Brake Wear and Rotor Grooving

[elvan]

Hi everyone,
I've noticed that the front rotors have developed a groove. Is this normal? I've never experienced this grooving in any other vehicle that was equipped with disk brakes.
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The last time I was in for service (22k mi), the service advisor told me my rear brakes needed to be changed soon as they were down to 3mm while the front pads were still @ 7mm. He then stated that the vehicle had a rear brake bias. I thought he was full of it so I decided to pass on the brake job. Any feedback in the matter would be greatly appreciated.

 

[Dr Plastic]

Grooves and ridges are not normal (on a new-er vehicle) but do appear over time and indicates that you will need to turn or replace the rotors and pads.

 

[Napalm]

That groove usually indicates your pads are very worn and/or gone. There's is a nifty device on the pad as a wear indicator - it's a little metal tab that once the pad is worn - will ride on the rotor and make noise.

usually squealing. if ignored - it eventually either breaks off or folds over - and continues to cut into the rotor.

site unseen I'm going to go out on the limb and say your rotors can't be turned. this isn't a bad thing and you probably should have new rotors away.


Brake Bias - yes it is feasible and quite likely that this generation explorer has a rear brake bias. But that doesn't mean 50% + of the brake applied pressure goes to the rear.

it's complicated. rotor diameter, pad sweep area, brake caliper pot size, and finally line pressure are all part of that game. but most people focus on just the line pressure - or they see the size difference of the brake rotors.

So not knowing exactly what's on a the 11 model. I wouldn't worry to much on it, other than to say it is farily common these days for minivans, and suv's to be harder on their rear brakes. to the point where there are a few models on the road known for wearing out rear brakes fast.

that said.

get it fixed - better yet if you are even mildly handy do it your self. disc brakes are very easy. it's the inspections that you need to be aware of.

There's probably a good tech article about it in here somewhere but if not I will create one. I am rather particular about brakes, I also used to develop ABS systems.


Incidentally - since you've got 4 or so years on your explorer - please take the time to have the brake fluid completely flushed from the system. I'll make up a detail on that too.

 

[gatzdon]

If your brake pads were really at 3mm, you should have changed them. When they get that thin, pieces can brake off, reducing the braking surface. Your groove is from 'something' stuck under the brake pad, be it from the wear indicator, brake pad material, or road dirt.

Also, I found that my explorer seems to have a rear brake bias. I use the Adaptive Cruise Control often and I wonder if the cruise control favors the rear brakes for most computer controlled braking.

 

[Napalm]

New cars (since about 2008+) often have a feature called electronic brake force distribution. Think of it as ABS V2.0. in that the computer system, and the controler valve has the ability to apply differential pressures to each wheel. it's not just front and back, but all 4. added to that it means that before puslating the brakes like older ABS systems, it can vary the pressure at a wheel before it starts to skid.

Thus the pulsating is a last step effort to keep the wheels in line. Under hard braking that is.


However it also works with your stability augmentation system - such that if in a turn the computer wants to keep you in line it will apply some brake pressure to just one wheel, or 2 on opposite corners.

therefore this rear brake wear, can be attributed to many things.


Also - the explorers are probably closer to a 50/50 front/rear weight distribution than most other front wheel drive devices - as such there is going to need to be more brake effort at the rear than say in a ford taurus.

 

[elvan]

If your brake pads were really at 3mm, you should have changed them. When they get that thin, pieces can brake off, reducing the braking surface. Your groove is from 'something' stuck under the brake pad, be it from the wear indicator, brake pad material, or road dirt.

Also, I found that my explorer seems to have a rear brake bias. I use the Adaptive Cruise Control often and I wonder if the cruise control favors the rear brakes for most computer controlled braking.

The whole situation just seemed very strange. When the car had it's cooling fans replaced @16k , both the front and rear pads were measured to have 8mm remaining. Then at 22k, the rear pads have somehow worn away to 3mm. It's not like the Ex was driven any differently during the 6k miles.

 

[tmg19103]

OP says front rotors. There is a sticky and this is a known problem for rear. My rear pads are almost gone at 34k. Have gotten 50 to 60k on my other vehicles.

