Good Brake Myth Article.

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w00ht

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Discussion starter · #1 · May 6, 2004

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Hey I found this article on my local SCCA site, written by Carroll Smith courtesy of Stop Tech.
http://members.aol.com/odrscca/racing2.htm
Interesting reading considering the brake threads we have had lately. He says it's almost impossible to warp a rotor, but rather what we see as rotor warpage is uneven pad material buildup.

 

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argh32

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#2 · May 6, 2004

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Re: Good Brake Myth Article. (w00ht)

I warped the front rotors on my S4 during a track day....the dealer replaced them under warranty.
No myth, just fact.

 

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w00ht

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Discussion starter · #3 · May 6, 2004

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Re: Good Brake Myth Article. (argh32)

Just for the record, did you read the linked article?

 

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R(ed)32

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#4 · May 6, 2004

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Re: Good Brake Myth Article. (w00ht)

Excellent article. Good find.

 

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w00ht

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Discussion starter · #5 · May 6, 2004

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Re: Good Brake Myth Article. (R(ed)32)

Thanks Red. I thought I's share.

 

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adoniram7

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#6 · May 6, 2004

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Re: Good Brake Myth Article. (w00ht)

That's funny: I have seen a warped rotor with my very own eyes,
and what came off of it wasn't pad material when turned....
Plus, I had warped rotors within 5000 miles, brand new, on my 2001
Jetta that the dealership actually replaced without complaining.
(Clear vibration through the brake pedal - anybody who's ever had
'em knows what's up there.). That ain't enough miles to come under
the subject of "pad material."
This is, frankly, complete and total b.s. Warped rotors are mostly
caused by improper torquing of the wheel lug bolts. When the rotor
gets hot, it warps since, for example, one of the bolts is torqued at
130 ft. lbs. and another, opposite one is torqued at only 80 ft. lbs.
That's why air guns for putting wheels back on are a bad idea
(and also for trying to take off the wheel after a flat on the side
of the roadside).

 

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XenoLlama

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#7 · May 6, 2004

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Re: Good Brake Myth Article. (adoniram7)

actually, the article doesnt discount rotors being warped by improper torque.
Just from driving.

 

fowtj

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#8 · May 6, 2004

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Re: Good Brake Myth Article. (XenoLlama)

I have heard this arguement before and it holds no water. He is arguing that the relative thickness of the rotor in certain areas is what people call warping. That simply is not the case. The rotor can maintain a constant thickness and still be warped. If you have ever seen a warped rotor spin on a lathe then you KNOW it is warped.
Warping is caused by improper torquing of wheels and by uneven temperature dissipation (ie. hitting a portion of a REALLY hot rotor with cold water so that it actually contracts at a dissimilar rate to that of another part of the rotor). Case closed, end of story. If you dont believe me, then torque your wheels unevenly, get your brakes really hot and then douse 1/2 of a rotor with a hose...

 

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w00ht

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Discussion starter · #9 · May 6, 2004

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Re: Good Brake Myth Article. (adoniram7)

Quote, originally posted by adoniram7 »

That's funny: I have seen a warped rotor with my very own eyes, and what came off of it wasn't pad material when turned.... Plus, I had warped rotors within 5000 miles, brand new, on my 2001 Jetta that the dealership actually replaced without complaining. (Clear vibration through the brake pedal - anybody who's ever had 'em knows what's up there.). That ain't enough miles to come under the subject of "pad material." This is, frankly, complete and total b.s. Warped rotors are mostly caused by improper torquing of the wheel lug bolts. When the rotor gets hot, it warps since, for example, one of the bolts is torqued at 130 ft. lbs. and another, opposite one is torqued at only 80 ft. lbs. That's why air guns for putting wheels back on are a bad idea (and also for trying to take off the wheel after a flat on the side of the roadside).

By your explanation wouldn't a "floating" 2 piece disc as on the R32 be immune to warpage by over tightening then?
I just read the article and figured it would make for good discussion on the board. I didn't write it.

 

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wrh3

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#10 · May 6, 2004

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Re: Good Brake Myth Article. (w00ht)

I try to be easy on the brakes when I know I will be at my destination in the next few minutes, just like I used to be easy on my turbo the same way (even though it was water cooled). If you think about heat soak like this you can see how it would cause rotors to warp. Say a deer comes out in front of you and you slam on the brakes. The caliper has just absorbed a great percentage of that heat. Now there are two paths you can take: a)you drive the car for a few more miles and allow the brakes to cool before parking your car or b) you pull off to the side of the road to see if the deer is OK

Well, if you chose option b, that HOT caliper is sitting over one part of your rotor and that part will not cool at the same rate as the rest of the rotor, I would think this might lead to warping hence my logic for allowing cool down time.