Brake fade and Slotted / Drilled rotors.

xtech · Postby **xtech** » July 5th, 2008, 8:51 am

In every brake pad there is the friction material which is held together with some sort of resin. Once this lot starts to get too hot, the resin holding the pad material together starts to vapourise, forming a gas. That gas has to have somewhere to go, because it can't stay between the pad and the rotor, so if forms a thin layer between the two trying to escape. The result is very similar to hydroplaning while going too fast in the rain; the pads lose contact with the rotor, thus reducing the amount of friction.

As the brake components cool down, their ability to absorb heat returns, the pads cool off which means they have more chance to heat up again before the resin vapourises, hence the next time you use the brakes, they seem to work just fine.

Antoher problem, the pads can transfer heat into the calipers because the rotors are already too hot and the brake fluid starts to boil as a result. As this happens, bubbles form in the brake fluid. Air is compressible, brake fluid isn't, so you can put your foot on the brake pedal and get full travel but have no braking effect at the other end. This is because you're now compressing the gas bubbles and not actually forcing the pads against the rotors. Voila. Brake fade again.

Well to fix this you give that vapourised gas somewhere to go. For newer vehicles, you find some way to cool the rotors off more effectively. Either way you end up with cross-drilled or grooved brake rotors.

While grooving the surface may reduce the specific heat capacity of the rotor, its effect is negligible in the grand scheme of things. The rotors will heat up to cool down no faster or slower. However, under heavy braking once everything is hot and the resin is vapourising, the grooves give the gas somewhere to go, so the pad can continue to contact the rotor, allowing you to stop.

For more info follow link

http://www.carbibles.com/brake_bible.html

Read about completely new stuff

Drums'n'Disc Hybrid

xtech · Postby **xtech** » July 5th, 2008, 8:58 am

An important note about drilled rotors: Drilled rotors are typically only found (and to be used on) race cars. The drilling weakens the rotors and typically results in microfractures to the rotor. On race cars this isn't a problem - the brakes are changed after each race or weekend. But on a road car, this can eventually lead to brake rotor failure - not what you want. I only mention this because of a lot of performance suppliers will supply you with drilled rotors for street cars without mentioning this little fact.

FullStop · Postby **FullStop** » July 5th, 2008, 9:04 am

what about dimpled and slotted rotors, since these are not drilled, they are not weakened, and the slotting also helps to remove the heat

*KRONIK* · Postby ***KRONIK*** » July 6th, 2008, 11:15 am

xtech wrote:, the grooves give the gas somewhere to go, so the pad can continue to contact the rotor, l

^^^^^^^^^
these are slotted

and the dimpled rotors are "designed" to allow more surface area for heat dissipation.........

RBphoto · Postby **RBphoto** » July 6th, 2008, 1:27 pm

Ah reach. I see plenty cars in trinidad that look like they get it done in a machine shop. xtech, any info on drum brakes?

xtech · Postby **xtech** » July 6th, 2008, 1:49 pm

follow the link nah it have a few paragraphs on it.

blackNshine · Postby **blackNshine** » July 7th, 2008, 10:56 am

xtech wrote:An important note about drilled rotors: Drilled rotors are typically only found (and to be used on) race cars. The drilling weakens the rotors and typically results in microfractures to the rotor. On race cars this isn't a problem - the brakes are changed after each race or weekend. But on a road car, this can eventually lead to brake rotor failure - not what you want. I only mention this because of a lot of performance suppliers will supply you with drilled rotors for street cars without mentioning this little fact.

damn.well done pal.

fras · Postby **fras** » July 7th, 2008, 11:13 am

xtech wrote:An important note about drilled rotors: Drilled rotors are typically only found (and to be used on) race cars. The drilling weakens the rotors and typically results in microfractures to the rotor. On race cars this isn't a problem - the brakes are changed after each race or weekend. But on a road car, this can eventually lead to brake rotor failure - not what you want. I only mention this because of a lot of performance suppliers will supply you with drilled rotors for street cars without mentioning this little fact.

Good info here man... I myself was looking to cross drill n slotted rotors!

xtech · Postby **xtech** » December 18th, 2008, 12:18 pm

ek4ever · Postby **ek4ever** » December 18th, 2008, 12:53 pm

xtech wrote:An important note about drilled rotors: Drilled rotors are typically only found (and to be used on) race cars. The drilling weakens the rotors and typically results in microfractures to the rotor. On race cars this isn't a problem - the brakes are changed after each race or weekend. But on a road car, this can eventually lead to brake rotor failure - not what you want. I only mention this because of a lot of performance suppliers will supply you with drilled rotors for street cars without mentioning this little fact.

