Thread: 05 Impala keep warping rotors

Check the balance on your tires, I used to get a bad vibration in my steering wheel when braking I changed out one of my front tires with a different one and the vibration is gone.

Originally Posted by Grimsin

I'll try that tomorrow, 100 mph or kmh?

Mph so 160or whatever kmh

Originally Posted by 1963SS

Partly true and partly false statement there. I never said they cool better. I commented on the performance and warranty claim that I had.The true part is that the holes in cross drilled rotors can cause cracking. I've ran these drilled and slotted rotors for years with no problems. NASCAR, Porsche, Corvette, Ferrari, Lamborghini and every other supercar manufacturer uses at least slotted rotors and most of them have holes in them. Some are drilled and others have the holes cast into them during the casting process to not create a weak area. . Even though resins that hold pad materials together are better than ever outgassing still occurs. Slots give the gasses somewhere to go. The slots also tend to give water an escape route in inclement weather. Brake fade is still an issue but I forgot that this is a Grand Prix forum.

I track my Corvette and use these rotors because I'm a late braking fanatic. I've had my Impala SS on road courses and the braking required has got to be amazing for a 4300 pound pig like that. For high performance use and on high performance cars many people think that there are advantages to drilled slotted rotors. I'm quite certain that NASCAR doesn't care about the brakes "looking pretty". They want to brake as late as possible and have the car slow down when applying the brakes. I raced SCCA and IMSA for about 20 years with Triumph Spitfires, TR-250's and finally a Porsche 911. Slotted rotors worked well and solid rotors would not cool as fast and tended to fade a whole lot more. I can't speak for Grand Prix's because I'm new to mine but for higher performance cars and driving styles I, personally" prefer drilled or at least slotted rotors.

Drilled rotors only "performance gain" is from reduced rotational weight. That is it. Solid rotors will cool FASTER than aAlso Porsche and Lamorghini don't use an off the shelf cast. There are some "benefits" to slotted rotors but everyone I know that autocrosses hardcore uses OEM style blanks.

A very quick google search found a guy on a Civic forum of all places put together a post with Q&A from many brake manufacturers

The link to the whole coversation is http://www.8thcivic.com/forums/suspe...dissolved.html

From Wilwood's website:
QUOTE
Q: Why are some rotors drilled or slotted?
A: Rotors are drilled to reduce rotating weight, an issue near and dear to racers searching for ways to minimize unsprung weight. Drilling diminishes a rotor's durability and cooling capacity.

Slots or grooves in rotor faces are partly a carryover from the days of asbestos pads. Asbestos and other organic pads were prone to "glazing" and the slots tended to help "scrape or de-glaze" them. Drilling and slotting rotors has become popular in street applications for their pure aesthetic value. Wilwood has a large selection of drilled and slotted rotors for a wide range of applications.

As for the porsche rotors, a few notes from a forum I frequent:
QUOTE

1) The holes are cast in giving a dense boundary layer-type crystalline grain structure around the hole at the microscopic level as opposed to drilling which cuts holes in the existing grain pattern leaving open endgrains, etc, just begging for cracks.

2) The holes are only 1/2 the diameter of the holes in most drilled rotors. This reduces the stress concentration factor due to hole interaction which is a function (not linear) of hole diameters and the distance between them.

3) Since the holes are only 1/2 as big they remove only 1/4 as much surface area and mass from the rotor faces as a larger hole. This does a couple of things:

It increases effective pad area compared with larger holes. The larger the pad area the cooler they will run, all else being equal. If the same amount of heat is generated over a larger surface area it will result in a lower temperature for both surfaces.

It increases the mass the rotor has to absorb heat with. If the same amount of heat is put into a rotor with a larger mass, it will result in a lower temperature.

3) The holes are placed along the vanes, actually cutting into them giving the vane a "half moon" cut along its width. You can see that here:

This does a couple of things:

First, it greatly increases the surface area of the vanes which allows the entire rotors to run cooler which helps prevent cracks by itself.

Second, it effectively stops cracking on that side of the hole which makes it very difficult to get "hole to hole" cracks that go all the way through the face rotor (you'll get tiny surface "spider cracks" on any rotor, blank included if you look hard enough).

That's why Porsche rotors are the only "crossdrilled" rotors I would ever consider putting on my car.

BTW, many of the above features are not present in older Porsche brakes. The above is for "Big Reds" and newer.

This is quite different from the standard drilled rotors you get from brembo/kvr/powerslot/"insert random ricer parts brand name here" brake rotors.

