Classic cars forum & vehicle restoration.

[FullEnglish]

Hi all,

Van is a Sprite Alpine 1964.

I took the brakes apart, derusted, checked the springs, shoes etc, and reassembled them as all the parts were good. Balancing them took ages, as they were fine until I activated the brakes a few times, whereupon they were out of balance again and I had to start over. I finally got them right, took the caravan for a test run of a few miles, and found out that one brake drum was really hot and was dragging. Balanced them *again* (last night), took the caravan to be inspected (like an MOT) only to have it fail on brakes - out of balance. One side now has twice the effect of the other side.

Does anyone have any idea how to go about adjusting the brakes so that they STAY correctly adjusted?

All ideas greatly appreciated!

Cheers.


**EDIT**

The rain stopped. Finally. Briefly.

Jacked the van up, and the brakes are indeed still balanced.

The inspection showed that one side has half of the braking effect of the other side. The brake shoes were whole, undamaged and had plenty of meat left when I inspected them, but I'm supposing one side must be glazed/contaminated.

Is it possible to get away with sanding down the pads and cleaning the inside of the drum? Although they are at least 20 years old, and possibly original to the van (1964) so could well be asbestos.

I'd change all four of them for the sake of it, but finding new ones can't be the easiest thing in the world.

As you might have guessed, I know naff all about drum brakes...

[Dalek63]

Your best bet is to soak them in petrol for a day or two, then in water with plenty of washing up liquid in it, that gets rid of the petrol or they might catch fire!!

Don't sand them down, old brake shoes contain asbestos and would be very dangerous !
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[kevin2306]

Not sure on caravan brake shoes but, when I built and raced classic motorcycles, when we had contaminated shoes (oil seal failure etc) we used to boil them in a large pan filled with water and washing powder..Daz was the weapon of choice!!. Cleaned them up a treat and much better (and safer) than sanding asbestos based products.
With old brake systems, always worth wearing an FP3 grade face mask during the strip and clean. spray any dust with water to reduce the risk of airborne particles

Kev

[Rick]

[FullEnglish]

So, it took 4 days to fix this, during which time I checked every single component of the braking system. That sounds like a long time, as it's a simple system, but examining components involved taking stuff apart, and it can't be tested until it is totally reassembled.

First off, the biggest problem was that I could only see when the brakes started to bite. Once I could no longer turn the roadwheel by hand, I had no idea if the brakes were working in sync, ie if the max brake effect was the same on both sides. So I came up with this:




That's the spare wheel (possibly off a VW originally, but I have really no idea). I used this wheel because it has holes around the rim. There's an eye welded into the frame at the back of the caravan (no idea what it's for, possibly for testing brakes?) This setup meant that I could apply max braking effect (with the handbrake) and compare effectiveness on each side. I just took up the slack and then counted the number of clicks on the ratchet until the wheel moved against the resistance of the brake. A further improvement would be to add a hefty spring scale to ascertain exactly how much braking resistance there is. The vehicle inspectorate's £20,000 machine said that one side was braking twice as much as the other side, my home-made ratchet strap test gave the same result. So it's reasonably accurate.



These are the brakes in question, nice and oily after I reassembled them, and attempted to get everything to settle into its correct place by driving round for a bit. Melted the grease in the bearings. Epic fail. I degreased everything, then adjusted the actuator left and right (loosen the bolt from behind slightly first, then tap with a hammer) and the shoes up and down (tap with a hammer) until the gap between the shoes and the rim of the backplate was equal all the way around. That fixed the binding issue, but I still had only half braking effect on one side.

I cleaned and greased EVERYTHING and used stainless steel washers to take up the slack in various couplings, which gave no change. I then started to swap parts from the "good" side to the "bad" side; no change until I came to the brake actuators.



Note the tabs (skillfully arrowed). On the "bad" side, the tab was ever so slightly bent. It was barely noticable and it restricted the movement of the actuator lever by around 2mm. I hammered it straight again, and it fixed the problem.

[D4B]

Well done, very satisfying fixing these problems yourself

[david_rachel]

[FullEnglish]

It turns out I'm still fighting with the brakes, after two further trips to try to clear inspection without success.



Does anyone know if the actuator (arrowed) is supposed to slide? If it's not supposed to be slide, where is it supposed to be screwed tight? (It slides up and down in a long slot in the backplate if not tightened up).

[D4B]

Yes I believe it is supposed to slide.... that might be your trouble?

[FullEnglish]

Aha, thanks. I did try allowing it to slide, but I wasn't sure it should and it didn't seem to work, so I tightened it back up again. Armed with this knowledge I'll try again.

It certainly seems to be set up to slide, with a big flat piece of steel against the backplate.

There really isn't much info that I can find on this system (type "caravan brakes" into Google and you get page after page on a Dodge Caravan, some sort of MPV thing that I'd never heard of before, and "alpine sprite brakes" just yeilds results endless results related to old British cars named either Sprite, or Alpine. Seems like not many people worry about these brakes too much as long as they're not stuck on.

[D4B]

My 1977 Honda TN7 has a very similar system on the front brakes, but instead of your sliding manual lever system, this has a sliding wheel cylinder:



and here is a photo as I found it:



and after some work but waiting for cylinder dust cover to arrive!



hope this helps

[Penman]

Hi
It must slide because that is what enables the shoes to centralise and press evenly on the drums.
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[FullEnglish]

Thanks everybody. The adjusters didn't slide when I first took the brakes apart, so I assumed they shouldn't. They must have just been stuck. I've cleaned them up, applied a smear of copper grease to the mating surfaces and they now slide nicely.

I also found instructions on how to set up brakes (sadly on the '72 to '83 model though, I'm still to find anything at all on my brakes, I've even been searching patent records). These instructions said to wind the adjuster all the way in, then back it out 2 turns so the wheels rotate with no braking applied. This seems to have worked.

However, the brakes are still poor. I can reverse it fairly easily against the brakes, it just graunches a bit. Albeit with a rather overpowered towcar.



I'm starting to wonder if the rod from the hitch and the cable attachment are the wrong way round. This is how it was when I got the caravan (I've checked the build photos) but as I see it, it just diminishes the force from the hitch to the brake cables. If the hitch rod attached in the middle and the brake cable assembly attached at the bottom, then the force would be multipiled.

[FullEnglish]

Turns out it's correct. If you assemble it the other way around, the braking effect is excellent, but the rod from the hitch bends and the flimsy bracket at the end stretches. Ten minutes of fabrication later and it's back how it was. At least I know that's correct now...

[FullEnglish]

The inline adjusters on the cables had come loose. I fitted bigger wire clamps and the brakes *seem* to work well now...

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.

The Haynes caravan book apparently has a way of checking braking efficiency, does anyone know what it is? I tried to buy the manual as a download; not possible (even in 2014??). I don't have time to wait for a copy to be delivered (I have to clear inspection in a week otherwise I have to start the whole process again).

Cheers!