bunch of brake questions

[gwoods]

Some jerk (me) has been racing my car too much. The rear pads are getting close to the point where I should start planning their replacment.

The front pads still have a ton of life left in them?? The rear pads got very hot at the last track days, hot enought to melt the high temp red paint off them. I think this is why they are wearing so fast.

Here come the questions...

1# Should I turn the rotors?

I'm leaning towards NO, I'll do the same brand pads and most likely the same part # so the bedding in should be quick (EBC's web site says 1000 miles!)

Also the rotors are drilled and I'm worried about them cracking if they are turned as of now I have ZERO cracks in the rotors that can be seen with the naked eye

#2 Pads

I ran EBC redstuff on the rear, these are street pads but supposed to be better then stock but not rated for racing..... as mentioned they did get very hot at the last track event.... hot enought to melt the zinc plating off the rotors and burn the high temp paint off the pads.

I am eyeing the ebc yellow stuff pads because they are designed for track use...

The price difference is $10...new rotors are $250 shipped if I decided I wanted them.

What do you guys think?

[zozoka1212]

These are your second sets. Holly sh_t. I thought I was bad.



If your rotor is not smooth your brake won't function 100%. Usually it does not need to machine off too much. I would resurface it lightly.

I also would buy the yellow pads. As you said they are designed for track use. Should do better then the red.

zozo

[gwoods]

Thanks for the advise zozo...

I have always gone through brakes and tires quickly?? I have to stop letting my wife drive the G LOL

So yellows and turn the rotors...

The brakes are not gone yet but they will be soon.... I prefer to have the parts in my garage waiting for me so I'm going to decide now and order parts next month.

[oldandslow]

Jeff Are You running the same pad compound on front and rear?

[gwoods]

most people would say your supposed too but I am not.

The front are some no name ceramic pads that I bought from the company that made my rotors.

The rears are EBC redstuff ceramic/kelvar blend.

The rear brakes get hotter at the track then the fronts less air flow I'm guessing.

[oldandslow]

I think the fact that Your running different pad compounds has thrown Your front to rear brake bias out of whack.I would get the same pad compound all the way around.I would bet that the ceramic pads up front dont start to work till a much higher temperature,which would overwork Your rear pads.

[gwoods]

I think I would feel a brake bias like front dive or rear pull back under moderate braking although my pad life does agree with your thoughts.

When I did the brakes back in Feb I tried to buy the EBC pads the whole way around but could not find anyone that had them in stock and my stock brakes were TOAST... from the track LOL So out of stock parts are the reason for 2 different pad compounds.

Even though I don't 100% agree with you I think I may try to do yellow stuff pads on all 4 corners to see what happens with stopping distance and pad life.

What do you think about turning the rotors???

[oldandslow]

I would not turn the rotors unless they were warped.If You ever do turn the rotors,make sure that the countersinks are deep enough,so that You dont end up with sharp edges around the holes.Before You move up to a hotter pad,try a matched set of high performance street pads.Race pads dont work till they get very hot,and they are useless till they reach that point.

[gwoods]

cool I'm thinking not turn the rotors...

The yellow stuff pads are supposed to work on the street but have a high enough temp for the track and the price difference is only $10 per set.

I just spent some time looking for EBC yellow or red front pads and came up with nothing!

[oldandslow]

If the Yellows are hi po street pads, then they sound great. EBC gave me free pads to track test when I had my 03 cobra.I dont remember which color they were,but they were one step up from the street pad.Probably the same as the yellows.They worked great for Me.I was able to buy more of them at PepBoys.

[BrandAidDesignG35]

Jeff, I'm installing some cross drilled rotors today or tomorrow, what are you impressions of using them at the track? (pads aside).

Just curious because I have a new set of discs and pads to install, wondering if they are better than stock rotors for stopping distance vs. rotor life?

Thanks man

[Focusedintntions]

Everything i've ever read or heard about brakes and getting them to seat properly....if you're going to with new pads you should have smooth ungroved rotors to maximize them....I would at least get them lightly turned to have a fresh surface. No 2 pads, regardless if they are the same brand/type, seat the same.

[gwoods]

Jeff, I'm installing some cross drilled rotors today or tomorrow, what are you impressions of using them at the track? (pads aside).

Just curious because I have a new set of discs and pads to install, wondering if they are better than stock rotors for stopping distance vs. rotor life?

Thanks man

Much better then stock... especially after repeated hard stops, like at the track.

The factory pads melted to the factory rotors on my first trip to the track. These brakes survived four 30 min sessions at Firebirds short track.

The more I think about it the more I agree with old n slows saying the pads wore out quickly because of the 2 different type pads.

