hoobby Posted August 19, 2019 Share Posted August 19, 2019 System has been overhauled due to standing for 10 years New master,wheel cylinders,pistons and seals,pads fitted. Still can't get the rear brakes to come on with any force have bled and bled the master and lines tried one man kit, pressure and vacum.lines flow with no air bubbles I can see the auto adjusters operate correctly with drums off tried pulling the handbrake on to center the shoes.fronts are fine had a bar on them they do not move. rears can be overcome by hand have bypassed the brake bias valve still the same Flexi hose doesn't expand and seems fine .pedal travels too far before coming firm feels like air but can't see how. have bleed down brakes many times before with no problems.i am at a loss what to do now and very frustrated with this as the only thing stopping a mot. Quote Link to comment Share on other sites More sharing options...
cam.in.head Posted August 19, 2019 Share Posted August 19, 2019 if the pedal moves down a long way with the handbrake ON then its air trapped somewhere or a faulty item . if it only travels a long way with the handbrake OFF then its an adjustment issue inside one or both drums. Quote Link to comment Share on other sites More sharing options...
Sutty2006 Posted August 19, 2019 Share Posted August 19, 2019 I was thinking adjustment. Have you adjusted the shoes on until they just start to lock the drum up, then back off until slight free. Then try the rear brakes again. Quote Link to comment Share on other sites More sharing options...
Jessopia74 Posted August 19, 2019 Share Posted August 19, 2019 Front and rear outlets on master cylinder reversed? Quote Link to comment Share on other sites More sharing options...
IanMc Posted August 19, 2019 Share Posted August 19, 2019 (edited) When I was a lad, I replaced a rear wheel cylinder on my Uncle's Ford Sierra. When I test drove it the brakes were terrible, despite the bleeding going perfectly. After a while (and comparing to the other side), I noticed that I had connected the feed pipe to the bleed nipple hole and vice versa. Just a thought... Good luck matey. Edited August 19, 2019 by IanMc Quote Link to comment Share on other sites More sharing options...
hoobby Posted August 19, 2019 Author Share Posted August 19, 2019 Master is plumbed in the same way as the old unit and gives a firm pedal with all outlets plugged the wheel cylinders have two different thread sizes for brake line and nipple.will try playing with the (non) auto adjusters are they a known problem always had the cam adjuster type before. 1 Quote Link to comment Share on other sites More sharing options...
1200bandit Posted August 19, 2019 Share Posted August 19, 2019 Have you checked the the rear clylinders are correct, has the new clylinders got a bigger diameter (bore) If it’s a bigger bore the brakes will be poor Quote Link to comment Share on other sites More sharing options...
cam.in.head Posted August 19, 2019 Share Posted August 19, 2019 19mm bore should be the standard ,dont think you can get larger . you definately have the inserts fitted into the cylinders and located into the slots on the shoes correctly ? if your car is pre 82/83 they should be manual adjusters ,usually stiff thou.later cars are fully auto. is the pedal hard with the handbrake on ( does the handbrake lock the wheels ok ?) Quote Link to comment Share on other sites More sharing options...
hoobby Posted August 20, 2019 Author Share Posted August 20, 2019 (edited) The wheel cylinders I fitted are 19.05 mm bore a.b.s. for ate system as these have only one mounting bolt hole as the original ones had did see others for delco and teves systems will it make any difference which is fitted as I have no idea what system I have other than it has an ate master and delco moraine front calipers .it's an 88 on auto adjusters.will try out the ideas above but on long night shifts so will get back as soon as I have tried these out.hand brake works perfectly locks solid. Edited August 20, 2019 by hoobby Quote Link to comment Share on other sites More sharing options...
cam.in.head Posted August 20, 2019 Share Posted August 20, 2019 and with handbrake on hows the pedal travel Quote Link to comment Share on other sites More sharing options...
hoobby Posted August 20, 2019 Author Share Posted August 20, 2019 1 hour ago, cam.in.head said: and with handbrake on hows the pedal travel .i would say the same on or off .tried adjusting the drums until they dragged i would say a slight improvement but still overcome by hand.i also put another 1/2 liter of fluid through not one single air bubble. Quote Link to comment Share on other sites More sharing options...
1200bandit Posted August 20, 2019 Share Posted August 20, 2019 Clamp off all brake hoses and check the brake pedal lf the pedal is ok remove one clamp at a time and recheck the padal , refit clamp and try the one by one If the panal goes down when one clamp remove this may be the circuit, line that is a fault Quote Link to comment Share on other sites More sharing options...
cam.in.head Posted August 20, 2019 Share Posted August 20, 2019 thats the way ! Quote Link to comment Share on other sites More sharing options...
Jessopia74 Posted August 20, 2019 Share Posted August 20, 2019 It is possible the rear bias valve is just stuck.? Quote Link to comment Share on other sites More sharing options...
hoobby Posted August 20, 2019 Author Share Posted August 20, 2019 1 hour ago, Jessopia74 said: It is possible the rear bias valve is just stuck.? i have tried bypassing the valve exactly the same.will start blanking the system off starting at the drums and work my way back to the master starting to think there must be a restriction on the circuit reducing the pressure?. Quote Link to comment Share on other sites More sharing options...
cam.in.head Posted August 21, 2019 Share Posted August 21, 2019 dont worry too much about the pressure .the valve is there to reduce the pressure if you brake hard . if you sort out the pedal travel all should be well. Quote Link to comment Share on other sites More sharing options...
