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Car Forum / GMC Cars / April 2006Brake advice sought
My daughter's 2000 Alero coupe began exhibiting brake pulsation at about 40,000 miles on the clock. Old dad suspected the front rotors were warped and replaced them and the pads, taking great care to ensure that the hub to rotor fit was clean and free of rust and bumpy imperfections. Carefully torqued the lug nuts, also. Then "burnished" the new parts per a procedure shown on a major brake pad manufacturer's Web site. The brakes worked smooth as silk afterward. Now, about 13,000 miles and 18 months later the pulsation is back with a vengeance. I used Bendix rotors and NAPA ceramic pads the last time. One rotor was made in USA, the other in Canada, so my confidence in their quality was high. If it turns out the rotors are warped again what brand or price range should I opt for this time? GM? Higher priced Bendix? Drilled and slotted? Different pads? Is there something else I should be looking at for causing this recurrence? >My daughter's 2000 Alero coupe began exhibiting brake pulsation at about >40,000 miles on the clock. Old dad suspected the front rotors were warped [quoted text clipped - 16 lines] > >Is there something else I should be looking at for causing this recurrence? Have the tires been replaced or rotated during the interval? I haven't personally observed it but it has been stated that over tightening lug nuts can cause rotors to warp. FWIW YMMV No tires were replaced during the interim, but your thought is a valid one. I don't trust those tire places with their impact wrench jockeys. >>My daughter's 2000 Alero coupe began exhibiting brake pulsation at about >>40,000 miles on the clock. Old dad suspected the front rotors were warped [quoted text clipped - 26 lines] > FWIW > YMMV > My daughter's 2000 Alero coupe began exhibiting brake pulsation at about > 40,000 miles on the clock. Old dad suspected the front rotors were warped [quoted text clipped - 17 lines] > Is there something else I should be looking at for causing this > recurrence? Here's opening up a possible case for argument. After experiencing this ordeal with disc brakes for decades, I am convinced that such is inherent to our present knowledge of the science. I feel as if something like the following occurs: the brakes have heated via normal usage and then inadvertently run thru a puddle of water where they were suddenly cooled. Hence, warpage has occurred thru 'normal' operation. No one to blame. Don't use them and they probably don't pulsate; don't suddenly cool them, by driving only in a dry, stable-temperature climate, & they probably won't pulsate. Garden of Eden for disc brakes? My 2 cents--hope to learn a simple cure myself! s "sdlomi2" <sdlomi2@spam.yahoo.com> wrote in message > Here's opening up a possible case for argument. After experiencing > this ordeal with disc brakes for decades, I am convinced that such is [quoted text clipped - 3 lines] > cooled. Hence, warpage has occurred thru 'normal' operation. No one to > blame. You make an interesting point with that scenario. I've heard they are just making them too thin and light to be durable. Car makers are interested in weight savings and perhaps they took out a few ounces too much. I've had disc brakes on older cars and did not have that problem, but newer ones seem more prone. My LeSabre with 110k is ready for a new front set too. New ones are not easily cut down like some of the older ones too. The only thing that bothers me with your line of thinking is that the original GM rotors lasted about 40,000 miles but the aftermarket ones went only about a third that. Certainly competition is fierce, but you would think that Bendix would have less incentive to scrimp on the heft of their replacements. > "sdlomi2" <sdlomi2@spam.yahoo.com> wrote in message >> [quoted text clipped - 13 lines] > front set too. New ones are not easily cut down like some of the older > ones too. On 4/23/06 11:06 PM, in article IJ-dnWKulP5V3dHZnZ2dneKdnZydnZ2d@comcast.com, "Silver Surfer" <h.mcguffinspamouflage@comcast.net> spewed forth this gibberish... > The only thing that bothers me with your line of thinking is that the > original GM rotors lasted about 40,000 miles but the aftermarket ones went > only about a third that. Certainly competition is fierce, but you would > think that Bendix would have less incentive to scrimp on the heft of their > replacements. I've seen/heard ceramic pads eat rotors, especially under the aforementioned rapid cooling under braking condition. I've had the best luck with semi-metallic pads and the higher quality rotors (don't remember the brand of the last pair I bought but they're at 30000 with no turning yet).. At least the rotors last and only need new pads every 20000 or so.. The main reason for using the ceramic pads was because they are original equipment on this machine. I just assumed that GM knew best and followed their lead. > On 4/23/06 11:06 PM, in article > IJ-dnWKulP5V3dHZnZ2dneKdnZydnZ2d@comcast.com, "Silver Surfer" [quoted text clipped - 14 lines] > of the last pair I bought but they're at 30000 with no turning yet).. At > least the