Which is better? Vented/ slotted rotors or regular rotors?

[M35SFIREMEDIC]

Which is better? Has anyone swicthed from regular rotors to vented/slotted rotors? What's the real difference? Do they preform better or are they just for looks?

[TDot]

Neither is good for you. The theory is that it reduces heat and gas build up. However, this was a design for old car brakes...circa 1960. Gas build up really doesn't happen with todays good brake pads...ven the simply decent pads. As far as heat build up, the need for slotted/drilled is really not needed unless you have your foot ON THE FLOOR EXTENSIVELY and braking hard. The slot will eat out your brake pads faster. Drilled will eat your pads too a little depending on the type of drilling. Drilled will/can/could crack around the drills. Drill is also weaker, that is really common sense because if you put a bunch of holes in something you WILL weaken the structural integrity.

If you HAVE to, slotted is "better"...solid is best.

That said, I do have them drilled, and they are strictly for looks...so sexy . I will be inspecting them once a month, and if I see any cracking in the next two years, right back to solids.

[MaxBolus]

I switched over to a set of slotted/drilled rotors many years ago, after it seemed that my stock rotors were warping after just a few thousand miles. (Due to some confusion when I placed my order, I ended up with slotted AND drilled rotors )

Anyway, I was very happy with the lack of brake shudder, and they seemed to last much longer than the stock rotors. (It's been a while, can't recall the exact times/mileage, sorry.)

But they eventually did need to be resurfaced, that's when the problem arose: I could not find anyone that would resurface slotted OR drilled rotors. This is something to keep in mind..

So I bought a set of OEM rotors and have had them ever since..maybe 2-3 years now. They've held up very well, not sure why. My driving habits have changed a bit, my miles driven are way down, which probably has a lot to do with it.

But they sure did look cool, gotta admit

[The Bodyguard]

I would concur with the "slotted" answer.... Our stock solid are terrible though... Solid may be great on a GOOD SET of breaks, maybe some other name brand??.. Our M lacks a GOOD set of brakes!! I have had the Ebay kit drilled/slotted from brakemotive for about a year or so... 28k miles and still have good response and good life left in the pads. I do spirited driving daily!! I'll have to see about the resurface issues when that time comes... Good to know though, I can prepare for the bbk I really want!!

[szh]

Generally speaking, the weight and density of the iron matters the most! Remember that the rotors absorb the energy of the car's speed and transfer that in the form of heat to the hub and axle as fast as possible.

So, solid rotors will work best in that regard. Drilled rotors do not have the "extra" heat removal reality that they claim - the vanes inside the rotors are much more effective at cooling than holes.

The reason I have considered (and used in the past on my old Q45 for some miles) slotted/drilled rotors would be for the "pad cleaning" effect - the edges of the slots will remove pad material in theory. These were Bradi rotor blanks (Bradi is a sister company to Brembo) that were very high-quality to begin with, so I felt the iron removal of the slots/holes wouldn't be as big a concern.

For today's semi-metallic ceramic brake pads used in automobiles, "outgassing" is not likely to be an issue.

The bottom line is that high-quality solid rotors are likely to have the best actual stopping ability - including with multiple hard stops, longevity, lack of cracking at the holes, etc.

My current Centric rotors (from Tire Rack) are exceptional. No "warping". Vibration and shaking during braking, by the way, is far more often a symptom of unbalanced wheels and tires and/or clumped pad material - due to poor pad break-in - than actual physical warping. Assuming the rotor is high-quality iron to begin with.

Note that drilled/slotted rotors cannot re re-surfaced easily (but it is possible with slow lathe speeds - costs a lot more). So, solid rotors are again best - the edge chamfering on the drilled holes (to prevent cracking) makes resurfacing damn tough.

Rotors should last as long as two to three pad changes. On my current M45, I seem to go through pads about every 35k to 40k miles or so.

And I use OEM pads for their best combination of longevity, lack of squeal, and excellent braking performance. YMMV!

Z

[Jon610]

Hey Bodyguard, how are you liking those rotors?? I found the listing on EBAY, have they held up well as far as rust?? What pad are you using?? thanks for your time.

[cruzad3r]

brakemotive brake kit is the best bang for the buck i've spent on modding car. i was skeptical as first but i'm pretty happy now. i've had it on for close to 1yr and around 15k miles of driving and they're still good.

i do noticed some slight "rust" discoloration after a wash on the car these days but after a quick stop, the disc looks like new again. So I highly recommended it if you need to swap brake and pads by yourself.

[CPJ LB]

the brakemotive rotors are still working excellent for me...I just changed the pads to Akebonos shortly after installing the kit...Big difference. (I also bought another set of the rotors because I couldn't pass up the bargain -- the extra set are stored away in my garage)

drilled / slotted rotors look far better than the stocks...also it lasts longer IMO.

I'm still debating on BBK.

[Ilya]

I may be going back to the tried and true Brembo 'blanks' that I had on the Maxima with some Akebono pads.

I have the brakemotive kit as well and have put on 28k hard miles (lots of spirited driving) and they are still performing, but I'm definitely starting to 'feel' (in the pedal) a bit of 'roughness'/'grinding' when braking. No actual noise or squeeling...but I'm guessing something needs to be resurfaced or the pads changed.

