2009 Ford Flex: DIY Brake Pad and Rotor Change
August 13, 2010
By now you've heard all about the front brakes on our 2009 Ford Flex Limited. Amazingly, the front brake pads have lasted over 60,000 miles, and there's still a bit more meat left. But the rotors have developed too much 'disc thickness variation' or DTV. It's not warping from overheating -- we wouldn't have surpassed 60k with such hard use. No, this moderately-driven family-mobile has a classic case of cold judder, high spots on the rotor built ever-higher by gradual pad material transfers.
One way this can happen begins with rotors that start off with imperceptible high spots, and then spend their lives in a driving pattern that's dominated by long freeway drives with infrequent brake use. You know -- road trips. Our Flex is the go-to road trip vehicle around here, so it's been on more than its fair share of them.
Anyway, over time the retracted pads can start to lightly brush the tops of those high spots, and a minute amount of pad material transfers to the disc. The high spots get a little higher and the deposition cycle repeats. Then, at some point, the driver lightly applies the brakes on a freeway off-ramp and gets a handful of steering wheel shake for his trouble. Some of the deposits wear off, so the shaking doesn't persist around town. But the high spots got a little higher in the process, so the same thing happens again -- easier this time -- over the next long-haul open-road stretch. The subsequent shaking while braking gets more noticeable over time. We've been living with this on-and-off for the last 10,000 miles or so.
But we've had enough. It's time for new pads and rotors. Yeah, rotors can be machine-turned on a lathe, but when you're done they're thinner and have less remaining thermal mass. If the price is right, I'd much rather install new ones. Doing it myself allows me to divert the labor savings into the cost of new parts. And I can't turn a rotor myself, but I can bolt-on a new one. Besides, 60,000 miles is a good run for a rotor.
On top of all that, changing front pads and rotors is deceptively easy on most mainstream cars -- easy enough to be enjoyable. Our Flex is no exception. Jump to the next page to see my Ford Flex brake pad and rotor change walkaround.
Sliding calipers like these have two pins on which the caliper slides. Usually, it's only necessary to remove the bolt that screws into the lower one.
NOTE 1: For reasons you'll see later, do one side from start to finish before doing the other side.
NOTE 2: Since you're doing one side at a time, do yourself a favor and turn the steering wheel so the caliper faces out.
With the bottom bolt out, the caliper pivots up on the upper one. The rubber hose gains even more slack while we do this, so there's no need to disconnect any hydraulic lines. The hose issue is THE reason why we're removing the lower bolt and pivoting the caliper on the upper one.
NOTE: If you get to a point where you think you have to disconnect a hydraulic line, you're probably doing it wrong. Seek professional help.
The sliding half of the caliper pivots so far up that we don't need to hold it up. In cars where it won't go quite this far over-center, a tie-wrap (or a friend) can be used to hold it out of the way.
At this point, the pads are just sitting there, nesting in the retaining clips. Pulling them out is easy work.
If we were only changing the pads, We'd put the new ones in right now. But we're changing rotors, too, so we're going to wait and do the pad part later. For now, close the padless caliper and make sure to keep anyone and everyone away from the brake pedal from this point until it's all done. Not even a little bit.
The slider bolt (yellow) is back in place, but it's only spun in a couple of turns. Now it's time to break out the big socket to remove the two bolts that secure the entire caliper assembly. These will be tight -- about the same as lug nuts. Here a 1/2-inch-drive breaking bar provides adequate leverage.
The first bolt is out. Now we have to remember to support the weight of the caliper with our free hand as we remove the other one.
We don't want to lay this thing on the ground, because that would make it necessary to disconnect a hydraulic brake line. Big no-no. Instead, hang the caliper from the spring using a chain of tie-wraps. An upper control arm works on cars that have those.
With the caliper out of the way, it's time to attack the rotor. Ford uses a Torx-head bolt to keep the rotor in place when the caliper is off. This isn't a critical part once the car is in service, but it keeps the assembly line workers safe when the car is on the line between the 'rotor on' and 'caliper on' assembly steps.
This bolt can be difficult because of the heat cycles and the rust that can build up after 60k miles of use.
In this case, my T40 Torx didn't fit at first, so I thought it was a T-35. I was wrong. The T-35 I bought was too loose. A solid rap with a mallet seated the T-40 in the bolt head and it came off easily.
Once that bolt is out of the way, the rotor comes off easily.
The new rotor simply slides over the studs. And look, there's no place for that retaining Torx bolt. Spin on one of the lug nuts instead, finger tight.
Time to cut the tie wrap, remembering first to support the caliper so it won't fall and ruin everything.
Then we re-seat the caliper, re-install the two large caliper retaining bolts and snug them down fairly tight. We'll torque them for good a bit later.
