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Old 12-05-2006, 06:55 PM   #1
06AWD
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Default So I'm getting my rotor resurfaced (aka the "my rotors are warped" FAQ)

Had a lot of vibration while braking from highway speeds. Took it to the dealer. They said the front rotors needed resurfacing. Now, I read a ton of stuff on here saying to get NEW rotors and not to resurface old ones... especially on a new car like mine. That it could happen again and that I was eating away at the life of my "new" rotors. Will resurfacing make the rotors more easily damaged, thus requiring resurfacing again, later down the road? Tha car is only 1 year old. I drive spirited, but give me a break... I just don't see how I already went through a set of rotors. Aren't they more of a high performace rotor than most cars have?

Let me know what you all think. Thanks.
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Old 12-05-2006, 07:02 PM   #2
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It's not uncommon for them to develop deposits from new - something to do with the coating on the rotors to keep them shiny during shipping (or so I heard). I had mine resurfaced within the first year and I'm still on them 4 yrs later - no repeat of the problem and no detriment to the rotor life. I'd say let the dealer turn them lightly then re-bed the pads and see how you go.
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Old 12-05-2006, 07:28 PM   #3
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Resurfacing grinds material down until you get an even smooth surface again. The factory repair manual says you can do this until the rotor has less than the minimum thickness. This is what Subaru did the engineering calculations too. Nothing is black and white in engineering. The engineers just picked a most reasonable point. So, resurfacing up to this point is "ok", according to the manuals.

There are exceptions:
- if you think you've thermally fatigued the rotor with a lot of braking (ie track day,hotspots, etc)
- if you think you've damaged the rotor in an accident
- ???

I think getting new rotors each time is a bit like changing your oil every 2000 miles... guarantees no problems due to wear, but is a bit wasteful $$.

Last edited by chimchimm5; 12-06-2006 at 12:31 AM.
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Old 12-05-2006, 08:03 PM   #4
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Vibration under braking is almost always caused by uneven pad material deposits. It is normal for the pads to deposit material (changes the braking system from an abrasive operating mode to an adhesive one) but these deposits form in uneven patches when you brake hard and then hold the brake pedal while stopped. If you do it enough, over time that 'spot' will get worse and if you drive on a bad patch like that hard enough, it will cause localized cementite formation on the rotor, which leads to accelerated wear and reduced performance.

More information here:
http://www.stoptech.com/tech_info/wp...rakedisk.shtml
and here is your solution for the deposits:
http://www.stoptech.com/tech_info/wp_padremoval.shtml

However, if you've driven on the uneven deposits for too long, removing them won't help much, as the rotor is already ruined.
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Old 12-05-2006, 09:19 PM   #5
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First off, thanks to everyone who posted informative info in their responses.

I drove the car in a TSD rally about 3 weeks ago. I noticed the brakes acting up little-by-little since then. So I haven't been driving on them for too long (I hope). But that was the only time I was really tough on the brakes for an extended period of time. So I suppose that's what caused the pads to depoit crap all over my rotors.

Quote:
However, if you've driven on the uneven deposits for too long, removing them won't help much, as the rotor is already ruined.
I assume the depoits from the brake pads (over time) cause small indentations in the rotors. Wouldn't having the rotors turned slightly fix this?
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Old 12-05-2006, 09:22 PM   #6
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Not indentations, but localized overheating which causes cementite to form in the iron. Cementite is an iron carbide precipitation that is extremely hard and does not conduct heat away very well.
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Old 12-05-2006, 09:59 PM   #7
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Listen to the man, he knows what he's talking about.......


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Old 12-05-2006, 10:05 PM   #8
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Im having the same problem as you. Thought i was alone. It hasnt even been a year yet and my brakes vibrate. Shouldnt warrenty replace them? Did you ask your dealer about that?
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Old 12-05-2006, 10:08 PM   #9
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Seems like a good time to go with performance rotors.
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Old 12-05-2006, 10:37 PM   #10
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Quote:
Originally Posted by AKESREX View Post
Listen to the man, he knows what he's talking about.......
Oh, don't worry about it, I know. How could you not with a post like this:

Quote:
Originally Posted by nhluhr
Not indentations, but localized overheating which causes cementite to form in the iron. Cementite is an iron carbide precipitation that is extremely hard and does not conduct heat away very well.
Today 08:19 PM

