How do you know when the rotors need 2be replaced?

Messages
19,528
Location
Lake Forest, CA
No, brake rotors are not needed to be replaced when you need to replace brake pads. You may need to resurface the rotors when you replace brake pads. If it is at minimum thickness before resurfaced, then it is needed to be replaced.
 
Messages
22,684
Location
CA
 Originally Posted By: HTSS_TR
No, brake rotors are not needed to be replaced when you need to replace brake pads. You may need to resurface the rotors when you replace brake pads. If it is at minimum thickness before resurfaced, then it is needed to be replaced.
Actually, a rotor that is at or below minimum thickness after resurfacing should be replaced. I prefer to replace the rotors at every brake job. Resurfacing the rotors costs between 15-20/rotor, and for an additional $60/axle, I can have new parts. But generally, the criteria for rotor replacement is the following: 1. Excessive corrosion 2. Rotor at or below minimum thickness 3. Heat damage 4. Damage due to operating with worn-out pads.
 
Messages
19,528
Location
Lake Forest, CA
 Originally Posted By: The Critic
 Originally Posted By: HTSS_TR
No, brake rotors are not needed to be replaced when you need to replace brake pads. You may need to resurface the rotors when you replace brake pads. If it is at minimum thickness before resurfaced, then it is needed to be replaced.
Actually, a rotor that is at or below minimum thickness after resurfacing should be replaced. ...
The question is why do you want to waste some money to resurface a rotor then measure the thickness and find out that it is at or below minimum ? The indy shop I go to always measure the rotor thickness before resurfacing and then measuring again after, to be sure the rotor thickness is safe.
 
Messages
1,778
Location
Wisconsin
on most vehicles rotors aren't very expensive. if its on a larger vehicle where the hub is included in the rotor its more cost effective to have the rotors turned to save some money. otherwise its just easier to replace them with the pads, depends on how you feel. i usually then try to stick with the same brand for brake items.
 
Messages
19,479
Location
Chicago Area
No, it is not typical to replace rotors with brake pads. They are often remachined, or left alone. And of course, replacement is always an option. It sure depends on the situation.
 

Kestas

Staff member
Messages
13,820
Location
The Motor City
Good advice above. I just wanted to add, that in my experience with a few cars, as healthy rotors start to reach their minimum thickness through wear (around 90K) they develop some shimmy. At that point I pitch them.
 
Messages
35,989
Location
ME
There are two minimums, service minimum and discard. Some chain shops will try to deliberately confuse the two. If you're below service minimum, there's a chance you'll hit "discard" before you use up the pads you've got, so more frequent inspection is a good plan. It's like spark plug gaps are allowed to grow beyond the listed spec. They'll take abuse beyond the discard thin-ness, but of course you shouldn't count on it:
 
Messages
1,389
Location
Nebraska
I don't get discs turned unless there is an abnormal amount of wear. I only change pads. The truck hasn't needed but brake pads once in 91,xxx miles. The Z28 had heat cracks in the front discs and I replaced them and the rear pads. The CRX had front discs that were too thin. The rear drums were simply too far gone and were cheap to replace. Discs/drums pads/shoes all around. Brakes are so cheap when DIY'd that it's a no brainer to replace as required. Chances are I'll never have to fool with anything other than a pad or shoe replacement as long as I keep it. Comparative costs for my driveway seen below. 1989 Honda CRX DX, front disc $21-$43...rear drum $17-$54 1998 Z28, rear $45-$62...front $33-$274 F250SD, rear $66-$85...front $30-$127
 
Messages
4,998
Location
Milwaukee, WI
Checker Auto used to resurface mine for free, so I would do it every time. 20 dollars a rotor is ridiculous, and I would probably just buy new then. 5-10 bucks a rotor seems more inline with what the time/equipment costs if you can't find a store to do them for free. I use a digital caliper because I'm too cheap to buy a micromenter just for this, and if I'm anywhere close I'll just replace. Minimum thickness is almost always stamped on the rim, but usually there's too much rust to remove to read it.
 
Messages
25,179
Location
Upstate NY
Can rotors always be machined? Someone told me that if the rotors were rusted (as in you did not drive vehicle for 6 months) then the brake lathe would just skip over the rusted areas and you would not get a good job of turning the rotors.
 
Messages
39,806
Location
Pottstown, PA
Change pads before they and the rotors are toast. Pad slaps are frowned upon, but I haven't turned or replaced a rotor on a car that only my wife or I have driven for ...heck, since before we were married 28 years ago. Check that, we had a 1979 Peugeot that had routine brake service under warranty. I finally got some aftermarket pads (my cost) and all the problems went away. The daughters disrupted that spotless track record. It's the user, not the mechanisms.
 
Messages
1,586
Location
WA
 Originally Posted By: Donald
Can rotors always be machined? Someone told me that if the rotors were rusted (as in you did not drive vehicle for 6 months) then the brake lathe would just skip over the rusted areas and you would not get a good job of turning the rotors.
Some can't. Most of the German makes can't be resurfaced. I worked at a BMW dealer for a short while. There were piles of used rotors out back. The mechanics told me BMW doesn't allow them to resurface them. I heard the same from VW mechanics.
 
Messages
34,975
Location
NY
 Originally Posted By: Gary Allan
Change pads before they and the rotors are toast. Pad slaps are frowned upon, but I haven't turned or replaced a rotor on a car that only my wife or I have driven for ...heck, since before we were married 28 years ago. Check that, we had a 1979 Peugeot that had routine brake service under warranty. I finally got some aftermarket pads (my cost) and all the problems went away. The daughters disrupted that spotless track record. It's the user, not the mechanisms.
That's how I've done it. It's now over 35 years I've been doing brakes that way, and I might have replaced 2 sets of rotors, and never needed a drum. The key is to check the brakes and replace them before they're toast. I do measure them to be sure they are within safe specs.
 
Messages
5,949
Location
Texas Hill Country
Here in Buffalo, the rotors just rot themselves apart. Usually the inside of the rotor gets so rusty, it chews up the pad that has plenty of life on it. I dispose of rotors everytime I change pads, or they get warped. I use the good pads (usually monroe ceramic), and the middle of the road rotors, usually wagners made in china.
 
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