lethalcav

I have a weird question for everyone. I have a 1990 toyota 4x4 pickup truck with a 22re. I am going through town and everything is fine then my brakes start binding and get tighter and tighter. Both front brakes are locking up. I can pull the vacuum line off the booster and it will unlock the brakes after about 2 minutes. I called the Yota garage and they said master cylinder that didnt work then they said booster, that wasnt the problem either. Then they said to replace brake lines because the rubber ones collapse, that didnt work either. Is there anything else I can try? Some have said the calipers but they are both locking up at the same time. I have also heard about a block toward the back of the truck. I dont know I just wanting to see if someone might have an idea.

abecedarian

so you replaced the master cylinder and servo?
check the brake pedal return spring?

lethalcav

What would you like me to check? If It is there? Yes

desconhecido

It's affecting both front brakes so it would likely be something common to the function of both brakes and the actuating pedal etc would fit that bill. So, I suppose verifying that everything associated is functioning properly.

If it's not the pedal and associated hardware, not the booster, not the master cylinder, the only other thing that appears to be common to both front brakes is a line from the master cylinder to a 3-way union and the union itself. The LSPV is towards the back of the truck, don't know how or if this could affect the front brakes in this manner.

abecedarian

okies... the spring is there... what about my other question?
in particular- you replaced the servo? (a.k.a. brake booster)
next time it does it, disconnect the brake pedal return spring and let the pedal flop to the floor then do that thing you do- disconnect the vacuum line to the brake booster and see what happens.

and the lspv should not affect the front brakes since the front and rear circuits do not share any fluid in the lspv and the range of motion of the bypass valve does not involve enough fluid to lock the front brakes.