Bumpyride Posted November 9, 2007 Share Posted November 9, 2007 I have been having a problem with my brakes (1987 defender - disks front pads rear) The brakes seem a little ineffective i have 1: replaced pipes were corroded already 2: new pistons and seals on calipers 3: new flexible pipes 4: flushed through brakes fluid and re-bled 5: new rear pistons When i get in engine off pedal goes to the floor with limited resitance. As soon as ive started and pump the pedal once or twice the pedal goes hard half way down. There is also a kind of whooshing noise when i first press the pedal. Is this normal? i'm possibly being parnoid and trying to compare the braking effectiness to a modern car however i can't help but feel there is something wrong There is only a limited list of things i still could replace - is the servo a possible area and what are it's usual symptoms of failure jim Quote Link to comment Share on other sites More sharing options...
Adz Posted November 9, 2007 Share Posted November 9, 2007 There should be a hiss from the servo - what happens if you pump the pedal a couple of times then hold the pedal down? Does it stay firm or gradually creep to the floor? Quote Link to comment Share on other sites More sharing options...
western Posted November 9, 2007 Share Posted November 9, 2007 could be a dying servo. Quote Link to comment Share on other sites More sharing options...
Bumpyride Posted November 12, 2007 Author Share Posted November 12, 2007 Sorry for the delay Have tried the haynes test of pressing pedal down and then starting up and waiting for a downwards movement in the pedal as the vacumm builds up. and Yes you can fill this. Tried to test the non return valve, but found it impossible to get out (anybody know of any tricks) have tried levering out and mole grips. In If not started if i pump the pedal the hiss is there and it does harden up as though the vaccum is reduced. Does this not suggest the value is working correctly? Is it possible they are not bled properly - what wouldbe the symptoms of this? Spongey pedal? Quote Link to comment Share on other sites More sharing options...
Bumpyride Posted November 13, 2007 Author Share Posted November 13, 2007 sorry has naybody any thoughts on this? Quote Link to comment Share on other sites More sharing options...
Les Henson Posted November 13, 2007 Share Posted November 13, 2007 Lever the valve out a small amount and spray WD40 around the rubber. 'Work' the valve about and it'll come out. If your servo is working ok there will be residual vaccuum inside and you sould hear a hiss as air goes back in. To test the valve, blow through it from the end that goes in the servo - you should be able to. Then suck and you shouldn't be able to. Les. Quote Link to comment Share on other sites More sharing options...
Big_John Posted November 14, 2007 Share Posted November 14, 2007 Is it possible they are not bled properly - what wouldbe the symptoms of this? Spongey pedal? From what I remember of my old Morris Marina (only just getting back into DIY mechanics after 15 yrs of owning less user-servicable motors), if they're not bled properly then yes, the pedal will be spongy, it shouldn't go all the way to the floor unless they weren't bled at all or you were doing something majorly wrong. I assume you're not actually losing any fluid? If not then the pipes and connections are reasonably sound. Could it be the master cylinder seals? Have a look here: http://forums.lr4x4.com/index.php?showtopic=5300 Not sure how you'd confirm that's what it is. If it was the servo then wouldn't the pedal be just as hard to press with the engine off or on? What happens if you pump the pedal a few times with the engine off - does it go hard half way down as you describe for engine on? The brakes should still work without the engine/servo - just you'd have to stamp on 'em harder. I'm by no means an expert, it could well be the servo for all I know...just trying to understand! John Quote Link to comment Share on other sites More sharing options...
Eightpot Posted November 14, 2007 Share Posted November 14, 2007 I'm having exactly the same problem - first pump and the peddle goes way down with little effect, pump it a second time and the brakes are spot on. I've just fitted new pads and there were no probs with the wheel cylinders, adjusted the rear shoes up, there's no fluid leaking anywhere, and I've bled the brakes three times now, all with no difference. I've just got used to doing two sharp taps on the pedal now, if I ever do get it fixed I'll have to try and remember not to or I'll end up going over the handlebars like on a raleigh chopper Quote Link to comment Share on other sites More sharing options...
Diff Posted November 15, 2007 Share Posted November 15, 2007 I'm having exactly the same problem - first pump and the peddle goes way down with little effect, pump it a second time and the brakes are spot on. I've just fitted new pads and there were no probs with the wheel cylinders, adjusted the rear shoes up, there's no fluid leaking anywhere, and I've bled the brakes three times now, all with no difference. I've just got used to doing two sharp taps on the pedal now, if I ever do get it fixed I'll have to try and remember not to or I'll end up going over the handlebars like on a raleigh chopper Your symptoms imply that there is a problem with the adjustment on the rear shoes. The fact that the pedal is hard and not spongy on the second stroke indicates that there is not air in the system. Suggest that you recheck the adjustment on the rear shoes as it does not sound as though they are adjusted correctly. On some models it is possible to put the shoes on wrong such that the adjusters do not act properly on the posts attached to the brake shoes. Hope this helps, Regards, Diff Quote Link to comment Share on other sites More sharing options...
JimAttrill Posted November 15, 2007 Share Posted November 15, 2007 If your front wheel bearings need adjusting it will give the symptoms you describe as it is driven as the pistons will be pushed back into the calipers as you corner. If it happens when not moving, then forget the wheel bearings Quote Link to comment Share on other sites More sharing options...
tacr2man Posted November 15, 2007 Share Posted November 15, 2007 If you want to isolate the problem , get a brake hose clamp and put on rear axle hose then try brakes, if they change action dramatically then it tells you that the prob is in the rear brake shoe adjustment. You can use same method for isolating air in individual front callipers Quote Link to comment Share on other sites More sharing options...
