Completed Front Brake TSB BR004-02 Myself - Some Observations

[MTL_4runner]

I don't want to take anything away from this thread because there is alot of excellent info in here on the Tundra upgrade. I just wanted to add that there are quite a few 3rd gens on YotaTech (classifieds) that are looking for the smaller 199mm SW13E calipers (including myself, same username on YT) so don't be throwing any working calipers out that came off your truck. I know many places will require cores, but there are a few that don't so you can definately finance at least a bit of your upgrade that way and help out some other fellow Toyota owners. Anyway just a heads up on that!

Paul, great job on the writeup for the caliper upgrade!

A few people had also commented on Yotatech on the fact that the newer D976 pads seemed to have a smaller contact surface area than the D812's, but it was mentioned that the original pads had more than enough material on them to create the friction necessary to stop, but the issue was that it was the backing plate that transferred the heat away from the rotor (there are huge temerature gradients created right at the pad/rotor junction) so the larger backing plate was part of the key not pad surface area. Then Toyota followed the rest of the design through making the calipers larger (more mass) on the 13WL's to act as a better heatsink/radiator for the braking system. Just a thought.

[UAGEODOC]

One of the characteristics that has caused the front rotors to overheat is that the rear brakes haven't been contributing enough of the work. This is evidenced by the observation that nobody ever wore out a set of rear brake shoes. The new calipers have a larger bore diameter, which means that it takes more brake fluid transfering into them to move them towards the rotor. With the new calipers, the same amount of foot pedal movement will now expand the rear wheel cylinders further and thus, the rears will contribute more. And putting on those 26-star adjusters in the rear will help keep the rears adjusted better too.

[MEvang]

Not completely true. The rear brake can only work as well as they do. The limiting factor is rear tire traction, and on pickups in the rain there is very little. So the rear brakes can only work harder when weight is applied to the bed, thus increasing rear traction. Hence the load sensing proportioning valve. This limits rear brake wear as does the shoe material used.
The new calipers have the same size bores as the old one. If the bores size was changed then master cylinder would need changed also or the pedal would be much softer.
Hydraulic fluid pressure to the rear would not be effected in any case. Modern master cylinder are have dual pistons one that services the front and one that services the rears completely independent of each other.
The 26 tooth adjuster does not adjust the rear brakes more, in fact it does just the opposite. If you read BR001-1 you will see they reduced the number of teeth on the adjuster from 30 teeth to 26. At this time Toyota engineers felt the brake were adjusting to tightly possibly warping the drums. This was not the case.
Back to the original question on why the pad contact area is less but the caliper is bigger. I think MTL 4ruuner is exactly right. Toyota odiously picked a new pad material, and the idea was to get the heat away quicker. You can do this in two ways. Increase the rotor size which would mean everything including the upright would need to be changed (maybe even the wheel) or just build more mass around the caliper. This is what they did. The caliper is up front and makes a good heat sink. Remember braking is all about taking kinetic energy and converting it to heat. To make it more efficient the heat must move away quickly.
Mike

[lelandstanford]

Checked EBC's website. D976 seems to have more friction area than D812 (industry spect not OEM spec).

http://www.ebcbrakes.com/Assets/2007ukautocat.pdf

[Picasso]

Just replaced my CryoSlots with plain Brembo rotors. Braking is nice and smooth once again. The stopping power is comparable to when I initially installed the TSB calipers with the CryoSlots. All I need to do now is to ensure that my rear brakes stay clean and adjusted properly so that these will last more than 20k miles.

The tolerance between the rotor and the hub seems tighter than the CryoSlots, which I thought were a little loose when I initially installed them. Something unexpected was the Easy Check wear indicator system that Brembo has incorporated into their rotors. This consists of two dimples of different depths drilled into one side of each rotor. Per the pamphlet that came with the rotors, if only one dimple remains visible over time, the disc has worn down over 80% of its wearable thickness. If both dimples are gone, it's time to replace the rotor. I'm thinking that these dimples are going to cause a brake shop to balk if you request to have this kind of rotor turned.

Photos showing the rotors and their dimples are in this album.

Now I have four rotors in boxes cluttering up my garage.