Can't wait to find the next problem....

http://www.explorerforum.com/forums/showthread.php?t=413677&highlight=rear+brake

 

[1995E]

I was glad I checked my brakes at 33,000 miles because the brake pads wore unevenly on both sides. This was with my 2011 Explorer XLT brakes. I only replaced the rears and my fronts are fine.

 

[Napalm]

Changing your brakes.

Part 1 - a disclaimer - I take no responsibility for any damage you do following these simplified instructions. However I will say I've never had any issues. I will also take the moment to say I've not replaced the brakes on a 2016 ford explorer, but they are 4 wheel disc with ABS, Electronic Brake force distribution, and stability assistance systems. All of which I have worked on with my own cars and other friends cars. I also take no responsibility for getting a person hooked on doing vehicle maintenance, purchasing tools, or anything else related to this endeavor.

Part 2 - shopping list and pre-job prep: Not just for the explorer but for any vehicle, I write this for any first timer as a guide. yes it's a bit much, yes I'm very very particular, and no most shops don't do things this way.

Brake rotors - I hate the centric company parts - and most other stuff made in China. I am unsure of their metallurgy and despite any sort of marketing claims, no car maker uses them as standard equipment. Even Kia. So despite the cheapness, don't cheap out here. I like Wagner, Raybestos, DBA, or any other quality name brand but please take a moment to check the box when you get them in hand. Example - I've used Oreilly store brand rotors on a car, they've been great. They looked and felt like the Wagner rotor they also sold - and the store brand box didn't say made in china.

Pads - Today I like anything that's a ceramic compound for daily driving. Now that's mostly a marketing term since almost all pads are ceramic to some degree - these are pads that's aren't labeled semi-metallic. For over 10 years not most OEM pads have been of the ceramic version for good reason. Any decent brand ceramic pad works and again I like to not skimp. Wagner, Raybestos, Hawk, are all good as are store brands that are made with them. Now pure performance brakes - well that's an equine of a different hue. Right now under my daily driver G8 GXP I use O'reilly thermo-quiet pads - now when I track that car it's Carbotech 1521's

other stuff: I like keeping a car of either PB blaster or liquid wrench penetrating oil - often used for getting the rotors off the hubs more so than getting bolts loose. Also keep some anti-sieze compound I like the copper based stuffs but any is better than none. I don't use brake quiet goo - I expect pads to come with rubber backs and in some cases shims. NON-chlorinated Brake parts cleaner is good, as is any other solvent like paint thinner. I do however prefer the brake parts cleaner.

Brake fluid - if your car is over 3 years old and you've never changed/flushed the brake fluid - it needs to be done. Brake fluid, with age, becomes some of the most corrosive substances on the planet. Next to Skydrol 3. They have similar chemistry, all the stuff that keeps the boiling point high and the flash point high for brake fluid (resistance to burning) and with an ester base is what makes Organic acids in the fluid (they are acids of Carbon, hydrogen and oxygen). it will take paint off, degrease bearings, start corrosion and in a pinch clean decades of oil out of cement - and well eat the cement. Now I exaggerate a touch, and I'm not a chemist but old brake fluid is bad. It is also gradually eating the brake lines, seals and etc in the brake valve body. This is why I tell people to flush them out. ABS controllers are not cheap, flushing out brake fluid occasionally is cheap insurance.

What to buy - well for DD use I like Valvoline DOT 3 stuffs. cheaper stuff might be OK but again, don't skimp. Look for higher boiling points - it's printed on the label. Now there are extremes, again if performance driving is your goal use something a bit more. When I track a Car I use either ATE brake fluid or I use MOTUL 600 if It's allowed. but DD use - cheap ole valvoline DOT 3 (and yes compared to the motul it's very cheap)

Brake lines - should be replaced after some time, I don't drive a car on public roads that has brake lines on it older than 10 years. In some countries this is an inspection requirement. (if the car is an actual antique I will inspect the brakes)

SS lines - NO you don't need them put that money toward better tires. Are they cool sure, do they help absolutely. I have them on my DD car - because I track it (road course not drag) not because DD use. Now SS brake lines, if made right, will indeed last a very long time. much stronger and more resistance to chemical wear. and if you want to get some for those reasons do that too. I've had great luck with one produced by Russel but there are other good company products out there.

