i have x-drilled rotors and naturally after getting them i started seeing posts about the reliability of these...things like them being prone to cracking, etc...
lately i've been finding dimpled/slotted rotors for sale...anyone have an experience or info on dimpled rotors
im guessing being dimpled instead of drilled is better (not including rotors with the holes cast into them during manufacturing)
I have the slotted rotors and havent had any problems with them. As for performance I didnt notice any hugh gains from the rotors. The stainless steel lines made a bigger difference.
thats all good but i was looking for thoughts on the dimpled rotors i've been seeing lately...they have dimples like a golf ball as an example instead holes
but then again no one responded with anything else so thanks j.s
For street use, even high performance street use, the cross drilling, slots, and dimples really don't do anything for brake performance. They are really only for looks. If you are trying to improve brake performance, choose a good set of premium pads with stock rotors.
What Jim said.
The dimples on the EBC rotors, for example, are meant to simulate the look of cross-drilled without increasing the risk of crack formation. They have no performance advantage whatsoever.
Trouble is, even shallow holes reduce overall rotor mass, and therefore reduce the rotor's ability to absorb heat.
@gdub520
The Drilled rotors are designed to allow air to pass to the surface to aid cooling and the grooves are designed to de-glaze the pad and dissipate any excess break dust, I would guess that the dimple variety wouldn't do either of these very effectively, I use Black Diamond Cross Drilled and Grooved Rotors on all four wheels, they are without a doubt in conjunction with EBC Green stuff front pads and Bosch Silent Rear pads the best I have ever used, you can really feel it on the tyres under excessive hard breaking, I have posted pictures in the appropriate area, fyi I have also used EBC front rotors and although better than the ford, they really are not up to the BD, the only thing that was a little weird was the amount of run in time, the Black Phosphate coating took some getting through.
Neil
Cross drilled rotors should have the hole counter sunk to help prevent rotor craking.. Both cross drilled and slotted rotors serve the same function.. that of removing pad gas build up when the brakes get really hot
.. not something you'll see in street driving and rarely, if ever, with our cars on the race track..
just something for show and having both drilled and cross slotted on the same rotor is really dum..
i thought the holes are to remove gases and the slots to improve braking cuz they cut into the pads keeping them "clean" to bite without brake fading
I got the EBC dimpled slotted rotors by mistake (company sent wrong ones!) And besides looking pretty cool and making a weird whirring sound under hard braking, I don't think they do a damn thing. Theoretically dimpled and slotted and rotors with holes will all help disipate heat by increasing the surface area, but this effect will be minimal.
Originally posted by Neil:
The Drilled rotors are designed to allow air to pass to the surface to aid cooling and the grooves are designed to de-glaze the pad and dissipate any excess break dust
Originally posted by mr_froge:
Both cross drilled and slotted rotors serve the same function.. that of removing pad gas build up when the brakes get really hot
Originally posted by hmouta:
i thought the holes are to remove gases and the slots to improve braking cuz they cut into the pads keeping them "clean" to bite without brake fading
No.
See
Wilwood FAQ: Why are some rotors drilled or slotted? and
Team scR: Those poor rotorsFor more brake system information try these links:
Stoptech White PapersGrassroots Motorsports Brakes articleCheers,
--
Terry McG
You'll always find someone who trashes the competition, go and have a look at the contradictory site.
http://www.ears.ie/index.htmFollow the Brakes and then disk and read on.
Neil
Hi Neil...
Originally posted by Neil:
You'll always find someone who trashes the competition, go and have a look at the contradictory site.
http://www.ears.ie/index.htm
Interesting, but I'm not convinced - there are other vendors that make similar claims, but with the same limited 'tech' to back it up.
FWIW, Wilwood sells drilled or slotted rotors too, they just tell you it's for looks, not performance. Baer used to have a really good FAQ on this, but it seems to be gone from their latest site (they too said, "we'll sell you holes and slots, but it's just a cosmetic thing").
A couple other related links:
The classic Altimas Net 'Cross drilled rotors' thread Comments on the above from Corner-Carvers.comI'd really,
really like to get to the bottom of this one...
