Rear wheels lock and unlock when brake pedal is pressed

[raulvargasdelos]

Gents,
My rear wheels stay locked and when pedal brake is pressed, they unlock and lock again, could this be a pressure regulator failing?

 

[Arde]

I think downstream of the regulator the left and right brake lines go from metal tube to rubber and then metal again near the wheels. Is it possible the rubber section deformed and keeps the pressure up after the pedal is released?
The regulator is a mystery to me, so no opinion.

 

[raulvargasdelos]

Thanks Arde;
I just had the rear calipers replaced because of this reason and the mechanic said the same thing. I do have the hoses so will start there and comment. Thanks again
Raul

 

[Arde]

Raul, do wait for others to opine. There are people infinitely more experienced than me on the board.

 

[jmackro]

There are people infinitely more experienced than me on the board.

Gee, I don't think I'm infinitely more experienced. But I do think you are on the right track to identify the rear flex hoses as the likely culprit. As these hoses age, the internal part of the hose can swell and act like a one-way valve. Pressure goes out to the calipers, but can't return, or at least, can't return quickly. So the calipers will lock, but eventually relax.

Might as well replace the front flex hoses also while you're in there. The fronts are probably just as old as the rears.

 

[dang]

Thinking out loud... Seems like hoses that are swollen would act like a one way valve and not allow the brakes to unlock when the pedal is initially depressed. There's a possibility the master is acting strange just for the rear line.

Boosters can do really strange things but affect front and rear.

 

[Dan Wood]

The rear brakes on our 2002 were squealing and it was due to the rear brake hoses being restricted and not allowing enough fluid to properly engage.

 

[Arde]

Gee, I don't think I'm infinitely more experienced. But I do think you are on the right track to identify the rear flex hoses as the likely culprit. As these hoses age, the internal part of the hose can swell and act like a one-way valve. Pressure goes out to the calipers, but can't return, or at least, can't return quickly. So the calipers will lock, but eventually relax.

Might as well replace the front flex hoses also while you're in there. The fronts are probably just as old as the rears.

Jay, you are. You restored three cars with your own hands... Three divided by zero is infinite...

 

[jmackro]

You restored three cars with your own hands... Three divided by zero is infinite...

OK, I'll take that as a compliment.

 

[Arde]

OK, I'll take that as a compliment.

It is, and I would buy any of your restored Alfas .

 

[rsporsche]

my recommendation is to start simple - definitely get rid of the old rubber hoses - whether you replace with OEM rubber or go to flexible stainless ... your braking will improve. i presume that the master is in good working order and you have already replaced your brake fluid ... of course when you replace your brake lines you will have to add new fluid and properly bleed the system. my curiosity is whether on the rear brakes you are finding anything (particles) in the brake fluid that might point to any breakdown inside the pressure regulator. as i remember, PMB sells a kit for repairing the regulator - check the FAQ for Best Sources ... their link is in the 2nd thread.

 

[raulvargasdelos]

Gentlemen;
Replaced rear and front hoses and it is a different world, thanks everyone for helping out!
Cheers
Raúl

 

[halboyles]

This is what those flexible brake lines look like inside when they go bad. Plugged one on the right.

 

[Honolulu]

dang: Seems like hoses that are swollen would act like a one way valve and not allow the brakes to unlock when the pedal is initially depressed.
Me: Yeah, the brake booster provides a LOT more pressure TO the calipers than does whatever makes the caliper piston retract. Ergo, brakes seize. Funny think though, I've seen rear drum brakes on 2002s fail to retract. Sufficient screwing around with those eventually brought satisfaction and the seizing did not recur. Why? Did we simply dink around with the lines enough that they cleared themselves?

 

[eriknetherlands]

Ok, now it's solved I can make the joke...

Thread title is
"Rear wheels lock and unlock when brake pedal is pressed"

When I first read it, I just thought

"...aren't brakes supposed to do that? "

 

[Arde]

Ok, now it's solved I can make the joke...

Thread title is
"Rear wheels lock and unlock when brake pedal is pressed"

When I first read it, I just thought

"...aren't brakes supposed to do that? "

There is also the guy that asked a friend to tell him from outside the car if the blinker lights worked when he moved the stalk. The friend said:
- Now they do, now they don't, now they do, now they don't....

 

[raulvargasdelos]

Indeed I had miswritten the question, English is not my first language so I apologize; the fact was that the wheels remained lock even when the pedal was depressed.
Like I wrote before, changed the flexible hoses and now they work perfect,