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Front calipers locking up after hard brake

737 views 4 replies 3 participants last post by  Rayd88  
#1 ·
Hello Everybody. I have a 2012 SR5 5.7l, 4x4, Tundra. Recently, I had to brake hard near home. Soon after, I had to apply the brakes again (not hard), and the front calipers locked up. I got back home with the front left wheel smoking. I had it towed to my local mechanic who replaced front pads, calipers, rotors and hoses. (it was due).
When I picked it up, he said during the test drive, the new calipers locked up again, but was able to get them to release by loosening the brake line at the ABS. He thought that I needed a new ABS module (no dash lights ever lit).
I took it to nearest dealer and was quoted over $3000 to do the job, however they didn't know if this was the problem. Dealer had truck for three days. The calipers locked up when they tested it, so they took the brakes apart, relubed and reassembled everything, and said they didn't lock up again. I drove home, hit the brakes hard, no problem. About a mile down the road, I had to brake (not hard), and they locked up tight. I loosened the brake line and they released. I've been driving for a couple of weeks with no problems, but I haven't had to hit the brakes hard. Dealer and Mechanic can't figure it out and don't want to just start replacing big $ parts. I can't find anything solid on the web. Some suggestions have been to flush the lines with new fluid, replace the new hoses, etc, and others tell me no because both sides are locking up. Anybody run into this before and/or have ANY suggestions? I would truly appreciate any ideas you might have....Thanks...Ray
 
#2 · (Edited)
Where in the brake line did you loosen? When the shop changed the "caliper", did that include the "caliper bracket" and caliper pins? Just curious. (Caliper bracket and pins can cause binding but not the fluid pressure problem observed)

Try loosening the lines at the master cylinder and see if the brakes release. If they do, then it's not the ABS (as the mechanic did earlier) but the master cylinder itself. Likely the push rod clearance problem.

I always check the push rod clearance when installing a new master cylinder:
 
#3 ·
John, Thank you for your reply. The line that I loosened on top of the ABS (the rear line out of four) is directly connected to the rear port of the master cylinder. I believe the rear port controls the front brakes. I have been researching this problem and thought it could be a MC problem. I appreciate your input, as I hope to somehow solve this problem. Ray(y)

PS...Shop put in all new (rebuilt) calipers which I sure included new pins, which the dealer checked also.