KaiB

Amazing, is it not?

Typical guy comes on, says he has heat problems with his front brakes.

Five or six experienced guys come in and say things like "work on cooling" or "adjust your rear bias" or....perhaps even "think about your driving style".

Typical guy says "thanks ya'll" and goes on his merry way. Two months later he brings the old thread back to life with a glowing report about his new cooling and rear bias and resolved problems...

And then there's Kibort....

2BWise

Find a spot on the pad backing plate that is clear of the piston and paint it there. That will give you the closest approximation of the pad temp. Both pads, inner and outer. For the rotor find the surface on the inner radius of the friction surface that won't interefere with where the pad rubs. The temperature that is of most interested is between the pad/rotor interface and you need to make sure both the pad and rotor are staying within their intended temperature range. You may need to ask the manufacture what the peak temp is. Most manufactures will have data of pad material output for various conditions. See if you can get ahold of pad mu vs. temperature.

Veloce Raptor

Mark--may I call you Mark?--let me be Frank here.

You don't want help.

You want a forum where you can pontificate endlessly with YOUR version of reality, while constantly claiming some alleged lap time as a mark of your absolute authority on the topic, while also simultaneously putting down any any all comments from people who know better.

You are not having a "discussion" here. You are having an orchestrated argument that allows you to salve some of your own insecurities.

And the classic example is your comical claim that removing weight from a race car makes it tougher on the brakes.

Others like KaiB above nailed it.

So...attack and deride all you want. It is sad to see. But until you look inwardly, and deal with the demons that compel you to to constantly deride and argue against common sense and facts and real-world experience, with fantasy and a compendium of irrelevant gibberish and a distorted view of reality, your threads will ALWAYS end this way.

Namaste.

mark kibort

Dave, all i can say is projection. Let me be frank as well. I do want help and many have contributed on and off this list discussion to give me ideas on ways to proceed. However, regarding you, I cant remember at anytime where i have want to put someone down for something i thought was said that was incorrect. You are more concerned with self promotion and put downs to make yourself feel somehow, more valuable here, than solving a problem or even discussing a topic.
Now, if we all listened to you... we would be short shifting because the torque curve falls off so fast, and a myriad of other misunderstood and incorrect ideas, based on a pure lack of knowedge.

What i say about lighten a car is totally correct, unless you or anyone here wants to post some truth that contradicts this and is valid. its simple physics, which you dont seem to grasp. if you go lighter, you go faster and more KE is stored in the car that has to be released to get to the same turn in speed. lighter is better if you want to solve the problem and go the same speed though. . The folks that chimed in and tried to argue the point, seemed to be missing key facts. especially, the ones that equated applied HP vs time to KE. KE has only two factors.... speed and mass. if you are going faster down that straight due to lightening the car, you will have MORE , not less KE to deal with. a good problem to have, but it doesnt solve the braking issue. air flow, bias, larger rotors, all are good places to start...... all of which (if you were reading) i have agreed to try. So, again, I AM LOOKING FOR HELP AND GETTNG A LOT HERE. the discussion is about what might more likely work best or which i should start with. so, it IS all about problem solving here and discussing the problem to gain knowledge.

The problem is that have to sift through your dribble of self promotion and insult posts. if you have some thing you want o contribute to solve the problem or produce a fact, WRITE IT. otherwise, GO AWAY! really! what possible reason would you have to even be here is this discussion is all about "me"?

I have discussed here, the problem i have. I have agreed to try all sorts of things that maybe the cause, but what i have disagreed with is the incorrect reasons for the problem, as well as any possibly incorrect ideas based on basic physics.

truth: lightening a car will in fact not lighten the load on the brakes, this is a pure and true fact. intuitively to you, it might, but that just feeds the misconception, just as having a lot of torque vs another car, gives you a faster car our of a corner. (when if both cars have equal power out of the corner, and the weights the same , they will accel the same).

you have a MO. you mock what you dont understand and then you proceed to make your case by a series of put downs to make yourself feel better. thats fine, but please take it somewhere else.

