rear brakes worn very uneven

[2011edgese]

I had to because the driver side rear inner pad was at 1%.Yup.... You read right. One percent. The outer pad was about 40%. The ppassanger side rear pads were inner was 25% and outer was 40%. The pins were free flowing. There was a bit of brake dust and slight rust on both calipers. I cleaned the old grease and put new. Even cleaned the pins to make sure with a ruff pad to bring back the shine. I also rebent the clips some i reused them so they grip the pads and not squeek.What could cause this 1%? When I pushed the caliper pistons in, I had to twist them while I opened the bleeder. Then closed the bleeder. I don't think I have to bleed them right?

 

Also. . I just realized my ebrakes don't hold as good now. Where the adjustment? At the calipers where the cable pulls on it? I'm using ceramic pads.

 

I uploaded the pic. One pad was the thickest on the other side. But the thinnest was the driver side inner pad. Just let me know what you all think. This ain't normal. Have these edges had rear brake issues? I know that the 2010 and under had smaller disks due to ppl complaining about brakes wearing fat.

[2011edgese]

Ok. Update. I suspect the problem was at the factory. Im using a thermal gun to read temps after drives and the rear brakes are cold. So no dragging like before that lead to my brakes wearing down very uneven. I suspect maybe the grease or clips were bad? Or maybe just corrosion. I didn't see any when I did them besides lots of brake dust. But now the car does feel alot more free moving. Something was hanging the calipers pads. I think this brake job solved it.

Edited February 20, 2014 by 2011edgese

[2011edgese]

okay I found out the problem. In which is not a problem. And is normal.I reached out to a tech friend who works on all types of cars. And he gave me the clear explanation that completely makes sense and why ford says its normal as well.if you have a vehicle, especially a SUV or crossover, and you have traction control, with the brake system designed to put more pressure on the rears then the fronts to eliminate the nose dip, then you will have uneven brake pad wear on the rears specially the center Pads. It is the fundamental design of it with traction control. So now I am very happy. Makes sense to me, what do you all think?

 

Alsoread on how traction control works and I believe you will be convinced yourself

Edited February 27, 2014 by 2011edgese

[akirby]

What the heck is a center pad?

[2011edgese]

Sorry. .. I should have typed in inner pads instead of center pads. so those are the pads on the inside of the car not the pad closest to the rim

[akirby]

I don't understand why the inner pads would wear differently than the outer ones under normal use. Calipers should apply equal pressure on both sides of the rotor.

[2011edgese]

I know. They should! I don't know why myself. But this is a very common thing now on these cars. Not only just Ford, other manufactures as well. I personaly think it's the design. Not optimal. That's what I think. Most dealers are telling customers that is normal on these cars now. I'm just glad I'm not the only one. Lol. When I did mines, I noticed nothing unusual about everything.

[akirby]

Rears wearing before the fronts is now common, but I don't think I've heard that one pad always wear faster than the other one. Caliper/pad designs have not changed.

[2011edgese]

That's my understanding as well. That's why I'm leaning towards is a design issue that has not changed. And that is the problem. Manufactures are implementing these new features on cars and ignoring to integrate others with them so they work in conjuction without flaws. Remember. .. traction control reduces wheel speed. Only way to do that is to apply brake pressure. Unless I'm wrong on that. But if traction control is constantly used to maintain optimal grip on all wheels on all turns, I can see the uneven wear easily. Google "uneven rear brake pads". There's millions of people with this now. And almost all of them are suv or ctossovers. Plenty of lexus and Mercedes aswell. And most people are told the thingI was told by my tech friend. It's the new brake system. Rats are eaten up gadget now and uneven due to traction control always regulating wheel spin.

[2011edgese]

http://brainonboard.ca/safety_features/active_safety_features_traction_control.php ecm with wheel sensors activate module pumps to increase brakes without the driver knowing. Pretty much what I suspected. Now. .. personally, I think the caliper system should be redesigned to eliminate the uneven wear. How? Don't know. Few ideas but to long to write. Edited February 27, 2014 by 2011edgese

[2011edgese]

But giving it a deep thought. It should not be very uneven. I sure there's other factors making it more pronounced.

[2011edgese]

Heres a post.. But for a 2006 Chrysler car.... This is pretty much what I've come across and told.

