Weak Braking - Tried Everything

The brakes on my 2005 TRD Off-road are weak, especially when towing. The pedal seems to take a while to engage, and it takes a lot of pressure and time to stop the truck. Again, this is especially noticeable when towing my aluminum boat. I've tried new pads (OEM and aftermarket), new rotors, all new rear brakes (adjusted several times), stainless brake lines, and replaced the master cylinder twice (aftermarket then OEM). Everything is bled properly, including the ABS module. None of the above has seemed to make a noticeable difference. Is there somethings else I should be trying, or is it possible that this is just how my brakes are? At his point the only things I haven't replaced are the ABS module and the booster.

 

I would assume it's the booster at this point. My mom's car had the same issue and the booster ended up being bad.

 

Short of the booster, have you changed the brake fluid recently?

Has it always been this way or just noticed recently?

 

if it takes a lot of pressure on the pedal to stop the truck, Booster may not be doing its job

 

Fluid is all new.

I feel like it's always been this way to some extent, but never felt quite right to. I've driven other Tacomas around the same age and the braking is much better.

The only reason I have not tried swapping the booster is because I've heard that a bad booster causes a hard pedal, which I definitely do not have. If anything the pedal is too soft.

 

Watching.

I understand your frustration. I have a similar issue. The pedal has a very linear / progressive movement to it. Until I am just 2.5in to the floor, that’s when I feel firmness. But it still feels like I’m pushing on a baked potato.
Feels firm and great when ABS kicks in on gravel.

I too have replaced literally everything except the lines itself.
Boat loads of Fluid, ABS Pump, Master Cyl, Vacuum Booster, Pads, Rotors, Drums, Calipers.

Too be honest I have given up and so has my mechanic and I just drive like grandpa.

There is a few thing I did that helped me.
Adjust:
- Rear Shoes (little star adjuster)
- Parking Break adjuster (2 areas of interest, inside Centre console and the attachment point between the pedal and cable. There are some adjustment there too.
- Vacuum booster rod to break pedal adjustment. I have had the most success with this. (you can adjust this to where the breaks just barely engage. Don’t adjust it too much otherwise it will always engage. But I may end up adjusting it further as I want my pedal feel to be harder/higher up, but I run the risk of burning my breaks, and tires.)

 

Well at least I'm not alone. I've adjusted and re-adjusted the rear brakes with the star adjuster, even had a shop do it to make sure I wasn't messing anything up. Didn't seem to help much, but I can give it another try. The vacuum booster rod to break pedal adjustment sound promising, I'll give that a try next. Is there another thread somewhere where this procedure is discussed?

 

Can confirm based on how my mom's car drove with a bad booster, pedal was super stiff.

 

https://www.tacomaworld.com/threads/brake-pedal-height.776832/

 

Wait. You have a TRD off-road? With A-Trac?

If that’s the case I recall that it does not have a break booster, and is actuated straight from the master Cyl electronically.

Or perhaps I’m mistaken…

 

Thanks bluberry. Was your length actually out of spec?
I'm assuming that making it longer is what causes the brakes to engage sooner?

 

And it is a TRD off road, but I definitely have a booster. I think maybe 2005 was before A-trac.

 

You said the ABS module is bled properly? Are you sure?

Not necessarily doubting you, but these trucks are pretty notorious for being difficult to bleed air out of the ABS. Really need TechStream or a fancy scan tool to actuate the module

 

Ohh that makes sense.

I don’t recall if it was out of spec as I was very frustrated that night troubleshooting this. Working under the foot well sucks. Barley any room in there.

Adjusting it to where is shows less threads (on the photo I sent) moves the whole pedal ratio higher and thus actuates sooner.

Again, I warn you doing this don’t over do it otherwise you will have the breaks constantly engaged. That’s what my mechanic and I agreed 2 years ago that it was not a good thing.
Now however, I don’t care if it’s a 0.00002 improvement great! Let it burn!

 

I had my trusted shop do it, they said they bled the ABS with their scanner tool. I guess there's no way to know for sure other than to take them at their word.

 

I did that already with the rear brakes, adjusted them super tight to see if it helped. It didn't help but I could definitely smell burning brakes when I finished the test drive, so had to back off the adjustment a bit.
Anything is worth a shot at this point, but I've kind of given up like you...I just know to leave extra room when I'm towing and hope no one ever pulls in front of me where I need to stop quickly.

 

How big of tires on your truck? Also, do you have brakes on your trailer?

 

Tires are 255/85r16. No brakes on the trailer, it's a pretty light aluminum fishing boat. Tire size is the one thing i've always clung to as a possible cause of the weak braking, but i've driven other tacomas with larger tires and they brake better.

 

I'm never a fan of towing without trailer brakes, even a smaller, lightly loaded utility trailer.

Usually, though, I'm towing pretty heavy and trailer brakes are a must. I've had a couple instances of the brakes not being there when I needed them and it was a serious pucker moment. Once I simply forgot to plug in the dang 7-pin, and once the connector wore out and failed to properly send a signal when needed.

 

What brand/model of tire and what condition/age? It should not make a HUGE difference but if you talk to the auto engineering types, technically the tires do the real braking.. not so much the rotors/drums.

Below is an AI blurb that explains it better than I can:

When someone says that on a car, the tires do the actual braking, they are highlighting the critical role that tires play in stopping the vehicle. Here's an explanation of this concept:

1. Friction and Contact: The brake system (which includes the brake pads, discs, drums, etc.) generates the stopping force, but this force must be transferred to the road to slow down the car. The tires are the point of contact between the car and the road. The friction between the tires and the road surface is what ultimately slows down and stops the vehicle.
   
2. Traction: Good traction is essential for effective braking. The quality and condition of the tires, as well as the road surface, determine how well the tires can grip the road. Worn-out tires or tires on a slippery surface (like ice or wet roads) will have reduced traction, making braking less effective.
   
3. Braking Distance: The distance required to bring a vehicle to a stop is influenced by the tires. Tires with better grip (appropriate tread pattern and rubber compound) will reduce braking distance. Conversely, tires in poor condition or unsuitable for the driving conditions will increase the braking distance.
   
4. Safety: Because the tires are the final link in the braking chain, maintaining them in good condition is crucial for safety. Proper tire inflation, regular checks for wear and damage, and using the right type of tire for the driving conditions are all important to ensure that the tires can perform their role effectively during braking.
   

In summary, while the brakes generate the force needed to stop the car, it is the tires that actually transfer this force to the road. The efficiency and safety of braking are heavily dependent on the tires' ability to provide adequate traction.