mshea

OK, I'm fed up with looking at my rusted hubs. There are several sources for aftermarket rotors....any recommendations/warnings?

Speedtoys

Ya..slotting ONLY works on full race pads, and then only is required on _few_ of them in racing only, and drilling costs you braking performance and rotor longevity.

romycha1

Really? I've never heard of that... and I thought it would increase braking performance since the rotors are cooled down faster.

TownDrunk

I believe it's the lack of surface area that degrades performance. Bigger calipers would take care of that

Speedtoys

Slotting doesnt grab anything..it shaves the surface of a glazed brake pad surface, and glazing takes extreme temps and conditions to exist at all. And not all full race pads will glaze.

if you are glazing street pads you are using the _wrong pads_..fix your pad material issues..yes, this might mean spening actual money. It never ceases to amaze me how people will buy a $30,000 car, put $12k into mods, come to the track, and bitch about how GOOD brake pads for their car shouldnt cost $250 per set. Meanwhile they sit out a $300 track weekend becaue they couldnt be bothered with more than $50 "performance" street pads at a race track day. Thats not directed to anyone here at all..just..wouldnt be the first time ive had to deal with that.

Rotors cool down according to how efficient the vanes are inside the rotors..THAT cools them. Curved vanes beat straight ones, MORE vanes beat fewer vanes, finely detailed and crafted/shaped vanes might beat plain cast ones. Air ducting that is directed squarely _into_ the back hat of the rotor where none of it is wasted on the inside face of the rotor is the only way to direct air _into_ rotors..air ONTO rotors is wasted $. There is 100's of times more surface area in those cooling vents inside the rotors than drilling could ever offer, not to mention the drilled holes dont pass any air thru them. The inside of your rotor acts like a cage fan, centrifically pumping huge CFM of air thru the rotor body.

The rotors need the _mass_ to absorb braking energy calmly, if you dont have enough rotor mass to absorb that energy with, your temperatures get too high too _fast_ and that is what cracks rotors. No manner of putting holes in a rotor is any less prone to cracking than any other method, a rotor doesnt expand linearly, heat stress a rotor that's been swiss-cheesed enough, and the outside holes will develop cracks at the outside edges then migrate towards the center of the rotor and then eventually fail. Period.

Rotor surfaces are all about friction surface to create braking with..think about that..take away surface area, what does the brake pad grip with? Depending how agressive the drilling is, you give up anywhere from 2 to 3 square inches of friction surface away from your brake system to do pretty much nothing except brake worse.

Cross drilling only takes money from your pocket, and gives it to someone else...guaranteeing shorter brake pad life (increased temperatures, or in worst cases with bad patterns increased wear) and a guarantee that your next pad order _will_ require another set of too expensive rotors with more drilling.

Also..like I said, the efficiency of the internal vaning determines how fast a rotor cools down on the track..street people have nothing to worry about temperature wise..you just dont. If you fade pads on the street, you are using the _wrong pads_ and drilling wont solve any problems..lost mass = more heat.

The only sane excuse for drilling in racing is to LOWER rotating mass, in which case you have an appropriately sized rotor for what you are planning to do with it anyways. Bikes do this, and serious race cars do this.

Hang around a club racing track day for NASA/SCCA sometime, if drilling/slotting was _that_ badass, how come -we- dont do it for that added performance kick? Its not that we cant afford it, its that we know it doesnt work as advertised..and we'd be losing more races due to failed components than anything else.

Speedtoys

So larger calipers makes up for missing rotor surface area?

I dont think so.

IN fact, most people in here that really think they -need- big brake kits for track use simply havent asked themselves if they can solve their problems in one or both of these two ways:

1) Learn better braking technique
2) Use the RIGHT friction materials instead of compromises


I sell a material that does -not- eat rotors, and will brake like you've never felt before on a racetrack..that will last racers for nearly a year, and its not some fancy named J-spec brand either. Youve all heard of it, just never _considered_ it, not to mention that retail wise, its very hard to find.

But..you see it in action ever Sunday on TV with 3400lb machines running up to 500miles and youve never ever seen a brake pad swap..my good stuff is -that- stuff.

..almost a forum sponsor..still trading Emails.

Speedtoys

Have you tried sandpaper, and paint? Besides..who do think is lookin?

Razz1

Ja, real waste of money. If you can't do it your self have a mechanic paint the rotors.

TownDrunk

Interesting. I'd have figured that all things being the same pad material, clamping force, etc... that getting a caliper that provides a larger swept area (what I meant by bigger calipers), would make up for surface area lost to holes in the rotor (etc).

Thanks for the info.

Speedtoys

Its..complicated, but not that simple.

If you had a caliper and pad that covered the entire rotor, all of that energy has to go somewhere..right?

And..the energy to do the braking has to be create by being in contact with the rotor.


A larger caliper/pad in that situation masks the larger problem.

Speedtoys

Also..plated/painted rotors..

DO NOT allow the pad area to be cad coated/etc or painted. It -can- easily contaminate the pad and ruin them.

If you end up with that situation, get some crap $20 pads from autozone or something to eat off the paint/coatings/etc.

Napboy

Fine, back to the original question. Any recommendation on getting a suitable replacement for stock rotors without paying the crazy dealer prices?

O'Renesis

I can only give a warning about my aftermarket rotors. These are EBC which are advertised as being "zinc plated". It turns out they are not plated. The excuse given by the supplier and EBC (UK) was,

"At the moment our only source of these discs is from America. The Americans like to have the hubs etc painted/coated in Black. As the casting comes already coated when we have Grooved and Spotted it we are unable to zinc plate this style of disc. Until I can find another source, all of our plain and GD discs for this car will be with the Black coating"



Have a look at Racing Beat's offering.

BaronVonBigmeat

Yes. Go to racingbrake.com and get their 1-piece rotors. For whatever reason, they stay nice and shiney, and they're guaranteed against warpage. They are slotted, but it doesn't cut all the way through, and stopping power is unchanged from stock. I don't know if they are any cheaper than the OEM's, but at least they won't warp after 30,000 miles.

For a street car, order up some Hawk HPS pads while you're at it. They're quiet and clean. No more filthy buildup only 3 days after washing your car. Stopping power is probably the same, but the feel is more linear and controlled.

Speedtoys

I dont offer any coatings as its such a niche market and nearly impossible to find an affordable coater, but my Brembo/Bradi rotors are $64/ea normal, $70/ea sport, $54/ea rears.

Not sure why they cost $100+ elsewhere.