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Car Forum / Honda Cars / December 2005Turning Rotors: a case study...
With all of the debate about turning rotors I thought I'd do a bit of measuring and documenting while doing a brake job. Here is my results. The car 1987(?) Honda accord; poor shape, 200,000K no brakes due to a ruptured line. This soaked the pads and as per MAP standards required new pads. Now disregarding the brake line (and the springs off in the right read drum that he couldn't afford to repair) the car would appear as a prime candidate for a DIY brake job in the front driveway. Both rotors had no major grooves, very small ridge> I could picture this as a easy pad slap. Now ASE standards have you measure several different angles to determine if a re-cut is needed. We concentrate on the warpage factor. I don't feel like buying a few hundred dollars more of measuring tools to tell me what one pass on a lathe will tell me. The right front rotor measured at .747 to start I took one pass at .002 on each side Final measurement was .742 The left front rotor measured at .697 on the outside edge and .703 at the inside edge to start I took one pass at .002 on each side. the start of the cut was heavy, I thought I'd have to do a second cut. Often we will see the O/S edge a wee bit thinner than the inside edge, but when I returned to the lath one cut was all that was needed. Final measurement was .696 I forgot to write it down, but discard was in the .660 range. Most people who do brakes at home won't measure the rotors and it was interesting to see the big difference in specs from the left to the right to start. We thought there would be at least one new rotor needed, but specs are specs. You can see by the measurements that the lath action took off very little metal, not enough to make a difference on heat dissipation, but the little work guaranteed me that this car (the POS it was) had decent front brakes when he left. This is why I turn rotors every time. In the big picture, more metal is lost in the time between brake jobs by the pads than on a simple clean up on a lath.  SignatureStephen W. Hansen ASE Certified Master Automobile Technician ASE Automobile Advanced Engine Performance ASE Undercar Specialist http://autorepair.about.com/cs/troubleshooting/l/bl_obd_main.htm http://www.troublecodes.net/technical/ > With all of the debate about turning rotors I thought I'd do a bit of > measuring and documenting while doing a brake job. Here is my results. [quoted text clipped - 37 lines] > in the time between brake jobs by the pads than on a simple clean up on a > lath. what does measuring disk thickness tell you about how accurately the disk was kept axial with the bearing? >> With all of the debate about turning rotors I thought I'd do a bit of >> measuring and documenting while doing a brake job. Here is my results. [quoted text clipped - 41 lines] > what does measuring disk thickness tell you about how accurately the disk > was kept axial with the bearing? If this were the only factor in the performance of brakes than I would be concerned. But by just removing the tire and rotor you can effect the bearing to rotor play if a small piece of dirt were to fall between them. In fact, how do you know your "new Honda replacement rotor is true to your old wheel bearing?. We do have a 5000$ on car lathe, that is suppose to be "the most accurate way to turn the brakes" but it broke again. (600$ was the last repair bill) and having a brother-in law that is a machinist, we can see no great advantage to turning it on the car of off, as long as the turn job is true. Wear of the rotor and warpage (runout) are the two biggest factors of a brake job. SignatureStephen W. Hansen ASE Certified Master Automobile Technician ASE Automobile Advanced Engine Performance ASE Undercar Specialist http://autorepair.about.com/cs/troubleshooting/l/bl_obd_main.htm http://www.troublecodes.net/technical/ >>>With all of the debate about turning rotors I thought I'd do a bit of >>>measuring and documenting while doing a brake job. Here is my results. [quoted text clipped - 45 lines] > concerned. But by just removing the tire and rotor you can effect the > bearing to rotor play if a small piece of dirt were to fall between them. ok, so now let's /cut/ a disk with a piece of dirt under the rotor. now we have a disk that is perfectly planar with respect to the dirt, not the mounting. and that causes brake judder. > In > fact, how do you know your "new Honda replacement rotor is true to your old > wheel bearing?. well, i've never had a problem with a new disk. i've had repeated problems with skimmed disks. you figure it out. labor and a $5k machine to futz about with a part that can be replaced with a flawless new disk for $50-$60 in about 10 