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Changing Brake Discs

Discussion in 'Car Repairs / Maintenance' started by RickH, 5 Oct 2021.

  1. RickH

    RickH

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    The videos shows brake grease applied to disc to hub mating surface, as well as to ‘ears’ of the pads, and back of pads that face the piston.
     
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  3. Mottie

    Mottie

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    You must accept that anybody can post things on YouTube whether they are right or not! Do you know this guy? What’s his mechanical experience and expertise? How long has he been in the trade? Is he in the trade or a keen amateur?
     
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  4. sxturbo

    sxturbo

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    L
    It's theoretical, in practice it's not really a thing.

    The light smear of grease on the hub just stops the disc seizing on the hub for future maintenance,

    The wheel nuts/bolts are done to a torque and the torque creates the clamping force between hub/wheel and disc. The clamping force is greater than than shear of the smear of grease, and thus stops the grease from allowing "slip".

    It's different if it's been troweled on like Jordans make up.

    The supposed shear would be split between the 4/5 wheel bolts, which are already made of a high tensile material. The grades and sizes chosen have a high safety margin and are designed for worst case scenario and not for best practice (best practice is seldom adhered to)

    Often (in 99.9% cases) the wheel bolts are coated in grease which will mean the clamping force of the bolt will be greater against the hub and disc etc.

    With the use of grease on bolts the torque loading is repeatable and consistent. Without grease it is not. Which is why on critical engine parts like head gaskets the bolts are always oiled or greased prior to installation.
     
    Last edited: 6 Oct 2021
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  5. Avocet

    Avocet

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    Yes, I think we've all struggled with wheels that are seized on to the centre nave with a bit of corrosion. I've certainly had to loosen wheel nuts and then alternately kick opposite sides of the tyre a few times to break them free. On one occasion, in fact, even slacken the wheel nuts and just drive the car slowly in a circle with loos wheel nuts to get it moving. The fact that you haven't had a problem just means the manufacturer's safety factors are high enough to cope with people greasing things they're not supposed to. In engineering terms, however, it's a dreadful thing to do!
     
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  6. sxturbo

    sxturbo

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    Between the disc and hub it's to prevent seizure.

    Between wheel and disc it's to prevent seizure.

    On the back of the pads and the ears it's to prevent seizure and noise (though these days it's largely taken care of with the shims they use now)
     
  7. JohnD

    JohnD

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    I wonder if there's an anti-corroson product that doesn't lube the threads.
     
  8. JohnD

    JohnD

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    I've often thought it's a pity car factories don't use grease and can't afford to properly paint the bits that don't show.
     
  9. RickH

    RickH

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    Even worse on boat trailers. They use electro plated steel, and after launching in salt water all the springs, nuts, shoes, levers all start corroding at very significant rate.
    You would think hot dip galv where possible, or stainless ....... its all about cost.
     
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  11. sxturbo

    sxturbo

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    All anti corrosion products have a lubrication property

    Even water on the threads acts as a lubricant momentarily until the shear forces over come it
     
  12. fixitflav

    fixitflav

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    I have a 2004 Mondeo and the caliper mounting bracket (to hub) bolts had heads smaller than standard for M12 on the front, M10 rear. Crazy idea. Also well rusted, and I had to drive an even smaller socket on to get them out. Replaced them with proper bolts, 19 and 17mm AF.
    Edited
     
    Last edited: 7 Oct 2021
  13. RickH

    RickH

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    now I'm confused.
    Videos showed Caliper held on by 2 machine screws and Caliper fixed frame also held on by 2 machine screws

    Found a link to parts schematic https://tinyurl.com/yucy8rjx
    It shows no such fixing screws for the Caliper assembly .... refers to unit as 'floating Caliper brake'

    Shows a guide pin & bush (item 7) ....anybody know what holds these pins into the Caliper Carrier ? ae they screwed in ? ..... maybe end of them has a hex or torx socket
    It does shows complete assembly is fitted to axle by bolts (item 8 ) but no part number listed.


    Anybody worked on these brakes ?
     
  14. Old Salt

    Old Salt

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    Ateca is very similar. Look at the top item 7, the dashed line of the exploded view shows it going into the sliding part of the caliper. You may have to slide the rubber sleeve back and get a spanner on the flats to prevent the cover from turning.

    If it is the same as the Ateca you will need a 7mm allen key or socket adapter to undo it. Available from halfrauds, I think the OE spanner is 14mm but its been a while since I did mine.
     
  15. Burnerman

    Burnerman

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    The caliper bracket will be held on with two bolts of some description.
    The caliper is held to the bracket with two bolts also.... maybe they are allen bolts in a sleeve with end caps on?
    John :)
     
  16. Harry Bloomfield

    Harry Bloomfield

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    I grease the interface too. The first time I had to remove them I tried a sledge hammer on the tyre, which failed to budge 'em. Second attempt was to lower the car down, undo all the studs and drive it back and forth, jamming the brakes on - which worked. After that I applied a thin smear of grease, to stop alloy 'welding' itself to the steel of the drums.
     
  17. Stivino

    Stivino

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    SEAT Leon too so, they are probably the same across the group.
     
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