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246 BRAKE -VACUUM PROBLEM

Discussion in '206/246' started by DINOMR, May 7, 2019.

  1. synchro

    synchro F1 Veteran

    Feb 14, 2005
    8,922
    CHNDLR
    Full Name:
    Scott
    Great, thx
     
  2. jselevan

    jselevan Formula 3

    Nov 2, 2003
    1,849
    1) Were the soft lines replaced during the caliper rebuild? If not, I have experienced one-way-valving associated with disintegration of the ID lining. Hydraulic pressure applied will not bleed off to allow the pads to separate from the disk leading to heating and fading. This assumes, of course, that the symptom is, indeed, fading as addressed in previous posts (and not soft spongy air).

    2) First test I would do is to simply raise the car (jack each wheel together or separately), and with the engine off spin the wheel to see if it drags. They should spin freely without squeal. If they are dragging, or if they require considerable force to spin, then the pad is not separating and heat will lead to fade. If this is the case, then a) use a flat screw driver or other appropriate tool taking care not to scratch the disk and see if you can easily press the pad/piston back into the caliper. It should be easy (especially after a rebuild); b) visually inspect the disks to see if one is blue or wearing differently than the others, and c) maybe consider changing the soft line. This will require a re-bleed, which might solve the problem anyway.

    Jim Selevan
     
  3. jselevan

    jselevan Formula 3

    Nov 2, 2003
    1,849
    Oh, one additional thought, whoever suggested that the brake problem was a result of insufficient vacuum, take them for a ride and accelerate to, let's say, 100 mph. Place the car in neutral so that the engine is idling, and aim for a wall. Then ask them when to apply the brakes. Not much vacuum created at idle, but it will definitely stop the car!
     
  4. TonyL

    TonyL Formula 3

    Sep 27, 2007
    2,467
    UK
    Full Name:
    Tony
    :( not in the dino with dodgy brakes
     
  5. DINOMR

    DINOMR Rookie

    Aug 6, 2017
    9
    Hi Jim
    The master cylinder was replaced and the also brake lines - apparently now braking much better but not yet perfect.
    So now the booster is being rebuilt
    Will keep you posted...
    Thanks to all for the advice
     

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