I just replaced my rear brake pads and had some grooves on the rotor. Not too bad, but visible. Should I have gotten my rotors cut? What are the negatives of not re-cutting the rotors and installing new brake pads? I don't feel that this should affect performance of braking, aside from maybe some sqealing. Any positive input appreciated.
Benefits of cutting rotors?
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Kestas
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There's pros anad cons to cutting the rotors. Cutting help true them up to reduce brake pulsation and knockback of the pads, and helps seat new brake pads more quickly. It also reduced the heat capacity of the rotors, which can result in brake fade.
I can't remember the last time I had rotors turned on a car. I usually change the pads before they wear to the metal.
Squealing is from something else.
I can't remember the last time I had rotors turned on a car. I usually change the pads before they wear to the metal.
Squealing is from something else.
Uneven pad wear is possible when doing a "pad slap." That is, when replacing the pads without cutting your rotors.
When the rotors are moderately to severely warped, it can definitely reduce braking performance.
When the rotors are moderately to severely warped, it can definitely reduce braking performance.
IMO, if the rotors are warped it is better to get rid of them and get new ones becoz when a rotor is warped it has structurally changed due to heat. No matter how much of rotating of the rotors, the problem will definetly come back with a bang becoz heat spots has already killed the rotor.
I'd say not a problem, I've only machined a rotor once because of a slight warp on them, but in a short time the warpage was back and it became worse quickly. I've done other brake jobs and as long as my rotors are in decent shape I won't machine them. I'd rather just replace them with a higher quality rotor anyway rather than machine them.
You shouldn't have any problems with keeping your current rotors, the pads will just wear in to the grooves that you were talking about.
You shouldn't have any problems with keeping your current rotors, the pads will just wear in to the grooves that you were talking about.
That's because what most people think are "warped" rotors really aren't that at all. I would encourage everyone to read this article on brake rotors. My own experience, especially recently with my Chrysler, bears out the truth of what it says about filming.
Modern brake rotors are thin and soft cast iron. They are considered a wear item. There might be enough metal on them to allow a skim cut, and that also might make the rotors so thin, tho still within spec, that they actually do warp from heat.
I don't consider changing or resurfacing the rotors unless the groove from brake pad wear is significant.
Ken
I don't consider changing or resurfacing the rotors unless the groove from brake pad wear is significant.
Ken
FWIW: All cars that we certified at Champion Chevrolet in Tallahassee,FL when I worked there got the rotors turned and smoothed on all 4 corners so that the buying customer would perceive "good" brakes. Cheap way to sell a car, but happens a lot at many dealers.
Almost all auto manufacturers now recommend "on the car" resurfacing. Why? It allows them to use spindle/hub/bearing assemblies with runout that would have been previously concidered excessive. So, what happens when you go to your favorite source and buy new rotors that are perfectly true, install them on your in factory spec hub and it shakes like a dog poopooing peachseeds?
Bob
Bob
If your factory spec hub is so poorly turned, I'd avoiding buying from that automaker.
Rust buildup on the hub or rotor causes the issues. Every so-called 'dog poopooing' that I've seen was caused by not cleaning the hub thoroughly prior to installing the new rotor.
Rear brakes don't do much braking. As long as there are no pulsating issues, the new pads will bed-in with the old rotors groves. No big deal.
Rust buildup on the hub or rotor causes the issues. Every so-called 'dog poopooing' that I've seen was caused by not cleaning the hub thoroughly prior to installing the new rotor.
Rear brakes don't do much braking. As long as there are no pulsating issues, the new pads will bed-in with the old rotors groves. No big deal.
Thanks everyone for the input. I don't feel any pulsing due to warpage, so I'm assuming all is well. I did get lifetime pads, so if I need to turn the rotors, I can get the new pads then.
The weird part is this is the second time to replace rear pads. Once at 60k and now at 112k, but still on original front pads and I didn't see the metal squealer that close to the disc. I think the rear brakes are doing the most work.
This thread is full of incomplete and inaccurate information. You just cannot paint the entire issue with such a broad brush. Every brake design is different, and what applies to one may not apply to another.
When I worked in a Volvo dealership, I was surprised to learn the Volvo attitude about brakes as it was very different from the domestic makes. Volvo's attitudes seems to be common with other european makes as well.
Volvo did not recommend machining rotors. Indeed, the rotors did seem to be soft and to wear quickly. Volvo also used a very agressive and abrasive pad. Pads wore quickly, and rotors needed to be replaced usually about every 2nd or 3rd pad change. Having observed the results of some independant shops that did turn the rotors it didn't seem to help much because they wore so fast anyway.
Most of the time that I worked as a tech or a service manager in Ford dealerships, rotors were routinely machined mainly because when someone insisted on a shortcut and not machining the rotors, they soon returned with brake shudder complaints. When the rotors are not exceptionally soft and the pads are reasonable, indeed it does help the pads seat in and ensures fewer problems.
I did observe that the rear discs on Expeditions and others were very hard and seldom really required turning. Indeed, they were hard to turn, requiring a sharp cutting tip and slow feeds to keep the tip from chattering and causing a "hearingbone" pattern on the surface.
Since leaving Volvo dealerships, I have observed a steady march of european type brake systems into both domestic and Japanese cars. The ATE (Continental - Teves) is becoming used on more and more applications, and customer dis-satisfaction with brake life is expanding with it. Ford used the ATE system on Contours and presently with Escapes. Chrysler has used it with many models, including many Jeeps. Honda uses it on the front wheels on the Accord. And I'm sure there are many more. I'm aware of these because I have had to deal with irate customers over them.
So as to if it is a good idea to machine rotors, it varies with the brake design. On some cars it is not only acceptable, but it is preferred. On other cars it is not a good idea.
When I worked in a Volvo dealership, I was surprised to learn the Volvo attitude about brakes as it was very different from the domestic makes. Volvo's attitudes seems to be common with other european makes as well.
Volvo did not recommend machining rotors. Indeed, the rotors did seem to be soft and to wear quickly. Volvo also used a very agressive and abrasive pad. Pads wore quickly, and rotors needed to be replaced usually about every 2nd or 3rd pad change. Having observed the results of some independant shops that did turn the rotors it didn't seem to help much because they wore so fast anyway.
Most of the time that I worked as a tech or a service manager in Ford dealerships, rotors were routinely machined mainly because when someone insisted on a shortcut and not machining the rotors, they soon returned with brake shudder complaints. When the rotors are not exceptionally soft and the pads are reasonable, indeed it does help the pads seat in and ensures fewer problems.
I did observe that the rear discs on Expeditions and others were very hard and seldom really required turning. Indeed, they were hard to turn, requiring a sharp cutting tip and slow feeds to keep the tip from chattering and causing a "hearingbone" pattern on the surface.
Since leaving Volvo dealerships, I have observed a steady march of european type brake systems into both domestic and Japanese cars. The ATE (Continental - Teves) is becoming used on more and more applications, and customer dis-satisfaction with brake life is expanding with it. Ford used the ATE system on Contours and presently with Escapes. Chrysler has used it with many models, including many Jeeps. Honda uses it on the front wheels on the Accord. And I'm sure there are many more. I'm aware of these because I have had to deal with irate customers over them.
So as to if it is a good idea to machine rotors, it varies with the brake design. On some cars it is not only acceptable, but it is preferred. On other cars it is not a good idea.
Hard to top that response so I won't even try. My personal practice is this. I replace both the pads and rotors with new. I will then have the old rotors machined (if they are able to be). Once that's done, I will coat them and store them until the next brake job. Brakes, along with tires, are some of the most important (and often neglected) items on your vehicle. Why take a chance with either?
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