Soft pedal, nothing seems to fix it

do you pressure bleed the brakes with the engine on or off?

 

Just an FYI. Got an 08 DC in 2020. Replaced the rear rotors/pads/ebrake parts and cleaned and greased rear calipers, it braked perfect. Fast forward after a new transmission and about 6 months of sitting (long story), went to drive and had a very soft pedal. Figured it was time to do the fronts, wound up replacing the calipers/rotors/pads LCA and Cam Bolts/Tie Rod Ends. Still had the soft pedal (ony when running, it would firm up with engine off. Replaced the MC, Power bled, and ABS bleed; soft pedal still there. Replaced the ABS unit and Booster with known good units; pedal remained soft. Yes I know how to bleed this truck. Last thing left was hoses and rear calipers (thats all that's left) decided to take a look at the rear calipers (thinking it couldn't possibly be them for a soft pedal and since they were cleaned inspected and lubed up quite recently). Top pin was perfect...but apparently the lower pin was bound essentially resetting the piston on the rear caliper everytime pressure was removed (you could see the rotor flex outward each time the pedal was pushed). Lesson here is don't use permatex brake caliper lubricant on anything rubber..and check the calipers first in the event of a soft pedal. It would have saved me a week of late nights and about 500 bucks.

 

Here's what I discovered when I replaced the rear brakes today: caliper pins were in excellent condition for a 2008 truck w/114k miles, no leaks in brake lines or banjo bolts, old brake pads had about 20% meat left, and rotors were very rusty.

Did it solve the soft pedal? Nope!

I have new front brake pads but I'm not so sure I want to replace them because they have about 50% meat. I'll probably change them tomorrow and then bleed the brakes.

I'm so frustrated right now! I haven't been able to drive the TT for over 2-3 months now.

 

You see post #30. If the rear rotors have runnout, they need more pedal travel to get a good feel.

More likely tho it is the bleed method.
Do as I suggested in post #30, pressure bleed them with a helper and while the pedal is down with pressure applied, strike the caliper with a block of hardwood and crack the bleeder (I use silicone hose into a bucket). Repeat at least 5 times.

This method knocks trapped air free which firms up the pedal. Of course I start by sucking out all the old stuff with a syringe.

 

IDK what's going on but when examing the inner front brake pads and lines by turning the steering wheel to full lock right and then left the brakes are now back to normal today. Actually, they feel more sensitive than before.

What in the world is going on?!!!

I know I should be happy I have my truck back but sadly I don't feel confident driving the truck for fear the pedal may go soft at any moment. And that's a scary thought, especially in California traffic.

I think now's a good time to trade in the truck.

 

****Disclaimer: long post****

So, today, after church, driving up a high hill with a downhill slope speed of 50mph (more like 65mph) I saw the upcoming traffic light turn yellow and then immediately red. Normally, I would let the truck coast downhill and not brake till the last minute hoping the traffic light would turn green before I reach the crosswalk (we all do this...don't we?). But this time I decided to brake midway downhill. And it was a good thing because the brake pedal started to sink!!! The truck wasn't slowing down as fast as I wanted it to so I adjusted my body positioning to push further onto the brake pedal to come to a complete stop. Not a good feeling guys!

I pulled over and pumped on the brakes. The pedal still felt soft and sunk. I turned the truck off and waited 20 minutes to discuss our options. Told the wife let's baby it home. But before we drove off I decided to pump the brakes again. The brakes started to firm up. Great! I felt confident enough to take the highway home (probably the dumbest thing I could have done). Before our exit, my wife mentioned if no one is behind us why not give that emergency braking method a try after we exit the highway. She read my mind! We exited and I slammed on the brakes at 50 mph. For a split second, I heard a weird different whooshing noise that sounded like it was coming from the brake booster. Then my attention immediately turned to the brake pedal SINKING AGAIN!!! I also noticed the initial hard bite/jerk from emergency braking was absent. We felt the truck's momentum decrease but not brake to a stop. The truck would eventually come to a stop after some distance of applying the brakes.

Once the road was clear of traffic, I did some light emergency braking at (40 mph). Pedal still sunk. We came to a red light, and I immediately put the truck in PARK and started pumping the brakes (don't ask why I did this), and immediately the brakes started to firm up. But this time it was much harder than before. I did a couple more park+pump methods and each time the brakes got harder and harder to the point the mushiness dissipated and the pedal travel stopped midway. So I attempted another emergency braking @ 50 mph and the truck screeched to a stop!!!

Did a couple more emergency braking and the truck screeched to a stop each time! 4 hrs later and the truck brakes hard and is that much more sensitive.

