UNR.Grad

Not to be rude, but no one has done any testing and come up with any concrete evidence that supports your side either.

Let's see how long we can haha

ebelen1

I think this thread is dead. If any mods are reading this, let's stop the insanity. No one has proof either way but those that have done the mod feel it's definitly worth the dollars put into it. Not one (that I've read) person that's done this has said "Oh I wish I didn't do this mod and spend the extra $200," especially when most that have done this already had warped OEM rotors...

bamachem

yup. find ONE person who's done this mod to say it was a waste of money or their time and i'll back off my claims. just one...

Robinhood150

Ok guys, there is some good tech in here with some personal bashing from both sides. Let's cool it with the little jabs at each other.

All personal attacks stop here. That includes sarcastic "grey area" jabs at each other.

sswearin1

amen

I've bought all the parts for this mod and still think it's money well spent becasue it's routine maintenance that with simple math (to put it simply, braking is the conversion of kinetic energy (motion) into thermal energy (heat) through friction; as well, ah, well screw it. this flamer dude has wax in his ears anyway)....

sswearin1

sorry, got that last post in right before you did robinhood.

SH0ck-D

based on purpose and use of the vehicle, everything can be justified and to everyone their own style and reasons for upgrading.

some people might want to upgrade to bigger and different styled rotors for their own reason, maybe because they look cool or it's just an extra sense of security in having better quality equipment. Whatever the reason if it works, it works.

Being able to stop using 8-12 feet shorter of what you were originally makes a huge difference, given everyday driving situations it's overkill, but given the random chance of an accident it might save someone else's life if inot your own. Performance wise, if you can take less distance to stop, that means you can spend more time going faster (IE, through the slalom, or autocrossing, granted noone in their right mind should do so in a 4Runner).

Now, in the 6 months I have owned my 4Runner, I haven't had the opportunity to really think about upgrading my brakes as I am mainly a long distance commuter to and from school (sacramento -> san luis obispo approx 300 miles), but given the opportunity, if an upgrade to a better name branded pair of rotors is only going to cost me an extra 20 dollars, It's worth it. 20 or so dollars spread over the lifetime of my car will probably accumulate to less than 1 cent a day.

thats how i will justify my spending.

Localmotion

if you are stopping 60-0 (skidding/locked up brakes), they both will take just as long to stop. but since we arent coming to a skidding stop, the bigger brakes would translate to less pedal focre needed to stop the car.

if you guys want to discuss this more, please do so off site.

youngbuck

So what are the PF pads, and why are they suppose to be better than the OEM pads? I'm thinking of going brembo flat rotors with OEM pads.

Localmotion

the Performance Friction pads are made with different material. I went with brembo flats and OEM pads and they are doing great...so great infact that I ordered a set of F/R brembos for my sisters accord, and plan on using OEM pads again.

surf4runner

DO IT!
no problems here

youngbuck

Alright, brembo flats with OEM pads it is. Plus, I'll probably save a few bucks over the PFs.

JC_ez

In my opinion, the Tundra upgrade will be a more 'robust' system in terms of durability, but theoretically it shouldn't offer anymore stopping power over the stock system. Since the diameter of the rotor is the same and the total applied force is the same (because the same master cylinder is used), there cannot be anymore mechanical advantage of the Tundra setup over the 4Runner stock setup. Here is some simplified math for those that need to see it. I'm not trying to flame anyone and I respect everyone's opinions..I'm just posting this because some people have been requesting some mathematically evidence for certain claims here. Enjoy

Torque is needed to turn a wheel. Acceleration and decceleration are the same thing. In fact, in physics we deal with accelerations that have a negative sign to indicate 'decceleration' and whether an acceleration is 9.81m/s^2 (acceleration due to the earth's gravational field, or -9.81m/s^2 is just due to the choice of directional reference.