Cheers,
--
Terry McG
I'll try not to write a novel on this, as I'm no expert at all, but this is a subject I've broached with a number of other people that are in the know, and I've done a fair amount of research myself on this subject.
Cross drilling/slotting of rotors on street-driven cars don't add too much apart from looks. This is especially true given today's pad compounds that are routinely used on street and semi-track cars. Notice I didn't mention motorcycles, F1 racers or anything else; I'm talking about this application on streetable coupes/sedans that will sometimes see track use. In short, Contours and other "sport" sedans out there...
Longevity
Most blank rotors that are drilled after they've been heat treated (i.e., placed in vats of sand to help them cool off evenly after being formed from the factory) will display a tendancy to form stress cracks or fractures due to the uneven heating and cooling placed upon the rotor. Potentially, all it could take is a couple of splases through puddles, staying on the breaks at a light after hitting and staying on them hard, etc. There is NO argument that longevity is adversely affected by going with a cross-drilled or slotted arrangement. This goes for pads, too as the slots and holes will eat your pads up faster than a blank rotor would.
If you can get a set that have been formed from the factory (Brembo does this, I think) as cross-drilled or have gone through some sort of cryo-treatment (Frozen Rotors or the like) to help strengthen the rotor, then I wouldn't be adverse to recommending them, as long there exists the understanding that you may be purchasing new pads/rotors MUCH sooner than you would otherwise...
Again, understand that going with slotted/cross-drilled in the majority of circumstances is going to shorten your rotor life.
Stopping Power
I've had folks tell me that their cross-drilled rotors have drastically decreased their stopping distances. I doubt this by itself has done this for a number of reasons:
1) Decrease of Surface Area - Less area that the pads can exert their force from the pistons. It's physics and it doesn't change to justify the amount you just spent on those fancy looking rotors. The pads and rotors they've just replaced are usually shot to hell, so the new pads and/or brake kit is usually behind 95% of the increased stopping power that they notice. Again, this is comparing blanks and cross-drilled/slotted rotors of the EXACT same size. If you're going from blank 11.5" rotors to cross-drilled 13" rotors, then things are going to be different. Hell, you may not even get the rotors up to full operating temp (depends on the type of pads you are using). I've heard of folks DRASTICALLY increasing their rotor size and putting track pads on and try to live with them for daily use. The first time they made an emergency stop in the cold sold them on going back to street pads...
2) More Pistions - This is where I get a little out of depth, but the more pistons you have exerting force across the area of the pad directly correlates to the increase of the amount of pressure put on the rotors. Someone with a better physics or hydraulics background please step in and explain it better, as I'm sure I've taken a rather hacksaw approach at this one...
3) Operating Temp - Another area I'm shaky on, but the bigger the rotor, the better the heat sink it is. Running bigger rotors that are cross-drilled can adversely affect your breaking distances, due to the cooling effect that it has upon the rotors. Brakes have a temp window that they operate best in. Too cool, the don't function as well. Too hot; well, everyone knows about brake fade... The deal here is that by going with MUCH larger rotors, you are changing that window. Whether good or bad, it depends on your driving and pad compound. I'm assuming that we are talking about street use here, so going with a really grabby track compound that has to hit higher than normal temps to function optimally and 2" oversize rotors that are cross-drilled probably isn't a good idea.
In short, I'd tend to agree that for 4-door sedans such as ours, cross-drilling/slotting is pretty much for looks. I've heard the wet-weather argument that they perform better in rain, but unless you're in Washington or Oregon, I'd try to find another excuse to justify them.
Performance-wise, I just don't think it lives up to the hype. The do look great, though.
Actually, read the articles. Most of them state what I'm trying to say in a much better fashion.
I have the EBC rotors and I do not much care for them...Better than stock but not by much and they do make strange buzzings sound but on my car it is all the darn time. It really is quite annoying. Unless you are autocrossing and road racing a lot of the time I see no problems with croos drilled rotors. However if you plan on doing a lot of racing perhaps just slotted is one of the best ways to go. The EBC pads are awesome however.
Mike
Ugh! The amount of bs that spews forth from some of that makes my head spin....
