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Discussion Starter #1
Have an 2002 Subaru VDC since new. About 120,000 miles at this time. Super vehicle, however, always fighting "warped rotors", or so they say. Recently, I had AZP Installs put in after market rotors, with ceramic pads. This vastly improved braking power, and brake feel. However, after a few thousand miles the pulsation was back. But, I noticed after a while, that sometimes the pulsation is there, and othertimes no pulsation. Pads are wearing great, rotors look great too. I wondered if anyone has had any luck replacing OEM calipers, with a higher quality caliper. My thought is: Is it possible that at times, could an OEM caliper pull in well on one side, but other pad, on other side of caliper not pull in properly, possibly causing the intermittant pulsation. I have really ruled out anything with caliper slides, or any foreign matter, or buildup on rotors. Even with non-OEM pads, and rotors, the braking is much better that original equip stuff. And by the way, when I get the pulsation, there is no associated noise when braking, and as I apply more pressure to pedal, the pulsation reduces. That why I brought up the point about my thought about possibly having OEM calipers, that intermittantly don't pull in evenly. Hoping I described this issue well. Let me know your thoughts.
Vinny
 

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Have an 2002 Subaru VDC since new. About 120,000 miles at this time. Super vehicle, however, always fighting "warped rotors", or so they say. Recently, I had AZP Installs put in after market rotors, with ceramic pads. This vastly improved braking power, and brake feel. However, after a few thousand miles the pulsation was back. But, I noticed after a while, that sometimes the pulsation is there, and othertimes no pulsation. Pads are wearing great, rotors look great too. I wondered if anyone has had any luck replacing OEM calipers, with a higher quality caliper. My thought is: Is it possible that at times, could an OEM caliper pull in well on one side, but other pad, on other side of caliper not pull in properly, possibly causing the intermittant pulsation. I have really ruled out anything with caliper slides, or any foreign matter, or buildup on rotors. Even with non-OEM pads, and rotors, the braking is much better that original equip stuff. And by the way, when I get the pulsation, there is no associated noise when braking, and as I apply more pressure to pedal, the pulsation reduces. That why I brought up the point about my thought about possibly having OEM calipers, that intermittantly don't pull in evenly. Hoping I described this issue well. Let me know your thoughts.
Vinny
The way you use the brakes plays the biggest role in this issue. By the way the stock rotors and brakes on the OB are known for being quite good and running into the 100,000 mile range with little to no issues. My last subaru the original rotors saw their first turning at 144,000 miles and they had very very slight build up on them and were 100% true and within spec. That car lived in San Francisco drove a 50 mile commute in and out of the city and towed trailers up and down the West coast from Seattle to San Diego.

The pulse you feel is build up cooked into the rotor. People who brake hard then sit stopped with the brakes clamped down hard generally see this issue far far far more than people who brake hard - then creep forward cooling the pads a tad and not cooking the hot pad to one particular spot on the rotor while sitting stopped.

The aftermarket rotors unless they are really really good aftermarket rotors are probably no better possibly lower quality than the stock rotors. The pad material on the other hand may be less prone to baking material into the rotor vs other brake pad material. The friction capability of a pad ie stopping ability might feel different between pad materials but your stopping power is limited to your tires. The stock pads and rotors can lock up the tires easily.
 

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Discussion Starter #3
The way you use the brakes plays the biggest role in this issue. By the way the stock rotors and brakes on the OB are known for being quite good and running into the 100,000 mile range with little to no issues. My last subaru the original rotors saw their first turning at 144,000 miles and they had very very slight build up on them and were 100% true and within spec. That car lived in San Francisco drove a 50 mile commute in and out of the city and towed trailers up and down the West coast from Seattle to San Diego.

The pulse you feel is build up cooked into the rotor. People who brake hard then sit stopped with the brakes clamped down hard generally see this issue far far far more than people who brake hard - then creep forward cooling the pads a tad and not cooking the hot pad to one particular spot on the rotor while sitting stopped.

The aftermarket rotors unless they are really really good aftermarket rotors are probably no better possibly lower quality than the stock rotors. The pad material on the other hand may be less prone to baking material into the rotor vs other brake pad material. The friction capability of a pad ie stopping ability might feel different between pad materials but your stopping power is limited to your tires. The stock pads and rotors can lock up the tires easily.
Thank You SubieSailor,

In my original post, I didn't even want to mention the transfer or friction material to the rotor. I have always been a big believer of this. That being said, we actually are very light on brakes in general. However, when we do possible come off a couple of long "pulls", it is very possible that we may be at a light with foot on the brakes. So that is a possibility in what you mentioned. I had always heard that the 2002 outback used the same rotors and pads on both H6 and the 2.5. That of course puts probably (with the H6) probably translates too, in normal driving around town, or on highway, then off, that rotors are quite hot, even though we did not break very hard.

