Rotor spec for your car is 1.102 nominal, 1.024 minimum thickness. That means when machining my preference is to not go closer than .030 of the discard or 1.054 for the unofficial minimum machining thickness. Rotors of course can be machined off the car and have been for decades. However the preferred method for your car is to machine them on the car. That provides automatic correction for any wheel hub run-out. That's one of the reasons they are fastened to the hub with those two screws. The other reason of course is so that during initial assembly they don't fall off on the assembly line before the calipers are installed. But when you need to remove them, how does a tech do it? I have two methods. One is an impact screwdriver that operates by inertia. There are spiral groves in between the inner and outer portions of the tool, and when you hit it with a hammer and force it to collapse, the inertia of the outer half not wanting to start turning, forces the inner section to try t turn and tighten or loosen a screw depending on the tools setting. Almost every motorcyle tech will be familliar with this tool, they have existed since the 60's at the least. In fact mine is probably the oldest tool in my tool box, having purchased it in the early 70's. But it does not always work, sometimes the screws are simply too tight, and I break the screwdriver bit pretty often. That forces me to use the second method, which ruins the screw. I take a large center punch, and start by making a deep pin hole into the edge of the screw, without hitting the rotor. Once the hole is there, I move the punch to an angle to force the screw to turn by driving it with the punch and hammer. With practice this is really simple and has never failed to remove one of those screws. On a few occasions I have even been able to re-use them. Lastly, 1 1/16" translates to approximately 1.060 (about .030 for 1/32) IMO you would not have been able to machine those rotors successfully, as they would be getting too thin to allow for enough material to deal with the heat generated by braking. Plus six years old on a vented rotor, the rust that builds up in the middle cooling vanes prevents the rotor from cooling efficiently. Plus, the same rusting makes the rotor structurally weaker and prone to "crushing" which is one of the primary causes of rotor thickness variation. All those things together make it unadviseable to have not replaced these rotors when doing the brakes. At the same time we haven't talked about how good the calipers really are, and the caliper slides, how free are they? What about the rear brakes, did you check them? The parking brake assembly? How is the fluid, should it have been flushed? There is so much more to replacing brakes, than just simply slamming a set of pads. That's why you will never see my quote things like the "$99.00 brakes, additional work extra routine".

Rotor thickness variation is a condition that can be imagined as the two sides of the rotor not being parrallel to each other. This can be caused by a "crushing" of the rotor by the brakes. It can be caused by uneven wear. Or it simply could have developed over time from a combination of forces. This problem is normally felt in the brake pedal by it pushing back at you with a rythm consistent with the current wheel speed. Rotor run-out is often caused by debris (rust) being caught between the new rotor and the old wheel hub, or by improperlly torquing the wheels, which can bend the hub, rotor and wheel. There is always a chance that excessive heat build up from heavy braking without sufficient time for the system components to cool is playing a role as well. This by the way is the most common cause for the report that we often see where a new car keeps having to get the rotors machined. It's not the cars fault, it is how the driver is using the brakes in heavy traffic! We also have rotor delamination, or rusting if you will. This causes a combination of runout and thickness variation issues. Typically rotor thickness variation of .002" is plenty to feel when driving. Otherwise you would have to use a dial indicator, and mark the high and low points on both sides of the rotor to see it. Rotor runout's of .005 or less will normally give no real signs they are present as the calipers of today have sufficient movement built into the system to "follow" the rotor. Between .005, and about .009 you will often feel the pulsation, but quite often you will hear the brake pads "saw" on the caliper supports as they get pushed back and forth. This "saw" is the grunting sound you get on a light brake pedal application as the car moves slowly such as 15mph or less. As I alluded to in the beginning of this response, a good technician does not even need to put a dial indicator on a car where the problem is rotor thickness variation. He/she will feel that right from the drivers seat. However, the technician DOES need to use a dial indicator, and measure wheel runout, then remove the wheel and (for most cars) put the lugnuts back on and measure rotor runout, then measure the front hub runout so that this problem is repaired the first time. Sadly this is one of the times where the good technician that does the job correctly needs to be paid to do so, yet the allure of the "free" brake inspection often prevents them from getting good at it because many are rewarded for being fast and getting the work in and out and as "cheap as possible" which in some occasions turns around and bites them for the effort. For the record, don't do "free" brake inspections, but I fix them.