The links provided that is. First we have a manufacture who makes claims that every option they have is simply better and of course if one upgrade is better and so too is the other, then clearly the benefits of BOTH of them is way over the top!
Then we hear from the Altima crowd who claim you can turn drilled rotors, but not slotted ones....
I'll put in my .02 and bow out quietly.
Drilled rotors for the street are a nice touch. Slotted rotors for the street are an alternative. Drilled rotors for the track are looking for trouble. They're going to crack over time. Remember that 'run cooler' statement? Yup, the cool air passing over the hot iron jsut doesn't mix well. Oh they'll only be hair line, or surface cracks at first, but do it over and over....
The dimples are simply a form of the gas slotted rotors. They look more like holes, that's a plus, but they won't have any more or less effect on the pads than plain old slots. They are there to de glaze the pads as the rotor passes over it. ANY type of slot or dimple is going to INCREASE the pad wear rate so the statement of making things last longer is in left field.
Wider rotors are an improvement in being able to absorb and dissipate heat. But on many front wheel drive cars this is not so easy. And they weigh more.
As for the upgrades listed in a post, there are three things that directly have input on your brake performance; rotor diameter, pad Cf, and piston area. Change one of these and you alter the equations. (makes me wonder if the qualified expert on the Altima list did more than one change at a time or simply put new rotors in with old pads to properly evaluate them)
To a point I'm like every other shop out there, I'll do my best to get you what you want, but not at the expense of selling you something you don't need or hyping it up to be more than it is.
Hi JaTo..
Originally posted by JaTo:
I'll try not to write a novel on this, as I'm no expert at all, but this is a subject I've broached with a number of other people that are in the know, and I've done a fair amount of research myself on this subject.
Thanks for taking the time!
Originally posted by JaTo:
3) Operating Temp - Another area I'm shaky on, but the bigger the rotor, the better the heat sink it is. Running bigger rotors that are cross-drilled can adversely affect your breaking distances, due to the cooling effect that it has upon the rotors.
This is the only part I'll disagree with - I don't think the holes really do much, cooling wise...
Most (all?) of the rotors we're talking about are internally vaned, like this
StopTech AeroRotor (from
StopTech FAQ 18: Fixed vs. Floating Rotors). Air flowing through these vanes, from the rotor hub, to the outer rim of the rotor is what does most of the cooling. To my mind, drilling holes in these vanes will a) reduce the weight of the rotor, therefore reducing it's total thermal capacity and b) reduce the efficiency of the air pump that the vanes create.
This
Corner-Carvers thread,
Brake Cooling, where to introduce the ducted air? talks about this, and includes some details on these really nice brake duct bits:
RoushGTR's Brake Duct, Photo 1 .
Almost makes me wish I had a Mustang
Originally posted by JaTo:
Brake Duct
Performance-wise, I just don't think it lives up to the hype. The do look great, though.
Nice wrap-up!
Cheers,
--
Terry McG
Simply put, at my track, i cannot think of one car that either uses a cross drilled or slotted rotor design, i assure you that after the decades (literally) that many of these people have raced most every type of rotor has been experimented with. As said earlier, it cannot be argued that the aesthetic qualities are much improved, but for performance, and wear and tear these are not the best route to go.
Hi Todd...
Originally posted by Todd TCE:
Ugh! The amount of bs that spews forth from some of that makes my head spin....
The Altima thread really is something else eh?
Originally posted by Todd TCE:
To a point I'm like every other shop out there, I'll do my best to get you what you want, but not at the expense of selling you something you don't need or hyping it up to be more than it is.
Kudos - it's too bad more vendors don't work this way!
Cheers,
--
Terry McG
Sorry...
Originally posted by terrymcg:
Originally posted by JaTo:
Brake Duct
Performance-wise, I just don't think it lives up to the hype. The do look great, though.
Nice wrap-up!
should be just
Originally posted by terrymcg:
Originally posted by JaTo:
Performance-wise, I just don't think it lives up to the hype. The do look great, though.
Nice wrap-up!
but it's too late to edit...
Cheers,
--
Terry
<fumble fingers>McG