Scruit Posted September 15, 2009 Share Posted September 15, 2009 My wife's 01 Outback has been having low/soft pedal issues for a while. When performing an emergency stop there was no real 'grab' to the brakes and I woudln't get the brakes to lock up / ABS to kick on even on wet road. Here's what I did: - Hawk HPS pads all round - Cryo rotors all round - Checked/greased slide pins on calipers - Flushed brake fluid through 2x, bled brakes - Adjusted the pedal height up - Checked the vacuum booster (Pedal firms up to rock solid on 3x pedal presses when enigne off, then sinks halfway down if you start the engine while holding the pedal down) - Tested the vacuum booster line check valve (it sucks, but doesn't blow... ) -Performed the brake beding in procedure from Hawk (10x braking form 35-5, don't stop. 4x braking form 45-5, don't stop. Cruise without stopping for 15 mins, then let the brakes cool down) - Bled the brakes again after the bedding procedure - New tires So, now it has a hard / high pedal that feels great for normal braking, but it still wont "grab" for en emergency brake unless I specifically concentrate on forcing all my weight down on the brake pedal (and I'm over 200lbs). So ai it stands, we cannot do an emergency sto pin the car - if you slam the brakes on panic-styl eit slows down gradually - takes 2x as long to stop from 60 as my car (05 LGT, same pads/rotors). I just can't get hte ABS to kick on or the wheels to lock up, even in the wet. It's beed 500 miles since the new pads/rotors went on so I'm pretty sure it's bedded fully now. I have it booked in to the dealer next tuesday. Does anyone have any last minute ideas before I sign my first-born over to Subaru? Link to comment Share on other sites More sharing options...
AZP Installs Posted September 17, 2009 Share Posted September 17, 2009 What proceedure did you use to Flush/Bleed the brakes? -mike Link to comment Share on other sites More sharing options...
Scruit Posted September 17, 2009 Author Share Posted September 17, 2009 What proceedure did you use to Flush/Bleed the brakes? -mike I have a vacuum bleeder. -Lifted all 4 corners up, pulled all the wheels. -Used a turkey baster to pull about 90% of the fluid out of the MC res. -Filled up with new brake fluid, being sure to not create bubbles -Went to the first wheel, cracked open the bleeder with the clear tube attached, then drew a vaccuum until the bleeder pump's reservoir was full. Toppe dup the MC with new fluid. MC never ran dry. Repeated until fluid came through clear, no bubbles. Closed the bleeder screw. Got about 3 cups of iced-tea colored fluid out. - Repeated the process on the other 3 wheels. Did this RR, LR, RF, LF first, twice around. Read conflicting versions of the bleed order, so I tried RF, LR, RR, LF. Drove the car down my gravel driveway, slammed the brakes on to get the abs to kick in . Did this 3 times. Went back and did the bleed process again. Put the new rotors/pads on. Did the brake bedding in procedure that came with the pads (Hawk HPS). Did the whole bleed process again. Right now the pedla is high and it brakes normally for normal driving, but slamming the brakes on results in the pedal going about halfway to the floor and no lockup or abs, just a gradual slowing. A few people have suggested bad ABS. Some say air in the ABS pump (but the pedal feels rock solid when you hit the brakes 3-4x with the engine off - air woudl mean spingy brakes, no?) Some say ABS electronics (but wouldn't any ABS electronic problem result normal brakes that I can lock up? Or the abs kicking in too much?) Right now it feels almost like the brake rotors are greased up - I can get *some* braking action, and I can get the lockup/abs effect if I push the pedal with my full bodyweight. Other than that it feels like the brakes are just unable to get a good bite. This situation existed before the brake work - in fact the new pads/rotors/brake bleeding were an attempt to correct this exact problem. Link to comment Share on other sites More sharing options...
AZP Installs Posted September 20, 2009 Share Posted September 20, 2009 Vacum bleeder is probably the issue. We've had issues with them introducing air into the system. We suggest the motive bleeder or the traditional pump-bleed-close-repump method. Mike Link to comment Share on other sites More sharing options...
AZP Installs Posted September 20, 2009 Share Posted September 20, 2009 Vacum bleeder is probably the issue. We've had issues with them introducing air into the system. We suggest the motive bleeder or the traditional pump-bleed-close-repump method. Mike Link to comment Share on other sites More sharing options...
