CybrFyre Posted July 18, 2011 Share Posted July 18, 2011 Hi. 2005 Subaru Impreza Outback Sport. When I first had the car, the pedal was exactly the right firmness and exactly the right travel to engage the brakes. One day, after a routine service (at this point, I don't recall what they were doing), there was excessive travel before the brakes would engage. The car would still stop just fine, but a noticable extra amount of travel. While one gets used to this, when switchin back and forth between cars, especially, the extra travel becomes quite obvious. For a few years after that, whenever the car was serviced, the brakes would be back exactly where they were supposed to be, but only for a few days. Then back to excessive pedal travel, again. And now, as of about a year ago, I'd say, the brake pedal sometimes (not always... might do it many times in a row, etc) will sink a bit as I'm pressing it down. Especially in the case of trying to brake gradually, this makes where the brakes grab a moving target. You migtht be slowing then the pedal will sink a bit causing you to press further then the brakes suddenly grab hold. There will also sometimes be a slight sinking when sitting at a stop light. It's almost as if the bit that decides how much pressure should be in the brakes isn't working right. The claim from the dealer is that this bit of sinking is a normal function of the system to keep the brake system from overpressurizing and blowing out. And while that might be true, the brakes did not used to do this. Any thoughts? Thanks. Quote Link to comment Share on other sites More sharing options...
greenleg88 Posted July 18, 2011 Share Posted July 18, 2011 that sounds very odd.. have you checked your brake fluid levels? thoughts that run through my head is theres a leak or theres air in the lines. have the brakes ever been bled before? or a caliper changed... you said after the car gets serviced, the pedal feels normal again... what was serviced on the car those times...? Quote Link to comment Share on other sites More sharing options...
95legwagon Posted July 18, 2011 Share Posted July 18, 2011 im not a mechanic ( i just work on cars) lol but that sounds like ur brake booster could be going...... just a thought Quote Link to comment Share on other sites More sharing options...
jarl Posted July 19, 2011 Share Posted July 19, 2011 I'm afraid what you need is a new dealer The line about blowing the brakes is just BS. Quote Link to comment Share on other sites More sharing options...
nipper Posted July 19, 2011 Share Posted July 19, 2011 UNless you are trying to stop at stopsigns from 60mph in 55 feet they are bs'ing you. Posabilities: Seized/sticking caliper(s) - my money is on this. This would happen inconsistantly. Power Brake booster (too soon) Collapsed brake line (too soon but possible) Old brake fluid would always give a spongy pedal. Booster test Get in car car off pump brakes 10 times start car pedal moves to floor all is good. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted July 20, 2011 Share Posted July 20, 2011 My god, how could you have possibly put up with this for YEARS without getting a second or third, or even fourth opinion!? Spongy brake pedal usually means there is air in the lines. Improper bleeding, or old fluid as Nipper said are the usual causes. Ploosibilitities: Someone could have replaced the fluid with the wrong type. Not all brake fluids are created equal. The master cylinder could be damaged internally. Caliper pistons could be sticking. Start with the fluid. It's cheap and easy. I like the Valvoline Synpower? synthetic stuff in the Grey bottle. It's Dot4 equivalent which has a higher boiling point so it lasts longer. Also helps firm up the pedal, even compared to brand new Dot3. Quote Link to comment Share on other sites More sharing options...
bheinen74 Posted July 20, 2011 Share Posted July 20, 2011 please provide the dealer who told you this. We need to avoid that place, and if I was you, I would find another dealer to go to as well. Places like that dealer need shutdown before someone is killed. Quote Link to comment Share on other sites More sharing options...
nipper Posted July 20, 2011 Share Posted July 20, 2011 My god, how could you have possibly put up with this for YEARS without getting a second or third, or even fourth opinion!? . Not to pick on this poster, but being in the feild (or was) it amazes me how people drive for years with something that can be such a catastrophic failure if it happens (ie kill or be killed). I think since cars are disposable now and seem to be maintanence free (whats a tune up?) they are treated more like appliances then serious machinery. Auto mfgs havent helped by isolating the driver more and more from the mechanical connections to the car. People forget that these are 3000,4000, hell almost 7000 with some big SUV missles. The two most important systems on any car make it stop and steer. ANY doubts about these systems (and tires are included in this) need to be looked at asap. Quote Link to comment Share on other sites More sharing options...
jarl Posted July 20, 2011 Share Posted July 20, 2011 Air in the lines would make the pedal "spongy", but for the pedal to drop suddenly there got to be a leak somewhere. Unless there's something *really* weird going on with the ABS, my vote is for a damaged master cylinder as well. On old cars this is usually the product of pressing the brake pedal too much while bleeding the brakes. The pedal will travel further down, into areas that are usually corroded by the brake fluid that hasn't been changed in a decade or two, and the o'ring/sealing surfaces get damaged. So, when you are done installing your brand new brake pads and shoes, your brakes are worse than when you began. From your description this has been going on for a long time, though, so I don't think the corrosion/crap on the master cylinder of a 2005 MY would be bad enough to produce serious damage. Quote Link to comment Share on other sites More sharing options...
rverdoold Posted July 20, 2011 Share Posted July 20, 2011 Booster test Get in car car off pump brakes 10 times start car pedal moves to floor all is good. Could it be there is a vacuum leak in the system? Testing as Nipper described should show if the booster is wrong. However I thought that after pumping the brakes you need to keep the pedal pressed and then start. It should move to the floor. Quote Link to comment Share on other sites More sharing options...
nipper Posted July 21, 2011 Share Posted July 21, 2011 Could it be there is a vacuum leak in the system? Testing as Nipper described should show if the booster is wrong. However I thought that after pumping the brakes you need to keep the pedal pressed and then start. It should move to the floor. Oopsy i forgot that part. A vacume leak would affect the engine rpm somewhay when the brakes were applied. Sometimes there is a hissing sound when the brakes are applied, but I think it is the all too common seized brake caliper(s) Quote Link to comment Share on other sites More sharing options...
