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New brakes - turn the rotors?

Chipster27

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For those that do their own brakes or work in a shop, do you turn the rotors every time you change the pads? If not, when do you determine the right time to turn them is? How many times can a rotor be turned?
 

STV_Keith

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For those that do their own brakes or work in a shop, do you turn the rotors every time you change the pads? If not, when do you determine the right time to turn them is? How many times can a rotor be turned?

I don't turn them unless they are warped. If you feel a pulsation in the pedal or a surge under braking, I'd turn them, but turn them as little as required to straighten them out.

There is a minimum thickness cast on the rotor. Whoever is cutting them should never go below that, but always check their work. These days, it's almost as cheap to buy new rotors as it is to turn warped ones.
 

Runs2rch

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No gouging or scraping on them they can go usually 3 sets of pads then just buy new. I hardly ever turn rotors unless there is a wear issue. Run an FF or GG rated pad.
 

Ragged Edge

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Rotors can be turned as many times as you want so long as they remain above the minimum thickness. You should have them turned every time you replace pads or you may not have a flat surface for the pads to grip and will compromise your brakes efficiency. That said I think the costs are about similar these days between having them turned and just buying new ones from a place like Rock Auto.
 

EmpirE231

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For those that do their own brakes or work in a shop, do you turn the rotors every time you change the pads? If not, when do you determine the right time to turn them is? How many times can a rotor be turned?

last time I did the brakes on my truck, I just bought new rotors.... from amazon, the AC delco rotors weren't too much more than paying to have them turned... not to mention the time to drive somewhere, have it done, and go back etc.
 

SBMech

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Anything made from around 2000 up needs new rotors every time. If you do machine them down to the discard they will warp fast as shit. If they don't have at least .30 on them left (estimated) after you cut them, it's a waste of time.

Modern vehicle braking systems are disposable, to make the unsprung wheel weight at each axle as light as possible, to get better MPG, to get more room for CAFE requirements.

If you tow with this vehicle, in my opinion, always go new all the way around. Stuff is pretty cheap relatively, compared to time wasted having to do it again after one panic brake.

IMO Always use the best stuff you can buy, because if it's one thing you don't want to have happen, it's a brake failure. Use Delco, Motorcraft, Meyle, Bosch, Brembo, Ate etc.
 

Carlson-jet

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Rotors can be turned as many times as you want so long as they remain above the minimum thickness. You should have them turned every time you replace pads or you may not have a flat surface for the pads to grip and will compromise your brakes efficiency. That said I think the costs are about similar these days between having them turned and just buying new ones from a place like Rock Auto.

Often, Rock auto has really good upgrades for less than what you can get at the local box store for the bottom end parts.

The OP question is a call that has to be made upon inspection. Here with all the salt and the rotors checking like crazy and rusting I just buy new. I did not do that practice out West. Often they didn't need to be turned if the pads had some beef left in them.

It is also VERY important to check out all the hardware, particularly the slide pins, seals and bushings on the calipers. Both desert heat and salt are not their friends.
 

OutCole'd

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I don't turn them unless they are warped. If you feel a pulsation in the pedal or a surge under braking, I'd turn them, but turn them as little as required to straighten them out.

There is a minimum thickness cast on the rotor. Whoever is cutting them should never go below that, but always check their work. These days, it's almost as cheap to buy new rotors as it is to turn warped ones.

X2:thumbsup
 

Bigbore500r

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Weird fun fact - If you have a 99-up Silverado 1500 / 2500 / 3500, they don't ever need brakes.....
Seriously. I've owned and sold 3 of them now, with over 150k on same pads and rotors. The truck I have now is at 134k...guy I bought it from gave me a box full of new delco pads. Said he bought them cause he figured it had to be time, but his mechanic checked them and said they had at least 70 percent left. My old Tahoe was the same way also. It amazes me, cause we have newer F150s at work and they eat a set of rotors every 30k
 

Chipster27

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Thanks guys. Kind of what I thought on a couple fronts.

New rotors are not that expensive. When I did my BMW I replaced the rotors because I wanted drilled. On the Honda I turned both the front and rears when I replaced the pads for the second time. I didn't turn them because they were warped, I turned them just to give the new pads as smooth/flat a surface as possible to maximize braking effect.

I did find it kind of odd that the Firestone shop that turned the rears a year ago would not turn the fronts. They were not out of spec, they just said the new manager had a policy to not turn rotors. I took them to another shop, they mic'd them and said there was still enough meat to turn them.
 