Scruit Posted September 20, 2009 Author Share Posted September 20, 2009 How would air be introduced? I make sure to keep the vacuum up/fluid flowing while I am closing the bleed screw. Link to comment Share on other sites More sharing options...
devobuzz Posted September 20, 2009 Share Posted September 20, 2009 It does sound like air in the system. You say the situation existed before the brake work. Was there any work done on the brakes prior to that since the car was built? Could it be an internal leak in the master cylinder? Link to comment Share on other sites More sharing options...
AZP Installs Posted September 20, 2009 Share Posted September 20, 2009 How would air be introduced? I make sure to keep the vacuum up/fluid flowing while I am closing the bleed screw. If there is a leak in the bladder of the vacum bleeder it can introduce air into the system. We've been doing brake work for over 10 years and the vacu bleeders have always caused issues. If you do it via a different method and it's still bad, could be a bad master cylinder. -mike Link to comment Share on other sites More sharing options...
Scruit Posted September 20, 2009 Author Share Posted September 20, 2009 I understand that higher-end power bleeders (that use pressure) can develop a leak in the bladder that separates the air pressure from the brake fluid, and that hight pressure air near a fluid can force air into the liquid (like carbonating a drink)... But there's no bladder in contact with brake fluid in a vacuum system, though... At least not in the one I have. I can understand that too much vacuum might pull air in from places that don't seal (master cylinder seals?) That could have happened. As fair as air getting past the threads of the bleeder, I put teflon tap on them so there were no air bubbles. Thanks for all the advice. I don't have a second person who can help me two-man the bleeding process, and I'm not inclined to bench bleed the master cylinder at the risk of getting air into the ABS (which may have already happened). Even a better bleeding process would be a waste of time of the MC is bad or there's air in the MC/ABS. At this point I'm done experimenting with the car (it's my wife's car, and the brakes being not 100% is unacceptable) so I'm going to let the dealership check it out. I'll post what they come up with. My frustration is just that this system should be simple enough and the problems should be easy to diagnose. Especially since I've been a shadetree for nearly 20 years and have done engine and trans rebuilds... Brakes should be a piece of cake but this one has me beat. Link to comment Share on other sites More sharing options...
AZP Installs Posted September 20, 2009 Share Posted September 20, 2009 That's probably a good call to have a dealer or shop investigate it further. My guess is air in during the bleed process or faulty part of the system sucking air in. Mike Link to comment Share on other sites More sharing options...
Scruit Posted September 20, 2009 Author Share Posted September 20, 2009 For reference, I did a braking comparison. My 05LGT against my wife's 01 Outback. Mine: 2005 LGT Limited, Hawk HPS pads, stock rotors, Yokohama Avid W4S tires with ~1000 miles (and two track days) on them. Hers: 2001 Outback LLB, Hawk HPS pads, Cryostop rotos, Yokohama Avid H4S tires with ~1000 (and no track days!) on them The test: Found a stretch of road about 2 miles long, visibility for 0.5 miles each direction. Set an orange cone at the midway point. Tarmac was very slightly damp, just drying out. Surface is asphalt/tarmac that was laid about a year ago. Incline up about 3%. Accelerated to 60mph the car, put the cruise control on about 1/4 ahead of first cone. While confirming there was no traffic around or behind me, and doing 60mph on CC, as my front bumper reached the first cone I applied the brakes for 100% braking effort. When the car stopped I got out and set a cone level with the front bumper. Result: 05LGT: The tires began to chirp, almost locked up, and the abs kicked in quickly and it was on ABS almost the while stopping distance, cycling on and off so quickly it might as well have just stayed on all the time. ABS was on about 90% of the time. The car stopped 60-0 in 95 feet. The pedal progressively sank down to about 75% of it's travel as the ABS worked. 01OB: The tires chirped, ABS kicked in for a short distance then released back to standard braking in 3 distinct cycles. Most of the time was spend in non-abs, non-lockup braking, as if I was braking with 75% effort, not 100%. ABS was only about about 20% of the time. When the ABS released the tires were still rolling. The car stopped 60-0 in 120 feet. The pedal dropped to about 50% of it's travel. Observations: When the 05LGT cycled from ABS back to normal braking the tires started to locked up immediately and the ABS came back in. When the 01OB cycled from ABS back to normal braking the tries did not lock up again immediately, it took about 15-20 feet for the tires to chirp again, all the time I was pressing the pedal and harder. Conclusion: The 01OB's ABS appears to be working as designed, it's just the braking effort is less than it should be, hence the tires not trying to lock up again for 20 feet each time. Even though the stopping distance is close to the tested braking performance from places like car&driver, the factory braking distance is tested with stock tires and brakes on a flat surface, not high performance brakes and tires on an incline. For comparison, the stock braking distance of the 05LGT is 125ft, yet the performance brakes/tires and include reduced that to 95, so the OB should have seen the same stopping distance. The 01OB is booked in on tuesday at the local subaru dealership. We'll see what they say. I told them I'd do the comparitive braking test in advance so they know how big of a problem we're dealing with. I'd say that the 01OB stopping in 125 feet when the 05LGT with identical tires/brakes stopping in 95 feet means that the OB has only approximately 75% of it's braking available to it at the moment. :-/ Link to comment Share on other sites More sharing options...
