Ridal Posted February 26, 2013 Share Posted February 26, 2013 KA67 Carina I have a terrible feeling brake pedal. The brakes become effective when the pedal is about half way to the floor but this varies slightly. The pedal seems to be firm but when I have my foot hard on the pedal and raise the revs at the same time, the pedal will sink even further. I replaced the master cylinder last year, bled the brakes from the nipples twice and have properly adjusted the rear drums (handbrake slack etc). No fluid is leaking. I haven't bled the system from the master cylinder onwards so it's possible there is air somewhere in there. I also haven't had a good look for bulging hoses either. I'm planning on doing a few engine mods soon which will increase the power so I'd really like to get the brakes sorted before that happens. Any ideas? Thanks, James Quote Link to comment Share on other sites More sharing options...
Valiant Posted February 26, 2013 Share Posted February 26, 2013 So there's nipples on the master cylinder and that's where you bleed it off? Bleed the whole system to each wheel untill you see clean fluid. See how it feels after that. Quote Link to comment Share on other sites More sharing options...
Ridal Posted February 26, 2013 Author Share Posted February 26, 2013 Sorry I mean the bleed nipples at the calipers/wheel cylinders. Bleeding the master cylinder onwards is the next thing to do. But would that explain the pedal depressing when the revs are raised? Quote Link to comment Share on other sites More sharing options...
Valiant Posted February 26, 2013 Share Posted February 26, 2013 Sorry mate I don't follow you. How do you mean bleeding the cylinder onward? Did you bench bleed the master cylinder before you fitted it? How does the pedal feel when the engine is not running? Firm? Low? Quote Link to comment Share on other sites More sharing options...
Ridal Posted February 26, 2013 Author Share Posted February 26, 2013 The brake fluid path is reservoir -> master cylinder -> proportioning valve -> calipers/wheel cylinders. There's a chance that bleeding the master cylinder separately will release some air trapped in there. I didn't bench bleed the cylinder when I fitted it. The pedal still has travel when the engine is not running. It's not as firm as my Corona's pedal though. So I guess it's either air in the system or bulging lines, more likely the former. Quote Link to comment Share on other sites More sharing options...
Celica RA45 Posted February 26, 2013 Share Posted February 26, 2013 does the car have a brake booster at all Quote Link to comment Share on other sites More sharing options...
WarrenW Posted February 26, 2013 Share Posted February 26, 2013 Clamp off your soft lines at the rear. - Does your pedal improve? yes/no Clamp off your soft line at the front. - Does your pedal improve? yes/no If you answer yes to the second one, clamp off each front soft line one at a time and if one side improves then that caliper or pad or slider of that side is at fault. Quote Link to comment Share on other sites More sharing options...
Ridal Posted February 26, 2013 Author Share Posted February 26, 2013 Yes it does. I checked the line to the manifold and it's clear. The one way valve is working as it should and the diaphragm in the booster doesn't seem to be leaking. I would have thought the booster would become less effective with more throttle/rpm (less vacuum) and cause more the opposite of what I'm experiencing. Could there be something else wrong? I wanted to clamp the lines for the tests you mentioned today but lacked the clamps. I'll get hold of some and see what I find. Quote Link to comment Share on other sites More sharing options...
azzurro Posted February 26, 2013 Share Posted February 26, 2013 can use vice grips in absence of clamps but be careful of over doing it and busting the soft lines. you say youve had the cylineder out so maybe you just need to adjust the rod between the pedal and booster correctly to bring the pedal up a bit? pedal sinking with revs* is a sign that the booster is working (from manifold vacuum assisting your foot pressure) but shoudnt really be that noticable. You prbably have air in the system somewhere that is compressing. bleed it again before adjusting the rod. *usual test that booster is 'working' is to put your foot on the brake when off and start car, pedal should drop slightly but be firm after that. Quote Link to comment Share on other sites More sharing options...
Celica RA45 Posted February 26, 2013 Share Posted February 26, 2013 when you took the master cyl off the booster ,was the rubber disc that sits inside still in the same posi of has it dropped off .and now making pedal feel funny .had same problem with a ta22 years ago Quote Link to comment Share on other sites More sharing options...
Ridal Posted February 26, 2013 Author Share Posted February 26, 2013 I can't remember. Is the rubber disc at the pedal linkage end of the piston or something? I should be able to get hold of some proper line clamps. I did wonder about that adjustment and will do as you say. I would have thought the booster would be less effective as the throttle opens due to loss of vacuum? Regardless, the pedal travels much too far for it to be ignored. I've got a good list of things to check now. Thanks for all the help everyone. Quote Link to comment Share on other sites More sharing options...
Celica RA45 Posted February 26, 2013 Share Posted February 26, 2013 good point im trying to remember which end it was in Quote Link to comment Share on other sites More sharing options...
Escorto. Posted February 26, 2013 Share Posted February 26, 2013 Rubber disc is in the hole where the master cyl slots in. Between the studs.. mine fell out yesterday. Mine has excess travel too. Also sinking at revs is wierd. Revs usualy means less. vaccum/ harder pedal Quote Link to comment Share on other sites More sharing options...
Ridal Posted February 26, 2013 Author Share Posted February 26, 2013 Well welcome to the club. I'll inform you of any of my findings anyway. It'll probably be Sunday before I have time to try anything unfortunately. Quote Link to comment Share on other sites More sharing options...
Celica RA45 Posted February 26, 2013 Share Posted February 26, 2013 ok then you guys need to put the rubber disc back in and it should be fine after that Quote Link to comment Share on other sites More sharing options...
Ridal Posted February 26, 2013 Author Share Posted February 26, 2013 Is the rubber disc you speak of part number 44626‑60010 in the link below? http://www.toyodiy.com/parts/p_J_1985_TOYOTA_CARINA+FR_KA67V-AXKRSW_4703.2.html Quote Link to comment Share on other sites More sharing options...
Celica RA45 Posted February 26, 2013 Share Posted February 26, 2013 rubber disc sits in front of that part no ,it shows it but no part no Quote Link to comment Share on other sites More sharing options...
Celica RA45 Posted February 26, 2013 Share Posted February 26, 2013 will have a look at a ra40 celica tomorrow to double check for you Quote Link to comment Share on other sites More sharing options...
Escorto. Posted February 26, 2013 Share Posted February 26, 2013 I did put it back in. Anyway thats enough thread jacking. There may be air in the master cylinder still. Have to undo the tube nuts on the lines and try bleed it out Quote Link to comment Share on other sites More sharing options...
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