Questionable braking after Tundra Brake Upgrade

[K-Tanz]

My truck was not stopping well and instead of being an adult and diagnosing the issue I threw parts at it and upgraded to 13WL Tundra brakes. Stopping was still no good, so it was off to the mechanic. He replaced the brake booster as I was not getting any assist from the booster

Now the truck stops well when I slam the brakes with the nose diving forward and the truck stopping as I would expect. As the mechanic put it "It will put you through the windshield". My issue is that at moderate and low speeds the truck doesn't seem to slow as well as it has in the past with low to moderate pressure on the pedal. I was expecting that brake compliance would be awesome with the new brakes and booster but it seems lackluster. Even pulling into a parking space I need to hit them with some force to get the truck to come to a complete stop.

The pedal is rock hard. My mechanic bled the master cylinder, there is zero squish in the pedal and the distance to depress the pedal seems similar to before repairs. The truck does not pull to either side with braking and there is no shudder or shaking. Am I likely just noticing different characteristics in the new parts I put on? I made a poor decision and ordered some "Callahan" (Powerstop) brand brake products online, and that is what is currently on the truck for calipers, rotors, and pads. Lesson learned. My plan is one of the following:

1-Put the old original brakes on and see how the truck stops. If it stops way better then the calipers or pads are garbage from the factory and should be returned.

2- Buy new calipers from Advanced or the equivalent and see if they make a difference. If they are way better then the Callahans I bought are crap. If no difference package them up and return them.

Any suggestions as to which method I should try first? Is there a good way to bench test the power output from front calipers to see if they're grabbing how they should? I am concerned that the Tundra setup I bought is just terrible quality as the first set of calipers they sent were initially defective. Also I did not have a chance to properly bed the new brakes in as prior to the new booster it wasn't stopping well enough to even perform the bedding in process. Not sure how much of a difference this makes but it is worth mentioning.

Thanks for the help!

 

[Dezert4Runner]

I did the powerstop 231mm TBU a couple weeks ago. I bed the brakes in correctly and I am happy with the performance and quality of the parts. Pedal travel is the same but most of the braking power is definitely towards the end of the pedal travel. I feel like most people who’ve done the upgrade had similar results, so it is normal. I upgraded to stainless steel lines front & rear, and bled everything with a Motive power bleeder, just for full disclosure.

With the above info out of the way, I am no brake expert but it sounds like the bedding needs to be done to get a better baseline of what is going on. I would definitely start there. I doubt the Callahan calipers are to blame if there are no leaks and no noticeable sticking on one side so that would leave the pads & rotors. Did you use OEM replacement rotors or the drilled & slotted ones? I ask because it seemed to me that the drilled & slotted ones I used with the Z23 setup had a coating over the surface that the pads contact and definitely needed to be bed in properly to remove it. If you have this type of rotor and didn’t bed them right it could have gummed up the pads or glazed the rotors or something. I’m assuming you haven’t driven more than a few miles on this setup?

 

[K-Tanz]

Did you use OEM replacement rotors or the drilled & slotted ones? I ask because it seemed to me that the drilled & slotted ones I used with the Z23 setup had a coating over the surface that the pads contact and definitely needed to be bed in properly to remove it. If you have this type of rotor and didnÂ’t bed them right it could have gummed up the pads or glazed the rotors or something. IÂ’m assuming you havenÂ’t driven more than a few miles on this setup?

It is the drilled and slotted rotor setup from Power Stop/Callahan. I've driven it a bit but no big drives, just a bit around town. I can hit the rotors with a wire brush on a drill and sand down the pads a bit and then utilize the bed in procedure?

 

[Cree]

It is the drilled and slotted rotor setup from Power Stop/Callahan. I've driven it a bit but no big drives, just a bit around town. I can hit the rotors with a wire brush on a drill and sand down the pads a bit and then utilize the bed in procedure?

Couple of things. Half of your problem is your rotors, the other half is the calipers, or rather your master cylinder.

Brakes require heat to function properly. Drilled and slotted rotors are very good at dissipating Heat. That's great under severe Duty like say on a racetrack. That's not so great for a vehicle traveling at low speed in stop-and-go traffic. What you'll find is it the rotors never really get hot enough to do their job until you're seeing higher speeds.

