I just want to check with all of you experts on something my mechanic has recommended. This is a mechanic who I really trust and he worked in the Volvo factory for 13 years.

I am having him replace the pads on the rear brakes (36K miles on them) and he has advised that the rotors should be turned, too. He says that otherwise the brakes will squeal a lot.

What do you all think?
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'94 940, 40 linear feet of vintage jazz, r'&'b, funk and soul

I don't turn the rotors when replacing the pads. I will sand the faces of the rotors with 80 grit to give them some bite to wear into the pads. The swept area of the rotor is pretty constant. The issue is getting the pads to conform to the old rotor.

I think the most important thing when replacing pads is to break them in gently. If you get them too hot right away the glue boils to the surface and glazes the pads. Use them as required when you need to, but if you can take it easy for a day or so they will give a better feel. If they get glazed, they have to be removed and sanded.

You can keep the brakes from squealing by putting a thin smear of RTV on the back of the pad. It damps the vibration.

Greg

you don't mention irs or solid axle, actual rotor specs are different. personally, I don't turn rotors unless there's enough to work with and I never turn rear rotors on Volvos or mercedes that have rear ates. only fronts that are vented. I used to work for a guy who turn them to discard thickness-solid axle-8.3 mm and reinstall them. of course they warped fast. if it's a solid axle car and after turning, they 9mm or thicker, then maybe. new spec is 10.4. i'd just buy the damn things.

btw, a warped rotor you won't feel in the steering wheel, only the brake pedal. the fronts you can feel in the steering when they warp. good luck, chuck.

I forgot why to turn rotors. the brake pads need a nice smooth, non-directional finish in order to break in and thus, work properly. turn them too thin, they overheat. once turned they need to be washed with soap and water to remove all the grit and grease before installing them. brake clean doesn't do the job. once you clean them right, they will rust in the sunlight while drying. when they rust, they're clean.

Are you feeling a pulsation in the steering wheel when braking? If not then don't bother turning them unless they have developed a substantial ridge on the outer edge. Personally I use some nice course sandpaper to "rough things up" and remove that glazed look they get sometimes. Lets the pads break in quicker IMHO. I am of the opinion that "turning" a rotor oftentimes leaves you with a thinner rotor that in turn heats up quicker and warps faster.