Maybe I will rant a little.My wife and I have two daily drivers.She drives a 2014 Jeep Grand Cherokee Diesel and I drive a 2015 Ford F250 Diesel.Love those diesels.About a year ago the engine light came on in the truck.I scanned the system and it said my particulate sensor was faulty.I went to my local Ford dealer who services the truck regularly and told him what I need.They said they would have to do scan to determine the real problem.I left the truck and when I returned, they told me I need a particulate sensor.I was handed a piece of paper that said $100 for the scan, $307 for the sensor and $50 to install.This scan only confirmed what I asked for when I went in.Begrudgingly I agreed whereupon they informed me that the part had not been available for almost a year and no one was sure when they would be available.I left and drove with engine light on, but I was contemplating selling the truck and needed to get rid of the light.Late last fall, I was in Syracuse and on an off chance, I went into a Ford dealer and they had one.I bought it and brought it home.They were as scarce in the US as in Canada.I hardly drove the truck all winter so never got around to installing it.Last week I took the truck in for regular maintenance and asked them to install the sensor at the same time.Simple huh?After two hours of trying to remove the old sensor, first they snapped it off and then tried an easy out and then handed me a bill for$200 and the new sensor still wasn’t installed.They suggested a new rear tail pipe with the preinstalled bung, I never asked the price and left.This sensor requires a 22 mm bung, looked everywhere, no luck, not even at Ford.I am still driving with the engine light on and looking for a solution.
Several weeks ago I took my wife’s car to Belleville and by the time I got there the right front wheel was smoking.I pulled in to a garage I have dealt with before and they were kind enough to look at it.It was determined I had a warped rotor, but they were backed up two days and I was an hour from home.I decided to let it cool down and go home, which I did.I was hoping it was a simple fix, so I ordered a rotor which even with the correct vehicle info, turned out to be the wrong size.I returned that rotor and went home to investigate further.The caliper is retained by two sliders with a hex drive head 13 mm.I don’t have a 13mm driver so back to town.Nobody has a 13mm hex driver of any type, so I go online and find a nice set at a reasonable price, so I order and a week later they show up.Every size in the book except 12 mm.Luckily a 5/8” is virtually the same size.Got the sliders out and the mounting bracket off, but the caliper was seized to the rotor.After extensive manipulations, they were finally separated.The pads were two pieces of charcoal.The pistons were seized and no matter what I did, I could not retract them off I go to CTC, order 2 rotors, a set of pads and a caliper.At this point I would like to mention that a complete brake job was done at a local garage only 18 months ago or 25K.No guarantee.I get home with the new rotors, pads, caliper and bracket, this is a pretty straight forward job, I probably should have done it myself 18 months ago.Well it takes about 10 minutes to mount everything, so why did it take two hours to do one side?Everything is new and should just fall into place, but every time I got things tightened up, the brakes seized up.After removing everything, checking, measuring and reinstalling the third time, I installed the caliper using the old bracket and ta-da, it worked.I decided to do the other side, and even though there was no seized caliper the the pads were like new, I wanted to keep everything balanced so I phoned CTC and ordered the companion caliper for the driver’s side making special note about the bracket.The next day I went to pick it up and discovered the ware house had sent the wrong piece, luckily there was a truck on the way and the correct piece arrived four hours later.Funny though, the exact same problem with the bracket, but I knew this time and had it fixed in a jif.
Wow Warren, it sounds like you hit the jackpot of incompetent mechanics. Have being in the trade for 30 years I can understand some of the techs decisions. Verify complaint, yep. But to leave your truck in worse shape then it come in and hand you a bill isn't really fair.
Oh yeah, warped rotors don't cause brakes to seize up and smoke.
Maybe I should open up my own shop............
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Wow Warren, it sounds like you hit the jackpot of incompetent mechanics. Have being in the trade for 30 years I can understand some of the techs decisions. Verify complaint, yep. But to leave your truck in worse shape then it come in and hand you a bill isn't really fair. Oh yeah, warped rotors don't cause brakes to seize up and smoke.
Maybe I should open up my own shop............
I,m with Mike,, Warren. Rotors wont cause the problem you had. Pulsing when stopping yes . Seized calipers will cause your problem. Sounds like they were trying out a new ,or old , "song and dance' on you. They weren,t very helpful toward the mechanics image. Its a tough enough trade without these kind of problems.
Sorry for the confusion. The first mechanic who checked and said warped rotor was just doing an initial assessment. He really hadn't tried to determine the cause, he was working on another vehicle and just took a moment to try to help me. Mike, you probably know him, he works at a heavy truck center just up Hwy 37. Very competent guys. It was when I removed the rotor/caliper that I found the seized piston. When I did the other side, the pads were like new, at least double the thickness of the damaged pads. Don't want to fault anyone who was only trying to help.
may want to check your choice of tools first you said 12 mm then it was 13 mm then 5/8 which is no where near a 13 mm.just saying.watching for the smoke signals
Actually, warped rotors do not cause pulsation, the caliper can move back and forth on the sliders when working properly. What causes pulsation is when the caliper fails to release (sticking piston or slider) and the car comes to a stop, the heat trapped under the pads heats up the rotor and effectively "heat treats" that section of rotor. Over time the rest of the rotor wears and the hard spot does not which creates the vibration when the pads hit the fat spot. We did some Rockwell testing of rotors on police cars years ago to try and figure out why some units got 25k on rotors and others got 8k. Turns out it was the driver holding the pedal down at the lights after a full stop that hurt the parts, not the high speed pursuits. Nothing to do with the original problem but a "nice to know" for everyone.
A friend was just telling me about this problem. He said to fasten a dial indicator on and turn the rotor. You will see high and low spots. Then there are different quality rotors. You can get cheap from China and you can get good from China. It all comes down to the price.
Actually, warped rotors do not cause pulsation, the caliper can move back and forth on the sliders when working properly. What causes pulsation is when the caliper fails to release (sticking piston or slider) and the car comes to a stop, the heat trapped under the pads heats up the rotor and effectively "heat treats" that section of rotor. Over time the rest of the rotor wears and the hard spot does not which creates the vibration when the pads hit the fat spot. We did some Rockwell testing of rotors on police cars years ago to try and figure out why some units got 25k on rotors and others got 8k. Turns out it was the driver holding the pedal down at the lights after a full stop that hurt the parts, not the high speed pursuits. Nothing to do with the original problem but a "nice to know" for everyone.
Warped rotors do cause vibration. I understand what you're saying but the caliper won't slide back and forth fast enough to compensate for the warp. Usually when they warp the rotor will go out of parallel too. The other thing that happens is hot spots occur like you described. The coefficient of friction changes at those spots causing a vibration. Either way the rotors need to be machined or replaced.
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I guess it may depend on the brake set up, the Crown Vic's would tolerate almost a full quarter inch "runout" without any perceptible vibration. The highspots were noticeable at .0010" and you could easily tell that the pads had been roasted under pressure because the resins were baked out of the pads and they start to flake around the edges.
