Rotor/Brake Pad Wear Opinions
 

what is TLC? i know it has to do with the cars exterior which i know nothing about...and why do people need to machine their brakes?

Re: Dumb question inside...only read if u arent gonna flame lol
 

tlc= tender lovin care! Anyway, where are you getting this from?

The reason people machine their brakes is so that they can get the rotors to last longer. When machining brakes, you are turning the rotors in a lathe. This lathe has a diamond tip (about 80 bucks to replace) that scrapes your rotors. It basically gives you a fresh surface to drive with. Also, a lathe can fix a warped rotor (when you get a pulsation in the brake pedul under braking). Those are the main reasons to machine the rotors. Now, there is a minimum thickness that a rotor can be. Every shop should have a book with the specs for each make and model to turn each rotor to. If you machine it past that point, then the rotor looses rigidity, and starts flaking apart. Pads are usually always replaced when you turn your rotors. You cannot turn these. Also, it's most likely more cost-effective to just replace the rotors and pads when you pressed-on rotors. That's because you will need to replace the bearing in the middle. The rotor is pressed onto the hub itself, and those bearings don't usually last when they are punched out to remove the rotor from the hub. So, clifnotes: machine rotors = longer life, safer braking. If not pressed on rotors, it's also mroe cost-effective. Anything else?

-A. Swift

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Most cars do not have pressed on rotors. Most slip over the hub. There are some very unique ones out there though that do. DSM's don't have pressed on hubs. Older cars with from disk brakes were one piece where you would have to take off the nut that held the bearings in and slide the rotor off of the spindle.

If your rotor is warped, 9 times out of 10 they can not be machined and stay within spec. It is more time efficient to just replace the rotors. But more cost effective to have them machined. It usually costs around $8-10 per rotor to have them turned. But the prices of most rotors are so cheap now that it's better to just replace them.

The minimum spec is also cast into every rotor. Although, with as much rust that gets into the non-friction areas, you usually can't read it anyways.

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Holy Shit, Erik was right for once.

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I wasn't sure if the dsm's had pressed-on rotors or not. My honda as them, and I needed new rotors, bearings and pads when I did them. Erik was also right about the warped part. Sometimes you can fix a warped rotor, but at it's most offset point, It may be below specs, and not turnable. That's why most shops, IF it's bad enough, will go with new rotors.

-A. Swift

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Yep. I've seen a car or two in my time.... ;)

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It has nothing to do with that, I am pretty sure terina gave you the answer.

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The Learning Channel. Check your local listings!

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On another note, this brings up a point that needs to be made before it happens again. If you respond to a tech thread to be helpful, great. Make sure you are qualified to give an answer based on the type of vehicle in question. Case in point, the pressed bearings being brought up when they are not relevant to these cars can cause confusion to people who don't know. This isn't to slam you swifty, your input is appreciated, just make sure it is completely applicable.

Re: Dumb question inside...only read if u arent gonna flame lol
 

That's what I should have put in parenthesis, as I was unsure if they are pressed on or not.

-A. Swift

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talking about supra TT brakes here, my other brother is in the market of one and they talked about machining brakes in one of the ads, which isnt talked about on here, which i now know why. thank you all.

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"TLC" were one of the biggest-selling female R&B groups of all time, riding a blend of pop, hip-hop, and urban soul to superstardom during the '90s. Tionne "T-Boz" Watkins, rapper Lisa "Left Eye" Lopes, and Rozonda "Chilli" Thomas managed to appeal equally to pop and R&B audiences, blending catchy hooks ...

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lol i know that TLC

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Usually the rotors need to be machined if there is runout on them. This is sometimes easy to detect when driving a car as the brakes will seem to shudder as the rotor is not as thick all the way around. If the rotors are off, measure them with a micrometer (assuming disk brakes) at several different points to see if runout is present (numbers are not equal). As stated above, turning (or machining) the rotors is the most economically sound option as it only costs $10/rotor at checker. There is no need to replace them unless they are under the minimum thickness spec. Checker can measure them and check them if you have no idea what you are doing at all. They would then sell you new rotors of turn them.

