Warped Rotor, daily driver

RamHemi18 · Jun 17, 2022

I changed the pads at 44K because the pads were squeaking and I couldn't stand it. Went with the Wagner OEX pads and the noise went away

EdGs · Jun 17, 2022

RamHemi18 said:
I changed the pads at 44K because the pads were squeaking and I couldn't stand it. Went with the Wagner OEX pads and the noise went away

My '15 had a squeak in the brakes as well. Only heard at very slow speed, like a drive thru, etc.
Annoying af, it was. did it from just about the moment I first got it with 28k on the odo. Changed my pads at 100k miles to Wagner Thermoquiets, and all good.

The OE pads surprisingly still had life in them, but I do no towing and very little hauling, and since I live in Flatistan, so no uphill/downhill to speak of unless I am traveling out of state.

TomB 1269 · Jun 17, 2022

Atcer2018 said:
Not to hijack this thread but does anyone know how to determine if a rotor is warped without any special tools? I recently picked up two Wagner E coated rotors on Amazon warehouse special for less than half price each. They do not appear to have been used. I just want to make sure they are not warped and true before I install them with Wagner OEx pads. I appreciate any advice.

You will need to be able to set up a dial gauge and check the run-out on both sides.

TomB 1269 · Jun 17, 2022

Rotors do not warp in normal passenger vehicle operations. To "Warp" a rotor you would need to heat it to near red hot to do so. However there are 2 things that can effect the rotor run-out or feel.
1. Over torqueing rims and then getting high heat load in rotor. This can cause the rotor to slightly distort due to uneven expansion and contraction due to the over clamped force of the rim to the hub and effectively "squeezing" the rotor. Even though over torqueing of rim is extremely common at all tire shops, the likely hood of this happening is low (usually requires a heavy load and a long down hill off ramp, etc.).
- usually easily remedied but cracking lugs and resetting to correct torque. You don't even need to lift off the ground just back off lug and reset. (i have done this more than one before)

2. Most common "warp" rotor problem is actually imprint of pad material to rotor face. This is very common as very few shops actually fully seat new pads when installed. There is a lot of back and forth about seating pads. It used to be required with old pad technology and materials. Most think its not required these days. I as well as Power Stop would disagree (you void pad /rotor warrant if you fail to follow their pad seating procedure). The heat cycling of new pads helps to "cure" the material and minimize "imprinting" on the rotor face. You can also over heat a lesser pad compound and cause it to imprint as well, much less likely.

Check out Power Stop seating process. It works very well. Also FYI, using this process when you start to feel a pulse in brakes can in some cases clear the imprint from the rotor face before it starts to cause wear anomalies in the rotor face and make pulse "permanent".

As for reusing old rotors:
1. front rotors I would suggest replacing if the vehicle has low miles (under 120K) and they have been in use for some time.
2. Any reuse of a rotor, if not taken to a shop and turned, should be scuffed with sand paper at a minimum to break down glaze on rotor face and allow for proper pad seating.

As for rear rotors, I rarely ever replace, nor turn as very few shops do it, and those that due tend to be M-F 8-4.

With respect to guide pins, rotor to hub/rim mounting faces.
- Mounting faces should be "clean" at least scrubbed with wire brush and a very light coat of anti-seize (it pays dividends when changing tires or future brake work)
- fyi I brush on anti-seize to back mounting face of rotor and carefully wipe off excess leaving just a thin film. I also do the same to the mounting face on the rim (verse actually applying to rim side mounting face of the rotor, less likelihood of contaminating pad area on rotor)
- pins clean (preferably replaced if any rust accumulates)and protective boots replaced unless they are in perfect shape (not usually the case)
-pins should get at least a coat of brake grease. I have actually changed to using anti-seize as I feel it decrease the likelihood of pins rusting / seizing in the bore. I do use a very small screw driver to insert some in to the bore before reinstalling pin, as well as giving the pins a coating as well.

Finally, to get brakes to operate well for a longer period and have less issues with pads hanging up in the carrier. I custom fit all my pads so they slide easily thru carrier and new tin clips (i.e. with just light pressure using pinky finger) before adding a small coat of brake grease. A file or careful use of a bench grinder will take care of the e-coat and material on pad ears.
- FYI, this process cleared up the issues with my Ford 150 front brakes which have a tendency to hang up in carrier regularly.
- this process also allows more room for heat expansion, further decreasing pads likeliness to hang up in carrier.

tron67j · Jun 17, 2022

crash68 said:
Rotors cannot really warp. Automotive experts note that rotors are metal discs that are cast under extreme heat conditions. It would take a similar application of heat by the braking system for rotors to bend, which is impossible. Other factors make rotors appear to be warped, so describing such rotors as “warped” is an easy way to explain the problem to vehicle owners.