Now we can finally re-open the caliper and get back to installing our new pads.
New pads almost always come with new clips. These are the points where the pads slide back and forth during use, so it's important to replace them. There are no retaining screws -- they easily snap in place. It takes seconds.
The ears of the pads nestle onto these runners. It's a sliding surface, so the places where the pads will make contact need to be coated with the supplied graphite-based grease. It can be applied to the clip or the mating ears of the pads. Either way works.
Here are the new and old pads. There's a little meat left, but not enough to keep them. Meanwhile, the new pads have two slots to the originals' single one. No biggee. These are still the correct pads. Ford engineers could have made this small running change for any number of reasons.
Thankfully, the new pad backing plates have riveted-on shims, so there's no need (in fact, no possible way) to smear the space between with more graphite lubricant. And the surface you're looking at even has a rubberized coating of some sort. Noise-wise, they've covered all the bases. For the DIYer, this is about as easy as it gets.
The new pads slot into place as quickly and easily as the old ones came out.
But the dual pistons shown here need to be pushed back in. They're sticking out because the old pads were thinned by use. The new pads are of course much thicker.
Don't laugh, this works. Sure, we could buy a piston retractor tool for a good piece of change, or we could pry the pistons back in like this.
The soft wood makes it easier to avoid nicking the rubber seals, and the width of this two-by-four allows both pistons to be pushed in at once. They have to go in together because, if one were pushed in singly, the other would pop out.
This is also why it is important to do one side of the car at a time. If both sides of the car were in this condition, the pistons on the other side of the car would pop out when the pistons on this side of the car were pushed back in.
The brake fluid in those pistons is being pushed back into the master cylinder reservoir through tiny passages, so the going is slow. It takes a couple of minutes. Steady pressure and patience are the key. In this example, a second plywood shim was added near the end to fill the ever-increasing gap.
While the pistons are being pushed back, the brake fluid level here will rise. Check often. This is more of a concern when the second brake is being done, because the combined fluid volume of two calipers is what will likely push this over the brink.
Overflowing will certainly be a bigger potential problem if the fluid level was ever topped off to the 'MAX' mark during the course of those first 60k miles. This is why the brake fluid reservoir shouldn't be topped off like that. The fluid level naturally goes down as the pads wear. Let it be. It's not leaking out. As long as it doesn't go below 'MIN', everything is cool.
Here, no fluid was added over the 60k miles these pads lasted. And so when both sides were done the fluid level came right back up to the 'MAX' mark, but no farther.
If the level does push past the 'MAX' mark, a turkey baster works best to remove some. Don't forget to permanently remove it from food preparation service -- buy a new one for the kitchen.
The pistons have been fully retracted and the seals are undamaged. Almost done.
The pistons have been retracted far enough, so the caliper slips over the pads with little drama and no effort.
Time to re-install and re-tighten the slider bolt.
Lastly, it's time to torque the caliper mounting bolts good and tight. Why do this now? It could have been done when the caliper was re-mounted, but there's something to be said for going through the torquing ritual at the end, to avoid second-guessing and make sure it gets done.
Done. Time to straighten those wheels, remove that lug nut and re-mount the tire.
And torque those lug nuts, of course.
Now it's time to move on to the other side of the car and do it all over again.
How much time did this take?
If I hadn't been stopping to take pictures, this entire job (both sides) would have taken just under 30 minutes. Few actual tools are involved. The T-40 Torx bit is the most exotic one here, but a torque wrench is a must for those caliper bolts. But any DIYer who so much as rotates their own tires should have one of those. If you don't have one, get one!
How much did this cost?
A set of Ford Genuine front brake pads cost $66.63, plus tax. As for the rotors, I had a choice at my Ford dealer: Ford Genuine rotors for $83.30 each or Ford Motorcraft factory-approved replacement rotors for $48.85 apiece. Since saving money is part of what DIY is all about, and since the Motorcraft ones still wear a Ford label, I went the cheaper route. Once I got them home, I noticed the Motorcraft rotor boxes wore the 'Made in China' label. Not sure if the same is true of the 'Ford Genuine' ones. I never saw the box.
Total parts cost: $164.03, plus tax. In this area that's 9.25%, so my total was $179.20.
Why go with Ford parts and not cheaper aftermarket stuff? Ford knows more about their vehicles than the replacement market does. They know their own brake system's noise, dust and wear susceptibilities better than any outsider could. And these factory parts lasted for over 60k miles -- well above average, in our hands, no less -- so that tells me that the Ford Flex brake engineers did their math right.
Dan Edmunds, Director of Vehicle Testing @ 61,180 miles (when I did the job)