Everything i've ever read or heard about brakes and getting them to seat properly....if you're going to with new pads you should have smooth ungroved rotors to maximize them....I would at least get them lightly turned to have a fresh surface. No 2 pads, regardless if they are the same brand/type, seat the same.

Me too but recently I've heard that turning is not needed if the rotors are not damaged. AND I am worried about cracks if I have these drilled rotors turned.

[Beancooker]

The yerllow stuff pads might not give you good braking when cool. When you get the pads heated up at the track, they'll work great. But for daily driving, I think they'll be a poor match.

Have you tried Hawk HPS pads? I had a really good experience with them.

As far as the rotors, I would think about having them turned, at least lightly. I am sure if you ate up a set of pads and got them that hot, there has to be some ill effects done to the rotors. Next time, buy slotted or slotted dimpled rotors. Cross drilled doesn't give that much of an advantage, and as you know, are prone to cracking.

[Focusedintntions]

Drilled rotors are prone to cracking b/c of heat cycling and weak/cheap steel....not so much turning...

[Sentientbydesign]

Lots of misinfo going around.

First lets address the rear wear problem.

Assuming that VDC is off 100% of the time, the problem with the rear brakes are that they are undersized. Considering that the G is nearly balanced. Even under severe braking, a decent chunk of the mass still sits in the rear.

As for seating/bedding. If you use the same pads again, there shouldn't be a need to turn the rotors (assuming they are smooth/flat). The rotors don't provide friction, they provide a substrate for the the brake material to adhere to. So when properly broken-in, the brake pads actually deposit and then rub against themselves (kinda).

The slotted rotors are probably causing some of the premature brake wear. Some are designed to make a new surface on the pads, basically cleaning/cutting them.

Jeff,

I wouldn't go with the Yellows if they are for track use. Most of the time, that means they don't work at normal operating temps and they are LOUD!!!

HPS with powerslots have been my experience and they've worked great together. If I had the money, I'd go with the powerslot cryos and HPS.

[SVTCOBRA]

I would vote for not resurfacing, unless it's obvious that they need it.

[Tampa G35 Sedan 6MT]

funny you have this problem but i have the same issue!

My rears are gone at 42k miles and i don't know why... they are I think all factory pads.

When i replace i will go with 4 wheel ceremic! But i know you need to have them all the same! My lexus had the same problem! I replaced the front first with ceremic and then i started to get a lot of brake dust in the back, dust that i never had in the rear... about 700 miles later the backs were shot. and i had replaced them like 5k miles before lol

That is your problem. I wouldn't cut the rotors if they are not that bad. the new pad will take a little driving and it will have the same shape as the old pads

DJ

[oldandslow]

Jeff   I looked at the EBC yellow info,and They look perfect for You!They describe them as a "race" pad,but with excellent cold bite.They claim that they dont need to be warmed up to work.They also claim that they work on the street.About those rotors...I wouldnt turn them unless they were warped or had large grooves in em.Even if You have slight grooves in them,bedding in the new pads will match them to the rotors.Buy Yourself an inexpensive dial indicator and magnetic base,and check the rotors for warpage.You dont want any more than .002 runout. http://www.shoprutlandtool.com...82115 You might find one on sale at harbor freight for 20$ or less.

[C-Kwik]

The front pads still have a ton of life left in them?? The rear pads got very hot at the last track days, hot enought to melt the high temp red paint off them. I think this is why they are wearing so fast.

The primary component of pad wear is simply how much use its seeing in relation to the amount of pad material present. Assuming the same pad material, the front brakes on any car is going to see more/heavier use. However, the rear pads on most vehicles are smaller than on the front. If the rear pads are however getting as hot as you say, it may be a sign that you have too much rear brake bias for your use/driving style/available traction.

Here come the questions...

1# Should I turn the rotors?

I'm leaning towards NO, I'll do the same brand pads and most likely the same part # so the bedding in should be quick (EBC's web site says 1000 miles!)

Depends really. Rotor condition is the biggest reason to consider whether or not you need to turn the rotor. If its glazed or heavily grooved, then you may want to turn them. If its still pretty smooth and still has a good transfer layer on them, then you're probably fine assuming you stick with the same pad material. If you decide to try a different pad though, you'll want to turn the rotors so you can bed the pads in correctly.

Also the rotors are drilled and I'm worried about them cracking if they are turned as of now I have ZERO cracks in the rotors that can be seen with the naked eye

A good set of drilled rotors will handle light turning just fine. These are rotors with radiused edges around the holes which eliminates the sharp edges where cracks generally like to form. I've had little problems having turned such a rotor and running them at a track.