marksmanta47 Posted August 21, 2019 Share Posted August 21, 2019 Had a similar problem with an old fiesta years ago - turned out one of the brake flexis hoses had collapsed , it had perished internally even though they looked ok , I’m no mechanic so that’s all I’ve got - good luck Quote Link to comment Share on other sites More sharing options...
hoobby Posted August 21, 2019 Author Share Posted August 21, 2019 1 hour ago, marksmanta47 said: Had a similar problem with an old fiesta years ago - turned out one of the brake flexis hoses had collapsed , it had perished internally even though they looked ok , I’m no mechanic so that’s all I’ve got - good luck going to change the flexi as its at least 18 years old but first going to make a small section up to bypass the flexi dont have much time at mo as working and its my turn to work this weekend . Quote Link to comment Share on other sites More sharing options...
hoobby Posted August 24, 2019 Author Share Posted August 24, 2019 (edited) Found a braided hose that would fit wound the adjusters out until they dragged and still the same,brakes do improve a little if the drums are dragging now totally frustrated and fed up this after all should have been one of the easiest job to do but there is something wrong.starting to think this ate m/c is not compatible unlike my old m/c which had a tiny bolt which can only be fitted once the piston for the forward brakes is compressed slightly and holds it there could this be the problem?. replacement m/c 1978 to Oct 1985 part number 03.2120-0538.3 mines a 88. Edited August 24, 2019 by hoobby Quote Link to comment Share on other sites More sharing options...
Exclusive Opel Posted August 24, 2019 Share Posted August 24, 2019 Is the push rod in the servo being pushed out far enough when pressing the brake pedal? There is adjustment on the pedal end. As it looks like you have changed the m/c, perhaps the rod needs to go a little further out. Maybe someone who has their m/c off the car could measure the distance the rod sticks out when pressing the brake pedal and compare it to yours? Quote Link to comment Share on other sites More sharing options...
IanMc Posted August 24, 2019 Share Posted August 24, 2019 Have you still got the old MC Graeme? If so, is to possible to swap the seals over to that, or is it a different bore size? Quote Link to comment Share on other sites More sharing options...
JULIAN BEST Posted August 24, 2019 Share Posted August 24, 2019 4 hours ago, hoobby said: Found a braided hose that would fit wound the adjusters out until they dragged and still the same,brakes do improve a little if the drums are dragging now totally frustrated and fed up this after all should have been one of the easiest job to do but there is something wrong.starting to think this ate m/c is not compatible unlike my old m/c which had a tiny bolt which can only be fitted once the piston for the forward brakes is compressed slightly and holds it there could this be the problem?. replacement m/c 1978 to Oct 1985 part number 03.2120-0538.3 mines a 88. I think you are on the right track, ie the small bolt screwed into the body at the top, I don't know exactly why it has to be there other than it is a stop pin for the primory piston, the one that operates the drum brakes, I have just had my master refurbished and that has that stop pin fitted, so you could be correct in thinking that you have the wrong Master Cylinder, which doesn't make sense if it is the one that was fitted to the car. Quote Link to comment Share on other sites More sharing options...
hoobby Posted August 24, 2019 Author Share Posted August 24, 2019 (edited) 7 hours ago, Exclusive Opel said: Is the push rod in the servo being pushed out far enough when pressing the brake pedal? There is adjustment on the pedal end. As it looks like you have changed the m/c, perhaps the rod needs to go a little further out. Maybe someone who has their m/c off the car could measure the distance the rod sticks out when pressing the brake pedal and compare it to yours? Thanks will look into that and play. 7 hours ago, IanMc said: Have you still got the old MC Graeme? If so, is to possible to swap the seals over to that, or is it a different bore size? I did consider doing that but old m/c has deep scores and will need Refurb before any seals are fitted. 4 hours ago, JULIAN BEST said: I think you are on the right track, ie the small bolt screwed into the body at the top, I don't know exactly why it has to be there other than it is a stop pin for the primory piston, the one that operates the drum brakes, I have just had my master refurbished and that has that stop pin fitted, so you could be correct in thinking that you have the wrong Master Cylinder, which doesn't make sense if it is the one that was fitted to the car. The bolt on mine is on the bottom but you did give me a thought the brake bias valve I may not have bypass it correctly.pics have white dots on pipes so m/c circuit one has one outlet and goes to the valve.. circuit 2 has two outlets one goes directly to the o/s/f wheel the other to the valve do the two circuits meet/ mix at this point?.a or b?.when I bypassed this I linked number 1 to the rear brake feed and plugged the open vale inlet and top of valve like so. (N/S/F comes out of the bottom of valve) Edited August 24, 2019 by hoobby Quote Link to comment Share on other sites More sharing options...
cam.in.head Posted August 24, 2019 Share Posted August 24, 2019 hi right ive just been out and checked mine for you and have definately got it piped up correctly. you said that if you blanked off the master cylinder completely the pedal was hard .yes .so pedal adjustment rod must be ok . if you keep the blank in the master cylinder for the rear brakes and pipe up the front ones what happens.do you get a good pedal ? if you keep the blanks for the front brakes but just pipe up the rear circuit do you get a good pedal ? if you pipe everything up but blank off the top of the pressure valve going to the rear brakes do you get a good pedal ? this should show up the offending circuit / similar and in conjunction with clamping the hoses to isolate calipers or cylinders. 1 Quote Link to comment Share on other sites More sharing options...
hoobby Posted August 24, 2019 Author Share Posted August 24, 2019 Ok got that made up some plugs will have a go at that tomorrow as got to go to work soon. 1 Quote Link to comment Share on other sites More sharing options...
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