Further proof of the uselessness of cross drilled rotors are found here:

Those Poor Rotors

QUOTE
Crossdrilling your rotors might look neat, but what is it really doing for you? Well, unless your car is using brake pads from the 40’s and 50’s, not a whole lot. Rotors were first ‘drilled’ because early brake pad materials gave off gasses when heated to racing temperatures – a process known as ‘gassing out’. These gasses then formed a thin layer between the brake pad face and the rotor, acting as a lubricant and effectively lowering the coefficient of friction. The holes were implemented to give the gasses ‘somewhere to go’. It was an effective solution, but today’s friction materials do not exhibit the same gassing out phenomenon as the early pads.

For this reason, the holes have carried over more as a design feature than a performance feature. Contrary to popular belief they don’t lower temperatures (in fact, by removing weight from the rotor, the temperatures can actually increase a little), they create stress risers allowing the rotor to crack sooner, and make a mess of brake pads – sort of like a cheese grater rubbing against them at every stop. (Want more evidence? Look at NASCAR or F1. You would think that if drilling holes in the rotor was the hot ticket, these teams would be doing it.)

The one glaring exception here is in the rare situation where the rotors are so oversized (look at any performance motorcycle or lighter formula car) that the rotors are drilled like Swiss cheese. While the issues of stress risers and brake pad wear are still present, drilling is used to reduce the mass of the parts in spite of these concerns. Remember – nothing comes for free. If these teams switched to non-drilled rotors, they would see lower operating temperatures and longer brake pad life – at the expense of higher weight. It’s all about trade-offs.


From Stoptech:

QUOTE
Which is better, slotted or drilled rotors?

StopTech provides rotors slotted, drilled or plain. For most performance applications slotted is the preferred choice. Slotting helps wipe away debris from between the pad and rotor as well as increasing the "bite" characteristics of the pad. A drilled rotor provides the same type of benefit, but is more susceptible to cracking under severe usage. Many customers prefer the look of a drilled rotor and for street and occasional light duty track use they will work fine. For more severe applications, we recommend slotted rotors.

That almost sounds like an excuse to use cross drilled rotors, and for your street car which probably is never driven on the track, the drilled rotors are fine, but as Stoptech states, they will crack and are not good for severe applications.

From Baer:

QUOTE
"What are the benefits to Crossdrilling, Slotting, and Zinc-Washing my rotors?

In years past, crossdrilling and/or Slotting the rotor for racing purposes was beneficial by providing a way to expel the gasses created when the bonding agents employed to manufacture the pads...However, with today’s race pad technology, ‘outgassing’ is no longer much of a concern...Slotted surfaces are what Baer recommends for track only use. Slotted only rotors are offered as an option for any of Baer’s offerings."

Then from Grassroots Motorsports:
QUOTE
"Crossdrilling your rotors might look neat, but what is it really doing for you? Well, unless your car is using brake pads from the '40s and 50s, not a whole lot. Rotors were first drilled because early brake pad materials gave off gasses when heated to racing temperatures, a process known as "gassing out." ...It was an effective solution, but today's friction materials do not exhibit the some gassing out phenomenon as the early pads. Contrary to popular belief, they don't lower temperatures. (In fact, by removing weight from the rotor, they can actually cause temperatures to increase a little.) These holes create stress risers that allow the rotor to crack sooner, and make a mess of brake pads--sort of like a cheese grater rubbing against them at every stop. Want more evidence? Look at NASCAR or F1. You would think that if drilling holes in the rotor was the hot ticket, these teams would be doing it...Slotting rotors, on the other hand, might be a consideration if your sanctioning body allows for it. Cutting thin slots across the face of the rotor can actually help to clean the face of the brake pads over time, helping to reduce the glazing often found during high-speed use which can lower the coefficient of friction. While there may still be a small concern over creating stress risers in the face of the rotor, if the slots are shallow and cut properly, the trade-off appears to be worth the risk. (Have you looked at a NASCAR rotor lately?)

And then, let's check out what was said on the aforementioned Altima thread [[[ Long thread at altimas.net that was deleted by that server. it is hosted here ]]]:

QUOTE
Here is how it works. The friction between the pad and rotor is what causes you to stop. This friction converts your forward energy into heat (remember Einstein: Energy is neither created nor destroyed, it is converted). Now that heat is a bad thing. Yes it is bad for the rotors but it is a lot worse for the pads. A warped rotor will still stop the car - it will just feel like ****. Overheated pads however WILL NOT stop the car. It is here where the rotors secondary responsibility comes in. Its job now is to DISSIPATE the heat away from the pads and DISPERSE it through itself. Notice that DISSIPATE and DISPERSE are interchangeable? Once the heat is removed from the pad/surface area it is then removed. Notice where the removal falls on the list of duties? That's right - number 3. Here is the list again. Memorize it because I will be using it a lot in this post:

#1 Maintains a coefficient of friction with the pad to slow the forward inertia of the vehicle

#2 DISSIPATE the heat

#3 REMOVE the heat from the brake system

Let's look more in-depth at each step now shall we? No? Too bad assclown we are doing it anyway.

