A long watcher first time poster here.... I need some advice on a never ending brake job project on my daily driver.. I have been throwing money at this too long and need for it to to be fixed finally! 1995 suburban 3/4 2 wheel drive, heavy duty, started with a slight dragging/ vibration within the rigth caliper noted at very slow speeds, replaced it and resolved the vibration but it developed a pull to right with braking, thought it was bad tires and waited till i replaced them. New tires and still pulls! next was new hoses , still pulled. went to the back brakes and discovered a fresh leaking left axle seal going bad with leakage on the shoes. New seals and rear pads, still pulled to the right and rear brakes locked --- wrong placement of leading shoes re-did back brakes still pulled to the right but resolved the back brakes from locking up. Last thing to do I thought was to replac the left front caliper , resolved the pull to the right! truck ran great for about a week Now its dragging the front brakes after warm up-- driving 5 miles. After driving and warming up the brakes I would jack up the front and note the right side by turning the tire, was dragging , thought it was a junk rebuilt caliper from Autocrap and replaced with another, warranties are great. After replacing the right again I thought i had it licked until i drove it and warmed it up again---sure enough dragging , pulled the abs fuse still draggs, jacked up the front and now the left side is dragging more than the right side. I am ready to pull all of my remaining hair out of my head on this one. I am now thinking Master cylinder or I am bleeding the abs system wrong. I did it the old way of two man pump pump hold --break open bleeder . HELP ME!
Joined: Sun Feb 05 2006, 11:51PM
Location: Pa
Posts: 3064
While it's not a modern abs system, a 1956 Desoto was in our resto shop years ago and the mechanic had the same problem. After letting him try 4 times, the boss put me on it. I wanted to start from square one and go through everything, flushed the whole system with denatured alcohol, and checked everything. Ended up finding crap in the master cylinder stuck in one of the tiny ports. Boy that older tech was pi$$=d ! The young guy fixes it it one shot
sounds like it might be a blocked compensator port in the master cylinder as mentioned in sticherbob's post. did the problem start after a master cylinder replacement? Pushrod length might be off (too long) causing the comp port to be closed. If not, flush system and clean any junk out of the master cylinder resevior
Joined: Sat Dec 10 2005, 04:28PM
Location: United States
Posts: 4954
If it's pulling to the right, it very may be a problem in the left Caliper. You probably should have changed both calipers. Turn the rotors and new pads are a good idea. I learned a long time ago to do both calipers at the same time. If one is bad, the other can't be too far behind. Rebuilts for that ought to be pretty reasonable.
May be air in the LF also. If so, bleed it and see if the problem goes away. If it does, I can bet it will come back in time. That means the piston is pitted and pumping air back into the brakes. Or, if you replaced the hose, you may have to bleed it again
Its only starting to grab after it warms up the brakes lets say about 5 miles. if it were the the abs unit it would do it form the start. What would a bad front bearing do? Any other ideas?
No more pulling to the right. its grabbing up front after warming up pulsating like grab. I already replace the left caliper and now redid the right one, new master cylinder and a rebleed of the whole system. I thought the right was sticking before I replaced it again. Thinking the right side rotar warpped now when heated up --grabbing.
Joined: Sat Dec 10 2005, 04:28PM
Location: United States
Posts: 4954
70 May be on to something then. There is a pin on the end of the metering valve. Try excersising it in and out and see. It may have a piece of garb in there causing a problem.
I guess I misread your message. Also, if I understand all this, you replaced the master. Did you happen to check to see if the adjustment is correct on the push rod to the master? It may be the new master is slightly different and the piston is being held slightly in the closed position. If there is an adjustment at the end of the rod, (This is the push rod that comes out of the booster) take the master off and back it off 1/4 a turn and see what happens
another possibility might be something sticking in the ABS valve body. Try to get your hands on a factory service manual for your vehicle and look for a trouble tree in the brake section that pertains to dragging front brakes or self applying front brakes.
discovered today while test driving it again that if I use the emergency brake the right rear locks . I had just replaced everything except the wheel cylinders. something must of came loose and is binding them . Never heard any scraping. I let you know later the out come when ONCE AGAIN I take another wheel off and inspect it.