No Butt No Putt

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I used to turn them every time. But on my Lexus they are $27 a rotor and 15 to turn them so I just replace them every other time.
 

Joker

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Never turn the rotors unless the front has a vibration.
 

VoodooMedMan

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Yeah I just inspect and based on that and driving the car turn or replace if I think it needs it.

Look up prices and go from there. If it's some stupid car that rotors are 100 each then they get turned if possible. If 20-30 bucks then whoever I'm doing brakes for needs to buy new rotors.

No matter what you do I think it's important to bed down the new pads before normal driving.
 

Maestro

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Pad slapping rotors minimizes efficiency and life of the pads and rotors. You have multiple variables that can cause brake fade. Turning rotor eliminates glaze, run-out and parallelism. You cannot turn rotors with hot spots, well you can but it will return quickly and is a waste of time and money.
I have put new rotors on cars and found excessive run-out. Rotate the rotors to try and reduce the run-out. If run-out still exceeds specs turn the rotors. Yes even new rotors. this will provide a longer life of the pads and rotors. Also don't go and buy cheap pads. you get what you pay for. For your best bang for you buck use an on car lathe to cut rotors. This will compensate run-out in the bearings and even increase the trueness of the cut, thus giving you longer brake life and better brake performance. Always wash the rotors in hot soapy water to remove oils and contaminates. especially if you had the rotors turned. To seat new pads light driving and no vegas runs for approximately 500 miles. So the manufactures says. I recommend Arebono pads.. Almost all manufacturer's put these on their vehicles and last 70K+ miles with minimum dust noise and great performance..
 

RitcheyRch

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I turn them once and the next time they get replaced. Brembo blanks can be had for pretty cheap these days.
 

TrollerDave

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Weird fun fact - If you have a 99-up Silverado 1500 / 2500 / 3500, they don't ever need brakes.....
Seriously. I've owned and sold 3 of them now, with over 150k on same pads and rotors. The truck I have now is at 134k...guy I bought it from gave me a box full of new delco pads. Said he bought them cause he figured it had to be time, but his mechanic checked them and said they had at least 70 percent left. My old Tahoe was the same way also. It amazes me, cause we have newer F150s at work and they eat a set of rotors every 30k

My 02 1500 has 136K miles and brakes work/look fine. I keep thinking I'm pushing my luck and need to replace them. Glad to read this.
 

Uncle Dave

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I don't turn them if If don't need to but just hit them with a light random orbital sand to rough up the surface for the new pads to bed in.

Very happy with my Hawk products as well as rotor pros.

UD
 

Flying_Lavey

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I've had this same argument with my uncle and my gf's grandpa a few times. They both just pad slap. There is a vibration in their pedals or pulsing brakes everytime I drive either one of their vehicles. They are so used to it they don't notice the slowly increasing pulsing/vibrations over time cause they drive them constantly. I've always had my rotors turned for less than $20 a pair.

Bottom line..... turn or replace the rotors EVERYTIME! The drop is performance and probable I'll effects on the braking system are not worth the risk of $10 to $20 a corner.
 

LargeOrangeFont

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I don't turn them if If don't need to but just hit them with a light random orbital sand to rough up the surface for the new pads to bed in.

Very happy with my Hawk products as well as rotor pros.

UD

Hawk pads are good aside from the HPS line. Worst street pads conceived by man.

If you are changing brake pad compounds, knock your rotors down quickly with 150 grit to rough them slightly. Spend about a minute per side. If you are using the same compound, throw them on and go. Only turn the rotors if they are grooved or you can feel imperfections with your fingernail.

I only use Brembo or Centric Premium or High Carbon blank rotors for replacements.
 

djunkie

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Weird fun fact - If you have a 99-up Silverado 1500 / 2500 / 3500, they don't ever need brakes.....
Seriously. I've owned and sold 3 of them now, with over 150k on same pads and rotors. The truck I have now is at 134k...guy I bought it from gave me a box full of new delco pads. Said he bought them cause he figured it had to be time, but his mechanic checked them and said they had at least 70 percent left. My old Tahoe was the same way also. It amazes me, cause we have newer F150s at work and they eat a set of rotors every 30k

Lol. This is so true. I'm at about 110k miles on my 2005 hd and the brakes look new.
 

LargeOrangeFont

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My friends 99 Silverado has over 300k and is on the original rear brakes, the front pads were changed once, rotors were untouched.