rotors last and only need new pads every 20000 or so.. If you theory is correct it would at the very least make me quit second guessing my own workmanship. >> My daughter's 2000 Alero coupe began exhibiting brake pulsation at about >> 40,000 miles on the clock. Old dad suspected the front rotors were [quoted text clipped - 28 lines] > probably won't pulsate. Garden of Eden for disc brakes? My 2 cents--hope > to learn a simple cure myself! s > If you theory is correct it would at the very least make me quit second > guessing my own workmanship. Who knows, may be a sub-conscious motive of my own. Nothing more embarrassing than to have to tell a good customer that it's time to do them again. s > My daughter's 2000 Alero coupe began exhibiting brake pulsation at > about 40,000 miles on the clock. Old dad suspected the front rotors [quoted text clipped - 3 lines] > "burnished" the new parts per a procedure shown on a major brake pad > manufacturer's Web site. The brakes worked smooth as silk afterward. > Is there something else I should be looking at for causing this > recurrence? Even though you made sure the hub to rotor surfaces were clean, did you measure the rotor/hub lateral runout with the rotor torqued in place? If you have more then about .0015" of runout, you will most likely get another pulsation problem. Those vehicles are particularly bad for brake pulsation. We see them in the shop for that all the time. Ian No, I did not check the lateral runout afterward. Don't have the equipment for doing so. Will borrow the necessary instrumentation and fixtures this time. As for proper torquing I ran across something on the Internet a while back that mentioned a special cone shaped washer or nut or something that is used for torquing the rotor to make the runout check. Have you any experience with such a thing? >> My daughter's 2000 Alero coupe began exhibiting brake pulsation at >> about 40,000 miles on the clock. Old dad suspected the front rotors [quoted text clipped - 16 lines] > > Ian > No, I did not check the lateral runout afterward. Don't have the > equipment for doing so. Will borrow the necessary instrumentation [quoted text clipped - 4 lines] > that is used for torquing the rotor to make the runout check. Have > you any experience with such a thing? Yes, it's part of a kit that we use in our dealership. We also have shims that are used to compensate for any lateral runout. Here is the company that provides the kit: http://www.brakealign.com/pages/products.htm Ian Thanks for the link. They don't show much in the way of pricing for their products, but my guess is that they are probably out of reach of the DIYers such as myself. >> No, I did not check the lateral runout afterward. Don't have the >> equipment for doing so. Will borrow the necessary instrumentation [quoted text clipped - 12 lines] > > Ian > My daughter's 2000 Alero coupe began exhibiting brake pulsation at about > 40,000 miles on the clock. Old dad suspected the front rotors were warped [quoted text clipped - 17 lines] > Is there something else I should be looking at for causing this > recurrence? In addition, make sure that the rear brakes are in good condition and well adjusted or the extreme majority of your braking action will the front discs. I'd also do a double check on your daughter's braking habits.  SignatureMr. Transmission Sucks! http://mrtransmissionsucks.com Her braking habits are enough to drive me nuts. When riding with her my feet are instinctively and constantly applying a braking force to the floor pan on the passenger's side. No hope of ever changing her despite much preaching over the years. >> My daughter's 2000 Alero coupe began exhibiting brake pulsation at about >> 40,000 miles on the clock. Old dad suspected the front rotors were [quoted text clipped - 21 lines] > adjusted or the extreme majority of your braking action will the front > discs. I'd also do a double check on your daughter's braking habits. > Her braking habits are enough to drive me nuts. When riding with her my > feet are instinctively and constantly applying a braking force to the [quoted text clipped - 27 lines] >> front discs. I'd also do a double check on your daughter's braking >> habits. Hey, SS, reckon riding the brakes on the passenger's side can warp rotors?????:) s Hey, SS, reckon riding the brakes on the passenger's side can warp rotors?????:) s By golly you might be on to something there. >> Her braking habits are enough to drive me nuts. When riding with her my >> feet are instinctively and constantly applying a braking force to the [quoted text clipped - 30 lines] > Hey, SS, reckon riding the brakes on the passenger's side can warp > rotors?????:) s > In addition, make sure that the rear brakes are in good condition and well > adjusted or the extreme majority of your braking action will the front > discs. I'd also do a double check on your daughter's braking habits. The majority of braking is done by the front brakes regardless. Something in the order of 70% of the braking is done by the front brakes. It's all about weight transfer. Signature-Mike- mmarlowREMOVE@alltel.net |
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