With the OEM stuff, the rotors did actually warp. May have been buildup too, but warped never the less. I actually was amazed that you did so well with the OEM stuff. What year is your subie? And is it the H6?
Vinny
 

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New Brakes, Bedding-In process

Instructions for bedding in your brakes

I installed all new brakes on my wife's OBW, including all new innards in both rear parking brake rotors.

When I installed the new brakes, which included four rebuilt Calipers and four new Rotors, my wife and I flushed out the entire braking system with Castrol Synthetic DOT 4 (backwards DOT 3 Compatible) - I was bleeding everything as stated in the shop manual and my wife was operating the pedal as I instructed her to. Some of the OEM fluid was literally black when it first came out, I went around and around and bled everything until a slightly-yellowish fluid began to come non-stop at each bleeding port.

When everything was installed with new fluid in the system, I went out on the highway (when and where hardly anyone was around) and followed the procedure given at the top of my post for "Bedding-In" the new brakes.

The thing both my wife and I noticed since then (and, even now about 5,000 miles later) is that the brake pedal is right up there and feels as though it hardly needs to be pushed to slow the car, compared to before.

With the old brakes, on more than one occasion, I wondered if the brake pedal would end up against the floor before the car would come to a full-stop!

Also, I replaced the complete right-front CV axle assembly with a quality rebuild. When I first started driving the new axle, it felt a little like it was binding just a tad. I read that some rebuilt axle assemblies are tighter in tolerances than the OEM ones.

During the above Bedding-In process, I had to floor the car from about 10 MPH up to 60 MPH, then slam-on the brakes down to 10, floor it back up to 60 and doing this ten times in a row. I then let everything cool down, then, went out and did the Bedding-In process one more set of times, working the speed up to 70 MPH before slamming on the brakes.

I know the initial tad of binding I was having from that newly-installed right front axle went completely away - my take on that being that, during all the flooring, I broke in the newly-installed CV right-front axle as that slight binding has been gone ever since I bedded-in the new brakes!
 

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Thank You SubieSailor,

In my original post, I didn't even want to mention the transfer or friction material to the rotor. I have always been a big believer of this. That being said, we actually are very light on brakes in general. However, when we do possible come off a couple of long "pulls", it is very possible that we may be at a light with foot on the brakes. So that is a possibility in what you mentioned. I had always heard that the 2002 outback used the same rotors and pads on both H6 and the 2.5. That of course puts probably (with the H6) probably translates too, in normal driving around town, or on highway, then off, that rotors are quite hot, even though we did not break very hard.

With the OEM stuff, the rotors did actually warp. May have been buildup too, but warped never the less. I actually was amazed that you did so well with the OEM stuff. What year is your subie? And is it the H6?
Vinny
If your rotors actually warp, it is most likely because someone was not careful in torquing the lug nuts, or you could have a wheel that has a mounting pad that is out of true. Rotors do not generally warp in normal usage, even when used hard, unless some external force (Uneven or excessive torque, or a warped wheel) also puts some forces in play. Good luck.
 

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Thank You SubieSailor,

In my original post, I didn't even want to mention the transfer or friction material to the rotor. I have always been a big believer of this. That being said, we actually are very light on brakes in general. However, when we do possible come off a couple of long "pulls", it is very possible that we may be at a light with foot on the brakes. So that is a possibility in what you mentioned. I had always heard that the 2002 outback used the same rotors and pads on both H6 and the 2.5. That of course puts probably (with the H6) probably translates too, in normal driving around town, or on highway, then off, that rotors are quite hot, even though we did not break very hard.

With the OEM stuff, the rotors did actually warp. May have been buildup too, but warped never the less. I actually was amazed that you did so well with the OEM stuff. What year is your subie? And is it the H6?
Vinny
That car was a 2001 Legacy GT 2.5 non turbo 180,000 miles stock pads easily ran 65,000 + though I generally replaced them at that point given they had about 20% pad left. Rotors on the Legacy GT were larger than the stock 2.5L outback and I think they may have been the same as the rotors used on the early H6's. The life it lived was worst case example of what brakes would ever see between stop and go San Francisco traffic - Bay Area commuting and hauling trailers ie racing sailboats up and down the Sierra passes many times a year and dragging trailers through LA to San Diego 2-3 times a year.

You can generate lots of heat and damage brakes and rotors by using light pressure for a long distance vs say shifting down a gear to help keep speed in check and using the brake harder and for a shorter distance to stop or bleed off some speed. Long down hill runs with extended light touch on the brake over a long period of time is worse than a heavy foot on the brake for a short period simply due to the heat you generate.

I have family members who can destroy brakes on any brand car in very short order now days those people are never allowed to drive any other family members cars and the occasional times I've driven their cars even if they are nearly brand new you would think their rotors looked like old bent bicycle wheels nearly giving you whiplash anytime you touched the brake pedal.
 