SchwarzeEwigkt Posted July 21, 2011 Share Posted July 21, 2011 My vote is for sticky caliper piston as well. My car did the exact same thing when one of the two pistons started to stick and the seal on the other started to leak. Replaced the affected caliper, all good. Quote Link to comment Share on other sites More sharing options...
Ricearu Posted July 21, 2011 Share Posted July 21, 2011 Sinking at a stop, under light braking (not enough to fully expand cup seals) is a clear indicator of a failing master cylinder. look into that soon, because if the primary circuit is dead, you could be stopping mainly using the rear (secondary) circuit. get this checked soon. oh and one more thing, pick a new dealer as that one should be fired. the whole service department. check to see if your car is under a recall. my forester was under brake master recall. Quote Link to comment Share on other sites More sharing options...
CybrFyre Posted July 26, 2011 Author Share Posted July 26, 2011 Thanks all for the numerous replies. I need to spend some time I haven't had yet reading through them. A couple of quick bits to chew on... 1) Evidently I had sticky calipers (pistons on said calipers) on the rear brakes causing those to stick from time to time. This evidently also got really bad in the last month. The pads in the course of a month went from 6/32 to 2/32... ouch! Prior to that they were wearing at a pretty normal rate. So, rear pads and rotors replaced (rotors were also really rusty and grooved) and the pistony thingamajigs in the calipers were lubed up so that the calipers were again moving as calipers should. Supposedly the front calipers are moving just fine. Of note, when I got home, I did notice a big round groove on the right rear rotor. Anything to worry about there? It seemed to smooth out next time I drove the car then seemed worse again back home (I have a feeling light is affecting how bad it looks). I can't seem to find a straight answer on the net about those grooves. No noticable grooves in the left rear or in the front. In the few miles I've driven the car (don't drive a heck of a lot as I have decent bus service to and from work) I have noticed the pedal sometimes seems to "catch" and feel stiffer when pressing the brakes and sometimes seems to feel like it starts to catch then something decides that there's too much pressure in the system or that the pedal is too high and adjusts the pedal back down a bit as I'm pressing it. I am, of course, only noticing this during light braking such as gradually coming to a stop. 2) I had previously tried the brake booster test. Car off, I can maybe pump up the break pedal a tad pressing the pedal repeatedly. Other than that, nope, can't pump it up. Does not get tight or hard to press. Light pressure on pedal and turn on car and the pedal does indeed sink down a bit as it seems the pedal is supposed to. 3) Front rotors are "warped" according to the dealer, which to me says that there's really brake pad material on them. Previously, I rebedded the brakes and this helped for a while (until I had to hard brake a few times to avoid various creatures crossing the road in my path). I'm wondering if the vibration from the extra material on the front brakes is enough to throw off whatever adjuster mechanisms are there -- note that during the usual gradual braking I don't really feel any vibration, but the question remains nonetheless. Thanks! Quote Link to comment Share on other sites More sharing options...
CybrFyre Posted July 26, 2011 Author Share Posted July 26, 2011 Sinking at a stop, under light braking (not enough to fully expand cup seals) is a clear indicator of a failing master cylinder. look into that soon, because if the primary circuit is dead, you could be stopping mainly using the rear (secondary) circuit. get this checked soon. oh and one more thing, pick a new dealer as that one should be fired. the whole service department. check to see if your car is under a recall. my forester was under brake master recall. Can you clarify what you mean by "primary circuit"? First time I've heard this terminology used w.r.t. brakes. Do you mean the front brakes are not engaging? Quote Link to comment Share on other sites More sharing options...
nipper Posted July 26, 2011 Share Posted July 26, 2011 Can you clarify what you mean by "primary circuit"? First time I've heard this terminology used w.r.t. brakes. Do you mean the front brakes are not engaging? This is very old terminology. This is when the brake system was split front and rear, front being primary. For quite a long time brake systems have been diagonal (Rt Frt Lf Rr). That ring on the rear rotor, is it rust or a score in the middle ish of the rotor. Quote Link to comment Share on other sites More sharing options...
subaruplatt Posted July 27, 2011 Share Posted July 27, 2011 Could it be there is a vacuum leak in the system? Testing as Nipper described should show if the booster is wrong. However I thought that after pumping the brakes you need to keep the pedal pressed and then start. It should move to the floor. I agree with the vacuum leak theory because it sounds like the feeling I get when stopped at a light with the car idled down. The idle is such that with AC and what not the normal power reserves decrease. Back on the throttle and sleepy time is over! Quote Link to comment Share on other sites More sharing options...
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