30 replies to this topic

[SteadyEddie]

Hey there! I replaced both rear brakes as a complete kit (backplate, shoes, springs, cylinder, housing) adjusted and bled the system.

 

A few weeks ago, I had an issue where if I braked more than a tiny bit, the rears would bite and lock on, and not stop when I released the brake either. The rear made a horrible judder and get some tyre squeal from the lock up. On jacking the rear up, I found that the rears seemed out of adjustment, so I tightened up the adjuster. Problem went away. 

 

Here we are a few weeks later and the same thing has happened again. Definitely feels like I must have done something wrong but can't work out what. I'll put in a picture of the rear brake assembly along with some thoughts:

 

- this happens with either the foot brake or hand brake which means it's not a master cylinder/fluid issue, but some sort of mechanical arrangement of the brakes

- I have disc brakes on the front

- When adjusting the rears the second time, they feel like they have a high and low spot when rotating, which suggests that the drum housing isn't round/shoes aren't in properly. Both sides feel like this

- From the sound, I think the rear driver side locks first

- After not driving for a few days and it's been wet (parked up with handbrake on), sometimes the rears are stuck on and I need to give it some beans to unstick them

- When I rotate the adjuster, the outer thread rotates in the backplate rather than the adjuster in the threaded insert. I'd expect just the adjuster to move within the thread, and the threaded insert to stay put in relation to the backplate. 

- I put copper grease on the places recommended in StevesonMotorCo's video

 IMG_20260122_111835321.jpg   41.1K   6 downloads

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 IMG_20260122_111446792.jpg   53.84K   9 downloads

 

Any thoughts welcome on what to check! Thanks gang.

 

[DeadSquare]

New brake shoes have a rough texture, and can BITE, until they bed-in, but it should only take 100 miles for them to acquire a smooth polish.

 

If the drums catch in places, they may be warped / worn, and if they are not too bad, they can be mounted in a lathe and 'skimmed'

 

The "Nut", (for want of a better word), in / on the backplate, through which the brake adjuster is threaded, MUST be a solidly fixed, integral part of the backplate.

 

If it isn't, and rotates with the adjuster, the backplate is faulty.

 

Unless you need the rear brakes to lock, for hand bake turns or left foot braking, I only adjust mine to pass the MOT as a parking brake.

[nicklouse]

Mmm I would not be putting copper past anywhere.

 

when during the adjuster you should feel it go clunk as it changes from flat to flat. Nothing else should rotate.

 

you do have a workshop manual to refer to?

[alpder]

Backplate not quite tight enough, so moving on the the radius arm?

[Spider]

I suspect there might be 2 separate issues here, possibly 3.

Shoes can bite like that when they have been contaminated.

As you purchased complete assemblies and have disc brakes up front, do the new assemblies have a suitable sized wheel cylinder ?

 

How old are the rear flexy lines ?

[Ethel]

I don't see how the wheel cylinder size would do it. It might make them lock up, but they should still release as soon as the pedal's released.

 

How free's the hand brake? A bit of excess cable tension might not be enough to lock the brakes itself, but it might be enough to prevent then releasing after the brakes have pulled themselves on with drum rotation over the shoes

 

The hoses & lines are very plausible, impossible to fit new brakes without disturbing them. Were the hoses clamped?

[SteadyEddie]

I replaced the final section of brake line on both sides of the rear brakes so I don't think it's to do with that. They bled fine as well.

I like the handbrake theory, I'll check the adjustment of that tomorrow.

I will also check on the adjuster to see if that rotates or not and get some photos.

Thanks so far everybody!

[bpirie1000]

Is there a lip on the drum?

[Ethel]

There are 4 flats on the adjuster so you should feel it "go slack" in 90 degree increments if it's moving as it should.

 

I thought the lining material on the shoes looked a bit on the chunky side. If you have some old ones, you could try them instead.

[coopertaz]

your shoes are incorrectly fitted. there is a leading and trailing edge to each. the leading edge has a larger gap from the front of the shoe to the friction material, the images in the haynes manual show the leading edge on the front shoe goes to the adjuster and the leading edge on the rear shoe goes to the cylinder. on your photots the rear shoe on your set up is the other way around, i have always fitted mine as per. the haynes way and had no issues. i have seen backplate assemblies from suppliers at shows which are provided the way round as your current fitment, both leading edges at the adjuster.

Also is there contamination on the shoes or are the marks just from the drum? also before fitting give the shoes a quick rub with some 600 grit wet and dry this to aid bedding in and remove any high spots

Also you are right the threaded insert should be fitted to the back plate

SMALL amount of copper grease on the pivot points and adjuster

With new linings the brakes are liable to stick till surface is totally smooth (bedded in) which is why you always lay up cars in gear and chocked with handbrake off

[GraemeC]

Also check the quadrants on the radius arms are moving freely. These can cause the handbrake to drag even if the main cable up to them is free

[andyapanel]

I chamfer the ends of the shoes.

Did you replace the levers, too? They can cause trouble.

Good luck solving it.

[Midas Mk1]

I chamfer the ends of the shoes.

Did you replace the levers, too? They can cause trouble.

Good luck solving it.

 Just about to mention the chamfered edge and you beat me to it aha

[Ethel]

your shoes are incorrectly fitted. there is a leading and trailing edge to each. the leading edge has a larger gap from the front of the shoe to the friction material, the images in the haynes manual show the leading edge on the front shoe goes to the adjuster and the leading edge on the rear shoe goes to the cylinder. on your photots the rear shoe on your set up is the other way around, i have always fitted mine as per. the haynes way and had no issues. i have seen backplate assemblies from suppliers at shows which are provided the way round as your current fitment, both leading edges at the adjuster.

Also is there contamination on the shoes or are the marks just from the drum? also before fitting give the shoes a quick rub with some 600 grit wet and dry this to aid bedding in and remove any high spots

Also you are right the threaded insert should be fitted to the back plate

SMALL amount of copper grease on the pivot points and adjuster

With new linings the brakes are liable to stick till surface is totally smooth (bedded in) which is why you always lay up cars in gear and chocked with handbrake off

 

I thought that, but they look to be as you describe to me.  - Turning the wheel forward the drum rotates from the longer unlined end of the shoe to the shorter unlined end.

[alpder]

Could it be that the fat friction material (as mentioned above) has increased the radius of the brake-pad surface so that instead of fully engaging on the drum, only the very front and the very back of the friction material is touching? That'd seem like a recipe for snatching. Maybe hold a loose pad inside the drum and run a thin feeler gauge around to see where it's touching, to rule this in/out.

 

Edit: "pad" -> "shoe".

Edited by alpder, 12 February 2026 - 09:26 PM.