AdventureTaco - turbodb's build and adventures

I said nothing about politics, that's a fact

 

Oh but you did. You hit that nail squarely on its head.

 

At first the brakes will feel "squishy" then you'll get used to it. I plan to swap in a newer master cylinder when I retire the truck from DD use.

Oh and


'd

 

Squishy is a good way to describe it.

Way better with the smaller MC.

 

Tundra Brake Break-in and First Impressions
October 28, 2017.

New brakes nearly installed, I waited anxiously to see how the replacement brake line that Steve @Wheeler's Off Road sent was mailed - was it fast, or would it be slow?

It was great - he sent it 1-day and I had it Saturday morning. Not only that, but he sent an entire brake line kit, so now I've got an extra line and set of crush washers to throw in the trail kit, in case something goes wrong on my or a buddy's truck! Thanks Steve!

Installing the line was pretty straight forward, especially as I'd done the other already. One interesting thing to note - and the reason that new lines are required - is that the stock Tacoma brakes use a line with a little "registering beak" on it (which fits into an indent in the caliper); the 13WL Tundra brakes don't. Additionally, the circumference of the interior of the banjo fitting is ever-so-slightly larger for the Tundra brakes (I hear).

​

At any rate, with the line installed, @mrs.turbodb came out and helped bleeding the system. A straightforward process, I started in the rear passenger, then moved to rear driver, front passenger, and front driver to ensure that the system was properly bled. Of course, the rear was good-to-go from the start since I hadn't messed with anything there, and the fronts had lots of air (needing to fill up the new lines, etc.). I made sure to keep the reservoir topped off as I went.

The process went without a hitch, mostly. One thing I discovered was that the bleeder valves on the 13WL calipers I'd gotten from Napa used a different size wrench than the old Tacoma bleeders (which are 10mm). In fact, they turned out to be 8mm, which extra-sucked, because I didn't have an 8mm flare nut wrench. Unfortunately, I'd already returned my Tacoma caliper cores, so I couldn't just grab the old bleeders and re-use them. I'll need to see about getting some different bleeders at the local Napa. Or Toyota. Or get another wrench.

System bled, it was time for the ultimate test - head out on the freeway (I-5), risking life and limb - to bed the new rotors and pads. At least I'd know quickly if I'd really screwed something up!

The bedding process, I'd learned, is a process by which you deposit a layer of pad material evenly across the braking surface of the rotor. This minimizes squealing, increases braking torque, and maximizes pad and rotor life.

Bedding in Advantages:

1. Gradually heat treats the rotor and eliminates any thermal shock in the rotor.
2. Burn off volatiles and moisture from the resin that is near pad surface. This will eliminate “green fade.”
3. Establishes a layer of transfer film about a few microns thick on the rotor surface. Shearing of the film during friction is an effective source of friction force. Otherwise, when using a freshly ground rotor without the transfer film, the main friction force would come from cutting, plowing, or scoring the asperities on the rotor surface. This leads to inconsistent braking effectiveness.
4. Mate the two surfaces to a near perfect geometrical match, so that the contact area is high, and therefore the friction force is increased.
5. The performance of a fresh rotor/fresh pad system would be inconsistent. This is due to ever-changing structures and properties of the two mating materials. Bed-in of pads and rotor will form a stable transfer film.
6. If bedding in procedure is not applied, a stable transfer film may not be established for a long time. In other words, the rotor surface would have to be constantly regenerating a film that is not quite stable for a long time. This effect would reduce the performance and increase the wear.

Bed-In Procedure:

1. Make a series of five gentle slow-downs from 60 to 45mph. Do it GENTLY to bring the brakes up to operating temperature. This prevents you from thermally shocking the rotors and pads in the next steps.
2. Make a series of eight near-stops from 60 to about 10 mph. Do it HARD by pressing on the brakes firmly, just shy of locking the wheels or engaging ABS. At the end of each slowdown, immediately accelerate back to 60mph. DO NOT COME TO A COMPLETE STOP!
   
   Note 1: With less aggressive street pads and/or stock brake calipers, you may need to do this fewer times. If your pedal gets soft or you feel the brakes going away, then you've done enough. Proceed to the next step.
   
   Note 2: During this process, you must not come to a complete stop because you will transfer (imprint) pad material onto the hot rotors, which can lead to vibration, uneven braking, and could even ruin the rotors.
   
   Note 3: Depending on the pads you are using, the brakes may begin to fade slightly after the 7th or 8th near-stop. This fade will stabilize, but not completely go away until the brakes have fully cooled. A bad smell from the brakes, and even some smoke, is normal.
   .
3. After the 8th near-stop, accelerate back up to speed and drive around for as long as possible without using the brakes. The brakes will need at least 10 minutes to cool down.
   
   Note: Obviously, it's OK to use the brakes to avoid an accident, but try to minimize their use until they have cooled.
   .
4. Repeat steps 1-3 for a second break-in cycle. This may not be entirely necessary in all cases, but is good insurance to ensure a good break-in. Additionally, if you've just installed a big brake kit, the pedal travel may not feel as firm as you expected. After the second cycle, the pedal will become noticeably firmer.

