Left front tire locking up under hard braking

I know this is pretty simple stuff but under hard braking my left front tire locks up and sometimes just the right front. I figure it's either a sticking caliper and/or I need a new master cylinder? Any suggestions before I start buying a bunch of parts I may or may not need? I appreciate the help and this forum! 2001 Tacoma xtra cab 4x4 w/3.4L V-6

 

I have a similar problem with my front left. It started with a warped rotor somehow that seemed to stick in 1 spot. It has been like that for about 2 years. I'm changing out a bunch of front end parts including new rotors so I will see if it goes away after this and a bleed. I'd try rebleeding the lines and having the rotor measured to see if it is warped and then machine it down if possible. Start buying parts if that doesn't work?

 

Bleed the brakes first. Check for any grease or oil on the front pads.

 

Same problem here. I think my right caliper is seizing up. Idk.. Tried bleeding it many times in the past. Haven't messed with it in a while and its getting terribly worse.. But I'm currently working on getting tundra brakes and all new rear brakes anyways. That should take care of it. Heh.

 

I bought the Brembo rotors and pads to cure the runout issues my Wagner rotors developed. The Brembos were way cheaper and way better quality than the Oreilly Auto Parts Wagners. These are the Tundra upgrade for the 1st Gen Taco. My truck stops way better than it did ever!
If you are going to do the upgrade, Look at these on Ebay;
Toyota Tundra Sequoia Set of 2 Brembo Disc Brake Rotors & Pads 25534 Great price and fast shipping.

 

Remember that Toyota OEM calipers are re-buildable (the OEM kit is around $25 for both calipers).
You do need a source of compressed air to be able to remove the old pistons.

 

while you are at it replace the flex lines... if they get weak spots the hydraulic pressure goes to the weak spot with less pressure for the caliper... you apply more pedal force because you aren't stopping fast enough and you lock up the other side caliper.

 

ABS or NonABS?
If you have ABS try unplugging the ABS module under the hood and drive it that way. See if it changes.

 

Pretty sure it's not ABS. I really should know this stuff but how would I tell? It's an 01 TRD xtra cab 4x4

 

And the pedal is a bit harder to push down