#1 Maintains a coefficient of friction with the pad to slow the forward inertia of the vehicle:
This one is pretty simple and self-explanatory. The rotor's surface is where the pads contact and generate friction to slow the vehicle down. Since it is this friction that causes the conversion of forward acceleration into deceleration (negative acceleration if you want) you ideally want as much as possible right? The more friction you have the better your stopping will be. This is reason #1 why BIGGER brakes are the best way to improve a vehicle's stopping ability. More surface area on the pad and the rotor = more friction = better stopping. Does that make sense Ace? Good. Let's move on.

#2 DISSIPATE The Heat:
Let's assume for a second that the vehicle in question is running with Hawk Blue pads on it. The brand doesn't really matter but that is what I am using as my example. They have an operating range of 400 degrees to 1100 degrees. Once they exceed that 1100 degree mark they fade from overheating. The pad material gets too soft to work effectively - glazing occurs. This means that a layer of crude glass forms on the surface of the pad. As we all know glass is very smooth and very hard. It doesn't have a very high coefficient of friction. This is bad - especially when I am coming down the back straight at VIR at 125MPH. Lucky for us the rotor has a job to do here as well. The rotor, by way of thermal tranfer DISSIPATES the heat throughout itself. This DISSIPATION lessens the amount of heat at the contact area because it is diluted throughout the whole rotor. The bigger the rotor the better here as well. The more metal it has the more metal the heat can be diluted into. Make sense? This isn't rocket science here d00d.

#3 REMOVE the heat from the brake system:
Now comes your favorite part of the process. This is what you thought DISSIPATION was. It is ok. I will allow you to be wrong. This is the step where the rotor takes the heat it DISSIPATED from the pads and gets rid of it for good. How does it do this? By radiating it to the surface - either the faces or inside the veins. It is here where cool air interacts with the hot metal to cool it off and remove the heat. Once again there is a reoccuring theme of "the bigger the better" here. The bigger the rotor, the more surface area it will have which means more contact with the cooling air surrounding it. Got it? Good.

Now let's look at why cross-drilling is a bad idea.

First - as we have already established, cross-drilling was never done to aid in cooling. Its purpose was to remove the worn away pad material so that the surfaces remained clean. As we all know this doesn't have much of a purpose nowadays.

Next - In terms of cooling: Yes - x-drilling does create more areas for air to go through but remember - this is step 3 on the list of tasks. Let's look at how this affects steps 1 and 2. The drilling of the rotor removes material from the unit. This removal means less surface area for generating surface friction as well as less material to accept the DISSIPATED heat that was generated by the friction. Now because of this I want to optimize step one and 2 since those are the immediate needs. If it takes longer for the rotor to get rid of the heat it is ok. You will have a straight at some point where you can rest the brakes and let your cooling ducts do their job. My PRIMARY concern is making sure that my car slows down at the end of the straight. This means that the rotor needs to have as much surface as possible to generate as much friction as possible and it needs to DISSIPATE the resulting heat AWAY from the pads as quick as possible so they continue to work. In both cases x-drilling does nothing to help the cause.

Now let's talk about strength - and how x-drilled rotors lack it. This one is simple. Explain again just how drilling away material/structure from a CAST product DOES NOT weaken it? Since you are obviously a man of great knowledge and experience surely you have seen what can happen to a x-drilled rotor on track right? Yes it can happen to a non-drilled rotor as well but the odds are in your favor when pimpin' bling-bling drilled y0! Since you are also an expert on thermodynamics why not explain to the group what happens to a cast iron molecule when it is overheated. I will give you a little hint - the covalence bonds weaken. These bonds are what hold the molecules together boys and girls. You do the math - it adds up to fractures.

So why don't race teams use them if they are so much better? Consistency? Hmmmm . . . no. I am gonna go with the real reason her chodeboy. It is because of several factors actually. They are as follows but in no particular order:

- Less usable surface area for generating friction
- Less material to DISSIPATE the heat away from the pads
- Less reliable and they are a safety risk because of fatigue and stress resulting from the reduced material

And what are the benefits? Removal of particulate matter and enhanced heat removal. I gotta tell ya - it is a tough choice but I think I am going to stick with the safe, reliable, effective-for-my-stopping needs solution Tex.
=====================

So basically, buy them if you think they look cool, but not if you think this will be an acceptable performance upgrade.

