Resurfacing Rotors--Brakes

My mechanic recommends resurfacing the rotors when the disc pads are replaced. Is this necessary? Advisable?

It’s the official, proper repair if the rotors are in fairly decent shape and will clean up without going under the minimum thickness requirement.
Using a rotor that is too thin is dangerous. In a panic stop it’s possible that the rotor could actually be pulled apart due to the braking forces.

Depending on the cost to surface the rotors and the type of vehicle involved, it is often more cost effective to replace the rotors with new ones rather than surface them.
While it is not often done and often overlooked, new rotors should always be thoroughly cleaned before installation as they may have rust preventative chemical on them.
Sometimes this chemical is visible; other times it’s not.

Every since they 86ed asbestos brake pads, this has been a necessary evil. I generally get new rotors every other brake job. When I don’t get new ones, I get them resurfaced.

If they are warped, they really need to be resurfaced. If they are not warped, resurfacing them will keep the disks from becoming glazed. Glazed disks will increase your stopping distance.

I agree with the others, either resurface or get new rotors. If you don’t you’re hoping that the new pads match the slightly irregular surface of the old rotor well enough to not cause a problem. Not worth it to me.

I don’t agree that rotors need to be replaced or resurfaced if your brakes stopped the vehicle evenly with no pulsation felt either at the pedal or as braking power when nearing a total stop. Most of the time it may be needed, however, so conventional knowledge says to just have it done every time.

Compromised stopping ability has never been a problem for me when reusing rotors. Brake a little gently for a few hundred miles to let your new pads bed into the rotors. This is good to do with new or resurfaced rotors as well.

We have one car with the original, never resurfaced rotors with over 240,000 miles with no problems. It had some braking power pulsation when nearing a stop until I learned to tighten the lug nuts with a torque wrench in an alternating pattern, of course.

I would rather go without resurfacing if the man doing the resurfacing was not trained properly and I want him to tell me if they came out undersize or with a poor finish. The trouble comes when a mechanic puts time into turning a rotor but it comes out poorly.He still wants to be paid for his time so he won’t suggest new rotors.

So quality job within specs or leave it alone.JMHO

I cannot speak to all vehicles, but on my BMWs and Volvos manufactured in the past 20 years, the tolerance between new rotor thickness and minimum allowable thickness is so little that, for all practical purposes, they cannot be resurfaced.

I generally agree with you, but you’ve left out one other important situation. If you’ve let the brakes get down to where the wear indicator is cutting into the rotor (or if you’ve got metal on metal with the pads!), you need to turn out the groove it cuts. The trouble is that most people don’t change their pads until the wear indicator starts screeching at them or the brakes start grinding, so they’ll always need at least one rotor turned.

So perhaps we who actually inspect our brakes can get away without turning them, but probably not so much the general mechanic-going public.

Brakes are kind of important. I replace mine, but if you still have enough meat left for a re-service, you can go for that. Since the cost of new is not much different than a proper re-surface, it does not seem to be worth it.

Here is another thing to consider about brake rotor resurfacing or replacement. If your 80 dollar per hour mechanic would take 20 minutes to test drive your car to determine if the brakes pulsate before visually inspecting and measuring the rotors, he might conclude after all that you don’t need new rotors. Would you be willing to pay 27 or more dollars for his time to make this evaluation or would you feel less like contesting a charge for resurfaced or new rotors?

The mechanic would be turning away work time for himself and money for his employer if he determined that work was not needed. Since, much or most of the time rotors either need resurfacing or replacement, that is the path of least resistance.

If you’ve let the brakes get down to where the wear indicator is cutting into the rotor

There is no way that wear indicator should be cutting into a rotor. They are made of flimsy flat spring steel that’s now where near as hard as a rotor.

I don’t replace or resurface the rotors unless they are pulsating or I’ve worn the brakes down too far and I scored the rotors. I recently just replaced the rotors on my 4runner (easy job btw) because they were pulsing when I hit the brakes…New rotors…and I had to replace a caliper too because one of the 4 pistons was stuck…Brakes are just like new.

The problem is on some vehicles (like my pathfinder) replacing the front rotors is involved. You have to remove the hub assembly. I never replace them unless needed. Some vehicles I’ve lasted 300k miles on the original set of rotors.

I dunno… I guess I don’t really know the metallurgical explanation of it, but any time I’ve done a brake job on a car that’s been screeching for any length of time, there’ll be groove on the rotor where the indicator was. I took my big pile o’ drums & rotors to the scrap yard a few weeks ago, but otherwise I could show you a picture of a few of them.

On my own vehicles I always inspected the rotors. If they were not scored, glazed, or warped, and the vehicles was stopping straight an true, they’re fine.

The problem for a shop is that they have no way of knowing how well the vehicle is stopping and if there’s been any change in feel. To be on the safe side they’ll generally replace the rotors. Some shops will still turn them if there’s enough meat, but most won’t. Aftermarket replacement rotors for most cars can be bought as cheaply as turning them.

That’s not the only problem. The other problem is that one you resurface the rotors, they are thinner and more prone to warping. So if you resurface rotors that are not already warped, they are more likely to become warped. It is a vicious circle.

I have done it both ways. On one car that was close to its last miles, I did the pads, the rotor looked good. Test drove and found no problems. Drove and stopped well until sold. On the other one, since I was hoping to get another X10KM out of the car, I changed the rotors at $20 each. Lasted for more than 30KM and the car was sold with good functioning brakes. If I am having the shop do it I ask how much the charge would be for each scenario. Usually it has been safer and more cost effective to change the rotors on newer cars.

Servicing the rotors (machining or replacmement) is not a matter of revenue generation or gouging. It’s simply the proper, recommended procedure.
It’s quite possible to replace pads only and have no problems. It’s also quite possible to replace the pads and have brakes that shudder or squeal.

It’s one thing for a DIYer to replace pads only. If there’s a problem there’s no one to blame but themselves if they have to redo it correctly this time.
A shop doing it for hire has to stand behind the work and if a shop replaces pads only and those brakes start shuddering or squealing within a week or 6 months you can bet the customer is going to be back complaining and in some cases; threatening the Supreme Court.

Most rotors have about .030 of an inch to work with so many rotors can be surfaced if they’re not horribly warped. The only question is machine cost vs. replacement.

I’ve seen some of those gas station jockeys turn rotors for 10 bucks a pop and the only thing they know is the FAST position on the brake lathe. Set it on FAST, adjust the cut to peel off as much as possible in one swipe, and you’re left with a rotor that has a dubious surface.

The proper procedure is multiple cuts on FAST,the final cut on SLOW, and the chatter band in place. If this is done, the rotor surface is as new.
Guys who turn rotors and actually care, can usually tell after one FAST cut if that rotor will likely clean up within the limits or not.

What I meant in my post was for DIY, as you said if it shudders I smile at myself. If a shop does that kind of work for me they will loose my business. For me at home to take the rotors off and get into the wnd car, drive somewhere and resurface them… it is easier to just change them with el cheapo rotors.

But the rivets holding the pads onto the backing will damage the rotors.