I have found, during this disucssion, that more air flow and possibly more bias to the rear could help my situation. Ive just engaged in discussion with those that have given reasons of why those techniques might or might not work. Its all about understanding the sytem, and know-it-alls like you that race and end up facing the other direction when they do, but are good with Internet pictures, dont have much value to me. (unless you actual post something factual)

so, Dave, if you dont like the discussion, go play somewhere else. its that simple. if you dont want to challenge the information i bring. (and by the way, its just simple high school physics that i bring up here) , then go somewhere else. but if you have some information that is factual, then bring it up and we can discuss it like adults..... you see some interpretation that is incorrect, bring it up. Love to hear it when im wrong, because thats how you learn. (well, thats how most of us learn)

have a great day Dave (Aka VR)

Mk

mark kibort

Im trying to have a conversation witih the guys that are suggesting solutions, which i will try by the way, and then there is you. WTF, are you just bored or sittin at acomputer cafe with VR trying to make yourself feel better?
I've heard bias, pad break in , lighten the car, and cooling. havent heard driving style yet, but would certainly consider that as well.
what i have disagreed with was some of the logic that didnt add up, and putting out there my problem, and narrowing it down to when it happens. (since it not an overall issue with performance, just one particular issue, in one particular circumstance). all systems have a point at which they will fail.... sometimes if the systems are being used beyond their capabilities, you have to move on to upgrade them. my discussion was around validating whether turn 2 braking zone at laguna, at 130mph and 3000lbs was beyond a 12.6" rotors capability. im thnking it is, but will try the cooling ( which im not convinced will work based on other test results) or brake bias, because i dont think im that far off, with the bias and have purposly dialed some out for stability reasons. But, will try it and adjust my driving style to see if it helps. there is a lot of fade to deal with and i was only calculating whether the rears can achieve enough braking force to actually solve the problem. maybe its a combination of all 3. anyway, ive driven cars that can slow the car down in this area of the track , but they have larger rotors. the disussion is around going larger, or trying to add cooling and bias too solve the issue. its a discussion not an argument. the only debates have been on the physics. Some have left out some dominant factors in their preception of the physics.

I think the pad backing plate might not be as hot, as its insulated by the pad itself, but ill put something there. the rotor is easy, as i have a surface on the inner diameter with no pad contact. the question is, what is failure temps? ive heard 1200 to 1400degrees for some race pads. do you think if i put the 800 degree paint on and its confirmed, i have no way of knowing if its 800 degrees or 1400 degrees. leaning toward the special paint that has a rainbow of output temp ranges.
what do you think?
thanks for the input here. this is exactly what i need to look at and have no experience with the temp sensing paint. so, looking at those that have done this before and corrected problems by doing so.


hahaha.... the brake bias seems like it wont work because im over heating the pads so dramatically, for several seconds of the final braking zone. Logically, if i think about it, the rears have to do a lot more work to make an effect on the stopping distance, to reduce the time at which im applying threshold braking to the fronts. Im certainly willing to give it a try, but also concerned with the fact that if i get the rears to stop more, what happens in trail brake-land, when i turn the car, the inside rear lifts and then starts to lock. will i have a loosy goosy car in the are of the turns where Im very stable now?
I think its not a hard modification to change the bias, so ill give it a shot, since many have suggested this and i havent tried it yet.
Thanks,

Mk

mark kibort

I found a rear bias that will double the force to the rears. Ill try it and see how it works. I think ill need a test day to try all these new tricks... imagine that!

KaiB

Lessee Mark.

Cooling - you don't really believe it will help.
Setting up proper brake bias - you don't really believe it will work.

Suspension, balance and setup all play a role here also, as does perhaps your very own braking/coner entry style.

You have so very many basic things to do, why not go out and do them.

mark kibort

Still feel this is true base on my response? if so, can you elaborate?

several reasons.... can you name 2?

two good points i agree. but kind of proves the point that lighter doesnt help , it allows you to go faster with the same problem.

Did you think about the net-force perspective here?
I remember going to thunderhill one really odd day. there was a 40mph tail wind blowing down the main straight. It was a new chassis and thought the speedo was not calibrated the same as a prior chassis. i was going 140mph down the main straight. previosly, 130mph was the absolute max! same power, shorter time, but i had much more KE !!
I could barely slow down to turn in speed. I had to start braking earlier to make it!
as you know, KE is 1/2MV^2. KE doesnt care how you get there, it just is what it is! and sure it takes power to get there, but again, to my earlier point..... i think you are missing the fact that its the Net power or force that is being stored in the car at terminal velocity before the turn.
I bring this up, because of all the solutions, lightening the car, (as great as its net effects are) is not a way to solve the braking over heat issue. it allows you go to faster, which gives you at least the same KE, which has to be dealt with to get to the same turn in speed at the end of the brake zone. VR or anyone else.... if im missing something here, I would love to hear it.