Tools: AH yes this is the best part of car maintenance. Do you need a garage full and complete sets of _________ and a lift and . . . . . well yes, we all do. it's good for the economy too. But, reality you need a good jack - not the scissor one - and a good set of jack stands (they often come in pairs and you might as well get 2 at a minimum). Get a jack that will hold at least 1/2 the total weight of the intended car - to some degree more is better here. Example - a 2012 ford focus weighs in at 3100 lbs+/-. And 1 1/2 ton jack would be fine for that, since as you jack up a car the jack never sees the full weight of the car - since some of the wheels are still on the ground. Same would be true of your ford explorer - but in this case you'd want at least 2 1/2 tonnes. 3 would be nice. Jack stands - for an explorer size I would use 3 ton rated ones. mostly because for the minor price difference over the 2 ton ones you might as well. However (again in sets) 2 ton stands would suffice. 3 ton ones also tend to be a touch taller. Don't however run out and buy 12 ton stands - way over kill and spendy. IN a very very rare case If you have a harbor freight near you I actually do recommend their jacks and stands - with coupons.

You need decent wrenches - I hate harbor freight ones - mostly because when I go help a friend that has a set there's in invariably one size that doesn't fit it's intended label. But everyone should have them a nice set of combination wrenches, they don't have to be ratcheting, they don't have to be snap on, they don't even have to be polished. I will however plug SK tools here which is what I use at home if you want to shop american made and good quality stuff check out a page called Tool Guyd and they have a nice write up. I do really like the Autozone store brand wrenches for they price. Kobalt and Husky ones are equally awesome. Starting out, working on any car built after 2000 I'd start off getting just a metric set if money was tight. and I'd want a set up to a 19mm. If you can swing it get the SAE sizes too. I don't own ratcheting combo wrenches - they are nice, some are even well made but I make do without. I'll say you can make do without a ratchet and sockets but to be fair you should invest in some. for brakes you can do the job with 3/8 pieces - I prefer 1/2 drive but I also use 1/2 drive for suspension work. I have broken a 3/8 drive extension removing brakes before however I do think it was an isolated event. If you get sockets, and ratchet, get an breaker bar - you might have to wack it with a mallet - don't wack a ratchet with a mallet.

If dealing with fluid lines - get an actual flare nut wrench. save the effort, time, BS that is a smeared B nut and just suck it up and buy a set - again often metric. Autozone store brand ones do work fine - smurf Harbor Freight.

Other odds and ends -
Pick with rounded ends - for dealing with caliper piston dust boots.
Rubber mallet - for rotor removal and the occasionally wack on a breaker bar
cheater pipe - when your breaker bar isn't long enough and the moron that did the job before you used a damn impactor. or rust.
magnetic parts tray - just damn handy
magnetic pick up tool - for when you drop that caliper bolt and it rolls way under the car while on stands.
decent clothes to protect your self. No you shouldn't work on a car with flipflops on, but you don't have to have a pair of redwing boots either.
Eye protection - use brake fluid removes auto body paint imagine what that will do to your mark 1 eyeball.

Before doing any job the first time - make the time to try and scope out of you might need other bits. Example - what sizes are the bolts for the calipers on the car - is it some odd ball thingamabob. Great example, the last Audi I touched for track prep used e45 (external torx) bolts for the caliper body bolts. amazingly I had one from another project but I'd never seen that used before on brakes. Mazda used to like 8mm hex head cap screw. so take some time - jack the car up take the wheel off and see what your getting into. THERE IS NO SHAME IS LOOKING AND DECIDING THIS ISN'T A JOB FOR YOU. there are many things I won't touch myself just because I don't want to or I don't have the tools and space.

I'm sure I've left out something - and again this is just a guide from a mildly educated azzhat with some opinions. I'll out lay my process for disc brakes but surely there's a guide on here

 

[chefduane]

Do this ^^. Follow Napalm's directions (or do a search here) for installing new pads. Pretty simple even if you are just mildly handy. Probably an hour or so tops for all four wheels. Much quicker if you have a Harbor Freight impact wrench and stands. If the rotor grooving bothers you then swap the rotors also. Just an additional few minutes to get the caliper off and swap them. I did all four of mine some time ago with Wagner Thermo-Quiet pads and Raybestos disks. Pads and rotors were $142.28 (including shipping) total from RA. Wagner also runs brake rebate specials from time to time. Do it yourself - saves time and money and you get all new brakes to boot.

