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Thread: Brake Pedal Pulsation

  1. #1
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    Mar 2009
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    Brake Pedal Pulsation

    Hi there,

    I have an annoying brake issue that I cannot solve. I have searched the forums without much luck.

    There is a significant brake pulsation through the pedal in my 87 Isuzu 110.
    The car has:
    New Master Cylinder
    New Hoses
    New Calliper Pistons and Seals
    New Pads

    New Drums
    New Shoes
    New Wheel Cylinders

    I have identified that the pulsation is likely to be from the rears as after each time I drive it, I lift up the car and spin the rear wheels and the rear brakes "stick" at a certain point. The sticking occurs on both the rear wheels, ie when I take one drum off, the other side still does it. The fronts spin as smoothly and consistently, even though the new pads are rubbing a little all the way around.

    I thought that perhaps the wheel cylinder pistons were not retracting enough so I replaced the new Britparts units to new Delphi units. This has not improved the issue.

    I also thought that the new drums may perhaps be out of round, however after putting the old drums in again, the issue remained. It is pretty unlikely that they are both out of round I would have thought...?

    I have attached a picture of one of the drums, have I assembled the unit correctly?

    What else in the system could be causing an issue?

    Thank you in advance for your help.

    Cameron
    Attached Images Attached Images

  2. #2
    Join Date
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    Hi Cameron, it has been a long time since I looked at a brake drum assembly but I seem to remember something about leading and trailing shoes in drum brakes, yours both look the same in the pic. Is it possible one of them is the wrong way around?
    I am sure someone will be along soon with a bit more knowledge than me in this area.
    Cheers,
    Paul.
    Paul.

    77 series3 (sold)
    95 300Tdi Ute (sold)
    2003 XTREME Td5

    I thought I was wrong once, but I was mistaken.

  3. #3
    Join Date
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    At its simplest - pulsating through the pedals is either warped disks and or drums out of round.

    You said you have new drums on the rears so I would be having a look at the front disks however you said the rears are binding both with the new drums and old drums so I would then be taking the rear shoes back out and examining the new wear marks on them and any marks on the inside of the new drums and seeing if anything is obvious with fitting of the shoes and then carefully putting it all back and trying again.

    Oh - as Harro mentioned have you got the shoes the right way around?

    Garry
    REMLR 243

    2007 Range Rover Sport TDV6
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  4. #4
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    Unless someone can come up with a solution, I'd be looking to try and isolate the front from the rear somehow to confirm which end its from. Either blanking off the line to the rear diff or perhaps clamping the rear hose so the rears don't receive pressure (personally not a fan of clamping but when you're running out of options....).

    If you've got the old rear brake hose see if you can blank that somehow and fit rather than putting vice-grips on your new hose

    Steve
    1985 County - Isuzu 4bd1 with HX30W turbo, LT95, 255/85-16 KM2's
    1988 120 with rust and potential
    1999 300tdi 130 single cab - "stock as bro"
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  5. #5
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    Hi Cameron, have a look at this.
    Land Rover FAQ - 109 rear brakes

    I don't know if it is the same setup as yours but may help.

    Had another look at your pic and you may have both the leading on one side and both the trailing on the other?
    As I said it has been a long time since I looked at Drums (and now I know why).

    Cheers,
    Paul.
    Paul.

    77 series3 (sold)
    95 300Tdi Ute (sold)
    2003 XTREME Td5

    I thought I was wrong once, but I was mistaken.

  6. #6
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    Having the shoes the wrong way around shouldn't make for a pulsating pedal, just crap brakes.

    For what its worth my One Ten has a slight pulsation that came about after fitting new drums and shoes this Feb or March. The pulsing is less than i've felt from an ABS equipped car so hoped it bedded in (and it has somewhat). Another club member has had an out of round drum too. It may be round but the mounting holes aren't concentric to the drum too. I guess it could also be that the hubs are out of concentric, and the previous drums were out enough in the opposite way to make up for it.
    Is this the first time you have personally changed drums on this vehicle?

  7. #7
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    Quote Originally Posted by isuzutoo-eh View Post
    Having the shoes the wrong way around shouldn't make for a pulsating pedal, just crap brakes.

    For what its worth my One Ten has a slight pulsation that came about after fitting new drums and shoes this Feb or March. The pulsing is less than i've felt from an ABS equipped car so hoped it bedded in (and it has somewhat). Another club member has had an out of round drum too. It may be round but the mounting holes aren't concentric to the drum too. I guess it could also be that the hubs are out of concentric, and the previous drums were out enough in the opposite way to make up for it.
    Is this the first time you have personally changed drums on this vehicle?

    To check the mounting holes are concentric re-fit the drum in a different position (but leave out the drum retaining screws because you'll cover the tapped holes), the wheel will hold the drum in place.

    Also clean up the face of the hub where the drum seats so its not sitting on rust/dirt and try. Are the tapped holes in the hub for the retaining screws raised at the edge causing the drum to not seat properly?

    It'll be interesting to find out the answer to this one......



    Colin
    '56 Series 1 with homemade welder
    '65 Series IIa Dormobile
    '70 SIIa GS
    '76 SIII 88" (Isuzu C240)
    '81 SIII FFR
    '95 Defender Tanami
    Motorcycles :-
    Vincent Rapide, Panther M100, Norton BIG4, Electra & Navigator, Matchless G80C, Suzuki SV650

  8. #8
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    Thanks for your help.

    Turns out I had the two leading shoes on one wheel and two trailing shoes on the other.

    I changed them over but it has not completely fixed the issue.

    There is still some pulsing through the pedal, nothing on what it was though.

    I am hoping that with further adjustment as things start to wear, that it may solve it completely.

  9. #9
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    As an old mechanic who used to work for Better Brake many moons ago I thought I'd throw my two bob in.
    In the picture you have what appears to be two leading shoes. Apparently you worked that out.
    The pulsing can still be caused by a new drum. We used to lightly skim ALL new drums and discs before fitting.....sorry about that.

  10. #10
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    Another thing... Most places now skim discs or drums too fast and leave them rough. If you can find a place to run it slowly on the lathe and leave it smooth, it's much better. Also it's best to radius grind the shoes to suit the drum it is going into, they work much better, bed in quicker.

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