Need a little help with brakes

Hey guys, so my 2000 tacoma prerunner brakes really poorly. The two issues I’ve found are that the brakes grab really low on the pedal and also whenever slamming on the brakes they are super hard like there is no power assist however the power assist works fine whenever you press on the brakes slowly like a normal stop. Whenever I do panic stop its hard at first and then goes down, this is pretty scary when you have to stop asap. It feels like a cushion of air preventing the pedal from going down. Trying to fix it myself I’ve replaced the booster twice, replaced the master cylinder and also bled the fluid a few times. While diagnosing, I tried clamping the rear brake line to see if they grab higher and they do so Im assuming my rear drums need replacement or adjustment but that didn’t solve the air cushion feeling when pressing hard. Any ideas? Thanks in advance!!

 

When bleeding the brakes, did you bleed the rear proportioning valve last? Also, are the adjustment mechanisms in the rear brakes operating freely?

 

No I bled the RR, RL, proportioning valve, FR, and then FL. I thought you go from furthest to closest to master cylinder. Yes the rear brakes work fine but they have a little bit of slack im assuming because of the higher pedal with the rear line clamped shut.

 

Check out this post.

https://www.tacomaworld.com/threads/brake-issues.637531/#post-21970266

 

So I just bled the proportioning valve and It was steady stream with no bubbles

 

This is good to see and share. I'd always bled my brakes like OP is saying, from furthest to closest bleeder. I'm sure I've incorrectly shared that or typed it on here. Oops.
So it looks like the principle of bleeding the furthest to the closest is still correct, just holding off on bleeding the LSPV until the 4 corners are done.

 

adjust your drums to where there is a *slight* NOISE when turning the hub. There should be very little actual drag. This will help brake pedal feel.

How are you bleeding your brakes?

 

I also read a hard pedal could be caused by lack of vacuum but my engine seems to run fine, no apparent vacuum leaks or anything

 

with the motor off press on the brake pedal until it gets hard. With slight foot pressure on the brake pedal start the motor. the pedal should drop a little bit. take your foot off the brake pedal and shut the motor off. now press the brake pedal. you should get 1 1/2 to 2 pumps before the pedal gets firm.

 

I went outside and tried it right now. I got 1 pedal with the engine off, the second pump was pretty firm after the halfway where my brakes start to grab.

 

Im thinking I should check vacuum with a gauge. It seems like the booster is working fine but the engine isn’t supplying enough vacuum?