Bumpyride Posted November 15, 2007 Author Share Posted November 15, 2007 Thanks a lot all, i shall try this weekend and see what happens. Quote Link to comment Share on other sites More sharing options...
Bumpyride Posted November 15, 2007 Author Share Posted November 15, 2007 I isolated the rear brakes through the flexible and yes the was a marked dfference, the brake pedal was stiff on the first depress. i shall check the rear shoes tomorrow, once ive checked the forum for handy hints. thanks again. Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted November 15, 2007 Share Posted November 15, 2007 The side note about this extremely useful procedure, of clamping the flex hose to isolate the problem front or rear (or left / right front, or master cylinder / servo) is that if you ever get tempted to fit stainless steel flex hoses you can't clamp them. At least, not and have them work properly again after you have released the clamp!! Just a thought for the future. Good Luck. Quote Link to comment Share on other sites More sharing options...
Bumpyride Posted November 16, 2007 Author Share Posted November 16, 2007 Can anybody enlighten me on what i should be looking for and adjusting in the drum, everything looks OK. A few hopeful points would be greatly appreciated. Quote Link to comment Share on other sites More sharing options...
Bumpyride Posted November 16, 2007 Author Share Posted November 16, 2007 in reference to the above adjustment of the rear brakes, i have been adjusting the "adjusting nut/cam" sorry to sound a bit thick, but am i trying to reduce the the movement required for the onset of braking as much as possible, thus removing the first wasted depression of the brake pedal? Quote Link to comment Share on other sites More sharing options...
Guest otchie1 Posted November 16, 2007 Share Posted November 16, 2007 in reference to the above adjustment of the rear brakes, i have been adjusting the "adjusting nut/cam" sorry to sound a bit thick, but am i trying to reduce the the movement required for the onset of braking as much as possible, thus removing the first wasted depression of the brake pedal? Mr LR manual says, "Turn the adjuster on the back-plate until the brake shoe is locked against the drum. Back off approximately two serrations so that the drum revolves freely." Buy some brake cleaning fluid and flush all the dush out of the mechanisms when you do it - also check the drum diameter - if it's too worn replace it. Quote Link to comment Share on other sites More sharing options...
Diff Posted November 19, 2007 Share Posted November 19, 2007 in reference to the above adjustment of the rear brakes, i have been adjusting the "adjusting nut/cam" sorry to sound a bit thick, but am i trying to reduce the the movement required for the onset of braking as much as possible, thus removing the first wasted depression of the brake pedal? Manual says back the adjusters off two serations, but can often result in too much pedal travel. My advice: Level ground, chock at least one front wheel in front and behind. Release handbrake, jack up one rear wheel. Leave wheel on. Turn one adjuster clockwise (looking at the back plate from underneath) whilst turning the wheel until you hear/feel it start to drag. Slacken it only enough to stop drag. Press brake pedal to settle shoes, spin wheel again to check for drag. If it isn't dragging, move on to the second adjuster on that wheel. Repeat as above. Then let the wheel down, jack up the other back wheel and do the same. Don't forget that all adjusters tighten by turning clockwise when viewing the back plate from under the vehicle. Hope this helps, Regards, Diff Quote Link to comment Share on other sites More sharing options...
Phil Hancock Posted November 19, 2007 Share Posted November 19, 2007 The adjustors on the leading and trailing shoes are at different hights, get the shoes on wrong and the adjustors push the shoes up and down rather than out, result excessive pedal travel. Quote Link to comment Share on other sites More sharing options...
Bumpyride Posted December 5, 2007 Author Share Posted December 5, 2007 Has anbody got a set of instructions on these drum brkaes. I think i'm seeing the brakes adjust up and down rather than in an out as noted in an earlier post, however there seems nothing obviously wrong with how they are positioned Quote Link to comment Share on other sites More sharing options...
Eightpot Posted December 5, 2007 Share Posted December 5, 2007 Still having problems with mine as well - think we could use a tech archive entry for this! I checked my rear drums a couple of days ago, and adjusted the shoes out as far as they'll go, but still getting a lot of travel. I also removed the drum and remotely pressed the brake peddal with a long stick so I could see what was happening - as soon as the brake peddle was moved, the shoes also moved outwards as you would expect. I did read a snippet of something somewhere that didn't go beyond saying that if the springs aren't attached properly they will pull the shoes inwards and depress the cylinders, creating exessive travel, though it didn't go as far as saying how the springs should be arranged. A picture would be good, but the latest version of the haynes manual I have doesn't show the shoe/spring layout Quote Link to comment Share on other sites More sharing options...
western Posted December 5, 2007 Share Posted December 5, 2007 The attached extract from the Defender workshop manual might help, with correct return spring location on the shoes. Quote Link to comment Share on other sites More sharing options...
Eightpot Posted December 6, 2007 Share Posted December 6, 2007 Just the thing Already I can see I've fitted the springs behind the shoes rather than in front, don't know if that makes a difference but I'll check later. Ta! Quote Link to comment Share on other sites More sharing options...
western Posted December 6, 2007 Share Posted December 6, 2007 Return springs should be nearest the brake back plate, bit of a fiddle to do, but very possible. Quote Link to comment Share on other sites More sharing options...
dirtbox Posted December 6, 2007 Share Posted December 6, 2007 Hey western, I've got a coffee stain just like that one on my manual! Very helpful diagram, was tempted to fit different axles on mine with discs- I know how they work! Sorry to hijack thread but does anyone recommend this? The old drums are a bit of a pain in the backside! Quote Link to comment Share on other sites More sharing options...
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