minutes? forget it. > We do have a 5000$ on car lathe, that is suppose to be "the > most accurate way to turn the brakes" but it broke again. (600$ was the last [quoted text clipped - 4 lines] > Wear of the rotor and warpage (runout) are the two biggest factors of a > brake job. no kidding. > well, i've never had a problem with a new disk. i've had repeated > problems with skimmed disks. you figure it out. labor and a $5k machine [quoted text clipped - 11 lines] > > no kidding. You may have had problems, and in a perfect world everyone would replace parts with new when worn with high quality stuff, but many want it done cheap. Anyway my point was to show how little metal comes off during a lathe job. SignatureStephen W. Hansen ASE Certified Master Automobile Technician ASE Automobile Advanced Engine Performance ASE Undercar Specialist http://autorepair.about.com/cs/troubleshooting/l/bl_obd_main.htm http://www.troublecodes.net/technical/ >>well, i've never had a problem with a new disk. i've had repeated >>problems with skimmed disks. you figure it out. labor and a $5k machine [quoted text clipped - 17 lines] > > Anyway my point was to show how little metal comes off during a lathe job. i have two points: 1. it ain't cheap enough to be worth bothering with [unless it's a disk that requires complete disassembly of the hub] AND 2. the results frequently aren't good enough to be worth the trouble. in fact it often /causes/ problems. i'd much rather live with a slightly scored disk than one that's been machined wrong and is now ruined. >> You may have had problems, and in a perfect world everyone would replace >> parts with new when worn with high quality stuff, but many want it done [quoted text clipped - 13 lines] > i'd much rather live with a slightly scored disk than one that's been > machined wrong and is now ruined. I don't think this issue can be resolved into a single best course of action. In another recent thread the subject of professional standards vs DIY standards came up, and I think that applies here. A DIYer who routinely leaves untouched disks that look good and have performed well is frugal and smart. A shop that routinely leaves untouched any disk is being sloppy. Jim, I gather you and I are on the same page on the DIY way of doing it. If the disks are serviceable as-is there is no point in doing anything to them except a quick wash with brake cleaner when we get our mitts off them. If they need more, replacement is the way to go. If we had free access to a lathe we might do the same as Stephen does - clean the surface up. Or maybe not. Mike > I don't think this issue can be resolved into a single best course of > action. In another recent thread the subject of professional standards vs [quoted text clipped - 11 lines] > > Mike Well said. SignatureStephen W. Hansen ASE Certified Master Automobile Technician ASE Automobile Advanced Engine Performance ASE Undercar Specialist http://autorepair.about.com/cs/troubleshooting/l/bl_obd_main.htm http://www.troublecodes.net/technical/ >>>You may have had problems, and in a perfect world everyone would replace >>>parts with new when worn with high quality stuff, but many want it done [quoted text clipped - 28 lines] > > Mike i used to work in a shop and had access - that's how i know these things can be difficult to center, giving inconsistent results. Ahhh, New equipment.... Some are sweet! SignatureStephen W. Hansen ASE Certified Master Automobile Technician ASE Automobile Advanced Engine Performance ASE Undercar Specialist http://autorepair.about.com/cs/troubleshooting/l/bl_obd_main.htm http://www.troublecodes.net/technical/ >> Mike > i used to work in a shop and had access - that's how i know these things > can be difficult to center, giving inconsistent results. "jim>> Anyway my point was to show how little metal comes off during a lathe job. > i have two points: > [quoted text clipped - 6 lines] > i'd much rather live with a slightly scored disk than one that's been > machined wrong and is now ruined. My point is different; We do it for free with a brake job It takes about 10 minutes to do total We have never had an issue with machining them wrong. Its to simple. But and idiot could play with the settings on the lath and screw it up... Perhaps the people who turned your rotors in the past were idiots? I agree with pressed on rotors... What a wonderful idea someone had... Take care, SignatureStephen W. Hansen ASE Certified Master Automobile Technician ASE Automobile Advanced Engine Performance ASE Undercar Specialist http://autorepair.about.com/cs/troubleshooting/l/bl_obd_main.htm http://www.troublecodes.net/technical/ Personally I have had very poor results in dealing with warped rotors through turning them. On my '03 Accord the rotors warped enough to cause brake shudder. Turning them helped for about 50 miles, when they warped again. New Brembo rotors cured the problem completely. 