Quote:
Im having the same problem as you. Thought i was alone. It hasnt even been a year yet and my brakes vibrate. Shouldnt warrenty replace them? Did you ask your dealer about that?
Warrenty will take care of it, yes. But getting them replaced is a little more difficult. My dealer just wants to resurface them. For me, and from the info I've read on here, as long as it solves the problem, I'm okay with that. Also noticed you have a TR as well. I wonder is this is more of a problem for our cars in particular, especially since it's been less than 1 year for both of us. Do you autox your car at all? Any reason why your rotors would have gone early?
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Old 12-05-2006, 10:49 PM   #11
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Quote:
Originally Posted by 06AWD View Post
Oh, don't worry about it, I know. How could you not with a post like this:






Warrenty will take care of it, yes. But getting them replaced is a little more difficult. My dealer just wants to resurface them. For me, and from the info I've read on here, as long as it solves the problem, I'm okay with that. Also noticed you have a TR as well. I wonder is this is more of a problem for our cars in particular, especially since it's been less than 1 year for both of us. Do you autox your car at all? Any reason why your rotors would have gone early?
I did autox once about 6 months ago. Other then that no racing. I dont punch it light to light, but i dont drive like a grandma either. Honestly im not that hard on my breaks. But now that i think about it, my car started doing this like 2-3 months after buying it or around there. I just figured thats how the ABS works on ReXs. Maybe subaru is using cheaper parts on the TR's? In either case id be better of buying new rotors (higher performance) instead of resurfacing the stockers. I dont have a problem with buying new ones plus pads. I just expected the stock ones to last longer then 20kmiles.
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Old 12-05-2006, 10:51 PM   #12
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How much would some nice aftermarket rotors cost? Are we talking thousands?
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Old 12-05-2006, 10:53 PM   #13
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Quote:
Originally Posted by 06AWD View Post
How much would some nice aftermarket rotors cost? Are we talking thousands?
Thousands youd be buying a new brake kit. Im not sure how much or which are good for subis. But im guessing around 100 bucks for fronts...?
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Old 12-05-2006, 10:56 PM   #14
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I was wrong, looks to be around $200 and up for a pair of rotors. Depending on brands.
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Old 12-05-2006, 10:57 PM   #15
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I wonder if this is a problem only on the turbo models. I've got a 2.5TS wagon, with nearly 81K on it, with the factory rotors front and rear. I've only had to replace the pads once in the car's lifetime, but then again, the majority of the miles on my car have come from the highway, where it's more go than whoa... I've been working on cars since I was a little kid, and I've been doing it professionally for the past 5 years or so, and I've never had a problem with turning rotors, provided that they stay above the Minimum Machining specification, once they reach that point, they should be replaced.

Just my 2 cents.
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Old 12-05-2006, 11:12 PM   #16
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Only get good quality ones if you're going aftermarket. The quality specs
for rotors (and lots of other things) are not the same between OE and the
aftermarket. The tolerence for several critical rotor dimensions is quite a bit
more permissive than in the OE business. Most of the Brembo rotors are at
the right place in terms of accuracy...... and that is in no way a product
endorsement, they just popped into my head right then.


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Old 12-05-2006, 11:17 PM   #17
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Quote:
Originally Posted by AKESREX View Post
Only get good quality ones if you're going aftermarket. The quality specs
for rotors (and lots of other things) are not the same between OE and the
aftermarket. The tolerence for several critical rotor dimensions is quite a bit
more permissive than in the OE business. Most of the Brembo rotors are at
the right place in terms of accuracy...... and that is in no way a product
endorsement, they just popped into my head right then.


Akebono Brake Corporation
Farmington Hills, MI &
Tokyo Japan
What would be a good brand? Now that im looking at some, the price ranges from like $100-$800. Depending on the style/brand. Stop tech has some slotted ones for $100/front and $90/back. What are some nice pads that dont squeek?
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Old 12-06-2006, 01:07 AM   #18
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You can get the brand I mentioned for about $50........ once again, not
an endorsement for Brembo. They are an OE supplier and their quality
tends to follow that path. Don't bother wasting your time with slotted
or drilled rotors- unless you're after the bling. There really isn't an
advantage worth talking about and there are lots of detractors to
drilled/slotted rotors. It's a topic that pops up on this forum all the time.
We make excellent OE pads for most WRX applications. There are many
other vendors that also have good friction products as well. We, of course,
are partial to our own product line


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Tokyo Japan
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Old 12-06-2006, 10:01 AM   #19
06AWD
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Found a link to some that are reasonably priced.

http://replacement.autopartswarehous...20Disc&dp=true

And whoa, what about this?

http://www.autobarn.net/brembobrakes.html

You weren't kidding about the $50.