Guys, I think the hard braking method + brake pumping may be the answer. I'll report back next Sunday if the brakes sink in or not.

 

Update: brake hard + pump = total BS

Brake pedal is back to being mushy/soft/sinking/etc.

Next on the list is to replace brake booster and MC. Dang it!

 

If the booster offers sufficient mechanical assistance, doesn't bleed off after sitting a month, then it's likely not the source of the problem.

Previously I posted about verifying the pushrod length into the MC. If it's too long, it can be the source of this problem. Was it checked?

Since this journey began, have you had it on a wet/snowy road to activate the ABS repeatedly?

 

I haven't given up on fixing this and I wanted to update this thread in case helpful to others. Between my original post and now I did a few things:

• Replaced hard lines in the rear (axle to wheel)
• Swapped flex lines for SS lines (4 caliper, 2 at rear axle)
• Replaced rear calipers
  
• Completely replace the parking brake system (ex. pedal) as it was destroyed and followed OE adjustment method
• Replaced the Master Cylinder with a Duralast unit which definitely seemed to improve the feel a bit (still had play, but felt more solid once it did bite)
• Performed another pressure bleed
• Replaced PCV on a hunch it may be impacting and on removing old one the step+spring broke off
• (note: did not try anything @KeepOnTruckin suggested - that is next!)

At this point brakes feel better, but still have some play. So that leads me to @KeepOnTruckin suggestions which I will try next and see if that addresses any remaining play. I'm not crossing my fingers but hopeful

 

When I had my master cylinder off it didn’t look like push rod was adjustable. There have been some comments on changing out the booster and it solving the problem but when I ask for more details on why it would cause a soft pedal they never reply back.

 

Question: if I removed (i.e., simply cut out) a brake controller the prior owner added, is it possible this could explain the soft pedal? I ask because I didn't know what this thing was at the time and just unplugged and threw away. Looking under the dash today I see some wires were clearly spliced/etc. Would I need to "undo" anything done when this controller was installed that could account for my seemingly unexplainable soft pedal?


For reference I believe it looked like below.

 

It has nothing to do with your truck brakes, only controls the voltage going to the electric brakes on the trailer.

 

Roger that. So looking back over responses I think rotor run-out is the most likely culprit. Going to take a look at that this week.

 

I went with the cryo treated ones it looks like there much more tolerant to warping. Didn’t do anything about the soft pedal.

 

Not sure if it’s been asked, but have you driven another Tundra to check the difference? I know if you drive my 2023 Silverado ( company car ) compared to my 2012 Tundra, my Tundra feels like a softer pedal. Just a thought.

 

@KeepOnTruckin - is the solution for rust on the wheel hub to clean the surface, or do you mean rust *inside* it, i.e., I should replace the wheel hubs? I don't notice any play in the hubs so my plan was to clean the surface, but I wanted to ask in case I am misunderstanding.

 

I haven’t driven any other tundras and the pedal feels softer then other vehicals I drive. In my case I bought the truck used and for the first couple of months the pedal was fine then it got soft not sure what changed I’ve been thru everything with only small improvements. It does feel similar to my dad’s 2003 Lexus ls 430 which has a similar configuration to the tundra. I think some of the feel comes from the way the brake pedal assy has that cam linkage setup giving it slightly more travel than a brake pedal that is hooked right to the booster. They are very effective brakes just seem to have a little bit of a dead spot at start of the travel. I love everything about truck so I’ve just learned to live with it.

 

LONG UPDATE:

The truck has been stationary since April 2023. I was convinced the culprit was the brake booster, so I placed an order with Sparks Toyota in Augst/September. Several months passed, and the status reflected the brake booster was still on backorder. I re-read threads from this & other forums and re-watched Youtube vids, and I was convinced the brake booster was not the cause. So, I canceled the order. For some stupid reason (I have no idea why) I assumed the brake pads were the cause. So, I replaced the front brake pads only even though both front & rear brake pads showed 70% life. I also re-bled the brakes for the 3rd time. FYI - the front caliper pins moved with ease. Never bothered checking the rear caliper pins, though. When I bled the lines, I did notice some air bubbles but nothing significant. And as expected the brakes firmed up after the bleed. But immediately lost pedal feel/stopping power whenever I would suddenly accelerate then immediately brake. It's a scary feeling! I'd say the brake feel was no more than 10% at the maximum whenever this occurred. Limped the truck home. Turned off the truck and pumped the brakes 3 times and the pedal firmed up like a rock. Pressed and held the brake pedal in place and turned on the engine, and the pedal slowly moved forward indicating the brake booster was doing its job. And lo'behold, the brakes feel was back. But I wasn't going to be fooled. I knew they would dissipate whenever I'd suddenly accelerated and braked. So, I left the truck as is. This was about a month ago.