20,000 miles later the brakes are still working perfectly. John > Personally I have had very poor results in dealing with warped rotors > through turning them. On my '03 Accord the rotors warped enough to > cause brake shudder. Turning them helped for about 50 miles, when they > warped again. New Brembo rotors cured the problem completely. 20,000 > miles later the brakes are still working perfectly. Where did you buy these? How much did they cost? They're not OEM, right? >>Personally I have had very poor results in dealing with > [quoted text clipped - 16 lines] > Where did you buy these? How much did they cost? They're not > OEM, right? summitsportcompact.com has great prices on brembo disks. quality is very good. >>warped again. New Brembo rotors cured the problem > [quoted text clipped - 4 lines] > Where did you buy these? How much did they cost? They're not > OEM, right? One of the online parts sources, though I forget which one. It was probably one of: rockauto.com, alleurasianautoparts.com or discountautoparts.com. Personally I trust professional level aftermarket brands, but stay away from the no name and "value" brands of auto parts. No need to go with OEM for these. I hated the rotors which came on the car, so why give Honda more of my money? John > One of the online parts sources, though I forget which one. It was > probably one of: rockauto.com, alleurasianautoparts.com or [quoted text clipped - 5 lines] > No need to go with OEM for these. I hated the rotors which came on the > car, so why give Honda more of my money? Sounds good; appreciate the info. > Personally I have had very poor results in dealing with warped rotors > through turning them. On my '03 Accord the rotors warped enough to > cause brake shudder. Turning them helped for about 50 miles, when they > warped again. my experience exactly. thank you. > New Brembo rotors cured the problem completely. 20,000 > miles later the brakes are still working perfectly. > > John > Personally I have had very poor results in dealing with warped rotors > through turning them. On my '03 Accord the rotors warped enough to cause [quoted text clipped - 3 lines] > > John A rotor that is "warped", not simply scored, is a very poor candidate for resurfacing. The metal's properties have been changed by the level of heat it has been exposed to, causing a permanent change in its structure. After machining, once heat is applied, it will revert to its prior condition. I went through this issue with my wife's Malibu, arguing with the Chevrolet service manager every step of the way. They resurfaced the rotors 3 times to cure pedal shudder, but it never worked because the rotors were warped. In this case. it was a design flaw by GM - they made them too thin in the first place, and paired them up with lousy pads. When I finally gave up dealing with them and did the job myself, the rotors were ~0.003" thicker than the bare minimum, suggesting that they were able to shave off a minimal amount of metal each time they turned them. But so what? The rotors were junk the first time they warped. OTOH, a rotor that is merely scored can be effectively resurfaced and returned to service, providing that not too much metal is removed. I've done this on cars when the pad wore too far and "kissed" ther rotor. A competent technician can do this. Doug >>Personally I have had very poor results in dealing with warped rotors >>through turning them. On my '03 Accord the rotors warped enough to cause [quoted text clipped - 8 lines] > it has been exposed to, causing a permanent change in its structure. After > machining, once heat is applied, it will revert to its prior condition. sorry - unless this disk has been operated well into red heat, you're not going to get much change in microstructure. you can however have problems with a bad disk if it was not heat treated properly after casting. when operated hot, /that/ disk will distort. more likely is that there are simply different cooling rates on different parts of the disk leading to local temporary distortion. that shouldn't happen on a disk of sufficient thickness and whose internal vanes have not lost too much material through rust. my experience is that the disk cutting process is far from perfect - those cutting machines see heavy usage, and you can mount the same disk up a dozen times and get 13 different centers. > I went through this issue with my wife's Malibu, arguing with the Chevrolet > service manager every step of the way. They resurfaced the rotors 3 times to [quoted text clipped - 12 lines] > > Doug > sorry - unless this disk has been operated well into red heat, you're > not going to get much change in microstructure. you can