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The only reason why most people don't have them turned much anymore is because most people don't have another vehicle to use while the other car is down waiting for the rotors to be machined.

Rotors are getting to be so cheap now that it is easier to just buy new ones. It's mostly a matter of personal opinion as to what you do. It basically depends on what the circumstances are at the time as to which road I take.

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IF you have the time to sit around, you can go to tires plus, or any place like that. They have a lathe that will cut your rotors for ya. Also, you can turn, and measure thickness on drum rotors. My old job had a machine for that too( usually, they are both as one big machine-disks, and drums) the micrometer was a little different, and it measures the inside if the drum. Take the measurement at different points, and you can usually tell if they are good or not.

-A. Swift

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Once again, this is wrong. Runout is not from the brakes being a different thickness. Runout is from a warped rotor. A rotor can be warped and still be the same thickness all the way around. Acutually they usually are. Runout is measured by putting a dial indicator on the brake caliper and putting the measuring end on the rotor, and then spinning the rotor. The difference between the high and low reading is the amount of runout. Then you need to do the same on the other side of the rotor. Add those 2 measurements together. Measure the thickness of the rotor, then subtract the 2 measurements from it. If that is still above the minimum thickness, then you can turn it down. If it is lower than the minimum thickness (more than likely) then you cannot turn it down.

Re: Dumb question inside...only read if u arent gonna flame lol
 

I call it all the same. That is the term they preached in school. You can check a rotor with a micrometer. You do not NEED to spin it. I had the dumb class at HTC when I was in HS two years ago. I learned the basics not that there is too much to brakes...

I do not know why anyone would replace them if they didn't have to but to each their own. It seems like pissing money away to me. A turned rotor is going to be just as good as new. It only takes about an hour if you drop them off at checker. If you have no idea how to check them, checker can do it along with turn them or replace them for you. I have only had to replace rotors in my old neon. Every other car I have done were fine with turning only.

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Sure you can turn the rotor a couple times but everytime you do you take away material and it will warp faster. Getting aftermarket ones that are good quality is the best bet if your buying new. Otherwise turn them until you cant anymore becuase they get to thin and out of spec.

Re: Dumb question inside...only read if u arent gonna flame lol
 

Alright, why do you always have to argue things when you are wrong?? Be a man and say "my bad". I don't care if "you call it all the same". This is about what is right, not what you think. This is a tech thread that can be searched. Wrong answers should not be posted!

There are 2 ways to check a rotor for runout. The only easy way is to spin the rotor with a dial indicator. When it costs $23 for a new rotor, it is easier to buy new ones. Also, a previously warped rotor is not as good as a new one. It will, more that likely, warp again soon on a DSM.

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If you cut them to true up the rotor and it is off enough, it will cause an out of balance condition. Then you get to buy new rotors anyway.

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JET's advice is spot on. EclipseTurbo and Rapor bring up good points as well that you should keep in mind.

Carlos, stop posting in tech threads already...

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I've found in most cases, they warp so quickly after being turned, that is not even worth it.It could be my driving though too, I'm hard on brakes

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Drive a lighter car Eric.

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From what I have seen and read in my opinion there is no such thing as a warped brake rotor. If there is it is very rare and more often than not it is merely mis-diagnosed "run-out". This may be way off but I think that in most cases whether on a racing car or a street car, rotors end up failing due to the friction pad material being unevenly transfered to the surface of the rotor. This uneven deposition results in a thickness variation or "run out" due to hot spotting that occured at elevated temperatures.

Getting them turned is not a good idea because the more material you take away, the less material there is for heat dissipation. You may get away with it here and there but what is your time worth? Who wants to keep pulling rotors off and putting them back on when they are fairly cheap to just by new ones.

I think it should also be stressed that your wheel and rotating assembly be balanced and not be uneven. An uneven wheel or a wheel thats mounting surface is uneven with cause undesireable stress on your braking system. A wheel that is not tightened properly could also cause your brake rotors to wear unevenly.