The other part of your problem, and I don't care what anyone else tells you, is that your master cylinder is now under sized for the calipers you're using. The short version is the 1 inch bore Master cylinders do not move enough fluid in the same pedal stroke 2 fully activate the tundra calipers. What that means is your pedal travel will be further and sometimes softer then you experienced with stock brakes. There's been debate about this for years, but having been on both sides of the debate, I will tell you that this is absolutely the case.

First thing I would do is ditch the Callahan rotors and get a set of brembos put up there. That will fix some of the problem. From there you have options. If you're still not happy with it you may be able to adjust your pedal some to where the throw is a little shorter. If you're not happy with that look into upgrading to a 1 and 1/16 inch bore master cylinder. There's a number of ways you can do that be it with an adapter or swapping boosters again.

 

[Dezert4Runner]

It is the drilled and slotted rotor setup from Power Stop/Callahan. I've driven it a bit but no big drives, just a bit around town. I can hit the rotors with a wire brush on a drill and sand down the pads a bit and then utilize the bed in procedure?

I’ve never taken anything to my rotors like that for fear of doing more harm than good, but I would think just going ahead and bedding the brakes correctly would be sufficient. It won’t hurt to do this and it gives you something to start with that isn’t throwing more money at the problem.

 

[IBallEngineer]

Couple of things. Half of your problem is your rotors, the other half is the calipers, or rather your master cylinder.

Brakes require heat to function properly. Drilled and slotted rotors are very good at dissipating Heat. That's great under severe Duty like say on a racetrack. That's not so great for a vehicle traveling at low speed in stop-and-go traffic. What you'll find is it the rotors never really get hot enough to do their job until you're seeing higher speeds.

The other part of your problem, and I don't care what anyone else tells you, is that your master cylinder is now under sized for the calipers you're using. The short version is the 1 inch bore Master cylinders do not move enough fluid in the same pedal stroke 2 fully activate the tundra calipers. What that means is your pedal travel will be further and sometimes softer then you experienced with stock brakes. There's been debate about this for years, but having been on both sides of the debate, I will tell you that this is absolutely the case.

First thing I would do is ditch the Callahan rotors and get a set of brembos put up there. That will fix some of the problem. From there you have options. If you're still not happy with it you may be able to adjust your pedal some to where the throw is a little shorter. If you're not happy with that look into upgrading to a 1 and 1/16 inch bore master cylinder. There's a number of ways you can do that be it with an adapter or swapping boosters again.

I will respectfully disagree with almost everything in this post. I did the TBU on my wifes 2000 over 2 years ago, and did not touch the master. It worked, and still works flawlessly. The bore size of the Master actually drops pressure as bore size goes up, which means it requires more effort. Soft pedal has nothing to do with anything but pressure, which can be air build up, leaks, or low pressure by design.

I installed FJ80 Axles, and by default front 4 piston calipers on my LC, and I did upgrade from the 62's 7/8 Master to the 80 series 1" bore. That's been 13 or 14 years now, still no problem.

On this forum there have been hundreds of people who have installed Tundra brakes and not had to re-invent the Master, or use Brembo. Maybe the Brembo stuff is good, but I used Centric brand I bought at the local parts store with no problem.

If you have a problem, there is a problem that needs to be properly diagnosed, don't throw more parts at it, please.

:couch2:

 

[Cree]

I will respectfully disagree with almost everything in this post. I did the TBU on my wifes 2000 over 2 years ago, and did not touch the master. It worked, and still works flawlessly. The bore size of the Master actually drops pressure as bore size goes up, which means it requires more effort. Soft pedal has nothing to do with anything but pressure, which can be air build up, leaks, or low pressure by design.

I installed FJ80 Axles, and by default front 4 piston calipers on my LC, and I did upgrade from the 62's 7/8 Master to the 80 series 1" bore. That's been 13 or 14 years now, still no problem.

On this forum there have been hundreds of people who have installed Tundra brakes and not had to re-invent the Master, or use Brembo. Maybe the Brembo stuff is good, but I used Centric brand I bought at the local parts store with no problem.

If you have a problem, there is a problem that needs to be properly diagnosed, don't throw more parts at it, please.

:couch2:

Disagree all you like. Your definition of "fine" may not align with everyone else's. Pressure is lower, but volume is the issue. Larger bore = More volume in less travel. I ran the 231s for 2 years and the pedal was always low. Firm but low. Bigger master fixed that. What it boils down to is you can't upgrade half the system and expect peak performance.

Also, when I said Brembos, I was talking about the OEM Rotors. The main point is get rid of the drilled and slotted.