however have [quoted text clipped - 4 lines] > disk of sufficient thickness and whose internal vanes have not lost too > much material through rust. Your opinion and a dollar will get you a cup of coffee. That's all it's worth . Repeated heating and cooling cycles will definitely change the distribution of carbon atoms in an iron matrix - and it doesn't have to be "red" hot. The temperatures created by the crappy pads used by GM did the job in less than 15,000 miles. > my experience is that the disk cutting process is far from perfect - those > cutting machines see heavy usage, and you can mount the same disk up a > dozen times and get 13 different centers. If that's your experience, that's too bad. You need to find a better technician, or learn to do it yourself. > Date: Sat, Dec 17 2005 6:21pm > From: doug > > > Date: Sat, Dec 17 2005 8:41am > > From: jim beam snip > > my experience is that the disk cutting process is far > > from perfect - those cutting machines see heavy usage, [quoted text clipped - 3 lines] > If that's your experience, that's too bad. You need to > find a better technician, or learn to do it yourself. Actually, he is talking about himself. He does not understand the physical relationship between runout (I believe this is the name - I am no mechanic) and perpendicularity of axis and contact surfaces - he concentrated on irrelevant coaxiality!: > Date: Sat, Dec 17 2005 9:02am > From: jim beam snip > i used to work in a shop and had access - that's how i > know these things can be difficult to center, giving > inconsistent results. > Date: Sat, Dec 17 2005 10:15 pm > From: "karl" [quoted text clipped - 9 lines] > > > and you can mount the same disk up a dozen times and > > > get 13 different centers. snip > Actually, he is talking about himself. He does not > understand the physical relationship between runout (I > believe this is the name - I am no mechanic) and > perpendicularity of axis and contact surfaces - he > concentrated on irrelevant coaxiality!: In a number of messages (maybe in all of his "cutting rotor" messages) jim beam emphasized the importance of centering the disks when their surfaces are being machined. This is what I was replying to - centering, within limits, is irrelevant, but I used the wrong term "coaxiality." Once again, important is the "perpendicularity of axes and contact surfaces," and anything that throws this off will cause problems. In fact, there is the possibility that jim beam, too, is talking about this when he writes about the importance of centering: in a message at another list he wrote of the importance of cleaning the mounting surfaces of the lathe and of the disk. >> Date: Sat, Dec 17 2005 10:15 pm >> From: "karl" [quoted text clipped - 32 lines] > importance of cleaning the mounting surfaces of the lathe > and of the disk. Another factor is also how the disk is actually cut. Not only is each axis perpendicular to each other, but the surfaces for the pads to be parallel. A poor cutting bit, taking off too much at a time, or a crossfeed that is too high can cause these kinds of problems. I just went through all of this with Chrysler, as the Jeep Cherokee's from 2000-2003 are notorious for premature warping of the front rotors (TSB issued). They (Chrysler) went through the trouble of changing the calipers and pads to another design in accordance with the TSB recommendations, but only cut the rotors (which I argued against), and they were warped again within 4K miles. I gave up arguing with them and purchased and installed a set of high performance rotors and pads. >>sorry - unless this disk has been operated well into red heat, you're >>not going to get much change in microstructure. you can however have [quoted text clipped - 10 lines] > "red" hot. The temperatures created by the crappy pads used by GM did the > job in less than 15,000 miles. diffusion, the migration of carbon atoms in the iron matrix, happens well below red heat. but /significant/ diffusion, recrystallization, graphite flake/nodule growth, or other phase changes, doesn't. and if you're trying to argue that a brake disk is martensitic, you need to think again. if your gm disk warps in 15k, you need to consider other factors. for honda, elastic distortion caused by incorrect wheel lug torquing has a huge influence. but if it's the disk alone, things like bad post-casting heat treatments, uneven material thickness, etc. can influence whether a disk stays true at high temperatures. the most likely item is cutting corners on heat treatment and reducing heat soak time. my money's on incorrect lug torquing. >>my experience is that the disk cutting process is far from perfect - those >>cutting machines see heavy usage, and you can mount the same disk up a >>dozen times and get 13 different centers. > > If that's