His 06 2500HD had 140k and the brakes still look fine.

It's amazing considering how quickly GM trucks from the 90s went through front brakes.
 

HOOTER SLED-

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My friends 99 Silverado has over 300k and is on the original rear brakes, the front pads were changed once, rotors were untouched.

His 06 2500HD had 140k and the brakes still look fine.

It's amazing considering how quickly GM trucks from the 90s went through front brakes.

I may be wrong......but 99 and up switched to bigger brakes and 4 wheel disc right? The older were smaller and rear drum right? My 99 Burb don't last that long. But that thing is a tank too. If the trucks didn't go 4 wheel disc, at least they are bigger......Better STOPPING power.
 

VoodooMedMan

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I may be wrong......but 99 and up switched to bigger brakes and 4 wheel disc right? The older were smaller and rear drum right? My 99 Burb don't last that long. But that thing is a tank too. If the trucks didn't go 4 wheel disc, at least they are bigger......Better STOPPING power.

They switched back to rear drum for some years but my 02 Silverado and 03 Suburban are 4 wheel disc. Over 100 thousand on each and original brakes. Silverado is on 35's too.
 

LargeOrangeFont

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I may be wrong......but 99 and up switched to bigger brakes and 4 wheel disc right? The older were smaller and rear drum right? My 99 Burb don't last that long. But that thing is a tank too. If the trucks didn't go 4 wheel disc, at least they are bigger......Better STOPPING power.

Correct. They went back and forth from drum back to disk and back to drum in the 2000's
 

lbhsbz

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Anything made from around 2000 up needs new rotors every time. If you do machine them down to the discard they will warp fast as shit. If they don't have at least .30 on them left (estimated) after you cut them, it's a waste of time.

Modern vehicle braking systems are disposable, to make the unsprung wheel weight at each axle as light as possible, to get better MPG, to get more room for CAFE requirements.

If you tow with this vehicle, in my opinion, always go new all the way around. Stuff is pretty cheap relatively, compared to time wasted having to do it again after one panic brake.

IMO Always use the best stuff you can buy, because if it's one thing you don't want to have happen, it's a brake failure. Use Delco, Motorcraft, Meyle, Bosch, Brembo, Ate etc.

You have absolutely no clue what you're talking about.
 

lbhsbz

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Pad slapping rotors minimizes efficiency and life of the pads and rotors. You have multiple variables that can cause brake fade. Turning rotor eliminates glaze, run-out and parallelism. You cannot turn rotors with hot spots, well you can but it will return quickly and is a waste of time and money.
I have put new rotors on cars and found excessive run-out. Rotate the rotors to try and reduce the run-out. If run-out still exceeds specs turn the rotors. Yes even new rotors. this will provide a longer life of the pads and rotors. Also don't go and buy cheap pads. you get what you pay for. For your best bang for you buck use an on car lathe to cut rotors. This will compensate run-out in the bearings and even increase the trueness of the cut, thus giving you longer brake life and better brake performance. Always wash the rotors in hot soapy water to remove oils and contaminates. especially if you had the rotors turned. To seat new pads light driving and no vegas runs for approximately 500 miles. So the manufactures says. I recommend Arebono pads.. Almost all manufacturer's put these on their vehicles and last 70K+ miles with minimum dust noise and great performance..

Not really....to all of it.
 

2FORCEFULL

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No gouging or scraping on them they can go usually 3 sets of pads then just buy new. I hardly ever turn rotors unless there is a wear issue. Run an FF or GG rated pad.

X2... rotors are almost as cheep as turning the old one
 

OutCole'd

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Like I'm going to take any braking advice from you :roll eyes :D:D

You're not taking the advise from me, you are taking the advise from Keith, i'm just agreeing with him.

What car are you working on?
 

2FORCEFULL

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Anything made from around 2000 up needs new rotors every time. If you do machine them down to the discard they will warp fast as shit. If they don't have at least .30 on them left (estimated) after you cut them, it's a waste of time.

Modern vehicle braking systems are disposable, to make the unsprung wheel weight at each axle as light as possible, to get better MPG, to get more room for CAFE requirements.

If you tow with this vehicle, in my opinion, always go new all the way around. Stuff is pretty cheap relatively, compared to time wasted having to do it again after one panic brake.

