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New brake pads are spongy

Discussion in 'Motors' started by Buchanan0204, 1 Jun 2013.

  1. Orionaut

    Sgarrista

    Joined: 2 Aug 2012

    Posts: 7,815

    +1

    Though the effect is not great when only replacing single axle sets. However Brakes can feel very strange for the first hundred miles or so if you replace pads "All round" while retaining old disks! I advise people who wish to do this to do one axle at a time, a week apart if they do not want to replace disks at the same time!

    The imperfect contact between new pads and old disks also means that all the heat of braking is generated at these points rather than over the whole disk surface. heavy braking before pads have bedded in can cause local overheating of the disks and is a major cause of disk warping after pad replacement. That is why you need to brake little and often untill the pads have bedded in propery.
     
  2. Nightglow

    Soldato

    Joined: 19 Jan 2010

    Posts: 6,780

    Location: South West

    Bleed it properly, it may take several attempts to purge the air from the system.
     
  3. Matt82

    Capodecina

    Joined: 13 Mar 2004

    Posts: 16,600

    Opinion or fact?
     
  4. telewebby

    Gangster

    Joined: 11 Nov 2009

    Posts: 193

    what car is it? It does sound like he has air in the system.

    The handbrake should have between 3 and 7 clicks for mot standards

    my order would be slacken off handbrake readjust to corect level and bleed the brakes

    Alex
     
  5. danb21t

    Gangster

    Joined: 30 Oct 2009

    Posts: 429

    Location: High Wycombe, Bucks

    Bet he bled the system with the rear brake compensator closed.
    The car needs to be lowered onto the rear axle to open the compensator otherwise bleeding the rear is near impossible.
     
  6. Buchanan0204

    Soldato

    Joined: 10 Jun 2010

    Posts: 5,163

    Location: Scotland

    Would the one click handbrake be an advisory?

    It's a mk3 mondeo.
     
  7. Buchanan0204

    Soldato

    Joined: 10 Jun 2010

    Posts: 5,163

    Location: Scotland

    What are you getting at? Sorry I'm not very technical (obviously)
     
  8. danb21t

    Gangster

    Joined: 30 Oct 2009

    Posts: 429

    Location: High Wycombe, Bucks

    Not a problem as your not doing the process.

    on most cars there is a valve which is linked to the rear axle. As the suspension moves up and down on the road surface it alters the amount of fluid that is allowed to the rear calipers.

    My betting was the mechanic has jacked the rear up which causes the wheels/axle to drop. Then changed the caliper and tried to bleed the system. As the axle was down the valve would have been closed, making bleeding difficult.

    Take it back get them to bleed it again.
     
  9. Buchanan0204

    Soldato

    Joined: 10 Jun 2010

    Posts: 5,163

    Location: Scotland

    Yes, he did jack it up as he works from his home and doesn't have a ramp. Most likely what it is.

    Thanks for the explanation.
     
  10. jon.bda

    Mobster

    Joined: 28 Oct 2002

    Posts: 4,922

    Location: Shropshire-ville

    Not bled right or the piston not located on the pad properly...
     
  11. Buchanan0204

    Soldato

    Joined: 10 Jun 2010

    Posts: 5,163

    Location: Scotland

    Took the car to another mechanic, a friend of my dads. Anyway to cut a long story short. He put it on the ramps and bled them again.

    They're now back to normal and feel a hundred times better.

    Thanks very much for all the advice. I would have drove around for weeks expecting it to improve going off the advice of the other mechanic.

    Cheers again.