 

 

"However the rear brakes will always be given a little extra force when going in a straight line at any speed and will deactivate the rear boost when in any turn.

4ETS, ESP, ABS, EBA and Electronic Brake Force Distribution do strange things under different driving conditions resulting in uneven brake wear which is normal for the ML's"

[akirby]

Traction control only operates on the drive wheels (FWD on the Edge). And if you have AWD then you won't have much wheel spin to begin with.

 

Stability control also uses the brakes on an individual wheel at a time when you corner too fast.

 

Now that the PCM has control over individual wheel brakes it makes it easier to change the braking balance for better performance whether it's front to rear bias or side to side bias or both.

 

In the past the only control was front/rear bias.

 

Also - having individual brake channels means a problem in one channel would only affect one wheel now.

[2011edgese]

Ahhh I see. Good info. I have the fwd. I'm guessing stability control function doing the work then. It would be very nice to get the data on the edges brake system. Like what does what and when. I've come across some posts of some brake systems using the rears to show down at Highway speeds. But in city driving, the crimes are used more. But this was for a different car manufacture. Anyone have this precise data from Ford? I don't think alldata would go into details.

 

also in my case.... D.S rear was the most unevenly worn. The P.S. was unevenly worn but not that extreme. And fronts were meaty and evenly.

Edited February 27, 2014 by 2011edgese

[2011edgese]

Here's a interesting post. Guy with a 07 civic had uneven rear pad wear. Dealer told him its 3 possibilities in this car.

 

1: air in the line

 

2: I forgot

 

3: braking lightly. One wheel will get slightly more pressure that the others by nature.

 

 

This was from the Honda dealer . So there's so many opinions! That's why it would be nice to get the core details how this system works.

[ls973800]

Anytime I've had extensive wear on one pad, be it the inner or outer, it was caused by uneven pressure from the caliper. The slide pins or keys have to be kept lubed and clean. If any of them stick, you will get uneven wear. Was your wear even across the whole pad or was it more on one end of the same pad than on the other end?

 

I have never opened any bleeder screw in order to push the piston back into the caliper. The only thing you need to do is make sure there is room in the master cylinder for the fluid which is pushed back into the cylinder.

 

Once you open ANY bleeder screw, you should make sure you bleed at least that line!

 

Note also that when you reassemble the front calipers, one bolt is longer than the other and must go into the top hole.

 

Last factor is that ALL bolts, nuts, etc need to be torqued to the proper amount. An over tightened lug nut on the wheel will cause warping of the disc. Over torquing of any caliper retaining bolts, pins, bleeder screws, lines, etc can cause uneven wear or improper operation.

 

Here is an excerpt from the Ford service manual regarding the guide pins.

 

The guide pins should slide with a reasonable amount of hand force. If the brake pads show taper wear or the guide pins are difficult to move, carry out the following steps.

• Disassemble the brake caliper guide pins and inspect the guide pins and guide pin bores for wear, damage and corrosion. If the bore is worn or damaged, replace the damaged component.

• Use a wire brush, rolled-up sandpaper or emery cloth to remove all corrosion and foreign material from the caliper guide pin bores. Clean any remaining foreign material from the bores with brake parts cleaner and compressed air.

• Assemble the caliper seals, boots and guide pins. Use an ample amount of the specified grease to lubricate the bores and guide pins.

• Inspect the brake pads. For additional information, refer to Brake Pads inspection in this section

[ls973800]

One other cause of uneven wear could be from a master cylinder which has blocked ports preventing fluid to return when the brake pedal is released. This will cause the pads or calipers to hang and wear faster.

 

Copied from the Ford service manual

 

Brake Master Cylinder

NOTE: During normal operation of the brake master cylinder, the fluid level in the brake master cylinder reservoir will fall during brake application and rise during release. The returning brake fluid creates a slight turbulence in the master cylinder reservoir. This is a normal condition and indicates that the compensator ports are not clogged. Clogged compensator ports may cause the brakes to hang up or not fully release. The net fluid level (such as after brake application and release) will remain unchanged. Fluid level will decrease with pad wear.

[ls973800]

One last post about uneven wear on the pads, either inner versus outer, or one wheel to the opposite wheel. This article again points out it is from a mechanical issue (rust, dirty, no grease, etc).

