'73 Series III rear brakes problem

[1973series3]

The brake lights staying on still makes me think the master cylinder is not releasing the pressure. I would go that route first. Personally, I would replace the cylinder as kits often don't match up 100% with whatever version you have.

That is what I was thinking too. But being new to these machines and their quirks, I wasn't sure if I was missing anything else.

I had no idea about the kits not matching up, seems like a new one will be the best next move.

[1973series3]

So, what was the rear hose like that has been replaced?
Was it leaking, or replaced as a matter of course?

I read on here that sometimes due to them breaking down they could possibly cause the issue I am having. I didn't seem to help me.

But I DO enjoy getting RN boxes in the mail.

[SafeAirOne]

The brake lights staying on still makes me think the master cylinder is not releasing the pressure.

Though I agree that dragging rear brakes is the result of retained pressure in the hydraulic system, I think the brake light is a red herring. Presuming a foreign (to the SIII) pressure-operated brake light switch hasn't been added to the plumbing, the SIII brake light switch is a mechanical switch. If the brake pedal is fully retracting (and the OP says it is), and the switch isn't broken, and the switch is adjusted properly, the light should go out regardless of any pressure retained in the hydraulic system.

[1973series3]

Okay, I replaced all of the rubber hoses with the braided stainless hoses and anew master cylinder from our host, bled the system etc.

Yesterday, after sitting for maybe 2 months, I fired Maggie up and the rear brakes were fine as I started to back up, but after traveling maybe 6ft, the rear braked locked up HARD. When it does this I usually drive forward a little and it sorta works loose, but when I hit my pedal going forward, it really locked up my brakes.

This event seems to culminate after she has sat for an extended time.

I eventually got it out of the garage and went for a drive.

I must confess, this is really getting me down.

[SafeAirOne]

Is the MC rod adjusted IAW/the FACTORY workshop manual?

[printjunky]

100% agree with Mark. Brake light symptom is likely a separate issue.

The most important variable seems to be the "sitting for awhile." Seems unlikely that would be a factor in whether the system retained pressure (other than by coincidence).

I doubt this is related, but it reminds me a bit of a condition I get sometimes, under certain circumstance (especially the "after it's been sitting " thing).

About 10% of the time, after getting wet, then sitting for 24+ hrs, the first time I brake, I get a "catch" in the brakes. Kinda makes a bang/chirp, and provides a moment of resistance, almost like it's going to lock up - but it never gets really close to that. As soon as I release the pedal, it rolls fine (and never feels like it wants to really lock up, even if I kept the pedal applied). No other affect, and usually just happens one time. I always assumed it was a matter of a little flash rust on the drum (and maybe a trailing/leading shoe position - can you flip those?). When it first happened it seemed a bit dramatic. But it is really not, and otherwise the brakes work great.

99% of the time, when it does this, after hitting the brakes (and "catching") once, it's done. It ONLY happens at VERY low speed (I go down a hill from my driveway, so apply brakes pretty quickly). Once in a great while it takes a couple of "catches." The degree of apparent dramatic-ness varies. Most of the time it doesn't happen, of course. When it does, sometimes it's barely a tick, others, it will be 3 stronger, separate "catches," before it's gone (like once on the hill, once (usually lesser) at the first intersection). It's always gone by a couple of brake applications AND if I drive without braking right away (eg: I'm not at home, on the hill), it doesn't do it at all (braking at speed probably clears it without having any noticeable affect due to momentum). Length of time sitting seems to be an important variable. That and the very slow speeds at which I usually brake for the first time.

[ignotus]

It can be that the shoes need some additional chamfering to stop from dragging. It seems to be a new phenomenon I think that crappily made parts are at fault, perhaps not the correct arc on the shoe. Read; http://www.series2club.co.uk/forum/f...ic,6606.0.html

[1973series3]

100% agree with Mark. Brake light symptom is likely a separate issue.

The most important variable seems to be the "sitting for awhile." Seems unlikely that would be a factor in whether the system retained pressure (other than by coincidence).

I doubt this is related, but it reminds me a bit of a condition I get sometimes, under certain circumstance (especially the "after it's been sitting " thing).

About 10% of the time, after getting wet, then sitting for 24+ hrs, the first time I brake, I get a "catch" in the brakes. Kinda makes a bang/chirp, and provides a moment of resistance, almost like it's going to lock up - but it never gets really close to that. As soon as I release the pedal, it rolls fine (and never feels like it wants to really lock up, even if I kept the pedal applied). No other affect, and usually just happens one time. I always assumed it was a matter of a little flash rust on the drum (and maybe a trailing/leading shoe position - can you flip those?). When it first happened it seemed a bit dramatic. But it is really not, and otherwise the brakes work great.

99% of the time, when it does this, after hitting the brakes (and "catching") once, it's done. It ONLY happens at VERY low speed (I go down a hill from my driveway, so apply brakes pretty quickly). Once in a great while it takes a couple of "catches." The degree of apparent dramatic-ness varies. Most of the time it doesn't happen, of course. When it does, sometimes it's barely a tick, others, it will be 3 stronger, separate "catches," before it's gone (like once on the hill, once (usually lesser) at the first intersection). It's always gone by a couple of brake applications AND if I drive without braking right away (eg: I'm not at home, on the hill), it doesn't do it at all (braking at speed probably clears it without having any noticeable affect due to momentum). Length of time sitting seems to be an important variable. That and the very slow speeds at which I usually brake for the first time.

To be clear, after sitting and not hitting the brake pedal and backing out of the garage it will travel a few feet and lock up solid on the rear wheels.

I had to put it in 4wd and force it out of the garage the last time. After forcing it to move it finally decided to act normally.

I will add, this never happened EVER until I replaced the shoes.

Hell, I'm about to put the old ones on the rear again(only the rear is creating an issue?) and mail these new ones back to RN so they can check them out.

[1973series3]

It can be that the shoes need some additional chamfering to stop from dragging. It seems to be a new phenomenon I think that crappily made parts are at fault, perhaps not the correct arc on the shoe. Read; http://www.series2club.co.uk/forum/f...ic,6606.0.html

I have suspected this but didn't want to taint any replies so I never mentioned it.

[SafeAirOne]

To be clear, after sitting and not hitting the brake pedal and backing out of the garage it will travel a few feet and lock up solid on the rear wheels.
I will add, this never happened EVER until I replaced the shoes.

This clarification could have saved lots of typing, had it come in post #1.

IT'S THE SHOES (or their installation).