Having just gotten reamed by the auto mechanic I was going to make this a pit thread but instead decided this was more a matter of opinion. I had to have some pretty expensive services done on my car the other day, yet despite the fact I was already being billed nearly $2,000, the mechanic was trying to scare me into getting major brake service I know I didn’t need.
Ignoring the fact I know the mechanic was lying to me about the condition of my brake pads (because I know how much life my pads have left and I change them myself), I got to thinking about something, which is the resurfacing of the rotors they always want to ding you for. While I understand that your rotors COULD get warped and have all kinds of other issues, it has been my experience that if you have the smallest nick or groove in the rotor, they demand to resurface it. I think this is a total scam which is only made worse by the fact that they often claim there “isn’t enough surface left” and that you need brand new rotors.
For years, before a friend showed me how to work on my car, I kept getting dinged for a new air filter every time I had an oil change as well, but now I am wise to that one too, or if it is really bad, I get the thing myself and replace it in about 10 seconds.
So, what I’m asking here is: What other things have car mechanics done to your car that you later either felt was a scam, paid WAY too much for, or was something you found out you could easily do yourself without being particularly mechanically inclined? I’d also be curious to get some feedback from the rest of you on this rotor resurfacing issue…
As a side note, once someone showed me how to do my brake pads myself, I couldn’t BELIEVE how stupid I felt for going to brake shops to have this work done. In fact, I can’t figure out how they even come up with their prices. The pads are $30 (and then free for LIFE thereafter), it takes me less than an hour to do it, and the mechanic charges $60 an hour and can surely do it faster…so how is it that a front brake job is $200+? Must be that ‘new math’.
Hmmm, in terms of the sort of scamming that you’re referring to, I think pressure to replace axles when it’s only the CV boot that is bad. I had a cracked boot which I (shamelessly) drove on for at least a month assuming I’d have to have the entire axle replaced anyway. Later, when Friend-of-Family-Car-Dude and I finally put the car up on jacks, we discover it was the teeniest possible tear. I replaced the boot and have been driving on it ever since. Not a peep from those axles! (Knock on wood.)
The one that pissed me off most outrageously was when I was driving a real POS and working two-jobs with crazy hours. My rearview mirror bit the dust and I was tired and overworked but had extra cash so decided to have the mechanic do it…First, they said that the replacement kind would have to be special ordered (for a junker like that I wouldn’t have cared if he taped tin foil on the dash- I just wanted it done.) Then it was special ordered and super-expensive to replace the “bolt setting.” Finally when they’d been holding the car hostage for days, I asked nicely why exactly they couldn’t just install the $11.95 kind from Advance Auto??? There was hemming, there was hawing, they didn’t want to give my car back to me, etc. so I went to Advance, bought the mirror, went back, installed it myself in their parking lot. Told them I would never and I mean never get yanked around at their garage again and went off with my nose in the air.
It didn’t fix my injured pride- the condescending tone of “Well little girl, what you’re gonna need is X,Y, Z and Bubba and I are gonna help your sweet little self out…” still rankles, but the nose in the air bit did help…
I can give you some example why you should have your rotors turned everytime you do the brakes. Your brake will work just fine without being turned but your braking efficiency is reduced. The nicks and scratches you speak of in the rotor face will wear into the brake pad too. This can cause the pad to overheat, especially if you drive aggresively or are driving mountain passes. This excessive heat is tranferred to the brake fluid and can cause it to boil. The rotors also glaze over from use. When you install new pads with glazed rotors, you will require more breaking force to stop the car for a few thousand miles. Besides the extra heat, the pads will also glaze. Check pads that have about 20,000 miles and were broke in with glazed rotors. See all the cracks in brake pad material? That is your brake pad material failing. I have seen cars with less that 10,000 miles on the pads have brake failure from the pads not being broke in correctly. Once those little chunks of pad start braking off around the edges, the pads won’t last very long.