 

[IBallEngineer]

Disagree all you like. Your definition of "fine" may not align with everyone else's. Pressure is lower, but volume is the issue. Larger bore = More volume in less travel. I ran the 231s for 2 years and the pedal was always low. Firm but low. Bigger master fixed that. What it boils down to is you can't upgrade half the system and expect peak performance.

Also, when I said Brembos, I was talking about the OEM Rotors. The main point is get rid of the drilled and slotted.

OK, let's not be ambiguous then. The OP stated:

"My issue is that at moderate and low speeds the truck doesn't seem to slow as well as it has in the past with low to moderate pressure on the pedal."

My definition of fine is "I don't have this problem". A larger bore Master cylinder will require more pressure on the pedal not less, not solving the OP's problem. That is not my definition, it is fact.

I do agree that lower volume requires a longer throw. Whether that is an issue or not might be subjective.

I do agree with getting rid of the drilled/slotted rotors, but I don't think that is where his problem lies unless he glazed everything instead of properly seating the pads.

:couch2:

Edit, it's possible he already had a problem with his Master/Booster.

 

[Cree]

OK, let's not be ambiguous then. The OP stated:

"My issue is that at moderate and low speeds the truck doesn't seem to slow as well as it has in the past with low to moderate pressure on the pedal."

My definition of fine is "I don't have this problem". A larger bore Master cylinder will require more pressure on the pedal not less, not solving the OP's problem. That is not my definition, it is fact.

I do agree that lower volume requires a longer throw. Whether that is an issue or not might be subjective.

I do agree with getting rid of the drilled/slotted rotors, but I don't think that is where his problem lies unless he glazed everything instead of properly seating the pads.

:couch2:

Edit, it's possible he already had a problem with his Master/Booster.

I'd say in this case, the rotors are the issue right now. I HATED the cross drilled RotorPros I ran on my Lightning. Man they stopped like absolute trash anything under 50. Panic stops and high speed stuff? Amazing, but everyday driving I hated those things. One or the other work for the street, but not both.

 

[gamefreakgc]

I also have the Powerstop calipers, they work fine on the older 96-00 brake booster. I have no experience with the newer style brake pump system, which might experience braking issue but I don't know for sure.

However, to the OP, bed your brakes. The pads need to transfer a layer of material on the new rotors to work like they should. Without a proper bed-in procedure done, they will have no grip until you mash on the pedal, like you said. Takes all of 5 minutes to do: https://www.powerstop.com/brake-pad-break-in-procedure/ - that's from the company you bought your brakes from.

Bed them in properly and report back and see if it improves.

 

[DaMonkey]

Couple of things. Half of your problem is your rotors, the other half is the calipers, or rather your master cylinder.

Brakes require heat to function properly. Drilled and slotted rotors are very good at dissipating Heat. That's great under severe Duty like say on a racetrack. That's not so great for a vehicle traveling at low speed in stop-and-go traffic. What you'll find is it the rotors never really get hot enough to do their job until you're seeing higher speeds.

The other part of your problem, and I don't care what anyone else tells you, is that your master cylinder is now under sized for the calipers you're using. The short version is the 1 inch bore Master cylinders do not move enough fluid in the same pedal stroke 2 fully activate the tundra calipers. What that means is your pedal travel will be further and sometimes softer then you experienced with stock brakes. There's been debate about this for years, but having been on both sides of the debate, I will tell you that this is absolutely the case.

First thing I would do is ditch the Callahan rotors and get a set of brembos put up there. That will fix some of the problem. From there you have options. If you're still not happy with it you may be able to adjust your pedal some to where the throw is a little shorter. If you're not happy with that look into upgrading to a 1 and 1/16 inch bore master cylinder. There's a number of ways you can do that be it with an adapter or swapping boosters again.

When I read this post, I thought it was very informative, and accurate. Particularly the part about fluid volume. Good share.

I've built a few custom brake systems and typically have tried different stuff until I am very happy with it.

Based on what the OP shared, the larger MC will do exactly what Cree is suggesting which is to bring engagement further up the pedal stroke and provide an earlier firm pedal which he seems to have toward the bottom (put you through the windshield lol). Small bore is easy to push pedal down smooth and fast until the pads really bite. Very irritating. I have not done the Tundra mod on my 3rd gen, but I've swapped bore sizes on other builds, and this is exactly the experience. Smaller bore is helpful when the brakes do bite, if you need more pedal pressure to get the stopping power, but that does not sound like it is the problem. Prob sounds like how much fluid volume and full engagement is just too low.

