Balancing caravan brakes - driving me slightly insane.

[Orca2]

Well done looks like a beehatch of a system.

[debcab06]

Well done that man!!!!

Years ago my old dad gave me a tip which I`ve always used when messing with brake shoes...... File off the leading edge of the lining material to about 30 degrees.

[Ian21401]

There had to be a cause and you persevered until you found it. Congratulations on keeping an old van going. Mine is only 20 years old but I feel like a pauper when I arrive at a site comprising of mainly upmarket models less than two years old. But I bet most of the owners haven't a clue how to fix anything.

[FullEnglish]

20 years old, that's a classic, nothing wrong with that!

[FullEnglish]

Unfortunately this isn't over. I took it back to inspection the other day, almost no brake effect at all. I can't turn the wheels at all with a ratchet strap at less than half braking, but it doesn't register on the machine.

Then I discovered that as soon as I adjusted the brakes on the back plate, they just sprung back after a couple of revolutions. Completelty pointless, poorly designed and non functional adjuster.

I gave up on the adjusters and fitted a "wire tensioning device" (no idea what it's supposed to be called in English) to each side so I could adjust each side independantly. The stupid floppy pivot mechanisim at the A frame had so much play in it that adjusting one side adjusted the other side as well, so I rebuilt it using proper steel and to tight tolerances. Tested again with a ratchet strap and a hang-scale, good brake effect and well ballanced.

Took it to inspection again, PRECISELY THE SAME.

No change at all. Not a bit.

I'm going to set fire to this thing soon...

[FullEnglish]

No, ok, I'm not really going to set fire to it.

I did something I haven't done for years, started phoning workshops. None of them answered. So I took all this apart AGAIN.

This time, I took the brake adjusters apart (which I've never done before) and discovered the very limited range of adjustment (which I assumed was entirely normal) was in fact caused by a buildup of old dried grease. Soaked the adjusters in white spirit and they now have the full range of adjustment. I also found some imperial sized nuts (wasn't easy, I can tell you) so after adjustment, I can stop the little blighters from moving again.

So, the question to any drum brake gurus is:

[IMG][/IMG]

What's the default position for the adjustor, the brake shoes (they move up and down) and, most importantly, the actuator (arrowed). The actuator has a great deal of movement and can be bolted up in any position along the horizontal plane.

i.e where do I position everything before I start adjustment?

[Orca2]

The arrowed thing looks like the actuator not the adjuster, the adjuster is the cone shaped thingy at the top of the brakes ,looks very like the drum brake adjuster on a Mini I had many years ago.

[FullEnglish]

Originally Posted by Orca2

The arrowed thing looks like the actuator not the adjuster, the adjuster is the cone shaped thingy at the top of the brakes ,looks very like the drum brake adjuster on a Mini I had many years ago.

You're absolutely right. Edited!

[60041]

The adjuster should not move once it has been adjusted: there should be 4 flats on the conical part which should give a definite click (more felt than heard) as the adjuster is wound in; make sure that the 2 wedges are clean and free to move in their housing, and that they are in the correct way. It is the spring tension pulling the wedges against the flats on the cone that give the notchy feel and should prevent it winding out again.
If the flats are not obvious, the cone may be worn so it may be worth replacing if possible. As orca2 says above, it looks like a standard Lockheed adjuster as fitted to Minis and many other British cars of the '60s and '70s, so it should be easy enough to get; if you cannot get one, try dressing up the old flats with a file.
Don't worry about the position of the shoes on the backplate, they will align themselves when the brake is adjusted correctly.
As for the actuators, you should assemble them so that they are fully retracted and make sure that the cables are slack; then wind in the adjusters until the wheel locks before backing the adjusters off about 2 - 3 clicks until the wheel turns freely. Make sure you back off both sides the same.
Finally adjust the cables until there is minimal slack before they start to apply the brakes.
If nothing is dragging and the wheels turn freely, your brakes should be sorted.

[FullEnglish]

Thanks for the information 60041, I appreciate it.

I took the adjuster apart partly to clean it, but partly to understand how it worked as well. When I'd played with it before, it was very sticky and had very little movement and when I rotated it by 90 degrees it hit a high point before it clicked over to the next flat plane. I assumed that this was the extent of the adjustment, and left it sitting on the high spot, which is why it clicked back.

All this is elementary to anyone who knows anything about drum brakes, but I don't (well didn't) and have just been learning by piecing bits together, from various forums.

I can't find any reference to the conical adjuster anywhere on the net, just the star wheel type. After taking apart, cleaning and understanding my adjuster, I found the trick of winding in the adjuster all the way and then backing it off, which made sense to me and seemed to work. I also found that whacking the drum with a rubber mallet served to align the shoes so I was able to get a couple of extra turns on the adjuster. There is only one problem with this, the adjuster winds pretty much all the way in before it bites and I'm certain I could reduce the tolerances a bit more if the square profile on the back of the adjuster was a bit longer. So I don't know how well ballanced the brakes are.

As my cunning ratchet strap brake tester didn't seem to work (not strong enough) I don't have any way of testing brake efficiency and ballance other than trying to pull away with the brakes held on with the handbrake lever. The brakes lock up on both sides on gravel. If I back the handbrake off one notch, both wheels *just* rotate.

Now we'll see what the inspection peoples' machine says on Monday.