your experience, that's too bad. You need to find a better > technician, or learn to do it yourself. i was a vehicle mechanic for 5 years and also have a materials degree. is that good enough? >>>sorry - unless this disk has been operated well into red heat, you're >>>not going to get much change in microstructure. you can however have [quoted text clipped - 36 lines] > i was a vehicle mechanic for 5 years and also have a materials degree. > is that good enough? Apparently not - it hasn't helped you to do the job correctly. Like I said before, there's one in every group. Although Dave Kelsen may once again take issue with that. >>>>sorry - unless this disk has been operated well into red heat, you're >>>>not going to get much change in microstructure. you can however have [quoted text clipped - 40 lines] > before, there's one in every group. Although Dave Kelsen may once again take > issue with that. so why don't you make a technical rebuttal? share your superior knowledge. It took you 12 days to come up with your lame-a.s text book reply. Yet you still don't get it - you're trying to argue a point that many people have already demonstrated to you that you are wrong about. I can't be bothered to repeat their - and my - valid examples and explanations. Perhaps if you took the time to review the threads in this post and you might begin to understand what I mean. I doubt it, but you never know. As I said, you ARE the one. >>>>>sorry - unless this disk has been operated well into red heat, you're >>>>>not going to get much change in microstructure. you can however have [quoted text clipped - 43 lines] > so why don't you make a technical rebuttal? share your superior > knowledge. > == 4 of 6 == > Date: Sat, Dec 17 2005 8:41am > From: jim beam snip > you can mount the same disk > up a dozen times and get 13 different centers. and > == 6 of 6 == > Date: Sat, Dec 17 2005 9:02am > From: jim beam snip > i used to work in a shop and had access - that's how i > know these things can be difficult to center, giving > inconsistent results. Why bring up coaxiality, or lack thereof? It is irrelevant as long as the contact surface with the pad gets machined. Relevant is that the machined surface and the mounting surface are perpendicular to the axis, and it is therefor important that the mounting surfaces are clean. This is the area you have to concentrate on, not centering. No wonder why you got "inconsistent results." > Date: Sat, Dec 17 2005 9:20 pm > From: "karl" snip > > i used to work in a shop and had access - that's how i > > know these things can be difficult to center, giving [quoted text clipped - 9 lines] > the area you have to concentrate on, not centering. No > wonder why you got "inconsistent results." In a number of messages (maybe in all of his "cutting rotor" messages) jim beam emphasized the importance of centering the disks when their surfaces are being machined. This is what I was replying to - centering, within limits, is irrelevant, but I used the wrong term "coaxiality." Once again, important is the "perpendicularity of axes and contact surfaces," and anything that throws this off will cause problems. In fact, there is the possibility that jim beam, too, is talking about this when he writes about the importance of centering: in a message at another list he wrote of the importance of cleaning the mounting surfaces of the lathe and of the disk. >>== 4 of 6 == >>Date: Sat, Dec 17 2005 8:41�am [quoted text clipped - 26 lines] > the area you have to concentrate on, not centering. No > wonder why you got "inconsistent results." you need to read around a bit more. if the disk plane is not exactly perpendicular to the rotation axis, on a floating [single piston] caliper, you have pulsing in the hydraulics because of momentum differences due to the mass of the caliper vs. the piston. with a fixed caliper and 2 [or 4 or 6] pistons, the mass on each side is the same and there's little net effect. ============================================================== TOPIC: Turning Rotors: a case study... http://groups.google.com/group/alt.autos.honda/browse_thread/thread/19594af6aa37ae67 ============================================================== > == 1 of 2 == > Date: Wed, Dec 28 2005 7:43 am [quoted text clipped - 40 lines] > fixed caliper and 2 [or 4 or 6] pistons, the mass on > each side is the same and there's little net effect. In two messages you wrote that "centering" the disks is important, and if this is not done properly it will give "inconsistent results." This is what I was responding to. Can you read? The relevant excerpts are right here. (I had written "coaxiality" when I meant centricity. I have corrected this already.) Correcting you, I wrote, "Relevant is that the machined surface and the mounting surface are