Are you referring to DIY??.....what about the drilled rotors from Brembo and other brake component manufacturers??

xtech · Postby **xtech** » December 18th, 2008, 12:54 pm

ek4ever wrote:
xtech wrote:I only mention this because of a lot of performance suppliers will supply you with drilled rotors for street cars without mentioning this little fact.

Are you referring to DIY??.....what about the drilled rotors from Brembo and other brake component manufacturers??

xtech · Postby **xtech** » May 14th, 2010, 7:30 am

up top

CD4Accord · Postby **CD4Accord** » May 14th, 2010, 11:28 am

I use slotted and absolutely refuse to use drilled on my car...

When Brembo makes cross drilled rotors they are sure not to penetrate any of the vanes etc, thus maintaining the structural integrity of the rotor as it is cast that way.
When your random machine shop or ebay seller makes a drilled rotor they take a regular blank and drill through vanes etc, thus weakening the rotor...

Then people could say Ferrari etc use drilled.... But let me put it like this, stock rotor size on nearly all of our cars would be 10-12 inches... When we drill and remove 20% contact area, it matters a lot more than on a ferrari which is using 15 or 16" rotors...

In most cases, regular blank rotors from a reputable company is the way to go... Slotted could also be considered but it will wear your pad a bit faster and cause a small increase in noise..

Finally, BREMBO NEVER HAS AND NEVER WILL CROSS DRILL AND SLOT A ROTOR.. so all of you who have cross drilled and slotted rotors and claiming its brembo... it isnt.
No one should remove such a signifcant surface area from a rotor... ever...

SiR8081 · Postby **SiR8081** » May 15th, 2010, 10:37 pm

am what ppl fail to mention is that race cars with drilled rotors are made from high quality aluminium and b/c they are made to perform rather than last, they fail. if you can afford to buy a kit for one axle at US$ 3000 - 5000 you should be able to afford new rotors. it isnt even the whole rotor, get the disc as these kits are floating. the disc is bolted. floating reduces brake fade

normal drilled rotors for the street like what brembo makes chances are the will not fail b/c they are made from steel. they are made to last, they are not made for the race track. if you want race track rotors you buy a Brembo GT kit.

so do not let anyone chain up your head. i am running Brembo Sport Brake Systems front and rear rotors on my SiR with absolutely no problems. i dont go to the track but note these brakes were not made for the track and as such i cannot carry my car to the track and expect the performace of brembo GT kit

my 2 cents

CD4Accord · Postby **CD4Accord** » May 17th, 2010, 8:51 pm

when you say it works bess.... in comparison to what?

Drilled + Slotted rotors will never work better than, drilled or slotted or plain old blank....
Whoever tells you otherwise is fooling you quite badly..

How much they charge you for that POS anyway? I'm sure far too much

CD4Accord · Postby **CD4Accord** » May 17th, 2010, 10:44 pm

Cyathole, have you ever seen a single manufacturer vehicle that comes with both slotted or drilled rotors? Find me one that came from the factory like that...
I assure you that you will only find drilled OR slotted... There is a reason that they don't do both but it involves complex things such as logic and intelligence...

I guess you just know more than Brembo and other world renowned brake manufacturers...
Why not start your own company?

CD4Accord · Postby **CD4Accord** » May 17th, 2010, 10:58 pm

Well, I have to admit I didnt expect to see renowned companies like wilwood and AP making them...
The problem with drilling and slotting is the amount of contact area removed.. I think its estimated as much as 25-30%... Doing this means you will need a bigger rotor to ensure a reasonable amount of pad contact... My guess is, this is how wilwood and AP can do it because it comes on a big brake kit..

Brembo on the other hand never does both, its a choice with them.... Also remember that drilling after the rotor has been cast is detrimental to the overall strength and life of the rotor... Drilled rotors are actually supposed to be cast that way...

Finally, I stand by my statement that no manufacturer will make a car with slotted/drilled... Normally it will be either/or

VexXx Dogg · Postby **VexXx Dogg** » May 18th, 2010, 10:07 am

I'm running the DBA 4000's on my LGT.
http://www.dba.com.au/node/5335
to be fair, I did a full brake system overhaul, so I can only compare to stock.

Before: Stock rotors, stock pads

After:
DBA 4000 Slotted, drilled rotors front, stock rotors rear
HAWK HPS pad front and rear
ATE Superblue DOT4 fluid
S/S brake lines
Cusco Master Cylinder brace

when cold, the pads kinda suck, but once warmed up....DAMN.