IMO Always use the best stuff you can buy, because if it's one thing you don't want to have happen, it's a brake failure. Use Delco, Motorcraft, Meyle, Bosch, Brembo, Ate etc.

my wife had a Mercedes that smoked the brakes in 5k..including rotors.... they said it was normal:eek
 

napanutt

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Often, Rock auto has really good upgrades for less than what you can get at the local box store for the bottom end parts.

This is where I get the brake parts for my 06 BMW. Rotors replaced every time I do pads. Less than 150 bucks for ceramic pads and rotors, per axle delivered.
 

napanutt

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Weird fun fact - If you have a 99-up Silverado 1500 / 2500 / 3500, they don't ever need brakes.....

No shit. My 02 2500 Silverado has 110,000 on it now and I've never done the brakes on it.
 

pronstar

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That pulsation you may feel is often than not uneven/inconsistent transfer layer of pad material on the disc.

This can be prevented by not parking pads on a hot rotor...like when coming to a hard stop when towing, leave a bit of room and allow your truck to slowly creep forward, so the pads aren't "parked" on the same part of the rotor for an extended period of time.
 

Carlson-jet

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This is where I get the brake parts for my 06 BMW. Rotors replaced every time I do pads. Less than 150 bucks for ceramic pads and rotors, per axle delivered.

Even with brackets and new extended lines to the calipers I upgraded my Charger to Brembo for the same cost as the local parts store wanted for crap 1-2 year junk. I feel no pity for national chain-stores. We have no mom & pops around here for auto related stuff.
We do have a major UPS hub who also need the business locally.
 

C-2

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I read there is no such thing as a "warped" rotor, as in "bent", and that's it's brake compound from panic stops. They feel warped due to the pad contacting the uneven surface, and it's not physically possible for the metal to warp like that. Just what I read....it's hard to wrap my head around the term warped.

I know too on Euro cars like MBZ that you never turn the rotors, new replacement always. And, just because they say Brembo does not mean they are good rotors - there are Brembo's from Italy, and junk Brembo's from Mexico.

I need to do the brakes on my 03 Excursion for the second time at 130K, so input on quiet pads and decent rotors is appreciated. Save me some research athe Ford truck forums :D
 

lbhsbz

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The only reason to machine rotors is to correct an uneven surface condition caused by careless installation or service resulting in an excessive runout condition or improper pad choice for the driving conditions. If the rotor is grooved bad enough to affect anything, it'll be below minimum thickness after it's cleaned up on the lathe. Most new rotors allow 2mm between new thickness and minimum thickness....that's .080", quite a bit of meat. A few are near the 1.5mm mark, but most give 2mm. When I talk about uneven surface condition, I'm not talking about circumferential grooving or different color bands around the rotor...I'm talking about something in one spot that doesn't exist in other spot...like a pepperoni pizza with one slice of that horrible Hawaiian shit with pineapples on it thrown in. When that spot passes through the pads, it will create a different friction level than the rest of the rotor and it will cause a judder.

Most domestics, with the exception of Ford, who has a larger presence in Europe than the other Big 2, and most Asian manufactures use brake systems that utilize adherent friction. In adherent friction, the brake pads don't work very well against a bare cast iron rotor...you need to bed them in to some extent...most decent pads will bed themselves in during the first 20 or 30 miles of normal driving, or you can bed them in with a purposeful road test in about 10 minutes. Adherent friction works by establishing a friction transfer layer on the brake rotor...this is what we're hopefully accomplishing during the "bed in" process. As the pads and rotors come up to temperature for the first time, the pad will deposit a layer of its material down onto the rotor surface...this is one of the reasons that grey cast iron is used for brake rotors...it's porous, and that gives it some "tooth" to hold onto that friction transfer layer. Once the friction transfer layer has been established properly, every time the pads are pressed against the brake rotor...or the layer of pad material on the brake rotor, we have the constant breaking and recreation of crystalline bonds across the interface....material moving back and forth between the rotor and the pad repeatedly on a molecular level. A very good example of this is the Akebono pads used on 2000 and later GM trucks. For the most common driving conditions, Akebono engineered these pads perfectly....they almost don't wear out. I know people with over 200K miles on their original pads. I have 90K on mine. I also know people that don't drive under the conditions in which these pads thrive, and they last 30-40K miles. We have 3 brake dynos and it's not uncommon to measure rotors at the end of a test cycle and see them thicker than they started out...due to the addition of the friction transfer layer. Adherent pads are not always adherent....under certain conditions or temperatures, they may act more abrasive...so look at the transfer layer as a snowball that wears. It's always breaking down and being rebuilt.

