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Discussion Starter #1
I'm look for the road race guys because I would think they would be the hardest on rotors for this question. I'm having trouble heat cracking HP rotors. Here are the conditions.
1. They have to stop 4510 pounds at near 160MPH in a 1/8 mile or less.
2. The front pads are Hawk drag pads for cold grip.
3. It is the stock Impala brake system but with 30" of vac from a pump and will lock up the tires if you try, so I have plenty of grip.
4. The rotors have to have the factory ABS in the back of the rotor.
5. I would like them to have the metric studs because I still run the stock rims and use the stock nuts.
6. I run 30" tall SUV tires on the factory 17" rims on the front so it has a ton of bite to the track and keeps the ABS from kicking in so it's harder to lock the front tires up at high speed. I'm sure this is whats killing the rotors as it stops the car instead of just locking the tires up.

I will have to look in my parts room to see what is on there now but they were expensive and supose to be really good. They are only lasting about 10 passes before you start seeing cracks. This setup stops 4500 pounds like it was a 3000 pound car but it's killing the rotors.

I looking for someone that truely abuses their brakes and still runs factory type rotors.
 

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Abusing Brakes?? Best Rotors?

Jeff,
I see Bill Harper PM'd you so you might already have the info....
But it sounds to me like you are a perfect candidate for the HD12 set-up that Bill put together! I have been running them for over 2 years and have been through at least 5 sets of pads. I feel that I am extremely hard on brakes and I have been very happy with this set-up!
Essentially you replace the fctory (sized) rotor with one of Kore-3's Billet Hub's, you retain factory ABS and can retain factory lug nut size if you desire - (I did).
Then you install a two piece "hat style" 12 X 1.25” Rotor with aluminum hat and swap you Impala or Caprice Calipers to the wider
9C1 Caliper and continue to use the "thinner" Impala Brake Pads.
You end up loosing about 2 lbs per side and gaining a lot of mass in the friction surface of the rotor.
I was running stock sized rotors (tried about 4-5 different brands) all with the same problem running Hallett (1.8 mile road course in Tulsa)
I could not complete a 20 minute lapping session without overheating the brakes - I would exit the track with front rotor temps exceeding 1000 deg. F (My thermal gun only goes to 999)

I now have the HD 12 set up in the front and the C5 rear (more mass and availability of better pad compounds) my last track day I ran all 5 sessions - the full time, never lost the brakes and my temps averaged around 750 front and 550 rear.

I think your problem is fixable! feel free to PM me with you number and a good time to call. I would be happy to discuss further.

[email protected]
]
 

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Discussion Starter #4
Thanks, I did send you my e-mail address to you. I will admit I really hate to change everything as the car stops fine. I also know there is not a lot of options for a factory rotor and that's why I'm making sure there is not something out here that I just was not aware of.

Thanks for everyone input.
 

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Not sure of the answer but is it possible in your somewhat unique situation you are shocking the rotors from stone cold to hot ? Not so much over heating as rapid change.

Don't know how long you sit after coming down the lanes but maybe dragging the fronts with the line lock before coming to the line to get some heat?

Also could your car stand more rear brake to help out the fronts?
Possibly going as far as putting a regulator on the fronts?

Gerry
 

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Discussion Starter #6
Thats a good thought as I would have ever thought a hard stop one time and then letting them cool all the way down should heat crack the rotors. I have never put a heat gun on them but maybe I should, then again I may not want to know how hot they are. It could be a scary number on a 90 degree day.

I am a little afraid to spend a bunch of money and have the same issue because of the MPH and the weight your stopping.
 

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As I said , just a thought.
Going from cool to stinking hot on the face before the core heats up may be a factor.

The type of racing I am involved with , bringing the rotors to temp is done as well as the pads ( pads more to do with compound)

Not a lot of pace laps at the drags though.

That being said , cracking rotors is a fact of life on a road race car.

Gerry
 

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Hey Jeff,
If you buy the HD12 kit, and decide not to keep it,.. Ill take it off you. Id be willing to bet its a keeper though. Do you have some sort of lay-a-way plan? lol


Good luck,
ZACH
 

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Discussion Starter #9
The problem is if it doesn't work the the rotors will be heat cracked and my guess is you will not want a set of heat cracked rotors.

I have a great lay-a-way plan for parts that are now bad!! I have a set of heat cracked rotors currently on the car, you want to buy them???

I was hoping someone would tell me "you need X rotor and the problem will go away". I now am wondering if its a problem you not really going to fix but the best you could hope for is a larger set makes it 20 passes before they do it.
 

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Honestly, not many people on your level, facing these problems. So nobody has the "right answer" for you.

I wasnt being sarcastic or anything, I just wanted to be a cool kid and say something, lol
Oh, also, I probably would still take the kit, there's alot more than just rotors that go into it.


