warped rotors?

[dark_rex]

i think one or both of my front rotors is warped. at high speeds, when i brake, the steering shakes pretty violently. my first guess would be the rotors have been warped.

where i am at 28K miles, will warranty give me new rotors? i don't want them to just turn them. also, will they say this was regular wear and tear?

i'm bummed about this. betty has been trouble free since i got the defective clutch replaced 10K ago. (except for that stinking "screeeeeeee" on the driver's window)

any thoughts on other causes for the steering shake? SOA's reaction?

dR

[aussieinstlouis]

warped or cracked are both possibilities. My guess would be that SOA are unlikely to give in on 'fair wear and tear' I know that when I cracked mine on my '94 WRX back home - there was nothing but my caning the brakes that caused it.

They get very very hot and then cool too quick and hey presto! a crack opens up along the vent vane line!

If they are cracked they need replacing - get slotted rotors to replace them. If they are warped - hope there is enough meat on them and get them machined and start saving for the slotted rotors!

PS: how high is 'high speed'??

[dark_rex]

the typical 80mph on the hwy.

even at 55 or less, a firm brake will not shake the car. that's why i don't think they're cracked, (or if they are, it's got to be pretty minor)

my opinion is, if they are getting hot enough to warp with my wheels (wide open 7 spokes, 17") and not track use, they should be replaced under warranty. i drove the same speeds in my 91 corrolla, and never warped or cracked a rotor. (actiually, they were still OE after 117K miles, only turned, w/ new pads a few times)

wouldn't cross drilled cool faster than slotted? i'm a n00b to brake upgrades, is it just a cost decision there? i've read about wilwood, stoptech, and brembo. what other options are there? if i go with better cooling rotors, can i chince on the pads? i imagine they'll be less susceptable to glazing, so i might get away with something like a bendix pad. i'm not a track or strip driver, just 95% highway.

dR

[aussieinstlouis]

cross drilled will cool faster but are more prone to cracking. The slotted gives a large surface area to dissapate heat without providing the same seed for crack propagation.

Cracking is also caused by the rotor not cooling uniformly.

It is not that they are getting hot enough to warp - it is the fact that they are cooling too quickly or not uniformly to warp.

The wheels you are running will probably make little difference to the stock brakes.

I am still running the stock brakes and am looking for a 4 pot kit that fits under the stock 16" wheels - there is a perrin/wilwood kit that looks pretty good.

[dark_rex]

i understand that it's rapid/uneven cooling, but my point is that that sounds like a design flaw.

no?

typically, that would be a symptom of an after market wheel blocking or disturbing airflow in the well. but mine are so open faced, i figured just the opposite.

should i go aftermarket? i could throw in some shi+ from my dad's store and save a ton if warranty won't cover me. but if i really should stay OE (i think they're hampden, not sure though) i'll just upgrade to wilwood or something nicer. i'm just pissed. i don't even have the go fast mods to warrant an upgraded brake package.

dR

[aussieinstlouis]

The way that you brake can be a factor - do you ever find yourself 'riding' the brakes?

This is only speculation - but the more open wheel may contribute to en-even cooling. I am only doing the devil's advocate thing on SOA lawyer type thinking.

I can understand you are pissed -

If you do not have go fast mods, just replace with stock if you can get good prices. I went to slotted back home because there was only a 10% price diff and my cracked ones were only good to be used as a door stop.

If your stockers can be machined - go for that.

My 0.02

[tan]

Wear Item Limited Warranty
Wear item coverage for all models except Right-Hand Drive Legacy is 3 years or 36,000 miles, whichever comes first. Items covered include brake pad/shoe linings, clutch disk linings, and wiper blades.

Straight from their website, so you have a chance.

For cross-drilled....it only happens in extreme cases of racing. Porsche still uses cross-drilled brakes.

For your day to day driving....cross drilled will be better than slotted, only because you'll get increased pad life compared to slotted (milled out rotors).

[dark_rex]

nevermind ride them, i barely use them. i generally engine brake or downshift b/c i'm on the hwy so much. even on ramps i find my self only braking when i need to come to a complete stop, or save my life.

i'll call them tomorrow, and get back to you guys.

anyone know what brand the OE rotors and pads are?

dR

[ScoobySteve]

Sorry to hear of your problem, dark_rex.