Judder conditions (what most people refer to as "warped" rotors) will surface as a steering wheel vibration when a minor uneven surface condition on the rotor develops and causes a torque variation. These surface issues can be caused by corrosion, improper pad selection, careless installation or even rotating the tires. Most vehicles produced in the last 15 years have a max rotor runout spec of less than .0025", some are down to 0.0016". That isn't much, but still, few use a dial indicator when installing new rotor, or after having machined a rotor and putting it back on the car. We measure bearing clearances when we build engines, but ignore specs when we do a brake job. It takes less than 2 minutes per side, if you slack.

Say we have a rotor with .015" of runout...fresh off the lathe..."Damn Gomer, these rotors were warped all to shit, it took 3 passes to get a clean cut" ...but "now it's all fixed up let's put it on the car"... and not measure shit because the 30 year old lathe that was used to machine the rotor with 30 year old adapters that have dropped on the floor, workbench, etc...used on the shop press or whatever makes two shiny clean surfaces that mean to the untrained idiot, "everything is fine Gomer, let's slap 'er back together"....and then when it comes back in 5K miles with a judder, "Them cheap modern Chinese tin foil rotors are too damn thin and warp up if ya take any meat off of 'em"

...when in actuality, this is what has happened: A judder condtion was present due to an uneven friction transfer situation, and someone took a perfectly good rotor, threw it on a lathe in an adapter fixture that didn't hold the rotor anywhere near straight, machine a bunch of runout into it while making 2 nice clean surfaces, patted himself on the back whilst reinstalling his newly fucked up parts, and sent the car down the road after steeling the customer's money. Why is the braking nice and smooth?...because both surfaces are parallel. Unless the runout is stupid excessive, the caliper will float back and forth and follow the brake rotor. Most vehicles use a floating caliper these days...fixed mount opposed piston calipers are less tolerant of runout, limited by speed fluid can flow through the crossover passage, before hydraulic feedback to the master cylinder, and a pedal pulsation occurs. I did it thousands of times when I was a dealer tech...I was wrong back then...I've since learned better. The car will come back with a judder, because the high spots on either side of the rotor over that period of time will pick up a different level of transfer lay from the pads than the rest of the rotor will, since those spots are contacting the pads more often and at slightly higher pressures than the rest of the rotor surface. If using an adherent pad, it can result in a buildup of friction material making a couple of thicker spots in the rotor. If using an abrasive pad, it can wear down those 2 spots...but this usually doesn't occur or last long enough to become noticeable because abrasive pads have a tendency to even things out, which is why with OE level components, Euro cars make lots of dust but almost never have brake pulsations or judders.

I've worked for Centric Parts/ Stoptech for the last 14 years, involved in product testing, development, engineering, and diagnostic support. I was an ASE master tech (certs have since expired), Toyota master tech, and had all of GM's undercar certs before I got out of the shop and started at Centric. I know a thing or two about brakes....it's about all I do. I've performed thousands of brake jobs over that period of time, a lot of testing, some from local shops that had given up. Out of all of those, there was a single problem car, a BMW, that both myself and the owner of the car finally gave up on. The rotors had absolutely no measureable runout using a DI with .0001" resolution, and at most .0003" thickness variation, he could feel it, I could not.


Edit:.. I had more than this typed out, but the interweb ate it and I spend the last 20 minutes trying to recover some of it. I'll carry on in the AM
 

Maestro

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For oe pads and rotors I suggest arkebono. I also like posi quiets pads. Cheap pads and rotors are just that cheap. They won't last and perform. Rotors do warp, distort, and become off center etc.
 

Bobby V

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Weird fun fact - If you have a 99-up Silverado 1500 / 2500 / 3500, they don't ever need brakes.....
Seriously. I've owned and sold 3 of them now, with over 150k on same pads and rotors. The truck I have now is at 134k...guy I bought it from gave me a box full of new delco pads. Said he bought them cause he figured it had to be time, but his mechanic checked them and said they had at least 70 percent left. My old Tahoe was the same way also. It amazes me, cause we have newer F150s at work and they eat a set of rotors every 30k
Yep..I have 130K mostly river miles on my 03 Tahoe and have never changed the brakes. My 06 1500 Chevy has 120K city driving and have gone thru 1 set.
 

lbhsbz

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I read there is no such thing as a "warped" rotor, as in "bent", and that's it's brake compound from panic stops. They feel warped due to the pad contacting the uneven surface, and it's not physically possible for the metal to warp like that. Just what I read....it's hard to wrap my head around the term warped.

