Brake pedal randomly travels 2x as much

Hey TWers!

A few months ago I bought a 95 Tacoma 3.4 4wd with 189k miles and have been really loving it, and have slowly been moving through it and sorting out problems. Just recently, while driving it, the brake pedal needed to be pressed twice as far as normal to engage. The truck still stopped okay, but it was really unnerving to have to press the pedal in so much. Immediately after this, braking returned to normal.

This increased pedal travel/loss of brake pressure feel has continued to happen, seemingly randomly, about once every time i drive it. Pressure always regains immediately afterwards, but I'm worried that if i needed to stop suddenly and the brake pressure wasn't there, it could become a safety issue.

When I pump and the brakes at a stop with the engine running, sometimes the pressure holds, sometimes the pedal slowly continues to press down. I don't evidence of any brake fluid leak upon initial inspection, and brake fluid is full. I haven't chased down the problem further yet, but thought I'd post here to see if anyone had any particular ideas on which direction to head.

Does anyone have an idea of what this might be? I've read through a bunch of other threads about weird brake issues but couldn't find someone with this specific issue. Thanks!

 

Ugh. Soft pedal can generally be fixed by bleeding the brakes, but it's weird that it comes and goes for you. Might be worth a try before throwing part$ at it.

 

More than likely that the brake master cylinder is flaky due to mud for brake fluid… just replacing the brake fluid will not rejuvinte the seals in the master cylinder.

 

Hmm. I'm gonna follow this thread because I'm fighting the same issue. My brake pedal does the same thing. About 70% of the time it works perfect but the rest of the time it goes almost to the floor before engaging. I have replaced literally everything in the brake system minus the booster and LSBPV. All replaced within about a year. I have Powerstop Tundra calipers, stainless brake lines, new OEM master cylinder, and new rotors, pads, drums, and shoes along with new brake hardware springs and stuff. My emergency brake cable is new but adjusted nearly as tight as it can go. I've bled almost a full gallon of DOT 3 fluid through the system with the Motive pressure bleeder. There are no visible leaks. When it works, it works way better than my Audi A5. I'm completely stumped. It feels like there is something wrong with the rear brakes. It's like the return spring is too strong or something so I need to pump the breaks just to get the shoes to expand far enough to grip, but that doesn't make sense cause I've replaced the auto adjusters and lubed them with anti-seize. I've double checked (and a shop checked again) that the adjuster is installed the correct orientation. I've adjusted the rear drums through the hole in the back plate until the shoes just barely touch the drum.

I'm open to any suggestion at this point.

 

Never had this issue in my Taco but my old bulletproof, 4 banger Camry had a similar issue. Mech replaced the master cylinder - no change, bled the brakes - no change, took it to a different place and they ran a test on the brake fluid and it was toast. @exidor12 I highly recommend starting at replacing the brake fluid unless you know for sure that the fluid has been changed recently. From there you can then troubleshoot knowing that you are working with fluid that is fresh and performant.

 

Bet you have an air pocket somewhere.....on new installs it can be a pain...
bet your gonna have to do a reverse bleed......

$340 Phoenix Systems (2002HD-B) Heavy Duty Reverse Brake & Clutch Bleeder, One Person Bleeder, Cast Aluminum

Amazon.com: Phoenix Systems (2002HD-B) Heavy Duty Reverse Brake & Clutch Bleeder, One Person Bleeder, Cast Aluminum : Automotive

See this at 5:15......

(148) Getting Kicked Out After This - YouTube


It comes and goes as the system heats up....causes the air vapor to expand....

Brake fluid supposed to be replace every 3yrs....5yr for synthetic....
otherwise rust and corrosion appear.....actually never 'appear'.....hidding in dark places.....

 

awesome, thanks everyone for your thoughts! current fluid is definitely a bit sludge-y, so i'll start by replacing the brake fluid & doing a good bleed later this week. hopefully that solves the issue, if not i'll probably try swapping out the master cylinder. looks like it's been a while since the LSPV & the rear bleeders got cracked... just hosed them down w/PB blaster and will continue to PB blast w/a bit of impact over the next few days, fingers crossed it goes smoothly. appreciate you all!