I think where i stand now, its brake bias as Winders has been pushing, and brake cooling, both of which i will be working on over the next month.

thanks

Mk

TXE36

Newton would disagree with you.

Very basic physics: F = ma, where F equals force, m is mass (practically weight here), and a is acceleration. Under braking, a is negative. Thus, for a given acceleration the force required to be exerted from the brakes is F/m. The smaller you make m (lightening the car), the smaller F can be for the same acceleration, thus the brakes are not used as much. If you chose that F is constant, then a given brake will provide more negative acceleration on a lighter car than a heavier car.

Low mass is always better. If you don't believe it, try this thought experiment. What if the car was weightless? Remember a = F/m, and now m is zero. Thus any bit of F will cause infinite acceleration and the load on the brakes would be near zero.

If that's not enough, try another thought experiment, do you really think making the car heavier would make it less hard on the brakes? Recall a = F/m again, but make m infinity, such that the car has infinite mass. Any acceleration would require infinite force or an infinite load on the brakes.

This simple analysis doesn't even get into cornering or tires. Neither of those things change F=ma.

-Mike

mark kibort

Im discussing it. figuring out if it can help. even though ive done some tests that kind of prove that the problem is in a huge, very fast temp rise. there is so much concensous, i will absolutely try it. I dont know if others have had my exact same problem, but there is enough push for the air flow being a possiblity , that why now give it a try and i will.
(my test was running a hot lap, using no brakes and then all out down the main straight, only to find the exact same fade point). I would think that no brakes would make the rotors cooler than an all out , full brakes lap, and then the approach to the turn 2 braking zone. now, whether the cooling can assist during the fast temp rise, and power dissipation last 2 seconds, or during the entire braking approach, is left to be seen.

rear brake bias ? i just dont see the force needed to remove the last 2 seconds , hidden in the rear brakes. again, i will always use the front tires to their limit, so certainly if i got rear brakes to work and then kept my braking slow down the same, sure i believe it will work. but im searching for improvement AND with that, i will double the rear brake bias next time out to see what effect it has and see how it effect handling, if at all.

fortunatelly, as far as set up goes, laguna is so smooth. sure, rear rebound and compression is a factor on initial dive, but once steady state, i dont know how much any changes could help. maybe stiffer springs up front to reduce CG rise could assist. style? based on compeitors, im not going as deep as a few of them, with equal cornering abilities (or even better in some cases). they have the bigger brakes, so i have a little bit of big brake envy in some case. Or, if i can get mine to work better (the point of the discussion), that would solve the problem.

again, there is always a chance that im asking too much of the 12.6" rotor. If i can find someone that is doing it now, that would be great information!
130mph down the main straight, 3000lbs, and lap times in the 1:37ish range. so far, I havent seen this. lots of 120s, as I was before with less hp with no issues, but at 130 to the turn in speed, maybe its just too much. BUT, i willl check out cooling and bias to see how much they help. I do think they will help, but i wonder if its enough vs just going bigger!

flatsics

2BWise

The backing plate won't be as hot, but it will be close. Much closer than anywhere else. When we measure pad temps we actually drill a hole in thru the backing plate and into the lining material and insert a thermocouple. As long as you use the same location each time the data will be comparable for consecutive tests. The temp range will be specific to the pad material you're using. The only way to guarantee the correct operating range would be to call the manufacturer, but for the most part you can be accurate enough if you can measure in 100C increments. You're goal here is just to find out what the threshold is and developing your parts to stay below that range. Run the car up until you just start to experience fade then bring the car in and inspect the paint. That will give you a good estimation of your target, then iterate thru until you can prolong the onset of that point.