For brakes to work correctly, brake pads must be applied squarely and evenly against the rotor. But friction can cause some brake pad materials to form residue on certain areas of the rotor, eventually contributing to uneven rotor surface levels. Some spots become thicker, while others may thin out.

Drivers’ own habits, including their braking tendencies, can contribute to uneven rotors. For example, riding the brakes for prolonged periods of time can cause hot brake pads to “paint” the rotors. So constant braking should be avoided.

^ this exactly. One possible cause that creates the pulsation that people associate as being "warped" is road debris that gets stuck to the rotor. As these high spots pass, the pads kind grab harder at that point and it, in a sense, reduces the forward momentum a bit more abruptly every time the spot passes.

RamHemi18 · Jun 17, 2022

TomB 1269 said:
Rotors do not warp in normal passenger vehicle operations. To "Warp" a rotor you would need to heat it to near red hot to do so. However there are 2 things that can effect the rotor run-out or feel.
1. Over torqueing rims and then getting high heat load in rotor. This can cause the rotor to slightly distort due to uneven expansion and contraction due to the over clamped force of the rim to the hub and effectively "squeezing" the rotor. Even though over torqueing of rim is extremely common at all tire shops, the likely hood of this happening is low (usually requires a heavy load and a long down hill off ramp, etc.).
- usually easily remedied but cracking lugs and resetting to correct torque. You don't even need to lift off the ground just back off lug and reset. (i have done this more than one before)

2. Most common "warp" rotor problem is actually imprint of pad material to rotor face. This is very common as very few shops actually fully seat new pads when installed. There is a lot of back and forth about seating pads. It used to be required with old pad technology and materials. Most think its not required these days. I as well as Power Stop would disagree (you void pad /rotor warrant if you fail to follow their pad seating procedure). The heat cycling of new pads helps to "cure" the material and minimize "imprinting" on the rotor face. You can also over heat a lesser pad compound and cause it to imprint as well, much less likely.

Check out Power Stop seating process. It works very well. Also FYI, using this process when you start to feel a pulse in brakes can in some cases clear the imprint from the rotor face before it starts to cause wear anomalies in the rotor face and make pulse "permanent".

As for reusing old rotors:
1. front rotors I would suggest replacing if the vehicle has low miles (under 120K) and they have been in use for some time.
2. Any reuse of a rotor, if not taken to a shop and turned, should be scuffed with sand paper at a minimum to break down glaze on rotor face and allow for proper pad seating.

As for rear rotors, I rarely ever replace, nor turn as very few shops do it, and those that due tend to be M-F 8-4.

With respect to guide pins, rotor to hub/rim mounting faces.
- Mounting faces should be "clean" at least scrubbed with wire brush and a very light coat of anti-seize (it pays dividends when changing tires or future brake work)
- fyi I brush on anti-seize to back mounting face of rotor and carefully wipe off excess leaving just a thin film. I also do the same to the mounting face on the rim (verse actually applying to rim side mounting face of the rotor, less likelihood of contaminating pad area on rotor)
- pins clean (preferably replaced if any rust accumulates)and protective boots replaced unless they are in perfect shape (not usually the case)
-pins should get at least a coat of brake grease. I have actually changed to using anti-seize as I feel it decrease the likelihood of pins rusting / seizing in the bore. I do use a very small screw driver to insert some in to the bore before reinstalling pin, as well as giving the pins a coating as well.

Finally, to get brakes to operate well for a longer period and have less issues with pads hanging up in the carrier. I custom fit all my pads so they slide easily thru carrier and new tin clips (i.e. with just light pressure using pinky finger) before adding a small coat of brake grease. A file or careful use of a bench grinder will take care of the e-coat and material on pad ears.
- FYI, this process cleared up the issues with my Ford 150 front brakes which have a tendency to hang up in carrier regularly.
- this process also allows more room for heat expansion, further decreasing pads likeliness to hang up in carrier.

Great write up. It makes sense. I didnt seat the pads when I did them a year ago. I didn't know I had to. Maybe I'll try scuffing the rotor with sand paper to see if I can save them. Or save the headache and just replace them with something new.

crash68 · Jun 17, 2022

GsRAM said:
in my opinion the surface is "warped"

The correct terminology is lateral runout.