Another thing to consider is a prop valve to bias the fluid forward. But typically, I have used bore size to tune the slow and steady action, and used the prop valve to tune the front/rear bias when jamming the brakes suddenly so I don't lose my ass end. I'm not sure it's a good idea to change the brake setup and not have a prop valve to balance the brakes after install. It would have to be a real stroke of luck for it to be blindly proper. Feels like most people in here say it's not necessary, but the biggest piece of evidence they point to is that nobody else is doing it. Cree's experience, and this information from the OP seems to indicate that the system needs the hydraulics tuned.

I replaced the fronts on my 3rd gen with quality stock spec pads/rotors and intended to upgrade bigger calipers later, but I've actually been real happy with my stock brakes. I tow a few thousand pounds often and have 31's, but no mountains to speak of. Of course I've been known to modify unnecessarily, and I love this truck, so I'm sure I'll give my brakes the stink eye some day.

 

[jgue467]

I'm sure OP has more problems but yeah cross drilled rotors suck in a t4r, they feel 'knobby' and I can just about count the holes as the pads go over them, feel rough and knobby, got PowerStop SLOTTED/curved vane rotors, sweet, smooth, powerful and they just work well in all conditions. Now we're braking (trailer towing and all) and all with 12" standard rotors! :cowboy:

 

[Drew76]

OP - You mentioned your mechanic bleeding the master cylinder. Did he bleed the fluid at all 4 corners? If the fluid is not new I would replace it all with new while bleeding the system.

I've had a rock hard brake pedal in another vehicle turns out is was the brake booster check valve going bad, not sure if our 4runners have something similar.

 

[Cree]

OP - You mentioned your mechanic bleeding the master cylinder. Did he bleed the fluid at all 4 corners? If the fluid is not new I would replace it all with new while bleeding the system.

I've had a rock hard brake pedal in another vehicle turns out is was the brake booster check valve going bad, not sure if our 4runners have something similar.

They absolutely do, and they absolutely fail. Reman boosters don't come with new ones, so this could be why he's lacking power assist. I missed that on my initial read through.

 

[96Runr]

Did the 231 TBU about 2 years ago, great stopping power at higher speeds, not much improvement at slower UNLESS I push petal firm.
Agree with MC analysis.... if your board, upgrade MC from T100.... for me, I haven’t be that board yet

 

[Drew76]

They absolutely do, and they absolutely fail. Reman boosters don't come with new ones, so this could be why he's lacking power assist. I missed that on my initial read through.

So I've had the rock hard pedal on my 4Runner before the TBU - only after sitting all night outside when it was like -20c here - only when I first start it up cold next day and only for a min, kind of freaks me out when backing down the driveway then realizing I can't stop without standing on the pedal. Seems like it's not that uncommon from doing a search. Maybe pulling out the check valve and inspecting/cleaning would be a good preventative measure for OP (myself included) or swapping it out altogether to rule it out.

 

[K-Tanz]

Thanks for all the replies, guys! For clarification it is my firm belief that the booster was smoked well before I had the booster replaced. I was experiencing terrible braking and instead of performing diagnosis like a big boy I took the opportunity to perform the TBU upgrade I had wanted to do for a long time. Original symptoms were fine braking at low/moderate pedal pressure, but with higher pressure the thing just wouldn't stop. It was so bad that on a steep trail and the pedal mashed the car was creeping downhill. For additional clarification here is a link to the setup which I purchased https://www.amazon.com/gp/product/B00EOBMFAY/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1

I cannot speak as to whether he bled at all 4 corners, but this is a job I am more than comfortable performing. The pedal, though, is rock hard and does not migrate towards the floor when held down. It is firm, with a firm short throw comparable to how it has always been. The first spot I hit resistance slows the vehicle, but but when I want to stop, say, pulling into a parking space, the amount of pressure which would historically stop the truck does not do the trick. I definitely have power assist now, the difference with firm pedal pressure is night and day and I am no longer at risk of running over and women or children; but I may be at risk of dinging someone pulling into a parking space.

I definitely did not properly bed in the pads. Is it necessary to hit them and the rotors with some sandpaper prior to bed in procedure as they have a few miles on them now and are not fresh out of the box? I will report back with results after bed in.