After the break-in cycle, there should be a blue tint and a light gray film on the rotor face. The blue tint tells you the rotor has reached break-in temperature and the gray film is pad material starting to transfer onto the rotor face. This is what you are looking for. The best braking occurs when there is an even layer of pad material deposited across the face of the rotors. This minimizes squealing, increases braking torque, and maximizes pad and rotor life.

How'd it go?

Since I decided that the only place I could get eight, 60-10mph slow-downs, and then 10 minutes of "no brakes" was on the freeway, we headed out on I-5 at 11:00pm, hoping to find light traffic. We did, but only once we got ~45 minutes north of Seattle, near Marysville.

As we put on the hazards and started our series of slowdowns, everything seemed to be going well. The truck was stopping fine (not pulling one way or the other), and no one hit us from behind.

We did have one State Patrol pass us, and then pull over a car just ahead of us - but they didn't seem all that interested in my hazard lights being on, or my erratic driving.

Strange. Or maybe people do this all the time. (No.)

After the second bedding cycle, I pulled over to take a look at the rotors. As I got out of the truck, the smell of brakes, and wisps of smoke greeted me. Guess that's a good sign. A flashlight on the rotors, and they had a blue tinge to them - another good sign! And, there was that film of pad material. Pretty cool, guess it worked.

​

At that point, we headed straight back home. It was 1:00am, and way past our bedtime.

First impressions of normal braking

When I got a chance to take the truck back out again for normal braking, I can only describe the braking as "completely normal," which I view as a good thing. The brakes don't lock as soon as I hit the pedal, but it's easy to lock them with additional pressure. To me that means that I've got more braking power than before (larger rotors, pads), but that it won't affect my day-to-day driving in any way.

The thing I don't notice is any squishiness. That's apparently a common complaint of folks who own 1996-2000 vintage Tacoma's, where we have a larger master cylinder (1'' bore) vs. the 2001-2004, with a 13/16" bore. Monte (@Blackdawg) talks about this in his post here.

My guess is that he's correct in his analysis. Perhaps the bedding process helps a bit, but I don't know how it could make too much difference - after all, the same amount of fluid (and thus pressure) is in the system. Therefore, more likely is that I don't notice anything out of the ordinary because I'm used to my larger master cylinder already.

An interesting test will be for Monte and I to trade trucks. I bet the brakes in Igor are more sensitive, and will feel strange to me. And Monte will wonder if my truck is even stoppable.

And then we'll both be happy to go back to what we're used to!

 

This is probably true. Drove for two months with the T100 MC and it was fine.

Much better though with the smaller one

 

...and I won't feel quite so bad with you driving my truck, once it's not running with 6 inches of ground clearance in Boulder Basin! hahahaha

 

Hey I don't drive other people rigs like I drive mine...haha usually..

 

Do you feel that in an emergency braking situation the braking distance has been significantly reduced?

 

I can tell you that braking from 60-10mph when I was bedding the brakes was FAST and controlled. Much faster than I expected, but it's obviously not something I do every day. I wished I'd tried it with the Tacoma brakes first to compare.

 

I'd be interested in how he could measure that, braking distance is a function of weight and tire contact. I think no matter what he'd be drastically different from everyone else, we all have too many variables. Looks like they bedded in really great though, and I'm sure you can lock em up, unfortunately locking increases stopping distance.

 

Was that process with the duratracs (31s) on or the KM2s (33s)?

 

I guess I am thinking of when that deer/elk/or the fucking idiot texting forces a hard braking situation. My truck is becoming severely lacking in that situation.

Purely subjective. i wasn't asking Dan to speak globally, for everyone, only about what he knows of his truck and compare that.

 

I gotcha, around PHX area I find I have to emergency brake a lot more often haha, lots of sunbaked octogenarians that think the blinker is an automatic license to change lanes. Cruiser emergency brakes like you wouldn't believe and can swerve great without lots of body roll. The Taco.... well that has armor instead, it can swerve great but the brakes tend to lock in the rear so it can get tail happy fast haha. My point about comparing brakes is it really isn't applicable for anyone but that person, especially with all the unsafe shit we pile on top of our trucks haha. Seriously looks like those brakes broke in perfect though, great job @turbodb, only ever bothered bedding in my old Maxima never even thought to do it with my Taco.

 

I was thinking about this too as I typed that last reply. Even with my own truck, the situation when I was bedding is different than when I'm loaded for a trip. Bedding I had the CVT, hi-lift, shower (still full from The De-Tour!, need to empty that thing), recovery kit, and two people in the cab. So, probably a couple hundred pounds less in the bed than on a trip, but similar in-cab weight. Still, did quite well.

Process was with the KM2's. The Duratracs are off forever, since they're on 15" rims, and won't fit the calipers! Let me tell you something about those - they are not good for my gas mileage. Shocking, I know!

 

Subd!

 

So a significant increase in unsprung weight will also change the braking performance. Really is like comparing apples to oranges.

 

Totally - that's why I wish I'd done the test with the Tacoma brakes and 31" wheel setup - because ultimately the idea is to improve braking performance of the vehicle, whatever the setup. Regardless, I am quite happy with the result - as I mentioned, braking with the new setup was surprisingly fast!

 

Good to hear. This will be my primary reason for doing the brake upgrade.

 

Good write up. What kind of problems have you heard about with the Callahan’s? I’ve been eyeballing a set but if there’s issues I'll look at other options.