This is a daily driven Saab 900 SPG. It may make its way around a track once in a while and lives too near the Tail Of The Dragon to not go there. It needs brakers that WORK. So which really works better, standard ventilated rotors or the drilled and slotted ones?
standard. Drilled and slotted just leave less surface area to grip in 90% of conditions, chew pads faster, and give more opportunity to crack, plus they're virtually impossible to resurface. The heat dissipation you'd see from a set is all but impossible to achieve for most cars, even ones at TOTD. Get some good pads, SS lines, Motul or other good fluid, and do work.
I had a set of Zimmerman cross drilled rotors on the front of my c900, and I wasn't really impressed by them. I used them with SAAB OEM pads, and they kept warping. I wasn't even running them all that hard. I wound up using Napa smooth rotors with Stoptech pads, and its a lot better.
GRM had a really good article about brakes a few years ago. Basically what it said is that for the vast majority of cases, solid smooth rotors are better. Rotors are heatsinks, and every last gram of mass in that heatsink helps. Cross drilling started because old brake pad materials gave off gasses when they were hot, the holes were a path to vent those gasses. Modern pad compounds don't have that issue & the holes are also a place where cracks can start.
My. 02¢, get good quality blanks, performance pads, get braided stainless hoses, or at least brand new rubber hoses, and flush & refill the brakes system with high quality fluid.
Slots can be useful if you have aggressive pads on the street that tend to not get warm enough to be truly effective.
For an OEM solution? Smooth rotors, well lubricated caliper slids, decent street pads with good, fresh fluid should be more than sufficient.
Most important thing? (Aside from good tires to actually stop the car) Bed the pads properly. Failure to do so will result in "warped" rotors as the brake pad material will be bedded unevenly on the face of the rotors resulting in high and low spots which will wear the surface unevenly, etc.
If you've run into overheated brakes already then you need to make a change to the thermal management of the system. If not? Put it together properly and run it.
The only reason to run drilled rotors is to impress people who think drilled rotors are good.
There are some good reasons to run slots, but on the street your braking system is so under stressed you basically just have to make sure the fluid is fresh and the pads aren't too thin.
Spend money on pads, not rotors.
I run El Cheapo blanks on my Spec E30 with pads designed specifically for the work they do. Never had a problem with fading. The rotors will heat fracture eventually but at the price I pay for them who cares? It's just part of regular maintenance on a race car.
mndsm wrote: they're virtually impossible to resurface.
i've turned a handful of drilled/slotted rotors before without issue, but yea even for some hard driving unless you have huge sticky tires they will do you no good. even some race cars dont use drilled/slotted:
Yeah, but those are also carbon ceramic.
Seems to depend on the car a little. My E30 likes nothing but normal Brembo blanks. I had Zimmerman cross drilled rotors on there when I got it, and they warped in a hurry after a little track use. The SVX, on the other hand, warps the stock brakes if you look at them funny, and the cross drilled and slotted option seems to hold up much better. The brakes are way too small for a car that big.
I guess I'm one of the few people that had excellent results with slotted rotors. On my 97 Civic, slotted rotors with Autozone Gold brake pads (still not that good) changed from Autozone Silver brake pads and standard rotors gave me much greater stopping power. It could be because of the FWD weight distribution. My 91 Camaro has drilled rotors and they didn't do E36 M3. So, performance pads are guaranteed to give you good performance, but rotors aren't.
My Protege5 uses Brembo blanks with quality pads. Very simple set-up.
Braided lines and good fluid and you're done.
Standard or maybe slotted if you want sharper bite and better wet performance, at the cost of faster pad wear.
Drilled is for racing where big money is on the line, or riceboys.
Good pads and fluid are the best upgrades.
Standard rotors, good pads, fresh fluid - high temp for the track.
I don't think I have seen a real modern race car use drilled or slotted rotors.
Drilled and slotted are the dumb. No real benefit whatsoever.
Advance Auto parts gold and silver pads are the same chemistry for most part numbers.
I do not believe in warped rotors. I DO believe in uneven transfer of pad material onto the rotor which causes pulsing and vibration. I have also seen crappy rotors have "hard spots" on the face which can do the same thing.
In other words, get an aggressive street pad, good blanks (NAPA is pretty good), and flush your system with good fluid.
Rob R.
wvumtnbkr wrote: I do not believe in warped rotors. I DO believe in uneven transfer of pad material onto the rotor which causes pulsing and vibration. I have also seen crappy rotors have "hard spots" on the face which can do the same thing.
I agree that pad deposits and hot spots (local hardening) are probably more common than true warping, but why don't you believe in warped rotors?
