31 replies to this topic

[Jimmer 84mayfair]

I filmed the adjusters backing off today as I pumped the brakes, no wonder I can't keep any pressure. If you watch the film from start to finish each adjuster is turning 2-3mm within a number of pumps of the brake peddle, it is more apparent if you drag the media toggle and play it in fast forward motion. All four on the front are backing off the same amount, the adjuster is way too slack, it will never hold pressure whilst this going on. I am going to take them off tomorrow and send them back. Hopefully this is just a bad set and they can send some that will do what they are supposed to do.

https://youtu.be/7SUyesCy7A4

[Cooperman]

That is very odd. I've never seen that happen before. It looks as though the adjusters are too slack in the backplate - but why?

The inside part of the adjuster is '4-sided' (or should be) so that the adjustment is incremental in 90 degree segments. Once tightened, it self-locks as the adjuster cannot move back through one lobe position after being set to brake-locked position then backed off by one segment.

Have the adjusters been tightened right up until the drum locks then backed off so that it just rotates with some resistance? 

[Jimmer 84mayfair]

Yes, that is exactly how I have adjusted them. I then removed the springs and shoes to see how tight the adjusters were, they can be turned with your fingers. I am going to send them back,... they're not fit for purpose.

[Cooperman]

My point it that the lobed shape of the tapered adjuster should mean that once adjusted correctly the adjuster is prevented from turning by the fact that the springs on the shoes pull the shoes onto the adjuster via the little spacer blocks. The shoe cannot move away sufficiently for the adjuster to rotate back because the drum prevents the shoe moving enough for the high point on the adjuster to move back. The adjuster is not meant to be stiff in the thread in the backplate and that is not what maintains the setting. Without any load it should be able to be screwed in by hand. The 4 lobes on the adjuster are what prevents unwanted back-rotation.

You need to see why this is happening. Do the adjustment shafts not have the lobes? Once adjusted correctly with a proper adjuster the adjuster simply cannot unwind - it is held by the lobes on the adjuster. That is how it is designed.

[Jimmer 84mayfair]

I am not sure I get what you mean, the wording sounds right,.. I have adjusted both adjusters on each wheel until the brakes are on,... then backed off the tension so that they have a minimal amount of drag on each hub. I assume a tiny amount will just wear off after a short drive. I am going to take a pic with the hub off just to make sure I have them set up okay. I am fairly sure this was how they were when I removed the old units....

[Jimmer 84mayfair]

The inside prong of the adjuster that runs around the flat and rounded area inside the hole of the shoe is rounded, the adjustment is made by moving the prong on an offset axis to the other side on the backplate. The springs are new, the brakes work fine for a day or two but then the peddle begins to drop. Evidentially because of adjusters not holding there set position. The pumping of the brake that I am showing in the film is the equivalent to a day two driving/braking.

Attached Files

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[Jimmer 84mayfair]

I note on the Somerford mini set up there is a metal hook coming through the hole nearest the piston on the cylinder, what purpose does this have? Mine does not have this, is there a retainer missing. It is not something I had in there before and they worked ok. Just wondering if the shoes are being twisted slightly in position and these retainers are helping to hold the shoes in a square position to the hub lining....
http://www.somerford...oducts_id=16903

[Cooperman]

Sorry, I thought we were talking about the rear brake adjusters - my mistake. The adjustment of the fronts is different on twin-leading-shoe brakes.

[panky]

Haynes just says 'the springs that hold the shoes to the piston - where fitted'. I suspect they are supposed to keep the end of the shoe in contact with the piston to minimise pedal travel, but I wonder how many cars still have them. The brakes seem to work OK without, as yours did. 

It's a long long time since I worked on a Mini with front drums but I'm sure there should be a friction plate or serrated washer under the adjuster to keep it tight.

Edit

Just found a diagram in and old Mini maintenance book. There are pins on the ends of the original shoes to locate the little springs, so I guess if new shoes don't have the pins then the springs cant be fitted.

Edited by panky, 03 January 2017 - 05:30 PM.

[Jimmer 84mayfair]

Film of the new master cylinder leaking...
https://youtu.be/t8S3inP53RE

I now think the master is ok, just the backplates on the front being the problem.

I think that the fluid level was excessive after disconnecting the pressure bleeder, the excess was then overflowing via the cap.

[Jimmer 84mayfair]

' I'm sure there should be a friction plate or serrated washer under the adjuster to keep it tight.'

That was my thought, the brake adjusters therefore should be reasonably stiff to offer some purchase, otherwise the winding back that is happening will always happen.

Mini Spares have offered to refund for them, but I am now worried that I might end up buying another set from elsewhere, but with the same problem. I imagine there are not too many people re-manufacturing these.

I could get another second hand original set off eBay but that seems counterproductive, the idea was to replace with new parts.

[smurfomatic]

Not sure if this is any help, but a couple of years ago I bought a set of front drum brake backplates, completely built up with adjusters, cylinders & shoes, from South Lakeland Minis via eBay. Was very handy as I'd managed to round off the adjusters on both sides!

[Jimmer 84mayfair]

The internal adjusters are designed rounded, but just move on an offset axis against the d-shaped hole cut in the shoe. The external adjusters on the backplate have a square to make the adjustment with a spanner, this is what you can see turning in the film I uploaded. My original backplates had slightly externally rounded squares, that's why I decided to replace them, unfortunately I threw them away, I am sure these original ones would have kept there position once set.
I have now created a problem that was probably not there in the first place!
Unfortunately now I only need to replace the backplates as I bought everything else already. If I buy two complete built sets, a majority of this set will be of no use to me. I could resell it I suppose. A bit long winded for such a seemingly simple set up.

[smurfomatic]

Sorry - when I said I rounded off the adjusters I meant the square bit on the back, which meant the brake couldn't be adjusted with a spanner any more.

 

I only bought the complete set as I've heard of problems just replacing the adjusters, add that to the fact the backplates were at least 35 years old and I wasn't too sure about the brake cylinders and I didn't mind paying for them. Kept the brake shoes as spares for future as they weren't too worn.

[Jimmer 84mayfair]

I have sorted this out, the brakes are now perfect all round. The backplate was allowing the adjuster to spin under heavy braking. I have replaced them with another new set, all is fine now. Thanks for your input.