Rotors
 

So I just had to drop my car off to get a tire fixed at Tire Kingdom. Went I went to pick it up the guy basically yelled at me for hitting the brakes to hard which caused stress fractures in the rear rotors, both sides. Has anyone heard of this and could this be a possible warranty issue (normally warranties dont cover "expendable" items). The car only has 3000 miles on it and for that to happen this soon is pretty ridiculous.

Sounds like a case of to many handbrake turns or driving around with the handbrake pulled up to me. Hitting the brakes to hard wouldn't cause the rear rotors to crack seeing how the front brakes do most of the braking anyway.

Never used the handbrake to turn, you dont really need it is "sport" mode.

Odd.

What have you been doing?

Burnouts?
Drifting?
Tracking?

Be honest.

It's my understanding that on the FR-S, the hand/emergency brake actuates a drum in the rear ..... not the disk brake rotors .... :iono:

humfrz

Ok, maybe thats the case, but you have an explanation other than abuse of some kind why a rear brakes would be heat damaged at 3,000 miles when people that have tracked regularly have stated that the car is heavily front biased on brakes.

Seems pretty unlikely that something would cause that type of failure other than abuse or something weird like driving with the handbrake half pulled.

That or the guy at the tire shop doesn't know what the heck he's talking about.

I call BS. I've never seen stress fractures in iron discs unless they are cheapo drilled units.

Your tire guy is probably not a brake guy and mistook pad lining deposit lines for cracks. I've seen those.

Also all street brakes (and racing brakes for that matter) are front biased because of weight transfer effects. Front brakes do up to 80% of all braking.

The rear brakes on our BRZ are only 4 mm smaller in diameter and vented just like the fronts. They are 6 mm thinner so that they will heat up at relatively the same rate as the fronts.

.....http://www.runemasterstudios.com/gra...images/yes.gif ...... that would be my guess ..... http://www.runemasterstudios.com/gra...mages/sigh.gif

humfrz

Burnouts not intentionally
Drifting here and there but never for long periods of time. Im talked about drifting turns on reg roads
No track days
Ive spun out once, in a parking lot. 2 donuts but didnt hit anything




[QUOTE=Suberman;1361297]I call BS. I've never seen stress fractures in iron discs unless they are cheapo drilled units.

Your tire guy is probably not a brake guy and mistook pad lining deposit lines for cracks. I've seen those.

Also all street brakes (and racing brakes for that matter) are front biased because of weight transfer effects. Front brakes do up to 80% of all braking.

The rear brakes on our BRZ are only 4 mm smaller in diameter and vented just like the fronts. They are 6 mm thinner so that they will heat up at relatively the same rate as the fronts.[/QUOTE

I knew that the brakes are biased. Like you said this is because of the weight transfer as well as the heavier front end due to motor weight

If I get a chance im going to pull my wheel off tomorrow and take a look. Ill keep everyone posted and thanks for the feedback. I really dont like the nervous feeling I have driving the car now.

No need to take the wheel off, just look through the rim and see if you see cracks. There is plenty of room to see between the spokes and it should be very obvious if there are any cracks.

Not cracks, hairline fractures. My apologies I shoulda made that clearer.

Never take advice from someone who works at tire kingdom.

Do you have race pads on?

Sounds like your stability control is working overtime. You're not "drifting" if you're in "sport" mode. Try it with everything off.

[ame="http://www.youtube.com/watch?v=3FkCXleL8MI"]Subaru BRZ Drift at Streets of Willow Springs - YouTube[/ame]

It could be what this is talking about:

Surface crazing or cracking on brake discs


http://ebcbrakes.com/site/wp-content...-a-concern.jpg
The picture above shows a normal cast iron brake disc that exhibits what we call crazing. These are tiny hairline cracks that are extremely small and not of real concern. These are microns deep and are exaggerated by the black brake dust generated under normal driving. This does show that the brake discs have been quite hot and could encourage you to have your discs Pro Cut skimmed which can be performed several times during the life of your brake discs or rotors.
The Pro Cut skim removes only 4-6 thousandths of an inch and does not cause the discs to go below thickness.
There is good logic for this type of “Renovation” of your brake discs rather than replace the discs with new ones for the simple reason that a good USED disc is actually a better performing product than a new one. New discs require lengthy bed in times during which time the disc materials “Settle” and grain structure alignment takes place. Also the Pro-Cut machine is brilliant at taking a minimal skim from your discs WITHOUT REMOVING THEM FROM THE CAR which exposes you to a re-seating process and possible disc distortion and vibration arising.

......from ...... the internet......

Is that something every shop would have?

:word: My sis is a probation/parole officer and TK's around here are one of the largest hires of crackheads, meth junkies, thieves, etc. They are like walmart, jiffy lube, etc in that they will hire anyone with a pulse.

Well, I don't know ..... you could call around.

If they were my rotors, I would get a second opinion from a brake shop.

If they confirm it's just "crazing", I'd go with:

"The picture above shows a normal cast iron brake disc that exhibits what we call crazing. These are tiny hairline cracks that are extremely small and not of real concern."

However, something has heated up the rotors, so you may wish to take a peak at them from time to time.

humfrz

@z3ro: post a picture, and I will tell you if its normal or not.

Pro-Cut is a brand of on car brake lathe (required equipment for Subaru dealers). It's more idiot proof than other brake lathes, but really any decent tech should be able to resurface your rotors with any brand of on-car lathe.

I'd avoid shops that use off-car lathes, as they tend to be less idiot proof, and they won't match the rotor to the runout of your wheel hubs.

This is my guess. The OP has been drifting more than he thinks and the stability control system has been activating the rear brakes and overheating them. I know it is a common issue for guys who track Porsches to go through the rear pads much quicker than the front pads due to leaving the traction control system on.