Hope you get this issue taken care of,
ZACH
 

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2. The front pads are Hawk drag pads for cold grip.
Jeff, I looked for the drag-race spec (Hawk DR97) in both HB103 (D52 pad spec) & HB131 (D614 pad spec) in the Hawk online information, and it wasn't listed--the stock calipers use either of these pad configurations.

Hawk Drag Racing Applications

DR 97 "Excellent static and dynamic coefficient of friction. Smooth linear torque. Low pad and rotor wear. Brake pads specifically designed for use in drag racing applications."

What pad spec are you actually using?

Have you consulted with Hawk about the problem you're having?

Since I'm not sure how much you actually drive the car away from the drag strip, my thoughts are to ask what have you done to properly bed the pads & rotors before going out and making a stop from 150+? There has to be something going on here that may explain the problems you describe, and I am thinking this is an area that might be worth exploring.

That said, with 4650# to stop from the speeds your car is capable of, something ends up being sacrificed. For typical street use, the OE rotor reaches it's limit quickly if pushed, but your situation is well beyond the normal operating envelope.

The mass of a larger rotor--thicker and/or larger OD--is able to handle heat transients much better than a stock rotor, as Todd has described.
 

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I'd also want to know what you are seeing as far as cracks go; you talking about hair line surface cracks or serious chunking issues with large cracks to the rotor edge?

What's the life span out of the rotors you're running and are unhappy with?

What is the 'daily driver' use of the car?


Moving to an alternate pad might help not put so much heat into the pad but you won't stop as quickly either. The same mass at the same velocity will require the same work. Take away the pad Cf and you'll be left with either larger diameters or more piston area. Both don't seem to be very workable candidates.
 

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Discussion Starter #13
The pads are HB131N.595 which Hawk said would be a very similar pad to the DR-97 and the best they had for Impala Brakes. The rotors are Baer Decela rotors 5577-020.

The cracking is just surface at the holes and slots but no chunks at this point. I agree the better the pad the more heat you're going to get but better stopping. It's doesn't need a better pad as it is working but the rotors don't like the heat. Going to a low friction pad is not an idea I'm will to go with. Stopping the car safely at any track size has to stay the top issue. I may just have to cahnge the rotors every year.

Is anyone else using these rotors and have any feed back on them?
 

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Discussion Starter #15
I didn't answer all the questions so if it helps then great. The pads were seated as the instructions requested. I would have to pull the sheet again but it requested you drive the car, stop so many times kind of hard then once or twice real hard but only at 40 MPH or so, then let the car sit and let the rotors cool all the way down and your set to go.

Do you really want to know what Hawk said??? The same thing any parts vendor says when you tell them what you want to do "Good Luck with that" but it does stop the car just fine. First you tell them what it weighs and then tell the the MPH you need to stop from. They ask what motor you have in it, what tranny and so and then think your just making stuff up because that could never make the power to do that or hold up. I actually had to fax over a time slip from Munice to one vendor before they beleived me that it was going 150 plus and you can tell by the bad 60 foot time that the power had to be there to make up the time with that bad of a sixty foot. Anymore I really try not to tell the vendors what I'm doing because they just don't beleive it and you have to spend the time explaining or proving you really are doing this. Only companies like Moser or Lingenfilter, that have seen the car run at Muncie, are easy to talk to.

Depending on the price I would consider going to the larger brakes, but I really like trying to keep the stock stuff if I can make it work. My question would be if the rotors crack on the new setup is someone going to take it back for a refund???? Stopping is not the issue as it works great so if the new larger setup still cracks the rotor because of doing something like this then it didn't solve anything.
 

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Discussion Starter #16
Baer, Wildwood and everyone else I talk to all said it need venting to stop or you were going to get fade stopping at that speed and distance. I agree the cracks may go away but not getting it stopped is a much larger issue.

Don't take that as me saying your wrong. I'm trying to see what others have done and it worked.
 

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You lost me at "holes" and complaining....


Got get some el cheapo $45 rotors from the local parts store, find someone who has some Raybestos Brute Stop pads. Then when you get stopped; take your foot off the pedal and get some cool down time. When they crack after 6-8 months chuck 'em and replace.
 

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Brake rotors are a disposable item went racing 2 tons of fun

Plain rotors will last better and crack less then slotted or drilled ones. I like DBA Australia rotors. The ones in the Corvette size weigh 6lbs each more than a stock Impala rotor. Open track use will still crack them but I have gotten a whole season out of a set with only minor surface cracks. Give Carbotec engineering a call and ask about pads. I run XP-10's but they can suggest and build a pad just for your need.

Bill H's kit will give you more rotor mass but if you want to keep it stock just budget for new rotors each spring and be done.
 

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Discussion Starter #19
Thanks for several options and the names of who the parts are made by.

The only other question is the non slotted/drilled rotors, did you see and fade with a solid rotor?
 

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Doesn't the 9C1 use different outter airdams and vented front backing plate/dust shield? They were used to provide increased airflow to the front brakes which obviously weren't designed for 160 mph quarter mile runs, but they could help with your brake cooling.
 
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