 

What Can Cause Uneven Pad Wear?

The key to correcting the uneven pad wear is in accurately identifying the condition responsible for it. Now that we've seen how a caliper pushes and pulls the pads against the rotors, let's consider the different ways brake pads can wear unevenly.

Inner pad wear

Inner pad wear usually occurs when the piston can't retract properly. The piston may be binding in a scored cylinder. The piston seal may be distorted or just plain worn out. Both of these indicate a caliper teardown and rebuild.

The pad may be binding on a corroded caliper bracket. If this is the case, you may be able to clean the corrosion with emory cloth and brake cleaner. (Remember to keep brake cleaner away from rubber parts.) After the sliding surfaces have been cleaned, apply a dab of brake lubricant.

Outer pad wear

Outer pads will wear prematurely if the caliper bracket or (more likely) the caliper pins are corroded or if they're lubricated with the wrong lubricant. Again, they should be cleaned with emory cloth and lubricated with brake lubricant. Improperly installed pin boots are another possibility.

Both pads on one side thinner than pads on opposite side

This is generally caused by a hydraulic problem, although it may also be caused by a sticky piston. More often, the cause is a restriction in the brake hose on the opposite side. The side with the premature wear may also have a brake hose with internal damage that acts like a check valve, preventing the release of the brake fluid.

It's also possible that there's a hydraulic restriction higher up the line than the brake hose on the side with the pad wear. For example, a faulty ABS modulator may not allow the release (return) of pressure on that side.

One other possibility is air in the hydraulic line on the side opposite the pad wear.

All pads wearing even but prematurely

Generally, this is caused by two-footed driving or even the choice of pad material—certain pad linings simply wear more quickly than others. But most reasons for premature pad wear are not related to the friction material. Properly functioning disc brakes result in even clamping pressures being applied to both the inboard and outboard pads on both calipers. In most systems, if the brake system is working properly, the rate of wear on each pad should be close to equal.

One thing to keep in mind: the master cylinder must allow the brake fluid to expand due to the heat generated at the wheels. If the master cylinder does not allow for this expansion, fluid will be trapped under low pressure at the wheels.

If we're talking about the pads on the rear only (ie., front pad wear is normal), then check for binding in parking brake cable.

[2011edgese]

Ls..... yes, I'm aware of these steps and did everything but user a torque wrench on the caliper. Also. .. These are factory brakes. So you can eliminate warpage or improper torque. All the outer rear pads were around 50 to 60%. But the inner pads were a lot low. D.s. was the worst at 1 percent. While the passenger was at around 15%.

 

What ever did this, I think is resolved with the brake job. The brakes feels really good. And there is absolutely no drag on either wheels. I jacker up both wheels on several occasions to make sure. I'm guessing a little of how the brake system works with a few other factors combining to possible binding. Like the clips not snugging as good. The pins not gliding as efficient and maybe even some debris lodged in the pads. Everything combined. When I did do the job, there was no noticable corrosion no where. Pins where gliding and floating nicely. And no drag on the wheel before I even took the wheel off. So its odd. That's why I'm leaning towards what lots of people have mentioned. It's normal to see this on these node brake systems. Also. .. im one of those crazies that do open the bleeder to push the caliper piston in. Lol. I can just visualize pushing tiny dirty particles up the abs module or passed sensors. Im firm with opening the bleeder! And yes. .. bleed afterwards. Some people say its not necessary, but on some cars it is. This is one of them.

[2011edgese]

Good info ls! It's a good read for sure. Now. .. In 6 months I'll check the pads again and if they ate wearing uneven on the same caliper, then there's something up with the caliper or must likely a hydrolic issue. Then I hunt more. But what's up with lots of dealers saying its normal on these type of cars? But I suspect maybe a slight wear difference is considered normal. Not a extreme 1% wear and 40% wear pads. But on the good news, brakes are 100 feel good and no noise. I didn't change or had the rotors surfaced. Just did a good cleaning and lubing and rebending slightly the clips for a snugger fit to the calipers.

[ls973800]

Well, between your throttle body/air cleaner service which resulted in better power, and your recent brake job which resulted in better stopping, you should be all set for awhile.

[2011edgese]

Lol. With my luck. I'm going to tumble over a hill.