I know too on Euro cars like MBZ that you never turn the rotors, new replacement always. And, just because they say Brembo does not mean they are good rotors - there are Brembo's from Italy, and junk Brembo's from Mexico.

I need to do the brakes on my 03 Excursion for the second time at 130K, so input on quiet pads and decent rotors is appreciated. Save me some research athe Ford truck forums :D

Rotors might warp, but I've never seen one that did. I've built fixures to measure rotor runout and thickness varation in 0.0001 resolution, and I've never seen an iron rotor change shape unless it was mistreated. Heat will not warp a brake rotor unless we get into stupid extreme conditions which will most likely crack the rotor before it "warps". we get rotors glowing orange and spitting fire and sparks on our dynos and when they're cool enough to approach...they're not warped.

PM me about brakes on your Ford...I'll hook you up.
 

Carlson-jet

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I read there is no such thing as a "warped" rotor, as in "bent", and that's it's brake compound from panic stops. They feel warped due to the pad contacting the uneven surface, and it's not physically possible for the metal to warp like that. Just what I read....it's hard to wrap my head around the term warped.

More to this, Rotor checking, Build up (as stated) and "Run- out". You are correct. unless it is involved in some type of catastrophic accident, rotors do not "Warp" in typical driving conditions. Good point.

I know too on Euro cars like MBZ that you never turn the rotors, new replacement always. And, just because they say Brembo does not mean they are good rotors - there are Brembo's from Italy, and junk Brembo's from Mexico. They are all cast in CHINA, Who is running the CNC lathe that day makes the difference.

I need to do the brakes on my 03 Excursion for the second time at 130K, so input on quiet pads and decent rotors is appreciated. Save me some research athe Ford truck forums :D

Can't help you there, but I will say we only have a few manufactures who control in house what happens to the finished product in the US these days. Each year they decide what rotors/pads to run depending upon demand vs profit. Global economy ya know.
 

C-2

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Rotors might warp, but I've never seen one that did. I've built fixure to measure rotor runout and thickness varation in 0.0001 resolution, and I've never seen and iron rotor change shape unless it was mistreated. Heat will not warp a brake rotor unless we get into stupid extreme conditions which will most likely crack the rotor before it "warps". we get rotors glowing orange and spitting fire and sparks on our dynos and when they're cool enough to approach...they're not warped.

PM me about brakes on your Ford...I'll hook you up.

Thanks for your kind offer, I'm still a bit out from doing it but will hit you up for your much appreciated advice; I'll return the favor. :)
 

rivermobster

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I read there is no such thing as a "warped" rotor, as in "bent", and that's it's brake compound from panic stops. They feel warped due to the pad contacting the uneven surface, and it's not physically possible for the metal to warp like that. Just what I read....it's hard to wrap my head around the term warped.

I know too on Euro cars like MBZ that you never turn the rotors, new replacement always. And, just because they say Brembo does not mean they are good rotors - there are Brembo's from Italy, and junk Brembo's from Mexico.

I need to do the brakes on my 03 Excursion for the second time at 130K, so input on quiet pads and decent rotors is appreciated. Save me some research athe Ford truck forums :D
They warp on a regular basis. Anything past.002 runout, you will feel on the pedal.

A dial indicator on the rotor surface will tell you everything you need to know.

There is some good info in this thread, and some misinformation as well.

Goes to show you can't believe everything you read on some interweb forum. [emoji6]
 

lbhsbz

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please explain how, and why .002" of runout only, as in a perfect rotor, set on a not-flat hub will cause a pulsation? What particular vehicle are you talking about here?
 

Carlson-jet

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They warp on a regular basis. Anything past.002 runout, you will feel on the pedal.

A dial indicator on the rotor surface will tell you everything you need to know.

There is some good info in this thread, and some misinformation as well.

Goes to show you can't believe everything you read on some interweb forum. [emoji6]

They (rotors) typically don't "warp". They exceed run-out in the beginning with poor installation which is more than the caliper can absorb over time. ( special shims are made for this) If a rotor is not installed correctly and shows excessive run-out upon installation it will eventually catch up and pulse in the break pedal. Now there are instances where rust between the rotor expands or the torque to the hub is inadequate and causes excessive run-out. This is rare compared to improper machining and installation.

What you will never see are the specs for a given rotor or compounds that make up a particular pad given over the internet as they are proprietary. Good luck finding those specs. :)
 
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