PS: The only other thing I might add to Napalm's post is - if you can take the time to find a posting with pictures, print it out and have it next to you when you do the job. Nothing like having color pix with descriptions next when you have stuff apart. Most of the posts here with illustrations I have found to be FAR BETTER and any Haynes or Chilton manual. Or even better, just Utoob search "brake job on 2011 AWD Explorer XLT" and I'm sure something will come up. Just watch the movie about what to do. Helps me a lot, I know.

 

[Napalm]

since I didnt' find ready available info.

let's start with common front brakes.

Step 1 - Place car in part - do not put on parking brake. jack up one side - place jackstand on suitable piece of car frame or suspension. With car secured - remove wheel. Now here I will stop and say - prior to jacking you should loosen the lugnuts with the weight on the wheel if doing this by hand - even if on a drive axle. With wheel removed - give a good look of the rotor, caliper and brake line.

Step 2 - Loosen but do not remove the top caliper to bracket bolt - there are 2, a lower and upper - most but not all modern cars are rigged with calipers that are meant to rotate off a pin so as to make pad replacement easier. not all cars are like this - I believe the explorer is though. Then remove the bottom caliper to bracket bolt - thus the caliper will swing so as to allow removal of the pads. remove pads often by prying out of their slots with a screwdriver. Caliper to bracket bolts are bolts into a guide pin - these pins usually have a hex or flat on them and need to be held still to looses. thus you will need a open end wrench on the pin body (often covered with a boot) and a ratchet or another wrench for the bolt.

inspect caliper pot boots - this is the big round thing that squeezes the pads - some front brakes have 2 of these. now is as good a time as any to squeeze the pots back into the caliper - as your pads have worn these pots, pressed by brake fluid, move out to accommodate. To fit your new pads they have to be pressed back into the caliper. For front brakes you can usually do this with nothing more than the old pad and a sturdy 6in C clamp. However they make tools for rent that can make the job a touch easier. Autozone, O'reilly, advance rents them. I usually use an old pad over the pot, and a C clamp to gently press it back in.

REAR brake calipers often have a ratchet mechanism internally that must be spun back into the caliper - as much as they need to be gently pressed back into the caliper. Thus you will need a tool for the rears - I like the rental tools as opposed to the thing you can put on a 3/8 drive ratchet to spin with. the Tool is much easier and often the rental is actually free. look into it.

Press back in gently - can't stress this enough. Go to your brake fluid reservoir, open the cap, but leave it on if you can. Now some people recommend opening the caliper bleeder screw (often on the top - back of the caliper and covered with a rubber nub). I like to open the bleeder screw after I've put a tube on it, and run the tube into a glass jar with a bit of brake fluid in the bottom so as to seal the end of the tube in fluid. This is difficult and a pain for most people. but opening the bleeder allows you to press the old fluid in the caliper out while you press in the pot. This isn't 100% necessary especially if the fluid was previously flushed or if you intend to do a full replacement - and I always recommend a full replacement.

So with lid off reservoir - slowly press the pot back in and make sure the boot doesn't get an air bubble. if it starts to bulge - with a pick or rounded over small tool - gently pry around the edge of the pot and "burp" the boot. if you go slow enough you won't need to, but I always seem to.

(note - this all sounds alot harder than it really is - and 30 second video sums this up better than I ever can - so do a youtube search - it really is easy peasy).

Ensure boot is collapsed and flush with the pot pressed in - then without pads - lower caliper back re-insert lower screw.

Step 3 - remove the caliper bracket to knuckle bolts - they are bigger, often loctited down and might require using that breaker bar and wacking with the mallet. soaking with penetrating oil might not help so don't despair. many modern cars loctite this from the factory - so you'll need the jarring of the mallet. remove and inspect bolts - now if not wanting to remove the brake lines (and often I do not) then by all means tie the caliper to the suspension spring or the strut saddle etc with either wire or twine - but you will want to support it such as not to kink or damage the brake line. again easy peasy, I often use a wire coat hangar.