I hear this about drilled rotors all the time and I do not dispute what is being said but it does raise one question in my mind. Porsche, to my understanding, has some of the best stock brakes you can get in a street car and a lot of them come with drilled rotors. Is it really just a fashion thing for them or do they see some benefit?
I used slotted rotors on my Volvo 745T and wasn't impressed. Then when I got my E36 328 it had drilled rotors, again not impressed. Now I just buy the regular old Centric rotors and spend the extra money on good pads.
I worked on a Trans Am team back in the late 80's & early 90's (Part time) and we were using drilled rotors when I joined the team but by the time I left we had stopped using them. As mentioned the compounds that brake pads are made from have changed and the "out gassing" that was common back then is no longer an issue. Now slotted rotors can have some benefit in the rain and with some pad compounds to keep the rotors free of build up or give a place for water/steam to escape to. Plus they don't encourage the cracking of the rotors that drilling causes. On our Trans Am race car we would get 1 -1 1/2 race weekends from a set of drilled rotors. I think back then these rotors were still $150-200 each undrilled! For a small budget team such as we were that was a big hit.
gearheadE30 wrote:wvumtnbkr wrote: I do not believe in warped rotors. I DO believe in uneven transfer of pad material onto the rotor which causes pulsing and vibration. I have also seen crappy rotors have "hard spots" on the face which can do the same thing.I agree that pad deposits and hot spots (local hardening) are probably more common than true warping, but why don't you believe in warped rotors?
Because anytime somebody brought me a car with "warped" rotors I used sandpaper on them to get rid of the pad deposits and rebedded in the pads. No more warped rotor. I can guarantee that I did not make them "true" by hitting them with sandpaper (or sometimes an angle grinder if really bad).
gearheadE30 wrote:wvumtnbkr wrote: I do not believe in warped rotors. I DO believe in uneven transfer of pad material onto the rotor which causes pulsing and vibration. I have also seen crappy rotors have "hard spots" on the face which can do the same thing.I agree that pad deposits and hot spots (local hardening) are probably more common than true warping, but why don't you believe in warped rotors?
It's dated, but there is THIS from Carroll Smith.
Rusted_Busted_Spit wrote: I hear this about drilled rotors all the time and I do not dispute what is being said but it does raise one question in my mind. Porsche, to my understanding, has some of the best stock brakes you can get in a street car and a lot of them come with drilled rotors. Is it really just a fashion thing for them or do they see some benefit?
Same with the corvettes. BUT..... they were designed for that initially. They typically are running larger sizes to compensate for the missing metal/surface area. Trying to replicate that with your 9.9" civic rotors isn't going to net the same performance.
Bobzilla wrote:Rusted_Busted_Spit wrote: I hear this about drilled rotors all the time and I do not dispute what is being said but it does raise one question in my mind. Porsche, to my understanding, has some of the best stock brakes you can get in a street car and a lot of them come with drilled rotors. Is it really just a fashion thing for them or do they see some benefit?Same with the corvettes. BUT..... they were designed for that initially. They typically are running larger sizes to compensate for the missing metal/surface area. Trying to replicate that with your 9.9" civic rotors isn't going to net the same performance.
And the Corvette and Porsche rotors still crask under heavy use.
In reply to Chris_V:
Ooooo, self slotting brakes!
In reply to Bobzilla:
So size really does matter 
. That is what I figured but I thought I would ask anyway.
I believe that modern OE "cross-drilled" rotors (like Porsche)are actually cast in holes, not truly drilled. Aftermarket is most likely drilled though. I tried to drill a set of rotors on my own years ago, it didn't go so well.... Ate the pads like cheese graters and cracked pretty fast.
wvumtnbkr wrote:gearheadE30 wrote:Because anytime somebody brought me a car with "warped" rotors I used sandpaper on them to get rid of the pad deposits and rebedded in the pads. No more warped rotor. I can guarantee that I did not make them "true" by hitting them with sandpaper (or sometimes an angle grinder if really bad).wvumtnbkr wrote: I do not believe in warped rotors. I DO believe in uneven transfer of pad material onto the rotor which causes pulsing and vibration. I have also seen crappy rotors have "hard spots" on the face which can do the same thing.I agree that pad deposits and hot spots (local hardening) are probably more common than true warping, but why don't you believe in warped rotors?
This is relevant to my interests.
I did brakes all around on my Mazda 3 about 15k miles ago. In the past couple months, I've noticed a low speed scraping noise coming from up front, and at highway speed the wheel will shake like a mofo, more so when I apply the brakes. The very same thing happened to my 2009 WRX, and I used the very same pads and rotors on each car (Centric blanks and Stoptech Street Performance pads). I will pop off the fronts and scuff/re-bed the pads and see if it helps.
You'll need to log in to post.
