass-thru system it came with (mostly because at the time I could only get a driver side wheel cylinder and it was necessary for the truck to be running).
Cusser   +1y
Did you bleed the rear brakes after installing that rear wheel cylinder 2 days ago (need to ask, you didn't state). Also, I'd check the connections for leaks where you made the conenctions to split the rear brakes into two separate lines.

If the flexible lines are bad, usually a leak. But they can go bad over time internally as well.
mercilessltd   +1y
Yes, I bled all 4 after replacing it. The reason I ask about pressure on the internal lines is I see no visible leaks, and the level in the master cylinder doesn't appear to change, except for bleeding.
newbiet   +1y
Like cusser said its probably a little bit of air. Are you manually bleeding them? Or do you have a pressure bleeder? Only thing to do is make sure all connections are tight and keep bleeding till you have a good pedal.
mercilessltd   +1y
Hm... well, guess I better go buy a big bottle of brake fluid.

Just outta curiosity, what are typical symptoms of a bad booster?