OP - You mentioned your mechanic bleeding the master cylinder. Did he bleed the fluid at all 4 corners? If the fluid is not new I would replace it all with new while bleeding the system.

I've had a rock hard brake pedal in another vehicle turns out is was the brake booster check valve going bad, not sure if our 4runners have something similar.

I found this thread about the check valve https://www.toyota-4runner.org/3rd-gen-t4rs/102376-vacuum-check-valve-brake-booster.html but there's not really instructions on how to replce the valve, or for that matter where it even lives. Seems like once the valve is purchased it should be pretty self explanatory where it goes?

I would prefer to start low cost and simple to start with, especially because that booster was not cheap. If the bed in procedure doesn't help (big if, there) perhaps I can find some junkyard Tundra rotors for testing purposes to see if they remedy the situation. My concern is if I change the rotors, bed them, test them, and it doesn't help, that Advanced Auto or whomever won't take the return and I'm out the cash for rotors I never needed. The check valve seems cheap and easy to install so I am open to changing that was well if it appears that it wasn't changed with the new booster.

Thanks again, everyone!

[Edit for clarification]

 

[Cree]

Thanks for all the replies, guys! For clarification it is my firm belief that the booster was smoked well before I had the booster replaced. I was experiencing terrible braking and instead of performing diagnosis like a big boy I took the opportunity to perform the TBU upgrade I had wanted to do for a long time. Original symptoms were fine braking at low/moderate pedal pressure, but with higher pressure the thing just wouldn't stop. It was so bad that on a steep trail and the pedal mashed the car was creeping downhill. For additional clarification here is a link to the setup which I purchased https://www.amazon.com/gp/product/B00EOBMFAY/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1

I cannot speak as to whether he bled at all 4 corners, but this is a job I am more than comfortable performing. The pedal, though, is rock hard and does not migrate towards the floor when held down. It is firm, with a firm short throw comparable to how it has always been. The first spot I hit resistance slows the vehicle, but but when I want to stop, say, pulling into a parking space, the amount of pressure which would historically stop the truck does not do the trick. I definitely have power assist now, the difference with firm pedal pressure is night and day and I am no longer at risk of running over and women or children; but I may be at risk of dinging someone pulling into a parking space.

I definitely did not properly bed in the pads. Is it necessary to hit them and the rotors with some sandpaper prior to bed in procedure as they have a few miles on them now and are not fresh out of the box? I will report back with results after bed in.



I found this thread about the check valve https://www.toyota-4runner.org/3rd-gen-t4rs/102376-vacuum-check-valve-brake-booster.html but there's not really instructions on how to replce the valve, or for that matter where it even lives. Seems like once the valve is purchased it should be pretty self explanatory where it goes?

I would prefer to start low cost and simple to start with, especially because that booster was not cheap. If the bed in procedure doesn't help (big if, there) perhaps I can find some junkyard Tundra rotors for testing purposes to see if they remedy the situation. My concern is if I change the rotors, bed them, test them, and it doesn't help, that Advanced Auto or whomever won't take the return and I'm out the cash for rotors I never needed. The check valve seems cheap and easy to install so I am open to changing that was well if it appears that it wasn't changed with the new booster.

Thanks again, everyone!

[Edit for clarification]

If you have power assist, for check valve is working. You don't need to do anything special as long as you haven't done a bunch of panic stops already.

You are describing what I experienced before I upsized my MC. A quick fix is a double tap on the pedal. You can upsize the MC for around 120 bucks.

Toyota Booster to GM Master Cylinder Parts

That won't be perfect, but it'll be a damn sight better than now. Let's you keep your new booster. Here's a few pages worth of reading that may or may not help.

http://home.4x4wire.com/erik/4runner/brakes/

 

[DrewZ28]

So rotors are NOT supposed to be hot. Excessive heat causes warped rotors. Drilled/slotted rotors will not cause the issue at hand. If brakes are not getting warmed up properly then it is an issue with the pads. Using a fully ceramic or "high performance" pad is not always the best. Those types of pads do require to be warmed up to stop properly. Best bet is to run an OE pad despite what type of rotors you have. I've ran drilled and slotted rotors on multiple vehicles, including a 700+ hp Camaro and my Impala which is a daily driver with ZERO issues.

 

[thegipper]

To me it sounds like a bad brake booster check valve. The same ish thing happened to me and it ended up being the check valve. It's a cheap part so you might as well eliminate it from the equation.