As for fade and bias; if you can adjust the bias rearward without any ill effects it will prolong the onset of fade on the front. If you have capacity in the rear and are not using it you'll overwork the fronts sooner. With your temp paint you can mark the rears too and see what the thermal balance is; front vs rear temps on an optimized brake setup with be close to equal. I'd speculate that the rears are way under utilized, but also probably way oversized. Most cars have way too much brake on the rear of the car. Move as much brake to the rear as you can tolerate on entry. It is not a huge contributor due to the lack of normal force, but it will provide some benefit in both shortening brake distances most of which will come early in the brake zone when you first jump on the pedal.

mark kibort

So Mike,

I think you are making the same oversight as others here. I get Newton! (but i also get Watt)
But, you have to remember its more than just F=ma, its power, which is the rate of doing work and work is Force x distance.
I say this, because your example is absolutely right on. I use this in my thought, that larger rotors are the answer. i can have the same stopping force, with 15% less pedal pressure which would reduce heat in the rotor.
but you are overlooking one factor. we are not trying to go the same speed and have the same deceleration to the same end turn in speed. If that was the solution, your right, problem solved. just go lighter weight by 200lbs and be done.
the problem is that with 200lbs lighter, your top speed is faster, so even if you have a lighter mass , you have equal or more Kinetic energy to dissipate. so, lightening the car, creates a higher velocity at the same distance, and now with the KE being higher, you have to dissipate it to slow to the same speed as before. THIS is the problem. you have to apply it to the situation.
And yes, going heavier will be much easier on the brakes. why, because the extra weight is going to give you less KE to slow down over the same distance. I add 200lbs to that race car, to 3200lbs and only achieve 115mph. the KE is less , so the heat dissipated to slow the car down at the max the braking system can achieve will be less.

KE at 115mph, 3200lbs =21,160,000

(as was posted earlier)
Again: rough KE for 3000lbs car at 120mph vs 2800lbs at 125mph:
1/2 x 3000lbs x 120mph = 1500 x 14,400 = KE= 21,600,000
1/2 x 2800lbs x 125mph = 1400 x 15,625 = KE= 21,875,000

I get your point. always better to lose weight. its a racers quest, daily.
lighter is faster.
BUT, in this condition..... a straight line acceleration and braking zone, it not going to help the overheating problem. Even though you are going to be faster in lap time, and before your braking point, the problem not being changed for the better. you will overwork the brakes just the same, if KE is the same.

Here is the problem of looking at only force. force doesn't generate any heat unless there is a distance and a time. (work and power. power is the rate of doing work, and the unit measure of work is the Hp-second or watt-second or energy). HP or Power is the rate of change of kinetic energy. you quote newton, but ill quote the first law of Thermodynamics. So, if you get to a higher speed with the lighter car, you can use the same force for a longer time, or a greater force for a shorter time, but in the end, the heat generated to slow the car down from 125 to 60mph (lighter car) or 120 to 60 base weight or 115 to 60 (heavy) will all be near the same. So, James Watt might disagree with you. KE is more heavily weighted with regards to speed vs weight. It makes sense if you break down why, and that's another discussion. but its the reason why going lighter wont help a braking problem. It would keep it the same or make it slightly worse. It will totally solve it if you dont take advantage of the lighter weight for acceleration , and end up at the same terminal velocity before braking, but i dont think that is your point.

mark kibort

awesome! thanks. good idea of finding the temps that ARE working now. (kind of obvious). i think i had a chart of alll the popular race pads and their coef. of friction plots. Ill see what raybestos has for the ST41.

i know the rears are hardly being used. lots of dust, but not much wear temps in the pits are about 100F lower in the rear both caliper and rotor. dont know how accuate that is, but just cant find the hot pit help. as you might have heard, im usually at the track trying to do all of it alone.

excited to try the brake bias change, measure temps and see what happens and what there is to see.

Mk

KaiB

Here we go again...(KE discussion agreed to, however)

Reducing your car's weight will not allow you to go 5mph faster at the short straight at LS.

It will allow you to enter the corner more quickly.

If you cannot reduce your car's weight, as said repeatedly here, PLEASE do something about your cooling and rear bias.

That's all you need to do.

Really.

Honestly.

(unless your suspension is the ****s, or your calipers need rebuilding, or your fronts are dragging or a whole host of other maintenance issues you could easily resolve)