Long story short, I scoured several out-of-state dealerships and managed to find an OEM brake booster from a dealership 2500 miles from me. Luckily my brother-in-law lived in that state so I had him pick it up & ship it to me. It's ridiculous how much these things cost!

I was going to install the brake booster myself but figured I didn't want to risk screwing anything up so opted for a professional to install it. I found a local Toyota/Lexus Specialist with a 5-star rating on Yelp and based on the reviews they seemed honest and knew what they were doing.

On my way to the repair shop, the brake performed beautifully. Probably because I was babying it. So, I figured I'd give it another brake check test half a mile before the repair shop. I quickly accelerated and broke, and sure enough the brake pedal dove down and I lost stopping power. FYI - any time I'd test the brake I made sure there was no traffic in front or behind me. I would use engine braking (shifting to lower gears) and pumping on the brakes to slow the truck. BTW, pumping the brakes did nothing.

I slowly limped the truck to the repair shop. They asked if I wanted them to diagnose the issue before installing the brake booster to which I refused because I was convinced the swooshing noise was a sure sign there was a leak in the brake booster. 3 hours later, the shop called and said they test-drove the truck 5 times and they couldn't duplicate the issue. And they said they didn't feel right installing the brake booster and charged me for it knowing it would not fix anything. Wow! I had mixed feelings. 1) So blessed to have found an honest shop but 2) confused and frustrated they couldn't duplicate the issue. So I asked if they would do another test drive with me as a passenger to which they obliged. They did 3 test drives: 2 with the owner driving and 1 with me as the driver. And we couldn't duplicate it.

The owner/mechanic told me the mushy brake pedal is a common issue with the TTs. He stated they may have fixed the issue with the newer models but it's an engineering issue from 2007-2012ish. He even called his brother-in-law who happens to be a Master Technician at a Toyota dealership and he confirmed. No one really understands what's causing the issue except for Toyota, but they don't deem it hazardous since people can still brake, hence no recall. But when I further explained the problem he stated what I'm experiencing is completely different than what the other TT owners are experiencing. According to him, what I'm experiencing is random complete brake failure. He advised I should take the truck to a Toyota dealership for diagnosis purely for documentation purposes and then call Toyota Customer Service to escalate the issue.

It's been a week now and since then I have driven the truck 3 other times (slow & fast) and the brakes have not failed. I don't know what the hell is going on. I can't help but think the brakes are going to fail me. But I can't take it to the dealership if I can't duplicate the issue.

So, I'm at a loss for what to do. I don't want to sell the truck but at the same time, I'm afraid to drive it.

 

Quick update: drove the truck 3 other times and no brake failure. The brake booster still makes a swooshing noise whenever I press the brake pedal but the truck brakes at the slightest touch of the brake pedal.

So confused!

FYI - I haven't taken the truck any faster than 50 mph. I'm purposefully avoiding having to drive on the freeway for now.

I'll give it a shot early next Saturday morning when traffic is zill.

 

Nemesis... I'm anxious to know if the problem is still gone!? I just replaced all 4 rotors, pads and calipers on my 2008 Tundra. I felt a significant difference but I was comparing that feeling to brakes I knew were sketchy at best for the past 3 years. After a few days it does feel like maybe I've lost a little bit of pedal stiffness but it still stops fine when pressure is applied. The "Whooshing sound" you described happens in mine too. However, when I do the maintenance manual brake booster tests, it passes as it the directions say it should. I'm curious to hear if you achieved what seems to be the impossible dream of stiff brakes on a Toyota Tundra.

 

Hey KJ,

First thing first, let's address the "whooshing" noise. According to the Toyota specialist, he told me not to get so caught up in the "whooshing" noise. He says it's common/normal. He's worked on Tundras with less than 50K miles and they too make the "whooshing" noise. So long as it passes the brake booster test it doesn't require replacing.

As for an update on my issue, I have not had any episodes with the brakes whatsoever. The brake press may feel slightly soft but it's nowhere near the brake issues I had previously experienced. I've traveled well above 85mph and the brakes engage at the slightest touch and emergency stops on a dime when tested.

In my case, I honestly believe it was the brake fluids and nothing more. Flushing out the brake fluids 4 to 5 times was the key.

If your brakes work as intended then "I" wouldn't worry as much about attaining "stiff brakes" as much as we would love. Just my 0.02