AZP Installs Posted September 20, 2009 Share Posted September 20, 2009 There are a lot of assumptions there. First you don't have any performance brakes on there. At least not for a single brake action on a straight road. Second the ob has very different sized rotors in the front and the rears are also different. I would not expect them to stop anywhere near the same. Also the abs system on the ob is calibrated differently than the lgt. Mike Link to comment Share on other sites More sharing options...
hadvw Posted September 20, 2009 Share Posted September 20, 2009 Have you tried warming up the pads? I found that I didn't really like the emergency stopping procedure with the HPS pads I had on my '05 LGT. When warmed up (3-4 strong braking cycles) they were fine. When "cold", not so much. I replaced them with Carbotech Bobcats, and am much happier with the initial bite. YMMV. Link to comment Share on other sites More sharing options...
Scruit Posted September 20, 2009 Author Share Posted September 20, 2009 There are a lot of assumptions there. First you don't have any performance brakes on there. At least not for a single brake action on a straight road. Second the ob has very different sized rotors in the front and the rears are also different. I would not expect them to stop anywhere near the same. Also the abs system on the ob is calibrated differently than the lgt. Mike What do you mean by "you don't have any performance brakes on there". Both cars have the same Hawk HPS pads, and the OB has cryostop rotors also. Going by the car reviews like C&D etc, the tested stopping distance of the OB is 133' versus 125' in my test. The LGT is tested at 125' versus 95' in my test. The OB stops about 6% slower than the LGT from the factory whereas my test shows it stopping about 25% slower. Link to comment Share on other sites More sharing options...
Scruit Posted September 20, 2009 Author Share Posted September 20, 2009 Have you tried warming up the pads? I found that I didn't really like the emergency stopping procedure with the HPS pads I had on my '05 LGT. When warmed up (3-4 strong braking cycles) they were fine. When "cold", not so much. I replaced them with Carbotech Bobcats, and am much happier with the initial bite. YMMV. It was the same basic problem before the HPS pads. low/soft brake pedal with insufficient braking effort despite maximum pedal effort. Now I have high/solid brake pedal, but still with insufficient braking effort despite maximum pedal effort. Something has changed since a few months ago, the last time I drove this car. When I drove the car this time around the lack of braking effort was clearly apparent to me compared with normal. Link to comment Share on other sites More sharing options...
Scruit Posted September 20, 2009 Author Share Posted September 20, 2009 The LGT has factory vented front rotors that are 12" diameter and 1 1/8" thick. The OB has 11.5" diameter vented front rotors that are 1" thick. Link to comment Share on other sites More sharing options...
Scruit Posted September 22, 2009 Author Share Posted September 22, 2009 Dealership said the brakes are working normally. Hmmm. Link to comment Share on other sites More sharing options...
AZP Installs Posted September 28, 2009 Share Posted September 28, 2009 Hmm, I'd still have them professionally flushed. If it's the same after that, perhaps the dealer is correct. As stated above, the braking on the 2 vehicles you have will be different, even with the same tires and pads and rotors because the pads and rotors on them are different sizes. -mike Link to comment Share on other sites More sharing options...
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