Brakes Locking up, Help!

mkiiitnr

Big Sinlge
Mar 24, 2006
25
0
0
kansas
Ok so heres the story, I was heading back home on a 2 hour drive when at the 1 hour thirty mark my brakes begin to lock up after i let off the brakes to slow down. I got the car towed home which took about 45 minutes and the brakes released at this time. so I decided to check the brake booster and it all check out per tsrm tests. so i decided to re grease the slides, apparently they were bone dry. so i took it out for a test drive and about 45 minutes later it happens again. I have no idea whats causing this. Help please!
 

CyFi6

Aliens.
Oct 11, 2007
2,972
0
36
Phoenix
www.google.com
raise the wheels up and press the brake hard, then go around and see which ones are sticking (what wheel has a lot of resistance on it) then further inspect that caliper. If the piston is sticking it could cause issues as well. Check to make sure the slides are actually sliding, i would be worried about why they were dry before, usually if grease got out water got in = corrosion.
 

mkiiitnr

Big Sinlge
Mar 24, 2006
25
0
0
kansas
The thing is the brakes seem to work fine, it's after a bit of driving that it starts to lock up. Wheels roll fine.
 

rayall01

New Member
Oct 10, 2008
901
0
0
67
Westfield, ma
This is most likely corrosion on the piston. By design, brake fluid absorbs water and eventually the moisture corrodes either the piston, or under the square cut seal in the bore, either which will cause binding of the piston.
 

dumbo

Supramania Contributor
Jul 16, 2008
1,911
0
0
Albera, Too Far North
I doubt it has anything to do with the calipers, since it only happens after driving for awhile I bet the fluid is heating up and expanding, theres some valves in the master cyinder that releases it. I would do some reading on master cylinders.
 
Oct 11, 2005
3,816
16
38
Thousand Oaks, CA
It is possible the ABS actuator is locking a wheel up. If it does, the wheel will usually be locked on hard, you will not be able to move. The ABS light should trigger.

If its the master cylinder you would expect both fronts or both rears to be locked.
 

TooGoode

rediculous DD
Mar 1, 2007
549
0
0
36
Chandler, Arizona
i have a really good feeling its your master going out. the same thing happened to me. the car would brake fine and roll easy until i started to drive it for more than a couple miles. all four wheels would be braking. i disconnected my vac line going to the booster while they were locked up and the car rolled free. change your master.
 

mkiiitnr

Big Sinlge
Mar 24, 2006
25
0
0
kansas
As far as i can tell its only the front two that are hot once it locks up, haven't had time to check the master cylinder but I will check it first thing in the morning