#2 Pads

I ran EBC redstuff on the rear, these are street pads but supposed to be better then stock but not rated for racing..... as mentioned they did get very hot at the last track event.... hot enought to melt the zinc plating off the rotors and burn the high temp paint off the pads.

Seeing as how this car is also your daily, you might not consider stepping up to a racier pad unless there is good reason to. If you weren't experiencing fade in the rear then I'd stick to the milder pad to make sure stopping remaind good on the street.

If your rotor is not smooth your brake won't function 100%. Usually it does not need to machine off too much. I would resurface it lightly.

I'd be more concerned with the pad to rotor interface than whether or not it is smooth. If there are light grooves in the rotor, then it reveale slight increases in surface area. However, this is countered by the direction with which the force of the pad on the rotor is applied. So there is not real gain or loss here. But when starting with a new pad, the peaks will need to wear itself and the pad down such that the pad seats evenly across the rotor. Minor grooves will seat in no time. Heavier grooves would require turning.

I think I would feel a brake bias like front dive or rear pull back under moderate braking although my pad life does agree with your thoughts.

You can not feel brake bias in that manner. Your body will only feel the deceleration period. It will not care which end of the car is stopping you. The only ways to detect bias issues are when approaching the limits of braking where you can detect which set of wheels lock up first. At that, you probably won't be able to detect the severity of incorrect bias. And unless you turn off the ABS, you may not be able to easily detect it this way either. If you could theoretically create the same amount of deceleration using your brake pedal, then do the same thing using only your rear parking brake, it would feel the same.

Lots of misinfo going around.

First lets address the rear wear problem.

Assuming that VDC is off 100% of the time, the problem with the rear brakes are that they are undersized. Considering that the G is nearly balanced. Even under severe braking, a decent chunk of the mass still sits in the rear.

A balanced car does not mean a braking system needs to be balanced. In fact, you'ld be hard pressed to find any car that isn't designed to be run primarily backwards to have greater rear brake bias. The key here is weight transfer. As you decelerate any vehicle weight shifts forward. The faster you decelerate, the greater the amount of weight being shifted. For a given amount of traction, there will be an optimal amount of brake bias needed to such that one set of wheels does not lock up before the other. When each tire can be held right at the point of impending lock-up (technically just beyond it), minimum stopping distances will be realized. As grip fromt ires increases, so does the need for more brake bias between the front and rear as the increased grip will allow more weight transfer, effectively putting more of the load on teh front tires as less weight is on the rear.

Here is a more comprehensive article on the topic:

http://www.stoptech.com/tech_i...shtml

The slotted rotors are probably causing some of the premature brake wear. Some are designed to make a new surface on the pads, basically cleaning/cutting them.

Slots and cross-drilling both wipe the pad face. There is slightly increased wear, but given it sounds like he has some kind of pad wiping mechanism on each rotor, I don't think this is what is causing the premature wear.

I'd probably consider what oldandslow mentioned first and consider that a pad with a higher coefficient of friction will be doing more work for a given amount of pressure from the caliper. This is particularly noticable driving around daily where the rear brakes are going to be asked to do a lot more work than elsewhere. From the stoptech article I linked:



Note mountain of rear brake bias between 0.1G to 0.4G. In theory, the ideal brake bias would be such that it varies directly with weight transfer (both lines on the graph would be the same. However, to my knowledge, the odd shape has to do with biasing handling traits of the vehicle towards understeer, particularly during what might be moderately hard braking.

That said, braking is obviously not even from front to rear and is not a linear proportion according to weight transfer or the size of the brakes. Driving style coupled with the actual brake proportioning curve of your car can dictate a lower brake pad life for you while another driver may experience much different results in the same car.

My suggestion is focus on overall performance. Wear is going to occur and trying to tune for even wear will likely result in poor braking performance. Just change pads and rotors as necessary and call it a day.

[oldandslow]

C-Kwik sure knows his stuff!!!   Thanks for the Info..

[gwoods]

Dear All,

THANK YOU for all the advise,

I have a set of ceramic pads that I bought when I purchased the rotors and front pads in Feb.

This weekend I'm going to swap the rear pads without resurfacing the rotors. This will give me a chance to test the theory about the 2 different pad brand/types being the issue.

This will also give me time to try to find a front and rear set of EBC Yellow Stuff pads. I think the yellow stuff will be perfect for me and I don't know what will happen to the ceramic pads on the rear at the track this fall.

[zozoka1212]

I'd be more concerned with the pad to rotor interface than whether or not it is smooth. If there are light grooves in the rotor, then it reveale slight increases in surface area. However, this is countered by the direction with which the force of the pad on the rotor is applied. So there is not real gain or loss here. But when starting with a new pad, the peaks will need to wear itself and the pad down such that the pad seats evenly across the rotor. Minor grooves will seat in no time. Heavier grooves would require turning.

