1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Weight Saving between a blank Rotor and Drilled Slotted?

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Old Feb 11, 2009 | 11:34 AM
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Weight Saving between a blank Rotor and Drilled Slotted?

Now I should put it out that the braking performance isn't going to matter in my application for either ones because of the T2 brakes all around, and if my stock ones were more than adequate on the track I'm sure any of them will work. But the reason that I ask the question is if there's a significant weight savings from one to the other, then thats sprung weight removed at the cost of more dust which I hate. But if the saving isn't all that much (say less than 1/2 lb combined per pair) then I would rather not deal with the extra brake dust.
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Old Feb 11, 2009 | 11:48 AM
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from my experience there is not much weight difference in the drilled/slotted vs. regular rotors of the same manufacture. the main difference is the rotors ability to expel gases and stay cooler. thus comes about the age old forum discussion solid vs. drilled vs. slotted vs. drilled and slotted. i have run drilled and slotted on 3 cars(1996 jetta, 1993 toyota pickup, and current is a 07 speed3). i have noticed a significant drop in brake dust with all 3(but i have also changed pads at the same time to ceramic pads, so the comparison isn't fair).

when i do finally get my gsl-se i am going to do a drilled/slotted setup. just not sure what calipers i am going to use.
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Old Feb 11, 2009 | 03:10 PM
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if you're going to track the car skip the drilling and venting. they crack around the holes.
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Old Feb 11, 2009 | 08:21 PM
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Originally Posted by j9fd3s
if you're going to track the car skip the drilling and venting. they crack around the holes.
Drilled rotors do. If the rotors are cast with holes, then they will not.

Also, slotted rotors are good only if they are chamfered, and not just a direct 90* angle cut.
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Old Feb 12, 2009 | 12:06 AM
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From working on car that have had both blank and slotted/drilled, the blanks have alot less dust and it would be the ceramic pads that you're using that reduced that. If you think about it, every cut edge on the rotor can cut more into the pads creating more dust, but the harder the compound (like ceramic) the harder it is to cut through it.

Originally Posted by brandontrek
from my experience there is not much weight difference in the drilled/slotted vs. regular rotors of the same manufacture. the main difference is the rotors ability to expel gases and stay cooler. thus comes about the age old forum discussion solid vs. drilled vs. slotted vs. drilled and slotted. i have run drilled and slotted on 3 cars(1996 jetta, 1993 toyota pickup, and current is a 07 speed3). i have noticed a significant drop in brake dust with all 3(but i have also changed pads at the same time to ceramic pads, so the comparison isn't fair).

when i do finally get my gsl-se i am going to do a drilled/slotted setup. just not sure what calipers i am going to use.
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Old Feb 12, 2009 | 12:13 AM
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Originally Posted by j9fd3s
if you're going to track the car skip the drilling and venting. they crack around the holes.
One of the guys that my engine builder built a car for (AE86 with a 13B pushing out 180whp, and weighing in at under 1900) has slotted and drilled and yes his holes are cracked but still tracks the car. He keeps on telling me that they're still good for alot more laps to come. So really how easy is it for them to crack full?

Also what about the new design of not fully drilled rotors ... so its like countersunk areas?
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Old Feb 12, 2009 | 09:07 AM
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***But the reason that I ask the question is if there's a significant weight savings from one to the other, then thats sprung weight removed ***

When removing weight from the brake discs that would be unsprung weight.

Cleaning rims after track laps is normal procedure with a race car.

Do the safest things you can when doing laps on track.
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Old Feb 12, 2009 | 09:40 AM
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Brake performance on the track is much less about unsprung weight, and much more about heat. Track cars generally have heavier brake kits because they use giant rotors and calipers.

IMO, stay away from the oem replacements that are xdrilled, they are just a waste of money. Save up for a real brake kit.
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Old Feb 12, 2009 | 10:06 AM
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Originally Posted by zenofspeed
Brake performance on the track is much less about unsprung weight, and much more about heat. Track cars generally have heavier brake kits because they use giant rotors and calipers.

IMO, stay away from the oem replacements that are xdrilled, they are just a waste of money. Save up for a real brake kit.
good call...
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Old Feb 12, 2009 | 06:13 PM
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Sorry I meant to say unsprung up there ... just too quick on the typing sometimes.

By a real brake kit what do you mean? Real rotors? I'd rather get stock rotors as they're the cheapest anyways.
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Old Feb 12, 2009 | 08:27 PM
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Originally Posted by dj55b
Sorry I meant to say unsprung up there ... just too quick on the typing sometimes.

