1997 Astra - rear drum brakes.

Discussion in 'Astra' started by ChrisM, Sep 11, 2006.

  1. ChrisM

    ChrisM Guest

    Ok,
    In my MOT, I was told that the nearside rear brake was 'slow to react...'

    In testing rear brakes individually, both give required stopping power, but
    testing together, offside stops first, then nearside...

    Speaking to a friend, his first thought was that the 'flexitube' to this
    drum may be restricted in some way. On further discussion with another
    mechanic however, they came to the conclusion that due to some sort of
    'balancing' valves in the system, the problem could actually be on the other
    side, as the faulty valve was allowing all the hydraulic pressure to the
    offside, and only to the nearside when the offside was fully activated.

    I've probably explained this rather badly, but does anyone know what I'm
    saying and care to add anything??

    (Astra is 1997 (R) - older shape).

    Thanks,

    Chris.
     
    ChrisM, Sep 11, 2006
    #1

  2. I've had MoT failures on proportioning valves (think that's the name?) in
    the past, and there were suggestions that my normal style of driving and
    braking wasn't sharp enough, so I wasn't exercising the valve in normal
    usage. (Car was a Renault or Honda from memory. My Astra seems OK in this
    respect.)
     
    Malcolm Stewart, Sep 11, 2006
    #2
  3. ChrisM

    me140 Guest

    Have you had the drum off and looked inside and made sure that one side of
    the wheel cylinder hasn't seized?
    The valves you mean and near the back in each brake pipe - about the
    thickness of a C battery but a bit longer. There are different ones and
    Vauxhall had the idea of wrapping a coloured paper band round them to
    identify the pressure - so of course by the 3rd year or so the paper has
    fallen off.
    If you need on and can't tell which one it should be just replace them both
    with 2 the same and it will be fine.
     
    me140, Sep 11, 2006
    #3
  4. ChrisM

    ChrisM Guest

    Yea, both wheel cylinders were leaking slightly, so we replaced both sides.
    Will look for these valves.

    Any thoughts about anything else that could be causing this problem??

    Thanks,

    Chris.
     
    ChrisM, Sep 12, 2006
    #4
  5. ChrisM

    adder1969 Guest


    Could be adjuster one side has seized thus needing more travel to
    actuate the brakes. If the cylinders were laking there could also be
    air in the system which I guess you'll fix when the system is bled.
     
    adder1969, Sep 12, 2006
    #5
  6. ChrisM

    ChrisM Guest

    Well, we bled the system when we changed the cylinders.
    One side (offside) squirted out like a good-un(as per normal) when brake
    pedal was pressed.
    Otherside (nearside - the 'slow' side) only oozed out slowly.
    We checked the adjusters both sides and all seemed to be well.

    Cheers,

    Chris.
     
    ChrisM, Sep 12, 2006
    #6
  7. ChrisM

    adder1969 Guest

    Ah, might be a rubber pipe that's gone bad inside. I don't know about
    the brake valve things so can't comment on those.
     
    adder1969, Sep 12, 2006
    #7
  8. ChrisM

    ChrisM Guest

    How do you mean, 'bad inside'? Are these pipes made up of multiple layers or
    somthing? Can the inside f*** up without the outside showing anything?

    Cheers,

    Chris.
     
    ChrisM, Sep 12, 2006
    #8
  9. ChrisM

    me140 Guest

    Just undo the pipe before the flexi - if the fluid pours out the same on
    both sides when you press the pedal then the flexi must be the problem - if
    not I suspect the valves.
     
    me140, Sep 12, 2006
    #9
  10. ChrisM

    adder1969 Guest

    Yes. Usually the inner pipe is braided for strength and the outer pipe
    over this is for protection.
     
    adder1969, Sep 13, 2006
    #10
  11. ChrisM

    Roger R Guest

    Don't forget to take your credit card with you if buying new.
    One cost me 107.51 at the beginning of 2005.

    Roger
     
    Roger R, Sep 13, 2006
    #11
  12. ChrisM

    adder1969 Guest

    Main dealer price?
     
    adder1969, Sep 13, 2006
    #12
  13. ChrisM

    Roger R Guest

    Yes, 'fraid so. - Such a bargain I bought two!

    Roger
     
    Roger R, Sep 13, 2006
    #13
  14. ChrisM

    me140 Guest

    Wow - are they gold plated?


     
    me140, Sep 13, 2006
    #14
  15. ChrisM

    Roger R Guest

    Looking at the receipt under 'Modulator brake' the Qty is 1, though I fitted
    two new units. Possibly they were sold only as a matched pair in a single
    box. (to avoid fitting individual units of different rating)
    The unit price is therefore 53.75 ea, but they couldn't be bought singly.

    ...and yes they were yellow zinc plated so they looked like gold.

    Roger
     
    Roger R, Sep 14, 2006
    #15
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