Smoother is better. Smoother is more contact. Light groove will only give you more surface area but not more contact area. It is because the rotor is running out and the pad is not going back and forth to the same place. It has a little play. That's why you see the grooves getting wider also not just deeper. Once there is a little groove on the rotor and the pad has some too and not going to the same place creates a little airpocket in between. The airpocket allows to cool down/warm up more then other surface area and creates more heat stress on the rotors. More heatstress creates more runout more pulsing less efficiency.

I had a friend of mine in Europe with lots of experience on tracks. He used to bring his rotors to my father shop to resurface them on the little CNC lathe. We had to use a wiper finisher insert on the turning tool to achive not more then 30-35 RA finish. Most of the rotors from factory comes with 40-60 RA finish.

After 1 track day we checked the surface finish on the rotors and they were around 45 RA. Few track days later half pads left they were well over 60 RA.

Also we used dial indicator to put his rotors back. The runout was not more than .001". Usually if you slap it on and indicate it you have about .005-.009" runout. The runout makes a huge different in performance of the brake.

Now if you actually take you rotor and resurface it on a bench lathe you may end up having worse finish then the factory. You ave to know what you are doing when you cutting the surface. Speed and feed is verry important as well the type of tool/insert you are using to cut.

I did not mean to start a huge debate. Just wanted to put my experience in.

Zozo

Sorry Jeff I know you closed it for a reason.

[gwoods]

No worries man,

Brakes and tires are some of the most interesting and under rated parts on a car! I could probably talk about both longer then anyone would want to listen.

I'm a hard person to give advise too because I've usually decided what I'm going to do before I ask for the advise... but oldnslow has me really thinking the pad compound diff is the reason the rears are wearing faster then the fronts.

[zozoka1212]

I thought so too. Sometimes ford guys getting it right too.



Also he had a good point with the yellow being a good choice for the daily drive.

zozo

[gwoods]

What I don't understand is why no one sells the front pads???

I can buy red, yellow and green rear pads from any site on the web but the fronts are out of stock or just not listed?

[Sentientbydesign]

What I don't understand is why no one sells the front pads???

I can buy red, yellow and green rear pads from any site on the web but the fronts are out of stock or just not listed?

It's possible that the manufacturers got fed up with Infiniti changing the front brake sizes too many times.

I think the 03/04 coup had the stock size and Brembo size (2). Then the 05-07 have the oversized Infiniti size (1). The G37 probably has a different size (1 or 2) and I'd venture to say that all of the sedans have different sizes too (2 or 3).

That's 6 different front pads for the G series between 02 and 08.

[C-Kwik]

Smoother is better. Smoother is more contact. Light groove will only give you more surface area but not more contact area. It is because the rotor is running out and the pad is not going back and forth to the same place. It has a little play. That's why you see the grooves getting wider also not just deeper. Once there is a little groove on the rotor and the pad has some too and not going to the same place creates a little airpocket in between. The airpocket allows to cool down/warm up more then other surface area and creates more heat stress on the rotors. More heatstress creates more runout more pulsing less efficiency.

This could be good info, but I'm having a bit of difficulty understanding you. What are you referring to as run out? I ask this because what you describe as a result of the rotors experiencing run out doesn't jive.

[zozoka1212]

There could be 2 different kind of runout. Vertical which should not be. If you have vertical runout then the rotor makers screwed it up. Horizontal would be up to the installation and the factory. Factory rotors came with some runout and if you install it and it does not seat flat you have runout. What we did is used a magnet base with indicator. Put the dial pin on the rotor and spin it after the bolts were tight. If you have more then .003" runout then your rotors going to have to wear faster.

zozo

I hope that makes sense.

[C-Kwik]

There could be 2 different kind of runout. Vertical which should not be. If you have vertical runout then the rotor makers screwed it up.

This is radial runout. And I'd expect there will be an ever so slight amount of radial runout, its really only affects rotor balance, which is solved when they balance the rotor anyways.

Horizontal would be up to the installation and the factory. Factory rotors came with some runout and if you install it and it does not seat flat you have runout. What we did is used a magnet base with indicator. Put the dial pin on the rotor and spin it after the bolts were tight. If you have more then .003" runout then your rotors going to have to wear faster.

zozo

I hope that makes sense.

This is more commonly referred to as lateral runout - which is the wobbling effect. But this is an issue that affects a rotor that has a smooth surface as well. How would this differ with a rotor that becomes grooved with wear?