I thought I knew quite a bit about brakes, I have attended work shops sponsored by Raybestos and built my own braking systems for race cars. But I learned a lot more when I attended the Bob Bondurant school for high perfomance driving. We spent over 4 hours just on braking systems and how they work. I wish I would have gone there before I quit racing stock cars.
There are products out now that allow you to “turn” your own rotors. It is basically sandpaper with a double back tape applied. Cut the paper to match your pad, stick them on the pads, reinstall and lightly tap the brakes while the car is running and in gears. This would appear to me to be an accceptable method if the rotors themselves are not turned. I can have rotors turned for $15 a pair which is less than the $30 they are asking.
My own experience with very slightly grooved rotors is there is no noticeable difference in braking capability (albeit I can’t say that I’m not putting some extra foot lbs of force on the pedal without realizing it. I don’t drive very aggressively, though I do have a heavy car ('96 Impala SS). Please educate me on this glaze phenomena. What exactly is the ‘glaze’ made of? Are you just taking about road grim that builds up on the rotor you can wipe off when you are otherwise changing the pads? I’m glad I’m hearing this from you as opposed to the auto mechanic. If it had been him, I would have told him that perhaps he should stop confusing his automotive and donut knowledge and I would have joked I probably need ‘headlight fluid’ as well.
I watched a quickie lube oil place pull out my air filter and crack the plastic head off of it. He then brought it to me and tried to tell me that it fell apart in his hands. I reamed the manager, had them button up my car and had the oil changed again somewhere else.
Also had a battery cable go bad on me once. The cable itself was $20, replaceable in well under 30 minutes, yet the mechanic tried to charge my gf at the time for 2 hours labor and about a 200% markup on the part itself.
My brother managed a service shop for quite a while… One of those national brand-name type places (Starts with S, ends with s, and has an ear in the middle, if you roebuck I’m talking about…)
In many cases they HAD to recommend X or Y which they knew was not totally necessary but was the “ideal” way to do it. Why? Fear of litigation like about everyone else in this society. All they had to do was ONCE not recommend that Mr or Mrs yokel not get the rotors turned and a subsequent brake failure would land 'em in court for negligence…
I’m not saying there aren’t a goodly dose of A*holes out there ready to BS you about what you need, but especially at the they have to say based not on profit but on fear…
Tis true that some shops try to suggest sell additional services, but that is their job! In that sense, I’m only making reference to those your whatsit looks like it will only last another 500 miles, why not let us change it now suggestions, not unnecessary service.
Back to the rotor turning issue-I have mine turned every other pad change for two reasons: it eliminates runout from the slight warping which occurs and I’ve got to pull the rotors off anyway if I’m going to repack inner and outer wheel bearings. I do the bearings while the shop is turning the rotors, so the whole job takes perhaps 2 hours. Seriously-my truck has over 350K miles on it, and I’ve put one replacement set of bearings in the front end, and replaced two tie rod ends owing to regular chassis lubrication.
In response to Yarster’s request as to the make-up of the glaze that seems to be so often in question, here goes.
Considering the effect of sandpaper on a metal surface you could simply say that the brake pads themselves act like a very fine sandpaper during normal use. This tends to leave the surfaces of the rotors looking glassy after several thousand miles. No way to get around it, that’s just is the nature of the design of brakes in general, (Drum brakes as well), so don’t think your rear brakes are not worth checking as well.
racer72 has almost all the right reasons covered nicely except, for the most inescapeable variant. Drivers habits. I have a close friend with a 2000-ish volvo that was in need of brakes just slightly after the 12,000 mile warranty period ended. Volvo refused to offer any help so he asked me for my assistance. (I really don’t like foriegn cars but, decided to help as he was nearly desperate). When I checked the pads it was apparent to me that for some reason either the calipers had stuck in the applied position, (I’ll get to this in detail in a short), or, he was “driving with two feet” as it is commonly referred to. Neither was the case when I checked the car and quizzed him about his driving habits. So, I checked the calipers and the hydraulic lines that they are connected to and found no possibility of a stuck caliper. I replaced the pads, resurfaced the rotors and, sent him on his way. It wasn’t until a few months later I figured out how this condition happened to his car so quickly. He simply has his foot ready to stop the car and, partially applies the brake as soon as he takes his foot off the accelerator. I noticed this while riding with him to a friends house. He absolutely had no idea of what it meant to “coast” or just apply the gas lightly in residential areas. It was on the gas then, on the brake. I explained to him after the ride that, the noxious odor coming from the wheels was a good sign that he needed to brake a little less often and not for extremely long stretches, (Like half way down the block on the way to a stop sign).