Somebody else here posted their rotors were warped. It was Platinum WRX if I recall correctly. I would say your options are threefold:

1) The dealer replaces your rotors under warranty (unlikely, I should think - but worth taking a shot anyway), or agrees to machine them for you.

2) You have them turned yourself. What would be the objection to doing this - concern that warping would just happen all over again ?

3) Upgrade your brakes.

The choice between just getting them turned and upgrading your brakes really comes down to how you intend to drive the car. Are you sure you will never, ever do an AutoX or a Track Day ? Then the stock brakes should be just fine.

But if you even think there's a chance that you might enter a competitive event, then upgrading your brakes is the right thing to do. There are many levels of upgrade, from just doing pads / fluid to full-out big brake kits. I've chosen the low budget route and the results on the track have been adequate and the brakes are just fine for daily driving. I've had no problems with the cross-drilled SPOs. They also fit under the stock wheels and no adjustments are needed with using the OE calipers.

[GV27]

There's a good chance that what you're feeling is built up pad material on the rotors. That would explain why you don't feel it with firm pressure.

You could try having them bead blasted - a machine shop will probably be able to do it, or a specialist. Don't pay more than a few bucks. Or just try srubbing them with steel wool and brake cleaner.

Chris

[Penguinking]

whats it called when they take the rotor and shave a bit of it off? i know it reduces its capability b/c ur removing some of the rotor, but at least sanding it down will smooth it out...right?

[thechickencow]

I don't think cross-drilled is the way to go. I've read a lot of stuff that was written by experts on why. Although I don't have the expertise to back it up, they certainly do.

Basically cross drilling was used back before technology advanced with brake pads. I believe they were put there to get rid of air pockets or something under the pads, IIRC. Slotted rotors are more useful because they can take things like mud or debris and send them out from under the pad, without giving up the surface area. The most important thing about a brake rotor is surface area, which allows for more heat removal from the pads to the rotors to air.

If I were going to upgrade, I'd go with slotted rotors (or solid). For my needs for autox next season, I will be upgrading fluid, lines, and pads, but keeping stock rotors unless I develop a problem with them.

tcc

[blackshadow]

My car shakes badly too. It only does it when i brake semi hard (or harder) at speeds above 60... is this what you're experiencing dark_rex? I only have 7000 miles and i don't ride the brakes.

[aussieinstlouis]

Originally posted by Penguinking
whats it called when they take the rotor and shave a bit of it off? i know it reduces its capability b/c ur removing some of the rotor, but at least sanding it down will smooth it out...right?

That is machining. The reduced thickness doesn't reduce the braking capability unless you machine them beyond the manufacturer's minimum thickness (in the shop manual)

[ScoobySteve]

Originally posted by thechickencow
I don't think cross-drilled is the way to go. I've read a lot of stuff that was written by experts on why. Although I don't have the expertise to back it up, they certainly do.

Basically cross drilling was used back before technology advanced with brake pads. I believe they were put there to get rid of air pockets or something under the pads, IIRC. Slotted rotors are more useful because they can take things like mud or debris and send them out from under the pad, without giving up the surface area. The most important thing about a brake rotor is surface area, which allows for more heat dissipation from the pads to the rotors to air.

tcc

Checked any detailed photos of the new Ferrari Enzo ? Cost be damned, it will be the finest street-legal sports car on the planet. It has cross-drilled rotors.

Here is my understanding of it. The extreme heat generated by hard braking tends to make the pads outgas. This will build up a layer of flim between the rotor and pad causing brake fade. Cross-drilling and slots are two approaches to addressing this issue. The idea is to vent these gasses to prevent any buildup as well as to provide cooling. If anything, cross-drilled rotors should be slightly superior at this task.

The drawback of cross-drilled rotors is that they tend to be harder on the pads than slotted rotors due to the less uniform surface presented to the pad. Your pads get chewed up faster. The other Achilles heel can be stress-cracks radiating out from the holes. Cross-drilling undermines the structural integrity of the rotor if done improperly. My SPOs are a one-piece casting and the holes are nicely chamfered, so I think the risk is of cracking is minimal.

I'm not saying that cross-drilled is better. Prevailing opinion seems to lean towards slotted but either type of rotor upgrade will be superior to the stock rotors. Increased surface area will provide more stopping power (more volume of swept area), for example, front rotors are always bigger than the ones in back. But they will not necessarily provide better heat dissipation w/o cross-drilling or slotting.