I have a 99 4runner and last week I had issues with the front brakes sticking. I figured it was the caliper because they were quite old and it was causing a shake due to my warped rotor. So over the weekend I replaced all the front brakes. Rotors, calipers, and pads (all from a tundra, because I upgraded years ago). Now after about 5 minutes of driving I can feel the front brakes engaging on their own. My vehicle starts to slow by itself and with some experimentation I've realized I don't even need to use the brakes to activate the problem. It seems to happen all on its own. When it happens I pull over and the front rotor and calipers are quite hot, like the pads have been dragging for a while. Now my worry is that this has been the issue all along and it was never sticky calipers at all, as it happening again on brand new parts. Does anyone have any idea why front brakes would be activating on their own after about 5 minutes of driving each time? Thanks

 

yes.
Oh you wanted information too!?
your rotors were warped because of the dragging brakes, not the other way around. Don't overheat them again or you'll warp the ones you just put on!
there are several things that can cause your issue, first we need to know for sure if it's BOTH front brakes dragging or just one.
Jack up the front end (both sides) and try to turn the wheels by hand, feel more drag on one side than the other?
If it's only one side stop here and let us know!!
If it's both:
Crack the bleeder loose on one side and see if BOTH wheels free up.
Pump up the brakes again and see if the drag is back.
Then loosen the nuts holding the master cylinder to the brake booster and see if the wheels free up.
then put it back and see if the drag is back
Then disconnect the pushrod from the brake pedal to the brake booster.

the results of these tests will prove if it's a problem with the brake hoses, master cylinder, brake booster, or pedal/pushrod adjustment.

 

Ok I'll try some of that stuff you mentioned at the end. I know for sure it's a new issue tho, because the rotor has been warped for months. Long before this issue with the calipers. And I also know it's both front calipers, cause I've jacked the vehicle up and tried spinning them. I just can't figure out why the front brakes seem to be applying themselves after about 5 minutes of driving. When I leave my house, everything seems to move and operate freely, and then after about 5 minutes of driving I start to feel drag and resistance.

 

The front brakes are "applying themselves" because the pressure is not being fully released from the calipers and as they drag they build up heat and that increases the pressure. Which then increases the drag and the heat and... wait for it... more pressure!