[M35SFIREMEDIC]

Thanks everyone, the information was very helpful. I might still consider drilled rotors..... maybe!

[azeiler]

I know I'm late to the party, but maybe this will help future readers. R1 Concepts has good quality braking parts at reasonable prices. I've been using their drilled and slotted rotors, and ceramic pads, for years and have installed them on two different cars. Very happy with their stuff. http://www.r1concepts.com/

As for resurfacing drilled and slotted rotors, a lot of shops don't know how to do it. One guy I talked to even told me it cannot be done and to just buy new ones. I just had mine resurfaced yesterday using a Pro-Cut machine http://procutusa.com/. It resurfaces the rotors while they're on the car, so it's matched perfectly to your hub. I think this is supposed to help prevent run out ("warping"). It looked pretty easy, took about 30 minutes and cost me $69. Brakes are working perfectly again.

[Carfreak70852]

I too am a little late here, but for M applications, get whatever is cheaper for you. I was on rockauto and found some slotted rotors for $15 ea. Easy choice for me. They're great rotors. http://www.rockauto.com/dbphp/x,carcode ... Rotor.html

[Larz]

I will defer to those more knowledgeable about brakes and rotors as far as what is considered to be 'best'. However, I have to say this: I had the brakemotive kit on my 07 M (RWD) for over a year before it was totaled. I had no issues of any kind and the pads had plenty of life left. I am also having the same set installed on my 09 M (also RWD).
I'm doing it for two reasons:

1) They are liquid sex to the eye and also give the car a more aggressive appearance.
2) They are a great value. For under $200 you get all new rotors AND pads. When the pads on one axle eventually wear down, you simply buy another complete set at a cost that is less than having brake service performed on only one axle and BAZOOM - you have 4 new rotors and pads all over again !

As for safety, I have had to brake hard and fast on the motorway when a random idiot does something stupid in front of me and the brakes worked smoothly and perfectly.

[azeiler]

I too am a little late here, but for M applications, get whatever is cheaper for you. I was on rockauto and found some slotted rotors for $15 ea. Easy choice for me. They're great rotors. http://www.rockauto.com/dbphp/x,carcode ... Rotor.html

I've bought numerous things from Rockauto over the years, just not performance stuff - great company though.

[kmiles]

I'm with Larz on this one. I'm putting my 2nd set of Brakemotives on this weekend. I drive in rain and when coming around bends on the freeway have had to stop suddenly. With the OEM brakes, that first hard stop made me very nervous, but since I've gone to the Brakemotive brakes with the slots, I've never have to worry no matter how wet the brakes are. They stop hard and fast when needed - even when soaking wet. I'm sold. I have about 50k on my first set and the rear brake pads are ready for replacement now. That is the one strange thing about the M35 - the rear brakes wear much faster than the front brakes.

[EniGmA1987]

I too am a little late here, but for M applications, get whatever is cheaper for you. I was on rockauto and found some slotted rotors for $15 ea. Easy choice for me. They're great rotors. http://www.rockauto.com/dbphp/x,carcode ... Rotor.html

I would not buy those. You are trusting your life to your car's brake system, and it is not possible to get any decent chunk of metal for $15 let alone a fully machines piece to fit our cars. No way that is a quality rotor.


As for the blank vs drilled vs slotted debate, everyone has their own opinions on what is best so it really doesn't matter.

Cross drilled rotors are not prone to cracking anymore because no one drilled the holes on a structural vein anymore. The holes are also chamfered so it isn't a sharp edge around the hole. Yes cross drilling does remove some of the rotor mass, which means less heat capacity for absorbing braking energy. However, the cross drilled holes do allow air to be circulated through much better, leading to faster heat dissipation. Depending on the number of holes and drill design you actually end up ahead in braking ability with cross drilled because the mass loss doesn't outweigh the cooling increase.
Slotted rotors these days work well because they bite harder into the pads. This leads to more stopping power, but less pad life. Slotted rotors do work best from what I have seen in the rain because the slot that bites hard into the pad actually will scrape away that wet layer on the top of the pad and give you a more dry surface to brake with. The trade-off of course is the less pad life, but you also get a slightly odd noise during braking as the pads move over the slot.

Whether any of that is actually needed on a basic car is up to you. I use it because the rotors don't cost any more and the great Brakemotive kit comes cross drilled and slotted and it is by far the best deal on brakes for our car.

[Larz]

I must agree with Enigma. I can't work out how a rotor can possibly be manufactured for $15, much less marked-up for retail and sold for $15. That does my head in and also scares me. The only thing that is capable of saving you in most bad situations is your brakes. If they grab that $15 rotor and it cracks or breaks or fails ..... need I say more?

The brakemotive kit costs less than a standard brake service and you get high quality rotors AND ceramic pads on all four wheels. That seems much safer to me.

[szh]

I must agree with Enigma. I can't work out how a rotor can possibly be manufactured for $15, much less marked-up for retail and sold for $15. That does my head in and also scares me. The only thing that is capable of saving you in most bad situations is your brakes. If they grab that $15 rotor and it cracks or breaks or fails ..... need I say more?

Yeah! Totally agreed.

Brakes and tires are among the most important parts of your car to keep in good working condition. When tires get below 3/32" tread, change them and don't skimp on the quality here. This is where the all stopping action occurs!

Z