The reason for I posted the whole explanation of rotor build up is someone is more likely to realize themselves that it due to their braking style that causing the problem if provided with the facts. If someone just states your brake problems are because your applying the brakes wrong, most people cop an attitude of "I brake just fine, been driving like this for years".

HEMIMANN · Jun 17, 2022

Metal Melting Point
(oC) (oF)
Iron, Gray Cast 1127 – 1204 2060 – 2200

Max Rotor Brake Temp ~ 1000 oF

Thermal camera shows how hot brake rotors get during use

It’s common knowledge brakes heat up during use, but how hot can they get? Simply put, pretty darn hot. Jason Fenske from Engineering Explained is back with another intriguing video made with help from a $55,000 FLIR thermal camera. This time, he points the camera at the brakes and takes some...

www.motorauthority.com

Not sure what rotors are made of today. Gray cast iron was cheap and reliable. I see some rotors today are made of steel, melting point is higher (2700 oF). Not sure if gray cast iron creeps at elevated temperature, nor how much. Not digging any further - too many summer chores to attend.

GsRAM · Jun 18, 2022

crash68 said:
The correct terminology is lateral runout.

The reason for I posted the whole explanation of rotor build up is someone is more likely to realize themselves that it due to their braking style that causing the problem if provided with the facts. If someone just states your brake problems are because your applying the brakes wrong, most people cop an attitude of "I brake just fine, been driving like this for years".

Yes, correct. I noted that in my second post to this thread.

lobo · Jun 20, 2022

Bearing play is one of the biggest causes of warped rotors. Jack your wheels off the ground and wiggle the wheel to check if there is any play in the bearings. If so, change the bearing. If you have bearing run out you will keep ruining rotors.

blackbetty14 · Jun 20, 2022

RamHemi18 said:
I changed the pads at 44K because the pads were squeaking and I couldn't stand it. Went with the Wagner OEX pads and the noise went away

Just did the same and at the same mileage. Easily had 1/2 pad life but they were squealing and I drive alot so decided this was the best course of action. Getting the factory rotors off after 4 years was a PITA. New wagner E coated rotors and performance friction carbon metallic and shes quiet and stops much better. Only been a few hundred miles but so far so good.

When you do a pad swap you should have a clean surface for the pads to break in on. Doesn't mean they need to be turned but you have to get all the old pad transfer material off... so 80 grit orbital sand the disk surface to get it off and smooth it out. Then install new pads and clean the clips real good and lube the pins. If your keeping your wagner rotors, clean them up like above and then sand the pads with 80 or 120 grit on a flat surface to resurface the pads as well. Then you have to do the right break in procedure which for my pads was (remember mine are performance pads):

5 light stops 50-30mph
5 medium stops 70-40mph
3 hard stops (no ABS activation) 100+mph - 30mph.
then coast with little to no braking for 5miles like on a highway to cool the rotors down
then inspect the rotors to show evidence of heat cycling (coloring in flange) and possesses an even transfer of pad material on the rotor surface

This is to build heat into the rotor & pad and the transfer material.

greg mayrhofer · Jun 20, 2022

everytime you change the pads you should change the rotors , for even wearing, and then they need to be burnished in to prevent warping the rotors , as they say you can pay me now or pay me later, my thoughts

El Toro Blanco · Jun 20, 2022

crash68 said:
Rotors cannot really warp. Automotive experts note that rotors are metal discs that are cast under extreme heat conditions. It would take a similar application of heat by the braking system for rotors to bend, which is impossible. Other factors make rotors appear to be warped, so describing such rotors as “warped” is an easy way to explain the problem to vehicle owners.

For brakes to work correctly, brake pads must be applied squarely and evenly against the rotor. But friction can cause some brake pad materials to form residue on certain areas of the rotor, eventually contributing to uneven rotor surface levels. Some spots become thicker, while others may thin out.

Drivers’ own habits, including their braking tendencies, can contribute to uneven rotors. For example, riding the brakes for prolonged periods of time can cause hot brake pads to “paint” the rotors. So constant braking should be avoided.

This!!! (Above). Rotors don't warp. They get material transfer from the pads that create 'high spots'.

Excessive riding/ applying brakes...and holding them tight at at stop, once they are heated transfers pad material to the rotors. These 'spots' of transferred material are what causes the shake, or shimmy when braking.