 

Over time the break fluid will absorb moisture. Brake fluid itself doesn't compress which is why brakes work great after fresh fluid. After some time though, they absorb enough moisture that it can start to compress which would make sense for needing to push the pedal harder. Let us know how the bleed goes.

 

Do you have ABS? There could be air trapped in there - find a gravel road to slam the brakes and activate the abs pump.

This is assuming you’ve bled everything else: master cylinder, each brake and then the rear LSPV.

 

And nothing lasts forever...eventually you'll have to replace master.....
or obtain a rebuild kit....

the more years you put off parts....the more likely you end of having to use Chinese aftermarket....

 

no ABS, yeah interesting point o'silver taco. i'm afraid we very well may be there already. will report back after bleeding!

 

Well, I got my brakes fixed. Not sure if my procedure will help you, but here it is.

I disconnected the brake lines from the master cylinder and bled it with it still installed on the truck. I then connected the brake lines again and bled the entire system 2 more times. I tightened the emergency brake cable as tight as it would go and now everything works great.

Sometimes you just need to take it all apart and put it back together. Basically, turn it off and back on again.

 

awesome, really glad to hear you got that sorted out matt! thanks for the reminder to follow up w/my results. after a couple days of pb blasting, a couple rounds of heat/cool, and a few taps with an impact driver, i got the rear bleeder screws out without breaking them! i replaced those screws, flushed the brake fluid as per @mic_sierra's suggestion, and bled the all the brakes a couple times. i didn't touch the LSPV as the screw looked pretty harrowing, some day in the future maybe i'll deal with it. anyways, brake pedal seems to be back to normal! so far, so good, fingers crossed.

thanks everyone for your input, it was super helpful in deciding a course of action!

kyle

 

Yeah I've bled brakes on these a number of times and have never had to touch the LSPV....

....but I way over flushed just to be safe....

Biggest pain is new caliphers.....getting all the air bubbles out of the tops is not a quick job.....
make sure you have an extra quart and some time.....

 

all my vehicles have done this to an extent. probably just a shitty bleed from the factory.

 

I've also seen problems where someone in past put some non oem part they could grab real quick..

And then the spec is to far off......

The Bendix shoes from napa I put on the rear drums started prematurely wearing on the forward shoe....started having a soft feeling....
only a year in.....

So bit the bullet and ordered the real ones from mcgeorge......

Its been another year.....time to check em again...
and coat the outer drums.....

 

Maybe the following will help somebody in this situation.

Last night I was adjusting the emergency brake cable and I just could not get it tight. I removed the drums again and saw that there was a piece missing in the circled area. Normally, that small cable goes under a tab that is bent down. For some strange reason, my truck is missing that bent tab on both wheels. With that little tab missing, the emergency brake cable needs to be pulled much further to operate properly. Guess I better figure out a plan to replace that little tab that is riveted to the backplate. Or, guess I better just replace the entire backplate. I also need to replace the bell crank adjustment bolts but I have no idea what size they are and they are rusted enough that I'm afraid of breaking them off. I'm open to other suggestions.

edit: After more research, it appears that there were 2 different backing plates used in the 1st gen switching in 2002. At first glance, my truck is the first version. But, I am having a hard time finding a picture of the part. If any of you are in a spot to take a picture of yours, it would helpful for me to track it down.

 

Thats a good reason to bust in there every couple of years.....
not only did lack of lube eat that guide away...
the shoes were most likely sticking in place and made it even worse...overwhelming the cable...

PTFE in a syringe....


This is definitely another bullet point to check when you get the soft pedal and the other obvious stuff checked off...


If I had a 6lug and lived in the rust belt......I would have an extra set rear drum dust shields on hand......for that inevitable day....

Hopefully they're easier to get off than the 5lug.....

 

@Wanderlust Bus this is what that curved metal piece looks like:


courtesy of https://adventuretaco.com/guide/step-by-step-tacoma-rear-drum-brake-shoe-replacement-also-4runner/

 

Looks like a complete overhaul of the rear brakes is gonna be my next project. If I have to take it all apart far enough to replace the back plate, I may as well just replace everything with clean rust-free parts. Shouldn't be too bad, I should be able to knock it out in a saturday afternoon once I have all the parts.