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Unusual Brake Pad Wear


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9 replies to this topic

#1 Baymtnman

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Posted 07 January 2005 - 01:18 AM

Dealer replaced pads and rotor for all four wheels of a 2000 Subaru Legacy at 11,200 miles on a warranty basis. Reason for early wear was determined by Subaru due to my mother's limited driving and the rotors had rust patterns. Almost exactly the same amount of miles (now at 22,300), I pulled the pads and they show the following wear pattern:
Measured by me from the shoulder of the working material on the pad to the top surface of the pad using plastic micrometer:



Wheel

Front (New=10.0mm)

Rear

(New=10.0mm)

Driver Side

Front: Inboard 1.2 mm

Outboard 7.0mm

Rear: Inboard 6.2mm

Outboard 1.1mm

Passenger Side

Front: Inboard 1.5mm

Outboard 8.0mm

Rear: Inboard 5.5mm

Outboard 2.5mm



Dealer inspected pads while on the car and indicated that this was a normal wear pattern, even though I questioned the inboard pad wear pattern.
Further, the front pads show a markedly taper.

To scare me off, the dealer said they just had another customer with the same pattern, and they also concluded it was a "normal" pattern.

This suggests to me that the initial culprit of the original early wear was due to the caliper not functioning properly, not my mother's driving pattern. Local non-dealer brake specialists agree with my position. With the same driving pattern, the rotors show no indication of rust, so I am doubtful of the original claim. She drives about 50miles/week or about 2500 miles/year, I drive the remainder when I come home for long trips.

I have contacted the Subaru Dealer Representative. What should my strategy be with these guys. I wish to have the entire system replaced and paid for by the dealer (not Subaru), as I suspect the dealer is attempting to cover up their original incompetence.

#2 Gnuman

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Posted 07 January 2005 - 01:45 AM

Dealer replaced pads and rotor for all four wheels of a 2000 Subaru Legacy at 11,200 miles on a warranty basis.

(snip)

This suggests to me that the initial culprit of the original early wear was due to the caliper not functioning properly, not my mother's driving pattern. Local non-dealer brake specialists agree with my position. With the same driving pattern, the rotors show no indication of rust, so I am doubtful of the original claim. She drives about 50miles/week or about 2500 miles/year, I drive the remainder when I come home for long trips.

I have contacted the Subaru Dealer Representative. What should my strategy be with these guys. I wish to have the entire system replaced and paid for by the dealer (not Subaru), as I suspect the dealer is attempting to cover up their original incompetence.


Baymtnman, Which dealer? I need to know as I live (very) near you, and I want to know who to stay far away from. Also, email me to arrange a time when I can take a look at your brakes. from those measurements, it looks like the caliper pins are sticking. The terrain you are in is also fairly dangerous without brakes that work correctly, and you will find me to be very picky about brakes and steering in particular. That any shop allowed two cars to leave with this kind of wear pattern sickens me. BTW, I do not think (without looking at it myself first, that you need the entire system replaced. Those measurements indicate that the calipers are not "floating" freely to allow both of the pads to be used (the inboard pad is doing 90% of the work, as that is where the piston is). This may be correctable, but I have to see the brakes to make that determination.

On a side note, there is a Bay Area Meet and Greet in El Cerrito next Saturday (the 15th). You can meet several of us in person then.

#3 Baymtnman

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Posted 07 January 2005 - 01:52 AM

Sanjay,

I was in Ohio (so you need not worry about local California dealers), and the pads are in Ohio, as if I need to pursue legal options, I need the evidence there. Besides, a non-dealer mechanic is preparing a letter that the dealer is misrepresenting the facts.

As far as slider pins are concerned, that may be possible, but with the taper combination, the calipers have to go.

You can contact me at keith_gale@hotmail.com for off-line communication.

I am in Ski Patrol and unable to meet on weekends, but am interested in meeting interesting people.

#4 Strakes

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Posted 07 January 2005 - 01:33 PM

Isn't there a Service Bulletin for certain late model Subarus for excessive and abnormal brake wear? Have you looked at all the service bulletins that apply to your vehicle?

#5 SevenSisters

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Posted 07 January 2005 - 06:58 PM

If the set up is like on a '91, the calipers aren't moving. Grease up the pins. You don't need legal action for a set of $64 pads.

Which dealer in Ohio? I avoid them but may have to go someday.

#6 Baymtnman

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Posted 10 January 2005 - 11:24 AM

Seven Sisters,

the dealer is K&O at 925 Canton Street (east side of Akron). It is not the $64 pads, the rotors are now damaged. The dealer cost is $780, assuming the calipers themselves are fine.

The sliding mechanism may be hanging up, but that does not mitigate the taper wear pattern. And for all four to have the same problem is somewhat confusing. I could understand one caliper, but all four???!!!.

#7 Baymtnman

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Posted 11 January 2005 - 10:51 AM

Isn't there a Service Bulletin for certain late model Subarus for excessive and abnormal brake wear? Have you looked at all the service bulletins that apply to your vehicle?


Yes, Strakes, I did check into the TSB on the brakes. From 2001-2004 there was a selected TSB on certain VINs for excessive wear on pads (though they couched the problem as due to rusting). It did indicate that the dealer should remove 0.1 inches to eliminate the rust on th backplate of the pad, thus freeing the pad.

Check this website:
http://www.scoobymod...tachmentid=2421

This website was better than the NHTSA's Office of Defect Investigation.

#8 Baymtnman

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Posted 12 January 2005 - 02:21 PM

Well, well, well..... Guess who just called. The dealership who did the original brake job at 11,200 miles and who also suggested that the brake pad pattern wear was normal just confirmed that they will do a "complete brake job" with no cost to us. images/icons/icon7.gif Sounds nice-but I have to call to figure out how they will solve the abnormal wear. I doubt that they will replace the calipers-especially the particularly nasty passenger front. But I wonder if just working on the slider mechanism will mitigate both the wear and taper problems.

I assume the slider mechanism controls asymmetrical wear between outboard and inboard pads. How does caliper malfunction cause taper wear???

Basic question-how does the pad release off the rotor when the foot pulls off the pedal.

#9 Gnuman

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Posted 12 January 2005 - 04:56 PM

I assume the slider mechanism controls asymmetrical wear between outboard and inboard pads. How does caliper malfunction cause taper wear???

Basic question-how does the pad release off the rotor when the foot pulls off the pedal.


There are two sliders: one on top and one on the bottom. if one is sticking and the other is not, you will get a taper. There are three basic parts to a disc brake caliper: the piston, the slider pins, and the C shaped caliper frame. when the piston is pushed out against the inboard pad, the force of this pushing is also directed (in an equal and oposite direction) on the frame. If the sliders are floating freely, this force is applied to the outboard pad by the caliper frame. If the slider pins are hanging up, then some of the force is eaten up by the force needed to overcome that resistance. The taper on the inboard caliper comes from the pin that is not sticking moving when the other one is (it will be tapered in on the side that is sticking). The taper on the outside is caused by this as well, in the other direction (tapered to the side that is not sticking, as this is the onlu side that is getting actual use). Clear as mud? :)

When the foot is placed on the pedal the pressure to the hydraulic fluid is increased. When the foot is released so is the pressure, which allows the piston in the wheel calipers to retract slightly. This releases the pressure to the brake pads.

#10 LosDiosDeVerde86

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Posted 13 January 2005 - 10:42 PM

you need new calipers




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