My way is not only LESS work, it's faster, and less expensive to the customer. What the customer would pay for a 4 wheel alignment on the car bucky posed would be the base menu price of $69.95 or whatever. This would be for a camber and toe adjustment at all four wheels, and a cradle adjustment if required, which is essentially a caster adjustment. Ironic isn't it, that the more creative, and experienced an automotive technician actually is, the LESS he/she may potentially actually earn. This alignment as I outlined would take approximately 50 minutes, allowing for a road test before it was performed to check for any pulling, vibration, and the steering wheel centering position at straight ahead. Then the suspension and steering components would be checked, tire pressures set and the machine set up on the vehicle. All adjustments performed, and then a final road test to confirm the vehicle is aligned correctly with the steering wheel centered. I asked about the "Ackerman Angle" which is commonly called "Toe Out On Turns". To check this angle during the initial caster swing you simply have to pay attention to how far you have to turn the wheels as the machine makes it measurement. Normally the machine will instruct the technician to center the steering wheels and it takes a starting measurement. It then commands the tech to turn the wheels to the right, somewhere in the area of ten degrees. Normally the RF wheel will achieve that turn first, and then the LF wheel will have to be turned just a little further. Now the machine commands the opposite turn. If everything is correct the routine will follow exactly the same, the LH wheel will achieve it's turn and measurement first, then the RF wheel will need turned just a little further. If "Toe Out On Turns" is incorrect, you will see something like the LF wheel achieve it's RH turn before the RF wheel does when turning to the right, and then again see it achieve it's turn to the left before the RF does. Typically when this angle is incorrect the tire shop, alignment tech see's a car with the front tires worn out so they replace the tires and perform an alignment. Then in a very short time the tires are worn out again, in fact so fast that the tires likely get warrantied, and the car goes back onto the alignment rack. What the tech see's is a car that is right in specs. At this point they don't have any idea why this happened because it's a very infrequent issue. Typically if the tech looks close enough he/she will see that the inner tie rods have different angles from the steering rack to the knuckles. Then putting the machine on the main screen page setting and turning the steering wheel, you would see the front end toe-in when turned to the right, and then you would see toe-out when turned to the left. (As in my example, or the mirror image depending on the problem) Here is another question. When adjusting camber by pivoting the knuckle at the base of the strut, what happens to the included angle?

Our Steelers didn't look too good in the second half of sunday's game. Hopefully they have brought back a few lessons that will be very necessary if they get to meet the Pats again this year in the playoffs. The Pat's look almost unbeatable. Now brakes. There are so many things that need to be examined here. Driving habits are important to the diagnosis. Heavy intown use, lot's of stop and go with little time for the brakes to cool off can lead to boiling of the fluid. This happens easier as the brake fluid absorbs water right out of the air overtime. Being a 2006 that would not be something I would expect to see, but that could be part of the puzzle. Question. When the problem happens, is one brake rotoir hotter than the other in the front? Are the front brakes both significantly hotter than the rear? I would use an infrared thermometer and actually measure brake temperatures during both a normal use situation, and then compare them to what is happening during a failure event. Could the pads show signs of whats happening? Not really. No more than what your description of the failure does. We need to seperate whether there is some type of hydraulic problem allowing air into the system, (very rare BTW without a visible leak) or if the brakes are dragging because of a mechanical problem on the car, or if they are dragging because of operator habits. Just like any other "investigator" all of these are possible until they are confidently ruled out. What other details can you tell us about the failure? This will be practice to assist the dealership in their re-creating the failure for testing. If you drove a certain distance today, how far would you have to go in order for the failure to most likely present itself? Does where you drive the car seem to have anything to do with the problem? In town, local highway, interstate? In driving in one of the previous situations, is the failure "Unlikely" to occur? (This is critical for the technician to get to experience the failure for diagnostics) Most of all DONT GUESS, whats wrong such as the way your post title starts, "brake calipers". If you go in telling them the calipers are bad, and they find a problem with them, they would replace them. But that could easily have nothing at all to do with the brake pedal problem! Stick to the symptom, what it feels like, when it occurs, and if there is something that you can think of that is likely to either get the symptom to show up, or not show up at all.