What is the point of the single, countersunk, machine screw used to hold a drum brake in place?
I mean, the drum is hardly going to fall off when you consider it's also held in place by the wheel nuts.
To me, it's a pointless screw, unless anyone knows otherwise.
Are there any other examples?
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It's to stop the drum sticking to the wheel and coming off during a roadside wheel-change.
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It's to stop the drum sticking to the wheel and coming off during a roadside wheel-change.
I thought that was what the handbrake was for ;)
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I thought that was what the handbrake was for ;)
On many cars with wheel bolts; you have to let the handbrake off when wheel-changing as it moves the drum relative to the hub and you can't get the bolts back in.
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On many cars with wheel bolts; you have to let the handbrake off when wheel-changing as it moves the drum relative to the hub and you can't get the bolts back in.
With studs and nuts the screw is, I agree, pointless.
Though with bolts it ensures that the holes in the drum are lined up with the threads in the hub.
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Though with bolts it ensures that the holes in the drum are lined up with the threads in the hub. >>
Wheel bolts? New fangled things only found on what we used to call foreign cars.
I remember doing a breakdown on a Renault which had bolts and a locating lug sticking out of the hub.
Freezing cold night, crouched on the hard shoulder of the motorway changing a wheel.
I managed to graunch my finger between this lug and the socket wrench I was using to tighten one of the bolts.
Can still feel the pain now.
The other problem with bolts was they could seize and shear if too much grunt was applied.
Saw a few where the owners had just left the headless bolt and relied on those that were left.
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Ah, thanks Screwloose - if anyone was going to know it would be you.
I recall the head of nearly every one I undid for service purposes was chewed.
We used to blow out the brakes with the compressed airline - asbestos dust all over the workshop.
Then rough up the shoes with a bit of emery paper/cloth - more asbestos dust.
That's health and safety 1970s style.
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The last time that I checked; there hadn't been a single case of mesothelioma directly attributable to motor repairs. [Plenty in making the brakes though.] Once embedded in resin; the asbestos vapour seems neutralized.
The other possibility was that the ever-present black dust was filtered out when inhaled through a Woodbine.....
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I lost my father to mesothelioma in 2003. He had never worked with asbestos at all.
It is very hard to pin down where, up to 40 years previously, you have inhaled the particles that can develop into the disesase.
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I witnessed as a child in the 1940s a test of an asbestos fireproof suit just acquired by the Navy. An official fire was organised using paraffin and the guy lumbered into the flames wielding a powerful foam or liquid extinguisher. Very dramatic when you were 9.
Thing is though, the suit, very like a diving suit, was woven from thick, furry, flexible white asbestos fabric, obviously very dusty, and I seem to remember the headpiece was a sort of hood thing, with mica goggles and a gas mask sort of attachment, made of the same stuff. I don't know what was supposed to protect the fireman from the suit. Mesothelioma (I think) or asbestosis had certainly been discovered by then.
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He must have needed an independent air supply to enter a fire? An even worse threat must be the number of homes contaminated with Artex.
I lost a friend to Artex; his first job after leaving school was mixing blue asbestos, plaster-of-paris and horsehair in an industrial bread mixer. He used to say that you couldn't see across the factory for dust..... Died at 43.
It appears, with hindsight, that it's the invisible particles that are the worst. Once combined into a carrier; they lose a lot of their potency. I was recently surprised to find that you can still buy asbestos cement roofing sheets.
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He must have needed an independent air supply to enter a fire?
Probably an oxygen rebreather
An even worse threat must be the number of homes contaminated with Artex.
It's OK as long as it isn't disturbed (it contained small amounts of chrysotile asbestos only). Paint or skim it and leave it alone, or steam it off and dump the wet result at your local council tip with an asbestos skip. Do not sand this stuff.
I lost a friend (...) couldn't see across the factory for dust..... Died at 43.
Some of the operations in southern Africa had processing facilities from which dust billowed. Workers shook the stuff off themselves and their clothes and changed colour.
It appears with hindsight that it's the invisible particles that are the worst.
That is the issue - AFAIK to do with the jagged nature of the fibres.
Once combined into a carrier; they lose a lot of their potency. I was recently surprised to find that you can still buy asbestos cement roofing sheets.
Asbestos cement sheeting (e.g. found on garages) is low-risk. The fibres are contained by the cement matrix (they are there for re-inforcement) You can wet it, remove it, and take it to the tip (see above). Don't smash it up or machine it - this leads to an escape of fibres. The stuff you can get nowadays does not contain asbestos.
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The roofing sheets I've seen on sale recently have been described as "fibre cement". I'd be very surprised if any asbestos fibre were present.
To return to the topic, my Passat clone has no countersunk screw(s) holding the front brake disks in place. Normally these rust to the hubs, but I did hear of one case of a disk slipping slightly off its register and the wheel replaced with the bolts torqued up. Of course, it came loose and disciplinary action was taken.
Stupid penny pinching by VAG and a worrying lack of a road test before handing the vehicle to a customer. This problem would have been evident at the first brake application.
659.
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My uncle worked in an asbestos factory when he still lived at home with his mum. I can remember my father telling me about his brother coming home from work absolutely covered in white asbestos dust, and it went everywhere in the house! Also, he went to work on the bus, so that must have also been severely contaminated, too.
Doesn't bear thinking about today. From what I remember I believe his brother died when he was about 50. You can probably guess what from.
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when I read the title I thought it was going to be about Boris Becker and a broom cupboard.
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I thought it was going to be about Boris Becker and a broom cupboard.
Then it would have been an inaccurate title; the reality of the case was quite a surprise - to him too.
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Returning to the (original) topic, I've recently started working on a Land Rover Series 2A.
I haven't got to the rear wheels yet, but the fronts have 3 screws per drum. I think they are unequally spaced, if so it means that there is only one position of the drum at which all three screws will fit.
Not sure of the benefits of this, as the wheel can go 'anywhere'.
Still, there's no sense in using an old motor and whinging about the design. If I don't like it then I'll just stop playing, it's only a sideline.
Actually, with front drum brakes, I guess it's essential to have the drum securely attached if you want to adjust the shoes to the optimum.
Cheers.
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If you've ever lost a wheel you'd be glad of the innocent little countersunk screw holding the drum on. It means you've got half a chance of continuing your journey with working brakes and the spare held on with 3 nuts borrowed from the remaining wheels. A brake backplate would make poor landing gear at speed. In fact, so important is this screw that it is made from specially formulated steel that welds itself to the drum material within seconds of being assembled at the factory.
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Given the title of this thread, and the number of views, I cannot be the first person to be disappointed by the discussion.....interesting as it is.......it pains me to state.
Edited by Alebear on 12/08/2008 at 20:57
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Me too, I thought it was going to be about Paris Hilton.
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With many designs you can't get at the brake adjuster properly without taking the wheel off, either bcause you need clearance for a spanner at the back, or there is a circular hole in the face of the drum but no corresponding hole in the wheel. The screw(s) hold the drum straight while you make the adjustment. I then ease the screw a little so that it will come undone next time.
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What is the point of the single countersunk machine screw used to hold a drum brake in place?
It's probably there to facilitate the production/assembly process.
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It probably also helps to avoid the drum or disc moving and allowing debris to fall between the disc/drum and hub mounting faces when removing the wheel.
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