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The H6 by the way weighs no more than 100lbs more than the H4. Engine and car weight have nothing to do with this issue - it has more to do with what brake behavior is causing excessive heat and pad material being baked into the rotor
 

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Discussion Starter #8
SubieSailor,
Wasn't even thinking about the little ('round 100 lbs.) diff in the two engines, just the potential of stopping a vehicle with more deceleration load to stop, than the 2.5. For now I'll keep the thought of friction material transfer in check as much as I can, to observe results.
Thanks,
Vinny
 

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Discussion Starter #9
The only rotors that actually warped, were the OEM ones, and this was done and a dealer that wire brushes the corrosion off back of wheels, and mating surface on hub, then torques the lugnuts to specs. So, the warping on OEM rotors was probably due to heat/friction material buildup. Once this would happen on orig equip rotors, it would never get better on its own. Unlike with the aftermarket rotors and ceramic pads now, it is itermittant. Sometime pulsation, other times none. Pretty wierd. Thank You for info.
Vinny
 

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You did the bedding process of 60mph to 0mph, ten times in a row, without letting them cool in between? (Only after the ten stops, as you wrote above) Ten seems excessive, especially if you're not letting them cool EACH time.

I've only had problems with rotors warping when lugs were not torqued properly.
 

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Here's a few pointers: My VDC went 167,000 miles on the original rotors. I know this because when I bought it used, every receipt, and I mean all the way back to the first 1,000 mile Mobil 1 oil change was in a folder in the glove compartment.

The caliper pins need to be lubed, lightly with caliper grade silicone to help them move in and out of the bracket when applying and releasing the brake. Same goes for the brake pad hardware, which by the way should be changed with the pads as they get divots from the pad pressure.

The rotors, when purchased new, regardless of what it says on the box, 90% of the time have a warp in the surface out of the box. The only manufacture rotor I have never had to correct the runnout on due to shipping and handling practices was Zimmerman, Volvo and Subaru.

The burnish on a pad is complete by the time you hit the third hard brake process. Any more than that and you are just burning up the pads and overheating the rotors. This is the only thing that can not be accomplished in manufacturing. Brake pad manufacturers have tried and it won't work on an assembly line.

Brake fluid should be flushed out every 2 years/30k miles. Its hygroscopic, meaning it absorbs moisture from the air. After 2% saturation of water, the fluid drops in boiling point and the system loses pressure. Physics: It takes more pressure to squeeze a water molecule than the mineral content of the brake fluid. Also, when it reaches this saturation point and boils at a lower temperature, the interior seals in the calipers suffer. Brake fluid should be a clear golden color. When it approaches a brownish tint, its time to flush. Black or green and the fluid has broken down and has a high saturation of water. Also with water comes rust, the number one killer of calipers, master cylinders, abs solenoids and valves.

There's a good chance the runnout on the new rotors was out enough when you installed them that the increase in heat buildup caused by the extra force on those "high" areas is causing buildup of the friction material on that area. Its occasional because it will wear in then wear off. The fix is to remove the rotors and have them refaced being sure the "hat" portion of the rotor is free of debris and rust before its mounted on the lathe, the hub on the car is rust free, use a light coating of ceramic caliper silicone on the mating surfaces of the hub and rotor, be sure the guide pins and hardware is lubed lightly, and the wheel itself is free of debris and torqued properly.

BTW, My Chevy Cavalier has 136,000 on one set of brakes and it gets driven hard. It likes to go fast.
 

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Well. That's gotta heat them up pretty darn toasty.
Correct, but the main thing they stress is to NOT, under any circumstances, come to a full-stop with the thing upon doing this procedure, as the hot pads in contact with the hot rotor will undoubtedly cook the rotor in that particular spot!

That's why they make it very clear to be on a road where you can do this and then continue driving for at least 15 minutes immediately afterward down an open highway! At 65 to 70 MPH, the brakes will cool to touch within 15 minutes!

In the end, the rotors do have a bluish tint, evenly around them, I did not cook-off the five-coats of Permatex blue spray anti-rattle/squeak adhesive off the front pads nor did I cook-off the high-temp grease still clearly visible on the slides and on the back, between the pad and a metal backing plate which exists between the new pad and caliper cylinder face. In fact, there was absolutely no smoke coming from any of the wheels during and after this procedure.

Heck, five years ago, my mechanic put new rotors on my work truck and when I got home, one rear rotor out of four was literally smoking, I thought the wheel was on fire!

The entire steel wheel was so hot I burned my finger when I touched the WHEEL - and the rotor was not a hint of blue but WAS BLUE! Come to find out the caliper was stuck! I still have those rotors and calipers and they have not been a problem since that initial overheating! IIRC, I "un-stuck" the caliper by pressing the brake pedal as hardly as I possibly could!

The brakes on this car have never been this good!
It's all in following the Bedding-In instructions to a T!
 
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