This is just my opinion. Take from it what you want.

CRAIG

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I don't want o hijack any threads or go off topic but since the original question has been answered I just want to ask a quick question and don't want to start a new thread about it.

Besides the obvious slotting/drilling, is there any difference between rotors or will cheap ones from napa work fine?

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I'd also like to know rotor differences since you can purchase solid, slotted, drilled, dimpled, and a combination of those. I've seen that people have had problems with the slotted rotors cracking but what about drilled or dimpled? Plus the vast number of different brands out there: OEM, Napa, Brembo,AEM, Powerslot, Rotora, etc always makes decision making fun.

Re: Dumb question inside...only read if u arent gonna flame lol
 

I believe its the drilled rotors that crack, not the slotted.Could be wrong though

Re: Dumb question inside...only read if u arent gonna flame lol
 

Yep, you're right. I stand corrected.
http://www.acquiredperformance.com/C...s/Dscn6151.jpg

Re: Dumb question inside...only read if u arent gonna flame lol
 

So you're saying the run out is cause by the pads' friction material accumulating on the rotor itself?

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I think if the drilled holes are chamfered, the cracking should be a non-issue

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I guess I don't understand how chamfering the holes would be of benefit? Granted I'll probably understand it when I take a materials class next fall but anyways. :)

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It was just a guess, in my head it seems to make sense though

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I am not saying that it is the only reason but it is a contributing factor. Here is why:

Regardless of pad composition, if both disc and pad are not properly broken in, material transfer between the two materials can take place in a random fashion resulting is uneven deposits and vibration under braking. Similarly, even if the brakes are properly broken in and when they are very hot or following a single long stop from high speed or if the brakes are kept applied after the vehicle comes to a complete stop it is possible to leave a unique deposit behind that looks like the outline of a pad. This kind of deposit is called pad imprinting and looks like the pad was inked for printing like a stamp and then set on the disc face.

Cast iron is an alloy of iron and silicon in solution interspersed with particles of carbon. At elevated temperatures, inclusions of carbides begin to form in the matrix. In the case of the brake rotor, any uneven deposits standing on top of the disc surface become hotter than the surrounding metal. Every time that the leading edge of one of the deposits rotates into contact with the pad the temperature increases. When this temperature reaches around 1200 or 1300 degrees farenheit the cast iron under the deposit begins to transform into cementite (an iron carbide in which three atoms of iron combine with one atom of carbon). Cementite is very hard, very abrasive and is a poor heat sink. If severe use continues the system will enter a self-defeating spiral the amount and depth of the cementite increases with increasing temperature and so does the brake roughness.

But I would say all of this is a direct reflection of the rotating assmebly being out of balance, combine that with a hard driving style, long stops from high speeds and you will have obvious problems. The choice of brake pads and rotors you chose will also affect how quickly they reach the failing temperature I stated above.

Again this is just my opinion, take from it what you want.

CRAIG

Re: Rotor/Brake Wear Opinions
 

Thread renamed and moved. This has turned into more of a tech thread than anything. Some good points have been brought up, I would like to hear some more opinions on this.

CRAIG

Re: Dumb question inside...only read if u arent gonna flame lol
 

Do you have the source for your middle paragraph?

Re: Rotor/Brake Pad Wear Opinions
 

Can't remember off hand. I found that information while researching brake pads and rotor characteristics.

CRAIG

Re: Rotor/Brake Pad Wear Opinions
 

I have tried to cut a lot of rotors with severe lateral-runout or what I call a warped rotor. Lateral runout is caused by over-tightened or unevenly tightened lug nuts. Extreme heat or rapid temperature variations also cause runout. Rotors with a lack of parallelism is a variation in the thickness when it is measured at several pleases around the circumference and is caused by soft spots and I see it every day . IMOP rotor refinishing is gay. I have wasted so much time checking & cutting rotors only to have to replace them anyway.