Someone had previously mentioned “runout” which is a good reason to turn the rotors but, can be spotted by a shaky steering wheel during braking if it is bad enough. Often times a slipped belt in the tires can be the source of a shake so, pay attention to when you get the symptoms of shakes. If it shakes while you accelerate, coast, turn or stop will all be indicators of other possible problems. IMHO, parallelism is the single most important reason why you should “resurface” or, “turn” the rotors each time you replace pads. As you stop your car, you apply a great amount of heat to the brake pads and rotors. This action of heating and cooling the surfaces tends to cause them to change shape over time and, will reduce the ability of your car to stop evenly on any road. Worse on slick surfaces so, if the pads when originally new placed 50% of the front wheel stopping power at each side then, after pad change you could end up with one side wearing out very quickly and the other not showing as much wear, (That’s if you didn’t turn the rotors).
Hydraulic proportioning valves tend to take up the difference in a system as it wears leaving one side more glazed than the other. Adding new pads to this old glazed system will make the differences grow larger and possibly overload the fluids ability to dissipate the heat created while stopping. That’s why you end up with bad pads so soon after replacing them. (I think racer72 noted this as well).
I did say that I was going to touch the topic of stuck calipers and, here it is. Calipers do not stick quite as often as the chain stores would like you to believe. Calipers are basically composed of two moving parts. The hydraulic piston and, the caliper body. Yes, the caliper on most cars must move itself in order to help stop the car. It moves along a channel or, slide, (Typically), and this is where the large portion of sticking occurs. So unless you have a multiple piston caliper, the body of the unit moves during braking. If your mechanic tells you the caliper is stuck then ask him if it is just the slides that need to be repaired or, if the hydraulic piston is frozen. I’ll mention that in order to remove the pads in the first place, you will have already loosened up the slides! Perhaps they can be freed with a minimal amount of trouble. Hydraulic freezing is indicitive of a badly contaminated system that will need more than just the calipers replaced.
So, I guess to make this long story find a meaning, TURN the rotors when you replace pads. If someone tells you the rotors are too thin to turn or, the grooves are too deep to safely remove there probably is some basis for it. I admit it is difficult to carry a caliper with you to inspect the rotors thickness and then compare it to the specifications in a service manual if you are a “do-it-yourselfer” but, if you have the time, consult a shop manual and, have a look for yourself. There are some black and white specs for each and every car.
Agree… I’ve probably done over 20 brake jobs during the last 20 years, and I have never resurfaced a disc or drum. If I thought a disc or rotor was bad (warped, grooved, rusted, etc.) I would simply replace it. It’s a very simple job.
I put 200k miles on my Explorer. I replace brake pads every ~25k miles or so… every other time I replace them I just buy new rotors. They’re only 30 bucks apiece. 60 dollars of maintenance cost every ~50,000 miles or so is literally nothing for the lifespan of my car.
Exactly my point. Why screw around with machining a rotor or drum when they’re only $30?? Of course, I might have a different opinion if they were double this price, and for some vehicles I suspect they may be…
While all the brake experts are here, one more question.
This past summer I put on new pads and rotors (all disc brakes) on my 98 Mazda 626. I can’t recall the brand names, but I did not go with the cheapest options for either pads or rotors. I think they were pretty expensive actually… After about a month the front brakes (one much worse than the other) started to squeal when applying light pressure. I did confirm the part numbers, and the fit is great from what I can tell.