Torque is mathematically defined as r x F (r cross F) where r and F are both vectors and x indicates the cross product of them. In simple terms, torque is only produced under 2 conditions: 1) Force is applied to a lever or radial arm a distance from the point where torque is desired and 2) Only the force component perpendicular to the aforementioned radial arm can produce torque.

For brakes, the radial arm is the radius of the rotor, and the applied force is due to the force of friction between the pad and rotor. Since the total exerted force of the hydaulic system has stayed the same and since the radius of the rotor has stayed the same, there cannot be anymore braking torque or "braking force" produced.

So now you say, "Well the Tundra system has bigger calipers so what you said above about having the same total exerted force is incorrect". Let me explain. You cannot make something out of nothing. There is always a tradeoff. Take for example using 4Lo to multiply the torque produced by the engine. Although you now have more torque, your top speed is compromised as a result. There is balance in everything...nothing is free. Thus, since the same master cylinder is used, there cannot be, magically, anymore force produced by the 4Runner's braking system.

Pressure is defined as Force per unit area. Since force applied is constant (as mentioned above) and since the Tundra pads have a greater area, the overall pressure is less, but still, overall braking force remains the same.

P = F/A => F = PA => since F is constant, if A increases, P must decrease.

The benefits from the Tundra upgrade will simply be: 1) thicker rotors = more material to dissipate heat better and 2) rotors will last longer because they are 'overbuilt' compared to stock rotors. The only real benefit here will be that a stock 4Runner will stop hard in x meters maybe 10 times before brakes start to fade while the same 4Runner with the Tundra setup will stop hard in the SAME x meters maybe 15 times before the brakes fade.

Therefore, highly modded 4Runner with more mass can benefit from a Trundra upgrade only to prevent brake fade and possibly 'brake warpage', but overall stopping distance cannot be helped by the upgrade.

A side note: my G35 coupe has similarly sized front brakes as a 4Runner and has a mass almost as much as a 4Runner. It has been driven hard, and I have never experienced any brake shudder.

WHORERUNNER

I'm not a math whiz BUT before when my brakes(previous cars) would need a new rotors and pads I would change them w/ the same equipment OEM(NO UPGRADE). You get in your car and say("WHOA now that's better") I'm 110% sure that those who have done this mod say WHOA NOW THAT'S MUCH MUCH MUCH BETTER. Now that's what I'm going for, there is so debate much MORE STOPPING/SAME STOPPING POWER. But I have seen guys when they put on bigger wheels w/ stock rotors/calipers,etc, have poor braking due to the larger wheels, once they upgrade to larger calipers&rotors(stock master cyl) they have balanced out their stopping, PLUS brake pedal feel is MUCH,MUCH, BETTER. All in all when you look at the pricing it JUST MAKES SENSE to upgrade. I will be doing my tundra brake upgrade very soon, and I can't wait to say, " WHOA NOW THAT FEELS MUCH MUCH MUCH BETTER"

bamachem

you only looked at the force applied to the rotors and forgot to include anything about the gain in applied forces thru the increase in the contact patch (where the pads meet the rotor - same scenario as where the tires meet the road). the amount of force applied to the pads and the amount of force that is applied to the road as stopping force is related via the coefficient of friction. when you increase the surface area where the friction is doing the work, you're increasing the amount of force that is applied at the pavement. you still can't stop any quicker in an emergency due to the ABS kicking in and reaching the upper limit of the frictional forces between the tires and the road. however, in everything BUT an emergency stop, you get better pedal feel, quicker reaction time to your pedal effort, and definitely more confidence from the overall upgrade in "feel"

MTL_4runner

JC_ez

I agree that the ABS limits the total stopping distance. Since I don't have the Tundra upgrade done to my 4Runner (yet), I can't say anything about pedal feel or increased confidence and I don't dispute that either since I think it is very possible. I am personally considering the upgrade myself.

