200 Series - Replacing Front Brake Pads (1 Viewer)

[toyotaspeed90]

Personally I’m not very worried about continuous braking because on a street driven vehicle I should be managing that with vehicle speed and gear selection. These are 6500-7000# refrigerators when loaded, not track cars. The vast majority of us are better served by having more brake mass to act as a heat sink from a sudden stop to zero where the rotor was relatively cool then gets hot and doesn’t have much subsequent airflow to convect that heat away.
The second part of my post being correct underlines this point. Quite a few people post here about warped rotors, and I’ve had to post that white paper over a half dozen times. My belief is those owners uneven pad deposits are caused by stopping from freeway speeds to zero and sitting with their foot on the brake in gear. Hot rotors, pad clamped in one position = lots of pad material in that spot. Now if we hypothetically tripled the rotor mass, outside of the unsprung weight issue adding momentum we’d have much cooler rotors when we finally came to a stop, and less pad transfer. Yes I know we wouldn’t want to actually triple our rotors but this was an example to make a point.

So yes, for a vehicle with our weight and typical use case, I believe factory rotor thickness helps braking performance and durability. Someone’s 911 turbo is a different story entirely.

Sure, heat up a 2" thick piece of metal by laying a weld bead on it and grab it 5 min later. Do the same to a 1/4" thick piece of metal with the same surface area. One will dissipate the heat because the other (thicker) will have a harder time to shed that heat.

My point is that you stating a thicker rotor is better because it will shed heat better is backwards. The surface area doesn't change, but the mass does.

 

[coleAK]

Hi I appreciate all of your input. I think I am going to start with new OEM rotors just so I know where I am starting from. Do you have a suggestion regarding the pads? It looks like you were concurring with Dan Lee suggestion.

If you don’t tow OEM Toyota are good. I tow a ~7k camper 5-10k miles a year and replaced with OEM rotors and stop tech pads for some extra “bite”.

 

[Sandroad]

A dealer here in MI will give me a discount on parts (because I asked!) and I can get front rotors for a '13 LC for $63.32 plus tax each.

 

[TeCKis300]

Guess you've never driven the car hard enough where stock brakes at a track catch fire.... yup, been there. They're for increased ventilation during continual hard braking (example- driving into a preferred braking area and then using the brakes at their full capability... over and over) to reduce fade.

Sure, heat up a 2" thick piece of metal by laying a weld bead on it and grab it 5 min later. Do the same to a 1/4" thick piece of metal with the same surface area. One will dissipate the heat because the other (thicker) will have a harder time to shed that heat.

My point is that you stating a thicker rotor is better because it will shed heat better is backwards. The surface area doesn't change, but the mass does.

I'm with you and know what it feels like having a 650hp missile coming in hot into a hard turn at over 140mph on the track.

You're not wrong, but might be focused on the wrong things here, especially for street. Even for track, I'm not going to opt for drilled holes and slots as opportunities for stress risers, unless it's a super high end brake system where those elements are designed in rather than decoratively cut into blank rotor. Cooling is another thing that isn't very differentiated between a new stock rotor, versus a worn stock rotor. We're not talking 2-piece rotors here with superior rotor ventilation with brake ducting and aero. Conversations not really germane to the 200-series.

What does make a difference is brake rotor mass. It's the first line of defense. More mass has more ability to sink heat and dampen peak rotor temperatures. Cooling doesn't matter as much if a rotor of less mass is going to reach a higher peak temperature in the first place, exceeding the max operating temperature (MOT) of street pads and causing them to prematurely disintegrate, or temps high enough to boil fluid. Brake capacity in converting kinetic energy and sinking it into the brake system, without overheating, is the first order of concern. This is compromised by lighter mass (or worn) rotors, that then won't cool down appreciably faster.

Gotta brake enough for the first turn to not overrun, before I worry about cooling and braking for the second turn.

 

[bloc]

Sure, heat up a 2" thick piece of metal by laying a weld bead on it and grab it 5 min later. Do the same to a 1/4" thick piece of metal with the same surface area. One will dissipate the heat because the other (thicker) will have a harder time to shed that heat.

My point is that you stating a thicker rotor is better because it will shed heat better is backwards. The surface area doesn't change, but the mass does.

Read my posts again. I never said it would shed heat, I repeatedly used the word "absorb".

Teckis is on point here, but I will add a little of my logic behind this.

Ultimately it comes down to what you do with heat created by friction of pads clamped onto rotor when it's turning. Measurement of thermal energy: BTU.

You're adding the same amount of thermal energy (BTUs) to the rotors from the same vehicle stopping the same way from the same speed, but if those rotors are more massive it takes more BTUs to raise that steel to a given temperature.. and if that temp gets high enough parts start to fail. More mass to absorb heat, more BTUs can be added (more braking done), before those parts get too hot.

So yeah.. my point is for a street driven SUV - even in the mountains - continuous braking and brake cooling is a small consideration. A much bigger one is can we stop hard to zero from freeway speeds to avoid an accident? The cooling can come later. In that scenario I need my brakes to not get so hot that things break.. and full-thickness rotors is a convenient and affordable way to do that job better, even if it's incremental.