Paul

[MEvang]

Originally Posted by Picasso

The tolerance between the rotor and the hub seems tighter than the CryoSlots, which I thought were a little loose when I initially installed them. Something unexpected was the Easy Check wear indicator system that Brembo has incorporated into their rotors. This consists of two dimples of different depths drilled into one side of each rotor. Per the pamphlet that came with the rotors, if only one dimple remains visible over time, the disc has worn down over 80% of its wearable thickness. If both dimples are gone, it's time to replace the rotor. I'm thinking that these dimples are going to cause a brake shop to balk if you request to have this kind of rotor turned.

It is always a concern of mine that company that sell sloted/driller rotors don't use the best quality rotor to begin with. It's very unlikely that they forge their own rotors. I would bet they buy the rotors from a Chinese source and then simply drill or machine the slots in house. This keep their cost down.
This leave you with an already poor quality product sold at a premium because they drilled in it. Why? Because people buy them. I'm not scolding you just making a point to those who still feel like these are the way to go.
The Brembo rotor are a good choice. The wear indicator will be no problem to machine over. Save you paper on this so if any one question them you can show them what it is about.
Mike

[jsutton]

Picasso:

Did you buy five SPEED BLEEDERS to have a spare?
I also see you specified 7mm and 10mm - are they different sized by front/rear or something??

I haven't seen this discussed or thought of it before.
Jim

[jsutton]

From the Speedbleeders thred:
"Called SpeedBleeders again this AM. They are sending me the correct bleeders. The two rear are 10mm and the front and proportioning valve are 7mm."

Five total needed.

[lenore]

Originally Posted by Picasso

My brake dragging at lower speeds has for the most part disappeared. At highway speeds it is still very evident, but it is at a lower level than it was initially. When I jacked up the car and spun one of the front wheels yesterday, it still felt like it did immediately after the install.

On my last trip of 270 miles, I got 18.8mpg while using the A/C the whole way, so the dragging doesn't seem to have much of an effect in that area. My transmission does shift out of OD much easier and sooner than before though. I do believe that this is a bed in issue which will just take time to resolve.

I DID FIND ONE OTHER POTENTIAL PROBLEM WITH MY BRAKES TODAY.
I tested for residual brake line pressure by opening the bleeder on the left caliper after driving for a while. No squirt of fluid came out, indicating no residual pressure. I then gave the brakes one pump with the bleeder still open to make sure that no air was introduced into the line during this test. The fluid was collected through a clear tube into a white plastic cup and when I looked at it, I noticed a small amount of black particles floating in the fluid. The particles looked like finely ground graphite which settled to the bottom of the cup. I then blead some fluid from the right caliper and found fewer but larger black particles in the fluid. To compare, I did the same at the LSP&BV bleeder. NO PARTICLES there.

When I drained the fluid from my original calipers after removing them, the last ounce of fluid that came out from the left caliper was almost entirely black. It was so much, that it darkened the quart of old fluid that I was draining the caliper into. The other caliper didn't have nearly as much of the dark particles, but it did have some. At the time I attributed this to normal deterioration of the seals in a caliper with 60k miles on it. Now I don't think that was the case. I still have the container of old fluid and some of the black particles are still suspended in the fluid and some have settled to the bottom.

The only black rubber parts in the brake system that I know of are in the master cylinder, brake hoses, and calipers. I don't know what is in the ABS box. Given this, can anyone give a recommendation as to what is causing this or how I should troubleshoot this?

On another note, my brakes still stop really well. No matter how hard I push the brake pedal though, it never gets to a point where it stops feeling a spongey. I'm afraid that if I press it as hard as I can that something is going to pop. Is this normal? Shouldn't there be a point where the pedal gets really firm?

Many thanks,


Paul

I was helping a friend do a brake job on a GMC and the culprit was the brake lines going to the caliper. apparently the rubber expanded inside the hose and was not allowing the caliper to release properly. Changed the hoses and everything works great now. by the way the brakes worked fine but just would not release completely...

[MEvang]

GM has had this problem for years. It is very bad on hoses that go through a steel attaching bracket. I don't know if this is the case on the GMC truck, but Camaros, Firebirds and many GM FWD vehicles are very bad for this. The hose simply collapse under the steel bracket.
Mike