From what I read, this could be a few things. Glazing, or possibly the leading edge of the pad is touching the rotor first and causing the pad to vibrate. I did take the pads out and wet sand them lightly with brake cleaner which did stop the squeal for a month or so, then it was back. Interestingly enough, the squeal went south for the winter but it does come back a little on warmer days. Spring is just around the corner though
I’d be interested to hear what you folks think about this…
Let me toss in a few things here about rotors and brakes, since this thread has kinda gone that way.
On turning rotors This is not a universally recommended practice. There is at least one carmaker that does not recommend turning rotors, under any conditions. They recommend replacement. The reason being is that most off car brakes lathes are not accurate enough to grind the surface flat and parallel as accurately as a new rotor. I can attest to this. I have seen cars come in for a brake job with no vibration and after the brake job with rotor turn develop one. I was even involved in a study where we looked at turning rotors with an on car lathe, and determined that there was overall no warranty cost savings (to the car company, we were only looking at warranty) Also, the other argument for not turning rotors is that every rotor has a predetermined (by the guy that designed the brake system) a minimum thickness. If the rotor is worn below this thickness, there is not enough mass to dissipate the heat generated. The more metal removed by the brake lathe, the less metal remains for the pads to wear away. In other words, the more you turn the rotors, the more often you will have to change them. A term I heard once at a brake seminar is “precious metal”
The arguments for turning are:
[li]Remove scoring (brakes going metal to metal)[/li][li] Remove normal wear (concentric light ridges)[/li][li]Relieve warpage/ parallelism problems[/li][li]Remove hot spots[/li][li]Just generally a good idea[/li][/list=1]
Based on my years of experience of working on cars (both my own and other peoples) I will agree with #1. The others have in my experience, on the cars that I work on, do not yield good results.
On the bad things that will happen if you don’t resurface rotors
Well first off if your old pads have not gone metal to metal there will be no scratches on the surface. Normal wear will put some concentric grooves (the surface looks wavy) Nicks would only be on the rotors from something impacting them and if this is happening, you have other problems. Of course the pad will wear into the concentric grooves (takes a few miles) at that time 100% of the pad will be in contact with the rotor (same as the old pad)
This will not cause the pad to overheat, over use of the brakes causes the pads to overheat. Yes if you overuse the brakes the fluid can boil, this has nothing to do with whether or not you turned the rotor 5,000 miles ago.
This comment is just flat wrong. The force required to stop the car from say X mph will require the brakes to dissipate Y amount of energy. This is not affected by the surface condition of the rotor (assuming a smooth surface of course) It may require a slightly higher pedal effort to develop enough friction to dissipate the energy. Think of it this way. If you took a phonograph turntable with a felt top, and turned it on you could stop it with your finger. You would have to press down with X amount of force (brake pedal pressure) to generate enough braking force to overcome Y amount of torque from the phonograph motor. If you then placed a record covered with WD-40 on the turntable and repeated the test it the finger pressure would increase, as the surface is much slippery, but you are still overcoming the same amount of torque on the motor.
As I have said before, it is overuse of the brakes that causes pad to overheat. Pad cracking can be traced to either brake overuse by the driver and/or the use of inferior (or inadequate for the usage, if you prefer) pads. I cannot recall the last time I have pulled cracked pads off of a car that had had quality pads installed previously. It has also been years since I turned a rotor.
Glaze as used in this context is used to describe the shinny surface that is generated when a brake pad burnishes a rotor surface. The people that want to turn rotors say, “But look the surface is all shinny and smooth, and therefore has low coefficient of friction.” The people that don’t turn rotors say “Yep you are right, but just what do you think a set of brand new rotors will look like in about 1,000 miles? BTW the stuff you wipe off is called brake dust. Oh, and you do need headlight fluid, I just checked.
