Unclear on something, if rotors have a slight warp in them, will having them resurfaced "flatten" them? Should a shop be able to tell if they are warped to a point they won't be good even with a resurfacing?

Yes, If they aren`t too bad. What kind of car. May be cheaper to get new. P.S. Torque the lug nuts to spec when you reinstall.

yes and yes , but they may end up being under spec after turning .

Yes, It should straighten them out
Unless they are warped to much.
Turning should take the warp out plus the resurfacing.

If you have a popular newer car, it may be cheaper to buy new ones rather than having your old ones turned.

Sheldon

Its a 2002 Taurus. Had them turned, new 55 dollar pads and they seem to be where they were at after 50 miles of driving?

Well yes and no. Yes turning will provide a true surface and as long as it can be done without going below spec they will work, at least for awhile. The bad news is they will be thinner and have less mass, ie. a less effective heat sink and therefore more prone to future warpage. The real question is why did they warp in the first place? Do you live in hilly terrain or use your brakes harder than most? If not it may just be a design defect it which case other cars like yours should also be affected. A dragging brake caliper could also cause the rotor to run hotter than normal, but you should be able to feel that in the steering. Slight warpage is normal if the rotors have been in service for a long enough time. By slight I mean under .005. Most of the time if you only have .002-.003 you'll barely feel it. Ideally they should be within .0005.

It's pretty common for cheap OEM and Chinese rotors to warp. They might warp again after having them turned. Don't bother turning them when you can get new Brembo rotors for a little over $100 a pair. I know from experience Brembo make top shelf replacement rotors.

http://www.buybrakes.com/store/BR27250

IF they are warped - they are more than likely JUNK. Cutting them will make the potential of warping again even worse.

Buy some new ones.

That's a pretty good question.

I just got done doing the brakes on the three cars in our corral, a Barracuda, a Mustang, and a Camry.

On the Camry, one of the tire guys had overtightened the lugs so much that one of the lug studs was destroyed, and both rotors were warped. It was easier , cheaper and faster to replace both rotors.

On the Ford, I had one rotor resurfaced (no warpage), and replaced one (deep grooves on the surface). I had a machinist check, and they were not warped, though this machinist claims that all rotors will warp slightly due to heat.

The Barracuda had two straight rotors, but a caliper seized, and both brake hoses also needed replacement. When the Barracuda's caliper seized, I was afraid the rotor had warped since the it was so hot I could have cooked a slab o' bacon on it. But, apparently, I got lucky and the rotor did not warp.

It seems that turning warped rotors will probably put them out of specifications. The FSM should be your guide (and the machinist's too). But you're not going to be able to find some of these old Mopar rotors easily and cheaply. That's why I think your question is a good question, and I'll be interested to see the replies to this thread.

Hey Paul, couple of suggestions for you. when you remove these rotors look at the back side of the rotor, the hub has holes in it that alows rust to build up on the back side of the rotor between the lug holes, and if the rotor is not clocked the same when it is put back on, it will warp when it gets hot, also make sure the hub is clean of all rust before you install a new rotor or it will also warp from it not seating flat on the hub, and tighten the lugs evenly. Rich

Certain cars replacing rotors is a must do thing when doing pads. The rotors were made soft so they do not warp as easily. Like Mercedes the rotors maybe just above specs when the pads need replacement but expect them to be far under before the pads get to the halfway point. Good thing for the most part (after looking around) the German rotors are relatively inexpensive.

I notice on the cheap Chinese rotors tend to work ok if you cut them again after bedding in the pads + 50 or so miles. A lot of work if you ask me though.

I turn new rotors just in case.
Better to check them before putting them on.

I usually just buy new ones, and haven't had problems with the "cheap Chinese" rotors any more than the better "made in mexico" ones.
The older Taurus rotors were very prone to warping. It is IMPERATIVE that you torque them in three increm3ents to whatever the FSM says, in a star pattern. Overtorquing or going up to t torque limiter using an air gun one lug at a time is a sure way to have tyhe rotors warp. I also used Performance Friction carbon metallic pads as they worked better and lasted longer.

I don't think a warped rotor can be saved but maybe I'm superstitious.
Anyway, where I live, the rotors are automatically turned to the minimum thickness, every time. Even if it takes only a light cut they still get cut to the max. That's so the brake shop guys can sell you a rotor next time. I would rather buy a new one than have some jerk work on my stuff knowing far less than I do about the subject, other than he messes up thousands of rotors a year.

R.

PS: The real way to surface a rotor would be to grind it, but that's hard to find.

Just depends on how bad they are warped and how much meat is left on them. Being later model rotors, I'd just buy new ones.

What your describing is something affected by DTV(disc thickness variation) and/or runout. The rotors are typically cut with the hub at the factory, on new vehicles, to provide the best overall condition for the car. It is not a problem to cut them as most parts have quite a bit of meat before exceeding tolerances. The best way is a method "on car" as it takes into account the hub on which the rotor is attached to. New pads on fresh cut rotors is best. Make sure you don't have a caliper hanging up. Replacement rotors will never be as good because they were not matched to the hub on your vehicle.

I have not had any rotor warpage issues since I started using a torque wrench on the lugnuts.

Most new rotors werent made to turn.Most are only .035 new to discard.You might be able to turn them but most will warp in a few thou miles.Contrary to most thoughts we have less problesm with the cheap rotors than the hi buck Wagner or brand names.Ive installed thousands and have had just about 0 problems with them.But if you want to spend $$$$ then go ahead.I probally do more brakes in a week than most here hhave done in 2 lifetimes.Rocky

I won’t say that Brembo rotors are bad, but they are pretty expensive. When you can good rotors at lower price ranges, why do you have to go for the branded ones? The braketimeusa com brake shoes durability of both the rotors in my experience lies in the same range.