So, I know brakes are supposed to be the easiest system to diagnose but this is kicking my butt... I have a 1997 T100 SR5 and I bought it just under a year ago with 190k miles with a 6 inch lift and 33s. Since I bought it the brake pedal has been mushy. I found that both front calipers were frozen, front rotors warped, rear drums grooved, and 1 bad wheel cylinder... So I replaced all of it! All new brakes, all around. Everything properly bled (several times) and rear drums adjusted. So now it brakes much better once the pedal engages at the floor. If I pump it the pedal comes up some more and doesn't sink to the floor. I bled the entire system many times starting from the LSP but it doesn't make the slightest bit of difference in the pedal feel. Would I be right to assume that the MC is bad as well? I just wanted a second opinion before taking the plunge, again, and buy another brake component... All of your help is very much appreciated. Thanks

 

If you pump the brake to build pressure, then keep steady pressure on it, does it slowly sink to the floor? If yes (and assuming you are not losing any fluid aka leak), then yes, it is the MC.

 

Nope, it doesn't sink... I have no idea what else it could be though.

 

It is possible to have a slight leak that sucks in air and not really see a major fluid loss.

Since you have all ready done most of the other brake system I would replace the Master Cylinder after rechecking all the connections that were apart.

 

i dont know what to te;; you, but i have a similar problem. the only thing is that i replaced the master, and it helped, but the brakes still suck. and i know i did just about everything i can do, done right. (dads a mechanic). replaced: lines, calipers, pads (F and R), master cyl. and i bled and adjusted everything. but the pedal will still seem soft sometimes and it takes me a lot of room to stop. but, it will lock up if i slam the brakes.

 

Thats not making me feel any better turkeykiller. And I have checked all my connections and lines etc for fluid leaks with no luck. I think if a leak were big enough to let air in, it would also be big enough to seep out pressurized brake fluid you know? Also, like I said before, the brake pedal does not sink once applied. If there was a leak I think it would be likely that the pedal would sink to the floor. I was a Yota tech during my college years but brakes were not my specialty. The only part I really don't understand in the brake system is that stupid LSP... Any other suggestions? Theres gotta be more people who have had this problem.

 

it could be the LSP. If the PO did not relocate the LSP when he lifted the truck. What the LSP does is sends more brake pressure to the drums as load increases in the back. SO if you lift the truck now the axle is lower than factory from the frame. Making the LSP think it has less load and will send even less to the rear drums. If it's off real bad then it would almost be like you had no rear brake.

 

thinking of one other thing, does the master cyl look like its the original? if not, maybe the actuating rod behind it needs to be adjusted as well.

 

I had thought about that actually and thats why I mentioned it was lifted 6 inches and I can see how that would decrease braking power on the rear drums but not why it would make my pedal go to the floor. Like I said, once it engages it brakes extremely well and can lock up. I am not sure if the MC is the original though. It is fairly clean looking so if I had to guess I would say it is a replacement. How would I go about adjusting the actuating rod? Is that very difficult? Thanks for the input. This is good!

 

You said you had the rear brakes adjusted up are they tight enough?? That all most sounds like the problem with new shoes and drums

These toyota`s with rear drums all use the emergency brake to keep the brakes adjusted up.

Good luck

 

So I may have made a breakthrough... I went camping up in the mountains this weekend and discovered the E-brake has little to no grab. Ya, I know... But for some reason the handle has felt like it was engaging ok but I never really park on hills so I didn't ever test it. Is it common for the rear drum self adjusting mechanism to just stop working or what needs to be done? Thanks again for all the answers!

 

After work yesterday I went home and jacked up the back end and went crazy adjusting out the rear drums. The adjuster wheels seemed to just keep going and going and finally I got some grab on the shoes on both sides. It immediately fixed the brake pedal sinking to the floor and the parking brake handle engages in half the distance. I do, however, still get front end dive but I think its because the LSP is not adjusted for the lift. Also the e-brake engages but does not seem like it holds as well as I'd like. I am happy though. No more pumping the brakes. Thanks for all the advice. It really helped!