What went wrong?

[DutchTriumph]

My 7 had a MOT failure, because of difference in the rear brakes. Difference ment right was doing almost nothing.
It turned out the right cilinder started leaking, just a little oil in the drum, nothing outside. I've replaced both cilinders, left and right.

It passed the MOT brake test. On the way home it went wrong. The MOT station was still in sight when the right rear wheel blocked for a short moment, I was not touching the brake at that time. After braking the wheel was blocked.

Never seen brakes looking like this.

After MOT









What could have happened?
The plus is that my 7 has a new MOT until 2019.

[Beans]

If the first picture is the right hand side, your brake shoes were fitted the wrong way round.
An overview picture of the complete set up might help. This is how the RH shoes should be fitted ...



Still not quite clear why it jumped from the retaining point.
Probably because the first part of the shoes lining to touch the drum isn't there.
The lining starts further away seen in the direction of rotation.
So needs a longer throw from the cylinder. Might be the cause of the leak.

And wondering how you managed to get the handbrake mechanism in place

[DutchTriumph]

If the first picture is the right hand side, your brake shoes were fitted the wrong way round.

Sorry, pictures are small on my phone, that was the left side. I've got no "before" picture of the right hand side. There's a new picture now, with a better over view.

The shoe didn't jump out of the retaining point, the retaining point is bent open.

I think it's impossible to fit all the parts when the shoes are the wrong way round.
The only difference I see is the top spring. You've fitted it behind the shoes, mine was at the front.

The leaking cilinder was probably lack of use, don't drive enough these days.

[Beans]

... ...

Looks like something jammed between shoe and drum, a few questions;
• What caused the damaged to the back plate?
• How does the inside of the drum look like?
• Retaining pin/spring/dished washer still in place?

As for the top springs, from the factory they are fitted to the back of the shoes, thus pulling them against the back plate.
But as long as I can remember I have fitted them to the front and never had any problems.

[DutchTriumph]

Every part was in the correct place, nothing missing, no loose parts in the drum.
The drum is fine, no damage.
What caused the damage is what I' trying to find out.

Don't like the idea of a spontaneous locking wheel. It blocked for a plit second an then it was loos again, I didn't touch the brakes at that time. The wheel jammed when I stopped.
It happened shortly after heavy breaking at the MOT brake test.

The only thing I had in the past is that after working on the brakes, the automatic adjustment was to tight. After releasing the adjustment, it set itself again. As it had to settle.

[skertonman]

Looking at the damaged brake shoe, it looks like it's been rubbing the side of the drum face, the bit that sits on the half shaft flange.

At a guess I would say that the damaged shoe has not been sat correctly on the riveted back plate shoe mounting, and been thrown off when that brake has been used individually on the MOT brake tester.

I don't think it matters which side the shoe the spring sits, as long as they don't foul the rotating half shaft.

Either that or Gremlins have gotten inside when you had the drum off!

[Cobber]

Did they remove the brake drum for inspection during the MOT?
Did they then have trouble refitting it?
If so then it's possible that the brake pedal was pressed while the brake drum was off, causing the brake shoe to unseat, and the damage could've been caused by forcing the brake drum on when refitting.

[FI Spyder]

Cobber's explanation makes sense to me. A couple of points to make. I always take pictures of RH and LH sides before dismantling. When overhauling cylinders of any sort, I lubricate the metal cylinders and rubber seals with red rubber grease (which sometimes comes with rebuild kits but can be bought separately). I don't rely on the brake fluid to do the lubrication. This also prevents the cylinder bore outside the piston travel from rusting.

[DutchTriumph]

Looking at the damaged brake shoe, it looks like it's been rubbing the side of the drum face, the bit that sits on the half shaft flange.

At a guess I would say that the damaged shoe has not been sat correctly on the riveted back plate shoe mounting, and been thrown off when that brake has been used individually on the MOT brake tester.

I don't think it matters which side the shoe the spring sits, as long as they don't foul the rotating half shaft.

Either that or Gremlins have gotten inside when you had the drum off!

The damaged shoe went a bit to the outside, after bending. I could free the wheel by loosening the automatic adjuster and limped home after that. I think the markings on the side of the shoe are from the ride home.

If the shoes are not correctly fitted the drum won't go over them.

The top spring doesn't really matter, it's not strong enough to pull the shoes to the outside.

How to catch a Gremlin?

[DutchTriumph]

Did they remove the brake drum for inspection during the MOT?

No they didn't work on the car, no tools are used at the Dutch MOT it's only a test of functionality.

[DutchTriumph]

When overhauling cylinders of any sort, I lubricate the metal cylinders and rubber seals with red rubber grease (which sometimes comes with rebuild kits but can be bought separately). I don't rely on the brake fluid to do the lubrication. This also prevents the cylinder bore outside the piston travel from rusting.

Thanks for the tip, to late for now, but will be used next time.

[Beans]

I still think the clue might lie in the back plate.
That damage to the edge looks like something got mangled between drum and back plate.
Have you checked if this plate is still straight.

... How to catch a Gremlin?

First find it

[DutchTriumph]

Straightened the retaining lip. The rear plate seems to be fine.





What about the automatic adjustment? The first time I push the brake pedal after working on the brakes, I hear the adjustments working.

It happened a few times they were to tight after working on the brakes. After releasing them they adjusted correct. Like the brakes had to settle first, and the adjustment after that.

Could the damage be a result of tight brakes?

[skertonman]

Having another look at the photo's is it possible you levered the drum off as it was tight. That might explain the damage to the back plate near to the shoe retainer, it would also explain the damage to the shoe and retainer if the lever used was behind the shoe as it levered off the drum, and bent both in the process.

I still stand by the Gremlin theory though, I heard years ago all British Leyland cars had them factory fitted, it would explain why all the Leyland cars I've driven over the years have all had their "individual" problems.

[jeffremj]

Could it be a set of poor quality brake shoes - a combination of soft metal and a lining that expands when warm?