Bamachem, if you are interested in my response to your latest post, please feel free to read and comment on what I say next. I like good mathematically talks

1) I don't think there are any gains in applied forces due to contact patch. First I must assume 2 things:

a)The master cylinder governs the total force available to the brake system and I think we can both agree that this is a constant (with or without Tundra upgrade, this stays the same regardless).

b)I am also assuming that the piston sizes are the same for the Tundra calipers (please correct me here if I am wrong since this DOES affect things).

Having a larger contact patch (pad on rotor) just distributes this same force over a greater area: as before, P(A) = F(constant)/A. Thus, the overall effect is less pressure applied by the Tundra pad onto the rotor, but since the Tundra pad has a greater area, the total applied force stays the same with or without the Tundra upgrade.

2) As for the increased force due to friction because of a larger contact patch, this force, contrary to instinct, stays the same. The coefficient of friction and the force due to friction are related by: Ffric = u x Fnormal where u is the kinetic coefficient of friction and F normal is the force applied by the brake system. Assuming that both 4Runner pads and Tundra pads have the same u, the only thing that can increase the Ffric (force of friction) is to increase the normal force. Since in 1) I proved (if my assumptions 'a' and 'b' are true) that the total force of the brake system stays constant, the Force of friction must also stay the same. Therefore, forces due to friction are independant of surface area. This physical result is true not just for brakes, but in all applications.

bamachem

You are correct in some of your math, but look at the way the frictional coefficient is applied in this situation.

you have X lbs of force supplied by the master cylinder. that force is distributed at the surface area of contact between the pads and the rotor. if the surface area of the (2) pads (on one rotor) is Y, then the pressure of them making contact with the rotor is X/Y psi - let's call that P.

if you increase Y, the you decrease P. however, look at how friction works. in this situation, the coefficient of friction is a complicated multiplier of the work that is dependent upon the surface area at the point of contact, the pressure applied, the materials in question, and the temperature at which they operate since their frictional properties change with temperature. you can't put a simple measurement on it without emperical data in this situation. how do you determine a value or formula for each one? simple. you don't. it FEELS better. the brakes FEEL more powerful - and dramatically so.

to me, if it FEELS more powerful, then it probably is. for that, i don't need to deduce it to engineering equations and argue over the pressures, coefficients, heat degradation, etc to know that it simply works better. for that, all i need is to FEEL the difference and know that it's substantial and that it's a dramatic improvement over what it felt like before.



oh, and to shoot down one of your assumptions... if the amount of force due to friction won't change with surface area, assuming that the overall pressure available to the caliper is constant, then why not have a tiny pad instead of a large one?

also, the same applies to tires. if the size of the contact patch has absolutely nothing to do with how fast you can stop, then why not just put some super-high pressure bicycle tires on a 4runner and then you could get astronomical MPG's? this is essentially what you are inferring since the weight of the runner is constant, then the pressure of the contact patch would increase and would exactly compensate for the lack of surface area. however, we know that this isn't right - it's because the frictional forces are dependent on surface area as well as the other aspects.

(hint to noobies - this is how we typically have a discussion on this board - please take note! )

MTL_4runner

JC I appreciate the civility and clarity with which you bring forth your arguements.
I'll respond in red above since that seems to be easiest.

I think you are pretty much correct except for the assumptions I might question. I agree with you though, I would put my money on heat resistance as being the single largest benefit to the upgrade unless someone else can come along and definitively quantify the other aspects. There may be a difference in stopping force (and thus stopping times, distances, etc) or there may not, but it certainly seems likely that there is, since everyone doing the mod says they "feel" a huge difference in braking. Keep in mind we noted above the "feel" part is usually related to how hard I have to push on the pedal to get the machine to stop.

gregbreakseverything

Will the OEM sized brembo rotors warp as easy as the stock rotors? Or is the extra thickness the only thing from keeping the rotors from warping. My rotors are warped right now, I dont have the money for the tundra setup at the moment, but I am also a believer of "do it right the first time". I just dont want warped rotors.

I wonder how many times i can type warped rotors in a post.