Last edited by 06AWD; 12-06-2006 at 10:06 AM.
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Old 12-06-2006, 11:31 AM   #20
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This is my favorite place to get Brembo OE blanks. $42 for the impreza. (I previously bought from them for my previous car; civic)

http://www.importrp.com/product.php?...4&cat=0&page=1

You can even chat with them on AOL IM.
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Old 12-06-2006, 11:39 AM   #21
06AWD
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Seems that the OE rotors are only available for 2005 and earlier. Only thing there for 2006 are slotted/drilled which go for $349/pair.
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Old 12-06-2006, 12:33 PM   #22
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The WRX is prone to pulsing because of the OEM ceramic pads.

They are fine for regular driving but are just not meant for repeated hard braking. They are meant to give smooth performance with low NVH issues and long life.

Pads work by constantly generating this transfer layer - and the OEM pads are not good at keeping this layer smooth when overheated - which is likely in the range of 5-600F. So if the pads are overheated - and you stop at a red light with your foot on the brake you may get a variation in this layer which is very evident when braking from higher speeds - the pads are hitting a very small 'bump' on the rotor.

I've seen countless rotors with visible pad imprinting. My question immediately is "Are your brakes pulsing?" (The term is 'judder')

Answer - "Yes"

Solution -
-Stop pressing an overheated pad onto the rotor
-Get better pads -but it can still happen. And when I say better I mean pads more suited to your driving style.

You can try to rebed them to re-generate/smooth this layer but the pads have lower amounts of abrasives so this may or may not be successful. And again - fi you use your brakes hard then the OEM pads are not especially well suited.

Your dealer would just prefer to turn the rotors because it will at least fix it until you leave and also because they likely don't understand this process. But if you drive in the same manner it will likely just re-occur - and now you have the same symptoms -but less rotor left before needing replacement.

Furthernmore - you are very unlikely to cause a phase transformation (from pearlite to cementite) with stock brakes. In order to generate cementite - which is an undesirable phase of gray iron -you have to heat the iron up above the phase transformation temperature - and that is about 1600 deg F iirc - and if you get the rotors that hot then your OEM pads are likely completely melted, your fluid is boiled, the caliper boots are melted etc.



or



your call.

Note:

06 WRX front rotors = 02-05
06 WRX rear rotors do not = 02-05
06 WRX rear = 05+ LGT rear (290mm vented)
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Old 12-06-2006, 12:51 PM   #23
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Quote:
Furthernmore - you are very unlikely to cause a phase transformation (from pearlite to cementite) with stock brakes. In order to generate cementite - which is an undesirable phase of gray iron -you have to heat the iron up above the phase transformation temperature - and that is about 1600 deg F iirc - and if you get the rotors that hot then your OEM pads are likely completely melted, your fluid is boiled, the caliper boots are melted etc.

So are you saying that if my rotors have deposits from the pads, it's b/c I caused the brakes to heat up to 1600 deg F ?

So: depostis on rotors = melted pads + boiled fluid + melted boots ???
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Old 12-06-2006, 01:29 PM   #24
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No -not at all. Re-read it. The OEM pads stop working at somewhere around 600F (typical temp range for a street pad). This is far below the temperature where you start to change the physical properties of the iron in your brake rotor. If you heated your rotors up to 1600 deg - pad deposits would likely be the least of your worries.

Most likely you did a little spirited driving and got the pads warm and juicy - at which point you may or may not have stopped and while the pads were still warm held them on the rotor. This produced a spot in the transfer layer that was uneven and now you feel it at high speed braking. The dealer will just remove this uneven layer - and 10 or 20 thousands of rotor thickness and send you on your way - free of charge ty very much. But there is a fair chance you can rebed the pads - it may take a few tries but it's been done - or even sand the rotors a bit and rebed to make it smooth again w/out removing unnecessary material. At worst - a VERY LIGHT TURN and proper rebedding should fix it.
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Old 12-06-2006, 02:15 PM   #25
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Okay, get it now, thanks. I read somewhere yesterday about the proper way to rebed the pads. Something about a series of stops (without coming to a complete stop) from 60 to 5 mph, then 50, 40, 30 etc. Does that sound right to you? And somehow I'm going to have to figure out how to do this on a highway in the middle of the day...

BTW, thanks for all your info! Huge help!
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