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Thread: Spongey brakes

  1. #1
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    Spongey brakes

    I have searched the forum on this subject, but couldnít quite get the info I was after, so Help Please!

    I have an í88 Highline that Iím going through in order to get it registered and the brakes are causing me no end of grief.

    I have fitted the following new items - servo, M/C, rotors, pads, hoses, all calipers have new seals and pistons. I wasnít having any luck with bleeding so had a professional mobile mechanic come out to do the job. He bled it up at the M/C and then down at the wheels (has done this on two separate occasions). He is also happy with the work Iíve done to date. Trouble is the pedal is very spongy and thereís a lot of travel before any real brake effect, in fact Iím hard pressed to lock the tyres. Iíd hate to be going down a steep hill towing my boat! There are no leaks at any of the various pipe unions.

    Given all the new components, what am I missing?

    Thanks

  2. #2
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    Have you checked your wheel bearings? If they are loose they allow the discs to wobble and push the caliper pistons back into the calipers, giving too much free movement.
    Good luck,
    Woolly.

  3. #3
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    Thanks Woolly. All wheels have new bearings and seals. The only brake component I haven't replaced is the brake pressure proportioning valve. I was hoping to see what feedback there was amongst the group before buying one in the hope it 'may' fix the problem.

  4. #4
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    Spongy Breaks

    Hi Wooly
    I used to hate bleeding the brakes BUT:-
    I'm not sure if you have tried bleeding the brakes from each caliper bleed point, starting from the one that is the most distance from the M/C then each caliper in that pattern but the difference is instead of pumping on the brake pedal, use a big plastic syringe, appropriate sized hose etc, and suck the fluid through the the whole system through the syringe while opening and closing the bleed valve when sucking and closing when not, once all the air has gone from each line you are working on the system is ok, of course making sure you top up the M/C as you go.
    Might sound a bit different and weird but it works better than any other way that I have done and you usually only have to do it once, I do it twice just to make sure.
    And you can do it yourself without bothering the "missus" or anyone with having to pump the pedal.
    Make sure you follow the Range Rover's manufacturers order of preference when bleeding as there is quite a number of bleed points on the front calipers and some can be overlooked.

    Regards:-
    Patrick M

  5. #5
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    Spongy Breaks

    Hi br>I used to hate bleeding the brakes BUT:-<br>I'm not sure if you have tried bleeding the brakes from each caliper bleed point, starting from the one that is the most distance from the M/C then each caliper in that pattern but the difference is instead of pumping on the brake pedal, use a big plastic syringe, appropriate sized hose etc, and suck the fluid through the the whole system through the syringe while opening and closing the bleed valve when sucking and closing when not, once all the air has gone from each line you are working on the system is ok, of course making sure you top up the M/C as you go.<br>Might sound a bit different and weird but it works better than any other way that I have done and you usually only have to do it once, I do it twice just to make sure.<br>And you can do it yourself without bothering the "missus" or anyone with having to pump the pedal.<br>Make sure you follow the Range Rover's manufacturers order of preference when bleeding as there is quite a number of bleed points on the front calipers and some can be overlooked.<img src="https://www.aulro.com/afvb/images/smilies/SmileBigEye.png" border="0" alt="" title="SmileBigEye" smilieid="295" class="inlineimg"><br><br>Regards:-<br>Patrick M&nbsp;&nbsp;

  6. #6
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    There is two circuits, I bet the primary circuit isn't being bleed. My peddle occasionally drops quite low before it works. I'm pretty sure there is either air or very dodgy fluid in the primary circuit so the secondary one is occasionally coming into effect.

    Mine probably needs new brake fluid through both circuits and a bleed. Yours sounds like it just needs both circuit bled.
    Proper cars--
    '92 Range Rover 3.9V8 ... slugomatic
    '92 Range Rover 3.8V8 ... 5spd manual
    '85 Series II CX2500 GTi Turbo I :burnrubber:
    '63 ID19 x 2 :wheelchair:
    '72 DS21 ie 5spd pallas
    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual :zzz:

  7. #7
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    Thanks again for feedback.

    Patrick M. Both the mechanic and I (on separate occasions) used the pumping the pedal method and no bubbles came out, so can certainly try your syringe method to see if that makes a difference. re the bleeding sequence, yes, followed the manual religiously so i know that's not the cause of my problems.

    Double Chevron - Yep, aware of the two circuits and these were bled accordingly as per the manuals instructions.

    I'm still wondering if it could be the proportioning valve though? Has anyone replaced this to fix such a problem?

  8. #8
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    How does the twin circuit brakes work inside the master cylinder? Possibly the primary circuit circuit is leaky internally inside the master, so you're ending up one the secondary circuit, even though they are both bled ?




    Here we go. Do the back brake work? if they are't working, I'm betting the primary circuit in the master is dead.

    Actually, what you are saying is 100% right. The differential/priority switch may be stuck over on the secondary circuit. Same deal, do you have rear brakes ?
    Proper cars--
    '92 Range Rover 3.9V8 ... slugomatic
    '92 Range Rover 3.8V8 ... 5spd manual
    '85 Series II CX2500 GTi Turbo I :burnrubber:
    '63 ID19 x 2 :wheelchair:
    '72 DS21 ie 5spd pallas
    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual :zzz:

  9. #9
    Join Date
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    Here's a thought, open the secondary circuit bleeders and pump the pedal. This should for the differential valve over to the primary side and allow full bleeding of it ... if you can't build pressure in it, then. Then pull the hose from the master .... if it builds pressurre at the master, the differential switch is bad. If it doesn't build pressure at the master ..... well its obviously bad
    Proper cars--
    '92 Range Rover 3.9V8 ... slugomatic
    '92 Range Rover 3.8V8 ... 5spd manual
    '85 Series II CX2500 GTi Turbo I :burnrubber:
    '63 ID19 x 2 :wheelchair:
    '72 DS21 ie 5spd pallas
    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual :zzz:

  10. #10
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    May 2021
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    Canberra
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    Good ideas DoubleChevron...thanks.

    My circuit is slightly different to the one you show. Note that my secondary circuit is the one that operates all 4 wheels and the pressure valve is only on that circuit, ie it's not interconnected with the primary. The braking effect i'm getting almost feels like my primary is the only one working, yet when the mechanic came back in my driveway after a short test drive, and used water to wash the rear calipers of excess brake fluid from the bleeding process, steam came off them, which would indicate the pads were at least making some contact with the rotors. In my experience spongy brakes always indicates air in the system, but it has me stumped. Fair dinkum, this car is coming close to becoming an artificial reef somewhere near by!

    brake cicuit.JPG

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