With caliper up.

Step 4 - no looking back now. Take some penetrating oil that's not WD-40, and spray the back of the rotor where it meets the hub - if you can spray some in the lug stud holes. often rotors seize on to the hubs with age - so this will help. I like to place 2 lug nuts back on the studs here - then try to wiggle the rotor. if it won't budge. Take the trust rubber mallet - wack the rotor face into the car (note this is also why rubber mallet not ball pien hammer or framing hammer - you might need the rotor again) Then take an wack the edge of the rotor toward the hub, and do so in various places around the dial. (like 3 o clock, 5, 8). they try to move it - often by now the rotors come loose with a wack, if so stop there obviously. if it doesn't budge spray some more penetrating oil and wait 2 minutes. begin walking again.

With rotor off - clean the hub face and the bases of the studs. at this point prior to new rotor installation - I like to put a light dab of anti-sieze compound on the hub face. very thin and spread out. this prevents the new rotors for rusting into place.

Now new rotor - prior to putting on the hub - take out of box, remove bag if there is one, soak down with brake parts cleaner and wipe down thoroughly on both sides. then I like to spray a shot down the vanes if I can because most rotors today are shipped out with a anti-corrosion coating on them. it tends to burn off so I clean then instead. Install new rotor to the car - hold it with a lug nut.

Step 5 - re install the caliper bracket over the rotor - run down the bolts. Now here I'll say you should use a torque wrench - and you don't have one right. if not do this - snug them down good, then try to get another 1/3 turn on there (2 flats). while not technical if it's your car, and you're driving it - I suspect you'll run them down good and tight. they are big bolts they can take it - usually.

Step 6 remove lower caliper to bracket bolt - then remove top caliper to bracket bolt - this will allow you to remove the caliper pins. the pins are the bit the bolts go into - or also the piece you are holding with your wrench to you can remove the bolts. the pins come out of rubber accordian boots - clean the pins off - apply new grease. Forgot to mention this above - next to the antisieze in most parts stores is disc brake grease, get some. yes there are a few other things you can use but this works well.

with clean and greased pins - place them back in the caliper body - thread in the top bolt and hinge the caliper up out of the way.

NOTE - some cars with performance brakes have full floating calipers - those are a different animal. Some have fixed body calipers (the ones that usually say brembo on them) that is also a different animal. Most production cars don't have them. Brembo style calipers are even easier to work with - the pads come our the top of the body and there is one or 2 bolts to remove. again - there are videos.

Step 6 - take out your new pads from the box - one pad will have a metal tang on it - this is the wear indicator - it goes on the INSIDE slots of the caliper assembly. your caliper bracket should have some thin sheet metal clips in there that hold the pads - they mostly take up the tolerances in the bracket slot and the tabs or ears of the pad backing plate. Clean these clips and apply a thin coat of brake grease on them - or apply some to the pad ears - either way the pad has to ride this rail so to speak. This does two things - quiets pad movements and prevents binding. binding leads to bent calipers or pins. Some grease in the right spots is a good thing. DO NOT - get grease on the rotor face or the pad faces. the back of the pad is OK though.

With pads in their slots - lower caliper back down - run in the lower bolt, re tighten the top bolt. Remember this part. Now again, torque wrench time, however if you don't have one snug down and a 1/6 more (one flat) is good too. These bolts are smaller so do be a bit careful - also the pins don't like being torqued that hard.

Step 7 - re attach wheel - torque lugs (again torque wrench) and lower car etc. Move to next wheel and rinse and repeat.


Other notes - for a performance car, often you'll hear about indexing the rotors. With larger wheel, small tire profile, big brake cars there is a need to check the rotor and hub assembly runout. or "out of roundness". I don't think this is an issue on the explorer or any other FWD car I've heard about. but if you find yourself working on a corvette, new mustang, Bimmer etc etc you will need to check this for the front wheels other wise you can induce what's called steering wheel shake.

again - thoughts and opinions from abrasive azzhat that likes to work on cars. I'm sure most mechanics from shops will shake their heads at some of it.