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do rotors need to be replaced for new pads?
This is a 204 V70 with 280mm rotors.
The rotors appear to be about 50% worn, currently at 24.5mm average. Can I just have the garage add a set of new pads and they will work with the rotors? The garage quoted $200CAD for 2 new rotors but if it's not necessary then I can just get them done the next time the pads wear out? Will 1.5mm on the rotots last a set of pads until the 23mm minimum? Front right: I took 4 measurements with the calipers, all slightly different. Rather than uneven wear, I think it's just the caliper. Average rotor thickness 24.74mm (absolute lowest reading was 24.62mm) Pads need doing as they are squeaking but look to have a bit left. There is a little ding in the outer edge of the disc on the bottom in these pictures - anything to worry about? Pictures attached. http://s5.postimg.org/ft5n43dbn/IMG_..._165033334.jpg http://s5.postimg.org/opgf813xv/IMG_..._165035377.jpg http://s5.postimg.org/e6l0wlqnn/IMG_..._165215287.jpg http://s5.postimg.org/i09vs0ilv/IMG_..._165805733.jpg http://s5.postimg.org/3v42q79kj/IMG_..._165810058.jpg Front left: Average rotor thickness 25.065mm (absolute lowest reading was 24.64mm) Pads need doing as they are squeaking but look to have a bit left. http://s5.postimg.org/6t5mxn6lv/IMG_..._171626096.jpg http://s5.postimg.org/ao9107prn/IMG_..._171630601.jpg |
I believe along the outside edge there's a minimum spec imprinted on the rotors. If you are putting new pads on, you'd want the rotors clean and flat to allow proper seating. A machine shop can deglaze or turn the rotors for you provided there's enough metal left. The risk is they may warp if they get too thin. That said, a lot depends on your driving style and city/highway mix. Considering you are already are already below 25mm, I'd say you should plan on replacing with the pads. Shop US web stores or even ebay and you should be able to find front rotors in the $50 US range per rotor plus shipping so the $100 C /rotor cost seems reasonable. If the pads are still good and you want to remove some noise, you can remove the pads, lightly sand the surfaces and then apply brake grease to the backs and pins. More typically its the rear brakes that make noise (ie squeal). Same there except backs may have a shim (lube both sides or consider replacing) or a a shim glued to the pad that may have worn or or got dislodged. Inspect, lube the backs and any bolts/pins etc. You can also use brake cleaner and lightly rub the rotor surfaces with fine sandpaper (300+... ) then wipe with a cloth wet with brake cleaner.
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Originally Posted by mt6127
(Post 430819)
I believe along the outside edge there's a minimum spec imprinted on the rotors. If you are putting new pads on, you'd want the rotors clean and flat to allow proper seating. A machine shop can deglaze or turn the rotors for you provided there's enough metal left. The risk is they may warp if they get too thin. That said, a lot depends on your driving style and city/highway mix. Considering you are already are already below 25mm, I'd say you should plan on replacing with the pads. Shop US web stores or even ebay and you should be able to find front rotors in the $50 US range per rotor plus shipping so the $100 C /rotor cost seems reasonable. If the pads are still good and you want to remove some noise, you can remove the pads, lightly sand the surfaces and then apply brake grease to the backs and pins. More typically its the rear brakes that make noise (ie squeal). Same there except backs may have a shim (lube both sides or consider replacing) or a a shim glued to the pad that may have worn or or got dislodged. Inspect, lube the backs and any bolts/pins etc. You can also use brake cleaner and lightly rub the rotor surfaces with fine sandpaper (300+... ) then wipe with a cloth wet with brake cleaner.
Won't the pads seat themselves within a couple days to the old rotor? |
There are two specs: the minimum thickness and the minimum thickness at brake pad replacement. If the minimum thickness is 23.00mm for your car, minimum at pad replacement is 23.80mm, so you should be fine.
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Originally Posted by mt6127
(Post 430819)
I believe along the outside edge there's a minimum spec imprinted on the rotors. If you are putting new pads on, you'd want the rotors clean and flat to allow proper seating. A machine shop can deglaze or turn the rotors for you provided there's enough metal left. The risk is they may warp if they get too thin. That said, a lot depends on your driving style and city/highway mix. Considering you are already are already below 25mm, I'd say you should plan on replacing with the pads. Shop US web stores or even ebay and you should be able to find front rotors in the $50 US range per rotor plus shipping so the $100 C /rotor cost seems reasonable. If the pads are still good and you want to remove some noise, you can remove the pads, lightly sand the surfaces and then apply brake grease to the backs and pins. More typically its the rear brakes that make noise (ie squeal). Same there except backs may have a shim (lube both sides or consider replacing) or a a shim glued to the pad that may have worn or or got dislodged. Inspect, lube the backs and any bolts/pins etc. You can also use brake cleaner and lightly rub the rotor surfaces with fine sandpaper (300+... ) then wipe with a cloth wet with brake cleaner.
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really depends what shape the rotors are in... at a minimum you should clean and lightly sand or rough up to help the bedding process. Its not uncommon for bikers to use scotch brite pads to deglaze rotors vs 300+ grit.
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It doesn't matter. If you put them on a brake lathe you'll see that they are definitely warped. What this person is really saying is that you don't notice that, what you notice is the different spots with different amounts of friction material. Okay. As it turns out (ba ha hahaaaaaa.....) I have to straighten them when you cut them anyway.
I would bet the advice given is very good. No doubt by somebody who uses the brakes a lot racing. One thing I find strange about all this is that the rotors rust noticeably every time it rains. How much lasting surface effects could there be? |
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