On **Mechanical Man’s **comments about driver habits is 100% correct. The only thing I would add is location can have an effect also. I worked at one dealership where the average brake life was 15,000 miles. I moved to another dealership, same cars, same pads average pad life was 10,000 miles I moved to a third dealership and the average (again same cars, same pads) went to 20,000 miles. WTF? First dealership was in the San Fernando Valley with a stop light every few blocks, the second was in West LA think stop light every block, the third was in Suburbia, with a stop light every couple of miles. Think about it.
Let’s define some terms here for those that aren’t real deep into automotive stuff Run out is where the surface is warped (think of a record that got hot in the sun) Parallelism sometimes called thick/thin variation. This is where one part of the rotor is thicker than another. Both of these will cause vibration!
I am not sure just what you are trying to say here. I find it reasonable to expect that if two new rotors were installed on the car with new pads that over the life of the pads the wear, heat and other factors that the rotors are exposed to would be equal. Therefore at pad change time, while the rotors are not new, they should be equal, and therefore the new pads should wear equally. At least this is what I have found over many years of experience.
If I am reading what you wrote correctly you are saying that they hydraulic proportioning valves work side to side on a car? Not on any car I have every seen or studied. Proportioning valves vary the pressure front to rear so that one end of the car does not have the brakes lock before the other. Please give me a cite for a car that has side to side proportioning valves.
I agree with most of this. Chain stores do have a bad habit of selling way more calipers than is necessary. We used to go to customers and ask them if they had their last brake job at MAS MUF*R? Yes, they would reply, how did we know? Because your car has 30,000 miles and 4 rebuilt calipers. Compare that to in 6 years at a dealer I changed 3 calipers total, all for leakage. As far as your comments about stuck pistons is concerned you are correct. Your comment about slides is not correct. If I can retract the slides when removing the pad that does not mean that the slides will be free enough to keep the pads wearing evenly in use. If it takes me 15 lbs of force to move the slide it is not free enough to work on it’s own. It has to clean and free moving. Sometime this means a wire brush (free, part of the brake job), sometime it means that a rod, or boot needs to be replaced ($).
It’s apparent that there is something less than unanimity on the merits of machining rotors at each pad change. For those who change pads and neither machine nor replace your rotors, do you literally do nothing to the rotor? Or do you rough it up with sandpaper?
The reason I ask is that every Haynes Manual I’ve read recommends that if you don’t get them machined. They strongly recommend machining(red flag?), but say that if you can’t or won’t do that, you should at least give it a swirl with sandpaper.
Any thoughts on this practice?
How, and how precisely, are rotors chucked up in the lathe when they’re machined? It would seem that the various surfaces need to meet three criteria when they emerge from the shop (all within certain tolerances):[list=1][li]Flat;Parallel to one another;Perpendicular to the wheel’s axis of rotation[/list=1]Items 1 and 2 should be easy unless something’s seriously wrong with the lathe. Number three seems a bit more sensitive.[/li]
I bring this whole issue up because I once took my rotors in to have them machined, and they came back with #3 seriously not met. The surfaces were quite flat, and parallelism wasn’t an issue - I checked all around with a micrometer and they were parallel to within 0.0002" or so.
However, runout, when measured once I put 'em back on, was about 0.020" on one side - about double the tolerance. The plane of the faces wasn’t normal to the axis of rotation. Steering wheel shook like hell under heavy braking.
My supposition is that the guy was just sloppy when he put it in the chuck, but I don’t know - maybe that’s just one of the perils of off-vehicle machining. How is the disc mounted in the machine?
That is exactly why my company does not recommend the machining of rotors. We have found that in a significant percentage of the cases on our cars that the lathe introduced an excessive run out, where none existed before. What this meant for the dealers was, the dealer sells a brake job with rotor turn. Customer comes back with a vibration. Dealer installs new rotors and eats cost and labor. Not a winner from a profit, or customer satisfaction point of view.
I have even gone so far as to set up a dial indicator on a rotor installed on a brake lathe to show how much run out is present.
As far as roughing up the rotor goes, it depends on the technician. Some guys do, some guys don’t.