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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / December 2005low break pedal, non-working parking break - self-adjusters not working?
Hi there, This is about a Mazda 626 '91. What I realized recently is that the break pedal has to be pressed quite low to work. In addition, the parking break pretty much does not break at all anymore. All break pads were replaced about 20K ago, so they should not be that worn out. I recall now that the parking break effect declined continuously and did not experience much boost when the pads were replaced. I checked the break pedal behaviour, it is not really spongy, just low, and rather consistent at that. I tried to break few times while driving backward, that did not seem to affect the height of the pedal. My question is if all this is consistent with the self-adjusters stuck in some position. Now, is there any way to turn them manually without taking apart the drums, just the wheels? I read somewhere that there are screws one can turn from outside the drums, is that a viable option? Thanks! Mike > Hi there, > [quoted text clipped - 24 lines] > Thanks! > Mike Yes... you will need a screwdriver, or if you have the tool to adjust the rear brakes, use that, but a screwdriver will work just as well...you want to adjust the rear brakes so that there is a slight drag on the wheel as you turn the drum. If by chance you DON"T have access to this thru the back of the wheel (the backing plate), then chances are you will need to adjust the parking brake lever itself. To do this, you will need to take off the console cover that sits around the parking brake lever and in the back of that is the adjustment. All you need to do here is take up the slack in the cable by loosening one of the nuts and turning the other one so that the cable gets tighter, then once you have adjusted it properly, tighten the other nut so that they stay put. As far as the front brakes are concerned, you make no mention as to how good a pad you replaced them with, if it was you who did the work, if you turned the rotors at the same time, etc....if you replaced them with cheap pads, chances are they may need it again. it also depends on what type of driver you are. Do you hear a grinding noise when you press on the brake pedal? if so, then it is time to replace the pads once again. If not, then chances are they are worn, and then you will need to check to see how much brake fluid there is in the reservoir. I am willing to bet that the fluid is on the low side and just needs topping off. When the brakes wear, the piston inside the caliper moves out further which in turn makes more room for the brake fluid to take up. Once you replace the pads with new ones and have to push the piston back, you will find the master cylinder fluid holder will fill up with more fluid. Good Luck.. Fwed Thanks! This is all solid info! So I gather that the rear brakes most likely can be adjusted, together with the parking brake. The front brakes, on the other hand, are not so simple. From what I know, there are leaks in both front calipers, since the fluid needs to be added from time to time. That could've worn out the pads sooner, although I do not hear any noises coming from them. I have no idea which ones were installed, and that happened in a different city :-( What I am still puzzled about is this. Can the added volume in caliper cylinders require the pedal to go this much lower? Or is there some other variable? Thanks! Mike > > Hi there, > > [quoted text clipped - 53 lines] > > Fwed since you are losing fluid, that will definitely cause the brake pedal to go lower....in fact if enough fluid leaks out, your brake pedal can go to the floor causing it not to function.... I would check the bleeder valve on the caliper (both calipers) to make sure they are closed... it almost sounds like whoever did the job didn't tighten the bleeder valve very well after they bled the brakes... I would use serious caution while driving as you have a great chance of getting into an accident if it isn't fixed... Good Luck. Fwed > Thanks! This is all solid info! > [quoted text clipped - 82 lines] >> >> Fwed OK, I understand the concept of when there is no fluid, the brakes do not work. But what is the mechanism for brakes to fail if there is enough fluid is in the system? Also, how does this affect the pedal height? If the leak is slow, it would act almost if there is no leak ... Thus if the system was to be simply sealed, the pedal would still be low ... The reservoir has to be refilled about every 10 months, that is when parking brake light goes on. The leak is rather slow and systematic. Thanks! Mike > since you are losing fluid, that will definitely cause the brake pedal to go > lower....in fact if enough fluid leaks out, your brake pedal can go to the [quoted text clipped - 94 lines] > >> > >> Fwed Slow leaks have a nasty tendency to become fast leaks at the worst time, like in a panic stop. You have no emergency brake, that means you crash. An overextended wheel cylinder piston will leak slow for a while, then blow out fast. A rust hole in a line will leak slow for a while, then blow out fast. A bad seal on a wheel cylinder will leak slow, then blow out fast. A worn out back brake system will extend the piston for a leak and make the emergency brake not work and give you a low pedal.... Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Aug./05 http://www.imagestation.com/album/index.html?id=2120343242 (More Off Road album links at bottom of the view page) > OK, I understand the concept of when there is no fluid, the brakes do > not work. But what is the mechanism for brakes to fail if there is [quoted text clipped - 107 lines] > > >> > > >> Fwed Brake failure will be caused just merely by having no fluid in the system. Other than that, outside of something breaking (not braking lol) i can think of nothing that would cause brakes to fail....pedal height is contingent on how much fluid there is in the system..... even if the brake pads are worn and the pedal goes near the floor, if you fill the reservoir up, the pedal won't go that far, unless they (the pads) are nonexistent or near nonexistent. when you push on the brake pedal, it causes fluid to be pushed to the caliper, thus pushing out the piston against the side of one of the pads. If the pads are worn, the piston will be out further, so there won't be as much pressure against the piston because the fluid will take up the extra room or slack... Hope this helps... Fwed > OK, I understand the concept of when there is no fluid, the brakes do > not work. But what is the mechanism for brakes to fail if there is [quoted text clipped - 130 lines] >> >> >> >> Fwed > OK, I understand the concept of when there is no fluid, the brakes do > not work. But what is the mechanism for brakes to fail if there is [quoted text clipped - 5 lines] > The reservoir has to be refilled about every 10 months, that is when > parking brake light goes on. The leak is rather slow and systematic. When you have a fluid leak, and the brakes are just sitting still unused, air and moisture can get sucked into the brake line through the leak, through capillary action and small movements of the brake fluid in the lines. Ted > Hi there, > > This is about a Mazda 626 '91. > > What I realized recently is that the break <snip persistent mis-spellings> "Brake", sir, not "break". Your car has "brakes". Thank you, Sir! May I have another? Unfortunately, I did not get to go to all kinds of places like Oxfords and Cambridges, and thus may lack full scale training in *very* proper English! :-) Mike >Hi there, > [quoted text clipped - 24 lines] > Thanks! > Mike I'd recommend that you take the car back to the shop that installed the brakes. These brakes (rear) adjust by use of the parking brake, not by brake application in reverse. Sounds like the rear brakes were installed incorrectly or something has failed in the self adjuster mechanism. Make sure that the parking brake gets adjusted when the brakes are repaired and always use the parking brake when parked to keep the brakes adjusted. Good luck  SignatureDave in Columbus I am going to guess your rear shoes are worn out to the point of fluid seeping out the cylinders which is why you need to add fluid. I don't get 20K on a set of rear shoes. My last ones were paper thin at 12K. I would be doing a physical inspection of them before trying to adjust them. You should 'never' have to adjust the emergency brake cable after it is installed. The adjustment for the e-brake is the rear pad adjustment, the cable adjuster is just for initial setup. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Aug./05 http://www.imagestation.com/album/index.html?id=2120343242 (More Off Road album links at bottom of the view page) > Hi there, > [quoted text clipped - 24 lines] > Thanks! > Mike Yeah, I also understood that just adjusting the parking brake cable is not an option, because it just hides the issue. Anyway, I think that the most likely cause of the low pedal and the non-working parking brake is a lack of adjustment in the rear brakes. These explains both problems with one cause. This page cites this as a specific reason for low break pedal, and that would also explain the parking brake problem: http://auto.howstuffworks.com/drum-brake2.htm As far as the leak goes, I think it is mostly unrelated to the low pedal issue for now. Mike > Yeah, I also understood that just adjusting the parking brake cable is > not an option, because it just hides the issue. [quoted text clipped - 11 lines] > > Mike Well, at least adjust the rear parking brake so that when the front brake system fails, you will have a your rear brakes to fall back on. Just for your info, the front brakes take approx 80% of the total brake pedal. What I mean by this is that when you apply the brakes, the cars weight shifts forward and adds to the resistance in the front end. If youadjust the rear brake, adjusting the rear brake IS an option, but it will not cure the problem by itself.... the proper thing to do is adjust the rear brakes, and also take care of your problems in the front brake system. Only then will you have a safe vehicle, not only for yourself, but for the safety of others that you share the road with. Good Luck... Fwed |
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