It's the internet and you can find anything......or a rebuttal to it. Most people in the world agree that the Gods of braking reside at a place called Brembo. They are certainly used on most every super performance car in the world and have been for years. Here's what they have to say:

Reliable on the road, superior on the track.
The discs of the Brembo Sport range are ideal for enthusiasts who use their vehicles for both normal road use and more performance-oriented driving. With their advanced characteristics, these discs combine the advantages in terms of durability of the best street discs with superior performance suitable for moderate track use.

More flexibility and durability, at all temperatures.
For greater versatility and to increase their ability to withstand extreme stress, Brembo Sport brake discs are made from high-carbon cast iron for improved thermal and mechanical resistance. They also feature exclusive pillar venting technology, which improves cooling capacity and increases resistance to cracking caused by thermal shock by over 40%. Cross-drilled and slotted finishes are designed and executed with meticulous precision. These holes or slots in the braking surface help dissipate heat and eliminate brake dust and gases.
Every Brembo product is designed in relation to the specific performance requisites. The discs of the Sport range are specifically designed to minimise thermal distortion and disc warping even in the most severe operating conditions. As a result, they ensure outstanding braking power in both everyday traffic and the most extreme high performance driving, yet are easily accessible to all enthusiasts.

Immediate, consistent braking in all conditions
The unique cross-drilled or slotted finish is another exclusive Brembo feature which improves braking consistency by dissipating the heat generated and gas released as the pads come into contact with the discs, keeping the pad surface both cool and clean. Both cross drilling and slots interrupt the water film forming when driving in the wet for improved brake response. This effect is most evident with cross-drilled discs, due to the different solid/hollow ratio of the surface and the possibility for water to flow through the ventilation holes.

I didn't have to search to make my original post. I've been there, done that, got the refrigerator magnet and the t-shirt. Brembo's site just pretty much summed up what I did say. They've had the same experiences I have.
Now I realize that they're probably wrong and they just make these to look pretty. Anyone can believe what they choose. I was only speaking from my experience. ......and, they do look pretty too.

Well I cant really go 100mph If I pass a cop doing this my licence is gone and my licence is my career..
Im only home 2 days a week and have only 1 vehicle so no time to or extra vehicle to get my rotors turned..
So if I get cheap rotors again and the best pads I shouldn't have this issue again?
and if thats the case what pads should I get?

actually thinking of grabbing the police package rotors and pads, thoughts?

Another thing if no one has mentioned. Might be worthwhile to swap the rubber lines as well. Over time they can break down and act like check valves not releasing as well as they should. If you are stopped in gear on flat road.. will the car roll on it's own?

Originally Posted by Grimsin

Well I cant really go 100mph If I pass a cop doing this my licence is gone and my licence is my career..
Im only home 2 days a week and have only 1 vehicle so no time to or extra vehicle to get my rotors turned..
So if I get cheap rotors again and the best pads I shouldn't have this issue again?
and if thats the case what pads should I get?

NAPA rotors arn't cheep, they've discontinued most of there economy stuff. I've had good luck with napa rotors and there ceramic pads. No complaints other than $

ps, driver mod.

If it was me... I'll pull up right in front of napa and jack that thang up and take the rotors off and in and have them cut. Or just drive the big rig there and drop them off and pick them up later.

Originally Posted by 1963SS

It's the internet and you can find anything......or a rebuttal to it. Most people in the world agree that the Gods of braking reside at a place called Brembo. They are certainly used on most every super performance car in the world and have been for years. Here's what they have to say:


I didn't have to search to make my original post. I've been there, done that, got the refrigerator magnet and the t-shirt. Brembo's site just pretty much summed up what I did say. They've had the same experiences I have.
Now I realize that they're probably wrong and they just make these to look pretty. Anyone can believe what they choose. I was only speaking from my experience. ......and, they do look pretty too.

It looks to me like Brembo is just trying to sell product instead of being honest about the abilities of it. It's pure physics that PROVES that cross-drilling hurts heat dissipation.

I don't think the rotors are actually warped and wouldn't bother getting them turned. Just get napa pads and rotors, police pkg or OEM is up to you. Make sure the mateing surfaces are clean (hub, rotor, and rim). Mabe ask about new bolts for the cradle, I think I read somewhere there torque to yeld, or whatever it's called. I'v personally never had a problem with napa brakes, a lil pricy but last much longer than car quest crap. Should be able to get a few years outta them.

They should have them, I know autozone did. It was police or just HD rotors.

Sent from the Milky Way

i just put a set of power stop pads on all 4 corners. those are nice pads, bite real nice.

found them on R! but took that part # and found them for less on line. dropped to 60 for the front f bodys, 20 for the rears, stock.