Easiest cure is to re-,bed your brakes.

1. Take it out on an open road with no traffic.
2. Get it up to 50mph+ (minimum) then brake hard and steady...down to 10 - 15mph. (Do not stop completely, or you won't do any good!)
3. Repeat this 3 to 5 times.
4. Drive as normal and see if you notice any improvements.

As also previously mentioned, over torquing, or incorrectly torquing lug nuts 'can' cause the rotors to not sit true and give some of the same indications.

I like doing the easy stuff 1st.

Good luck!

Elkman · Jun 20, 2022

Pads as supposed to be made from softer material than the rotors so one does not need to change the rotors with every break job. This is also a factor as the front brakes do more than 50% of the work in stopping the vehicle and will wear faster than the ones on the rear.

People screw up when they put in some special pads that will wear slower but cause the rotors to wear faster which is not a good trade-off.

I only had to replace the rotors on one vehicle and that was a 1998 Chevy Tahoe which had warped rotors at only 28,000 miles. I bought some aftermarket high quality rotors and had them put on by the shop. The cost was no more than buying OEM rotors from the dealer and I knew that the factory rotors were deficient. These new rotors were still OK when I sold the Tahoe with 178,000 miles.

Rotors are one of the places where the manufacturer saves a few dollars and this costs the buyers down the road. It is one place where it pays to buy aftermarket products, much as with gaskets and seals, to get better materials and longer life.

HEMIMANN · Jun 20, 2022

greg mayrhofer said:
everytime you change the pads you should change the rotors , for even wearing, and then they need to be burnished in to prevent warping the rotors , as they say you can pay me now or pay me later, my thoughts

I agree with this, instead of constantly trying to re-seat brake pads. I generally run until pads are down to min. 3 mm, then replace rotors and pads (still don't know why some replace calipers also). Rotors indeed have been thinned for cost saving over the years, and it's not so much that there's excessive wear-down but environmental exposure to road salt, dirt and the like.

Since brake systems last much longer today that decades ago, it makes more sense to me to replace these components open to road junks and the higher mileage when pads need replacing.

Also, the new coated rotors are much better than the raw metal OEM rotors. And if you want more braking power you can opt for slotted and drilled powerstops with carbon fiber ceramic pads, too.

AJNY · Jun 20, 2022

I found places that charge 15.00 a rotor to turn. You usually can cut the rotor twice. Always get brand new pads to ensure an even fit. A machine shop usually has a lathe.

TomB 1269 · Jun 21, 2022

RamHemi18 said:
Great write up. It makes sense. I didnt seat the pads when I did them a year ago. I didn't know I had to. Maybe I'll try scuffing the rotor with sand paper to see if I can save them. Or save the headache and just replace them with something new.

Try doing a break in process 1st to see if you can "clean" the rotor face..

Sand paper will not work as you have to "true-up" the rotor face and that has to be done on a lathe. Sandpaper will only scuff the face to breakup glaze when reusing rotor without turning them and installing new pads. Should be done only on rear in my opinion.

TomB 1269 · Jun 21, 2022

AJNY said:
I found places that charge 15.00 a rotor to turn. You usually can cut the rotor twice. Always get brand new pads to ensure an even fit. A machine shop usually has a lathe.

Yes, most can be turned twice, but remember less rotor = less metal to dissipate heat from braking. In the old days the rotors where much thicker than today.

RamHemi18 · Jun 22, 2022

This has turned out to be a great thread with awesome input from everyone involved. Lets throw another scenario in here to keep it going. Lets say you decide to replace the front rotors and pads for even wear in....Do you replace the rear as well, even though they don't engage as much as the front?

JPT · Jun 22, 2022

RamHemi18 said:
This has turned out to be a great thread with awesome input from everyone involved. Lets throw another scenario in here to keep it going. Lets say you decide to replace the front rotors and pads for even wear in....Do you replace the rear as well, even though they don't engage as much as the front?

I typically replace the rears every other time I replace the fronts (general practice, not Ram specific), even if there still is meat left on the rears.

My thought process is, I have all my tools out, I would hate to have to add an additional day of work, to just do the rears when they wear out. Pads are cheap, so doing the job a little earlier really only saves me some pad life.

But as I said, I replace the rotors every time. So, I was going to replace the rear rotors anyways, so the only difference in doing it early is the life left in the pads.

Warped Rotor, daily driver

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