perpendicular to the axis." Can you read? You do not "need to read around a bit more," it's right here. Pulsing "because of momentum differences due to the mass of the caliper vs. the piston," and "the mass on each side is the same and there's little net effect." Rubbish! <snip> > Pulsing "because of momentum differences due to the > mass of the caliper vs. the piston," and "the mass on > each side is the same and there's little net effect." > Rubbish! really? why? i'd love to see your explanation. <snip> > Pulsing "because of momentum differences due to the > mass of the caliper vs. the piston," and "the mass on > each side is the same and there's little net effect." > Rubbish jim beam wrote: >>really? why? i'd love to see your explanation Karl - he's not worth the time or effort to try and discuss this with. But I think you already know this ;-) doug > The left front rotor measured at .697 on the outside edge and .703 at the > inside edge to start [quoted text clipped - 3 lines] > cut was all that was needed. > Final measurement was .696 I'm confused. You just told us that you took 0.004" of material off the rotor, but your initial and final thicknesses only vary by 0.001"? >> The left front rotor measured at .697 on the outside edge and .703 at the >> inside edge to start [quoted text clipped - 6 lines] > I'm confused. You just told us that you took 0.004" of material off the > rotor, but your initial and final thicknesses only vary by 0.001"? Because the rotor wasn't true-- the outside edge was thinner than the inside edge, so only 001 was removed from the outside. SignatureStephen W. Hansen ASE Certified Master Automobile Technician ASE Automobile Advanced Engine Performance ASE Undercar Specialist http://autorepair.about.com/cs/troubleshooting/l/bl_obd_main.htm http://www.troublecodes.net/technical/ > > I'm confused. You just told us that you took 0.004" of material off > > the rotor, but your initial and final thicknesses only vary by 0.001"? > > Because the rotor wasn't true-- the outside edge was thinner than the > inside edge, so only 001 was removed from the outside. That's what I suspected, i.e., a lack of parallelism. Thanks for confirming it. Eric > == 1 of 6 == > Date: Sat, Dec 17 2005 3:54am [quoted text clipped - 8 lines] > That's what I suspected, i.e., a lack of parallelism. > Thanks for confirming it. Thanks for "confirming" suspicion of lack of parallelism are superfluous - Stephen H had told us of it: > Date: Thurs, Dec 15 2005 4:48am > From: "Stephen H" snip > The left front rotor measured at .697 on the outside > edge and .703 at the inside edge to start > With all of the debate about turning rotors I thought I'd do a bit of > measuring and documenting while doing a brake job. Here is my results. [quoted text clipped - 37 lines] > in the time between brake jobs by the pads than on a simple clean up on a > lath. anyway I installed new front rotors on my taurus today, turning the old ones was $20 ea, new ones was $27...guess I could've saved $14........ Oh well, maybe next time.. A couple years ago my brother asked me to fix his brakes, said they just quit workin'. The rotors were wore down through the vents, mustaben steel on steel for at least 10,000 miles..... wonder if they were past the minimum thickness.... > anyway I installed new front rotors on my taurus today, turning the old > ones was $20 ea, new ones was $27...guess I could've saved $14........ > Oh well, maybe next time.. Not worth the $14 "savings" IMO. John > anyway I installed new front rotors on my taurus today, turning the old > ones was $20 ea, new ones was $27...guess I could've saved $14........ Oh [quoted text clipped - 4 lines] > on steel for at least 10,000 miles..... wonder if they were past the > minimum thickness.... Seen that before; and had customers drive out of the store like that too! As for the Taurus, You did just fine Ford Taurus factory rotors were crap. Wouldn't hold a clean cut for 2 months. Almost all Taurus brake jobs would have pulsation when they came in and most cutting would help, but on a few they would come back. we learned new rotors were the only real solution. Even on My and my Mom's Taurus. SignatureStephen W. Hansen ASE Certified Master Automobile Technician ASE Automobile Advanced Engine Performance ASE Undercar Specialist http://autorepair.about.com/cs/troubleshooting/l/bl_obd_main.htm http://www.troublecodes.net/technical/ >>anyway I installed new front rotors on my taurus today, turning the old >>ones was $20 ea, new ones was $27...guess I could've saved $14........ Oh [quoted text clipped - 6 lines] > > Seen that before; and had customers drive out of the store like that too! there's laws about letting a vehicle leave the shop in that condition, regardless of how it drove in. you need to check into them. > As for the Taurus, You did just fine > Ford Taurus factory rotors were crap. Wouldn't hold a clean cut for 2 > months. but that's the point guy!!! you get /trained/ to skim disks as the "solution", but [and here's the point that i find fascinating] your experience contradicts what you were told! but you still /repeat/ what you were told! can you tell what's wrong with this picture? > Almost all Taurus brake jobs would have pulsation when they came in > and most cutting would help, but on a few they would come back. we learned > new rotors were the only real solution. Even on My and my Mom's Taurus. >> Seen that before; and had customers drive out of the store like that too! > > there's laws about letting a vehicle leave the shop in that condition, > regardless of how it drove in. you need to check into them. Realistically, there isn't much that can be done. The customer can't be forced to pay for repairs he doesn't want, and restraining either the customer or his property isn't allowed - those are crimes. If a peace officer shows up in time he can take the car off the road but a citizen legally can't (at least not in the US - in any state I know if.) When I was in aviation we would occasionally see planes in obviously unairworthy condition come through and all we could do was inform our FAA safety inspector. Mike ">> >> Seen that before; and had customers drive out of the store like that too! > > there's laws about letting a vehicle leave the shop in that condition, > regardless of how it drove in. you need to check into them. Some states yes, not this one (we wish there was!) >> As for the Taurus, You did just fine >> Ford Taurus factory rotors were crap. Wouldn't hold a clean cut for 2 [quoted text clipped - 4 lines] > experience contradicts what you were told! but you still /repeat/ what > you were told! can you tell what's wrong with this picture? It has to do with the quality of the OEM part. Sometimes they are better, other times (as in the Taurus) there worse. BMW, VW Volvo and now even Ford Focus have a extremely soft metal for the rotors. Replace them with the pads they wear that quick. SignatureStephen W. Hansen ASE Certified Master Automobile Technician ASE Automobile Advanced Engine Performance ASE Undercar Specialist http://autorepair.about.com/cs/troubleshooting/l/bl_obd_main.htm http://www.troublecodes.net/technical/ > ">> >>> [quoted text clipped - 19 lines] > BMW, VW Volvo and now even Ford Focus have a extremely soft metal for the > rotors. Replace them with the pads they wear that quick. I replaced the front rotors on our '85 Volvo with aftermarket rotors from NAPA and pads from Volvo when money was tight (the Volvo pads don't rattle like aftermarket pads do). Now the pads are about half worn and the rotors are severely worn. Mike > ">> > [quoted text clipped - 18 lines] > BMW, VW Volvo and now even Ford Focus have a extremely soft metal for the > rotors. Replace them with the pads they wear that quick. if you do a basic surface scratch test for these disks vs. others of "harder" metal, you'll not find much difference. what i know for sure is that some oem pads have a high silica content [with some aftermarket pad producers copying their lead]. silica is an aggressive abrasive. this is specified by the manufacturers you cite allegedly to eliminate disk glazing and cope with surface rust on salted roads, and it does have some benefit for those purposes. reality however is that it's all about life limitation. > As for the Taurus, You did just fine > Ford Taurus factory rotors were crap. Wouldn't hold a clean cut for 2 > months. Almost all Taurus brake jobs would have pulsation when they came > in and most cutting would help, but on a few they would come back. we > learned new rotors were the only real solution. Even on My and my Mom's > Taurus. The only Taurus experience I've had was on one my #2 son owned for a couple years. I didn't get into the brakes, but when he was in Montana the clutch went out. Turns out the clutch on the 2.4L 4 cyl is only 6 inches diameter! It seems to me the Ford strategy for cars (but not for trucks) is to make something that gives three years good service, and anything goes after that. Mike >>As for the Taurus, You did just fine >>Ford Taurus factory rotors were crap. Wouldn't hold a clean cut for 2 [quoted text clipped - 10 lines] > > Mike yes indeed! it's all about the first owner; all the others can go hang. buddy of mine used to work at one of their r&d facilities. all their time & money was going into cost control [which is ok] and life limitation [which is not, since the price differential between say ford & honda is minimal]. if a ford was 1/3 the price of a honda, i'd have no problem with it, but i'm wierd like that.
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