By a real brake kit what do you mean? Real rotors? I'd rather get stock rotors as they're the cheapest anyways.
Respeed, get the TII kits. Then if you want to go bigger, there is a place in Japan that makes an adapter plate for the TII's that space them out further to run the FD discs. The business name escapes me, but if you are interested I can look around for you.
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Old Feb 12, 2009 | 09:27 PM
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I already bought the T2 kit from Re-speed, its in my first post. Thats why I'm asking the question
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Old Feb 12, 2009 | 10:35 PM
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If your going to have to have t2 brakes all around you should have more than enough braking with stock t2rotors and good pads.
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Old Feb 13, 2009 | 11:49 PM
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How much brake you need is the answer to a very complicated formula. When I first drove -- either hard on the street or on a road course -- I needed more braking power. I had fade problems with my SP 13B. Once I had a dozen or so track days under my belt, I found out I needed less brake. After I became a better driver, I didn't slow as much for the turns.

But back to your original question -- you can do the math fairly easily yourself. Figure out how many holes are drilled, multiply by the volume of each hole, then multiply by the density of iron.

For my money, I wouldn't touch drilled rotors for any serious performance application. I don't think brakes are a good place to save weight.
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Old Feb 14, 2009 | 12:41 AM
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You don't think that at 2240Lbs your car might just be light enough? As elwood said, the brakes are the LAST place to look for weight savings. Get rid of those heavy *** stock seats for some FRP or carbon seats. They will knock off more weight than the X-drilled rotors, with the added effect of holding your *** in place when your flying around the corners (or missing them altogether like at Fanshawe :P)

Gimme a call, I'm home til Tuesday or so. Since the snows nearly gone I'm gonna get the rear end up and start spraying all the rear control arm and watts link bolts with 2 cans of PB Blaster, just to get it ready. Do you know the bolt size and thread for those? I'll probably end up breaking some.
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Old Feb 14, 2009 | 01:43 AM
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Blanks it is then ...

Chris ... I'm not sure what my work schedual is for next week, but most of the stuff in the back end there is 17-19-21mm I believe and if I didn't break off any and my first shell was from the junk yard ... I doubt you'll break any. They're pretty heavy duty. But make sure you get a wire brush handy to clean up the ends.
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Old Feb 14, 2009 | 07:22 AM
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Originally Posted by j9fd3s
if you're going to track the car skip the drilling and venting. they crack around the holes.

Originally Posted by Jeezus
Drilled rotors do. If the rotors are cast with holes, then they will not.

Also, slotted rotors are good only if they are chamfered, and not just a direct 90* angle cut.
Yep, plain old blank rotors will be fine.

If you ask me, the drilled rotor craze is one of the things that should have never made it to main stream motorsports and certainly not in street performance use. Professional level motorsports have a "life" schedule for every part on the car. All parts are replaced at the end of its life no matter if it shows age/failure or not. Main stream motorsports and street use parts until they fail. Last thing you want to have fail is a brake rotor.

I have felt it - 1/4 of a brake rotor flinging around inside a front wheel. Your new Kodiac wheels would not look to good after that

-billy
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Old Feb 14, 2009 | 09:03 AM
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just dont buy the cheap *** brake rotors that are made in taiwan or china. they are cheap but they dont last long
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Old Feb 14, 2009 | 10:36 AM
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i usually go to the local carquest or napa, and buy the cheapest oem brakes.

funny thing though, the turboII 4 piston brakes are cheaper than my gsl se ones
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Old Feb 14, 2009 | 11:06 AM
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Originally Posted by wackyracer
just dont buy the cheap *** brake rotors that are made in taiwan or china. they are cheap but they dont last long
What are you talking about Wacky? I always though Taiwan was synonomous with QUALITY!!!! And those Chinese folks sure are churning out alot of product. How can it not be good?????????????????????????????????????????????? ??????????????????????????????????????????????


Sorry about that. Key got stuck. My keyboard was made in China.
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Old Feb 14, 2009 | 11:25 AM
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Originally Posted by orion84gsl
What are you talking about Wacky? I always though Taiwan was synonomous with QUALITY!!!! And those Chinese folks sure are churning out alot of product. How can it not be good?????????????????????????????????????????????? ??????????????????????????????????????????????


Sorry about that. Key got stuck. My keyboard was made in China.


I have cheapo drilled/slotted on my Integra because the previous owner thought they looked mad tyte.

They haven't died yet, even with a trip up and down pikes peak.
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Old Feb 14, 2009 | 12:33 PM
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personally i don't like drilled and slotted. think it looks... stupid, just hype
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