You can't really turn slotted or drilled rotors.  That's about the only advantage.  Most rotors today on vehicles built from the mid '90s onward are throw away anyway, because they lack the material needed to be turned.  Around here its hard to even find a place that turns rotors and drums anymore.  15 years ago most auto parts stores did it.  Now when a car need brakes they toss the old rotors and just install new rotors and pads. 

With that a given I always opt for some form of gas relief, be it slotted or drilled.  Basically that gas acts as a cushion under hard braking and keeps the pads from applying as hard as they could.  The slotted or drilled rotors are also often higher quality than the Chinese made parts store rotors.  I've seen those fail from bad metallurgy where the center literally ripped right out of the rotor. 

In Oz, a pair of cheapish rotors run bout $350.
At 5000 miles since 95, I'm never gunna need to replace them because of wear. Even if I get to drive it a LOT more if I ever stop work.
When I do drive it, it's not like Grandma .... I buy tyres for traction, not treadwear, they timeout any way. More smiles per mile.
If drilled/dimpled and slotted induce more chequering,  cracking .... but cool better, brake better, I can live with that.

Last edited by 50vert (9/20/2018 4:06 AM)

DBA, PBR and EBC, (always wanted to do that), are the combination I have settled on.
Still need to decide wether to go plain or slotted/drilled. Hence this post.
Unless I hear a good reason not to, I will probably go slotted only.

Last edited by 50vert (9/20/2018 9:09 AM)

Rudi, after seeing your avatar, I think I know how you know.

Thanks everyone.
Steve, what sorta mileage before you started to feel pulsation?

Anyone else notice that when MS installs a custom part on his 66, a lot of the time he'll end up going back to oem parts? Down at the police station they call that a clue. I gotta rethink my thinking.

Well goldangit!!
I've noticed, just never put it together.
Guess that's why you were getting paid to be down at the police station, and I ....... wasn't.
There is that big slab of aluminium under the bonnet though .... don't think it's leaving anytime soon.

Last edited by 50vert (9/21/2018 5:17 AM)

If the rotors were cheap I'd pin it on the rotors, not whether or not they were drilled.  Cheap rotors =  cheap metal = problems.  Too many impurities in the iron from using recycled junk being sent to China by the boatload for high scrap prices. 

By that rationale why upgrade the brakes at all?  4 wheel drum brakes worked fine for 40-50 years, why not just keep them?

Because technology has improved, and times have changed.  Very few guys are going to be happy with 4 wheel drums anymore, because we don't drive these cars daily, and the cars we do all have big 4 wheel discs.  You get used to how modern cars brake, and the old cars feel like they take forever to stop by comparison. 

There's also the fact that highway speeds, and even just regular road speeds are considerably higher than they were even just 15-20 years ago.  I don't drive any faster on the highway than I ever did.  I've pretty much always done 80.  20 years ago that meant I was passing everyone.  Today I'm in the middle of the pack and get passed plenty by people driving 85-90.  Even the speed limit was raised from 55-65 around here.  At those speeds your brakes better be top notch

The slotted and/or drilled rotors are not necessary, but they do provide better braking, even during regular driving for two reasons.  First, those rotors tend to be premium and made from better material.  If you get DBA, Baer, Brembo, Stoptech, etc rotors they are more expensive, but made from good metal with good metallurgy that isn't prone to fail or warp like the cheap parts store replacements. 

Second, the slots and/or holes do help under hard braking in a couple regards, both by increasing clamping force on the rotors by venting surface gas build up, and by assisting with cooling and reducing brake fade. 

I got tired of warping stock rotors on my WRX, so I upgraded to the DBAs.  I also used factory brackets to allow the use of larger rear discs from an Outback.  EBC green pads, and braided stainless flex hoses and that car now stops as confidently as it does everything else. 

In part its about balance.  A lot of guys will think nothing of doubling the horsepower their car makes, but spend zero money or thought on the idea that they should double how well it brakes too.  Cars that are more powerful than they can brake or handle are dangerous.  On some cars (Fox bodies for example) brakes should be among the first upgrades you make because the factory systems were so deficient that the car was unbalanced off the showroom floor. 

Basically anything marketed as "high performance", etc. now comes with slotted or drilled rotors.  Its been a slow transition for sure, but my prediction is that it just continues to radiate outward as trends like this do.  At one point the only American made car that had 4 wheel discs was a Corvette.  Now you can't buy a new car that isn't 4 wheel disc.  Just a matter of time.

Cars are going to continue to get more and more portly and more and more powerful.  That's the trend of the past 30 years.  At some point OEMs are going to start using any braking advantage they can get so that braking distances never go up.  Multi piston calipers are expensive compared to drilled or slotted rotors, and rotors from a practical standpoint can only get so big, especially on smaller cars where the wheels aren't going to fit 15" rotors.  Its a logical progression.  Technology once considered expensive and common only in racing gradually makes its way into our daily drivers.  Turbos, disc brakes, traction control, etc. all started in racing and are now commonplace on even fairly pedestrian transportation. 

I've never owned a car that had them from the factory, and again, not saying they are strictly necessary, but they do improve braking.  With rotors being throw aways now anyway I don't really see any reason not to run them other than cost, but again, you tend to get what you pay for with rotors, and the performance rotors are typically better made to begin with, so...

pbrownrk wrote:

I have a new 2018 Ford F150 with less than 4000 miles. It has 4 wheel disc brakes and I admit thinking that was probably more than was needed. Well! I got a lesson on braking last week. In the early morning as the sun was just coming up a deer jumped in front of the truck crossing the road. No way any of the many cars I have owned over the last 50 years would have missed that deer. I was really amassed at how fast the brakes slowed down the truck running at 65, made me a believer in four wheel disc.  

 
Give credit where credit is due: the anti-lock braking system is largely responsible for that amazing braking. Before antilock, the driver had to modulate the brake pedal to keep from locking up the wheels. With antilock, the deiver just presses down the brake pedal as hard as he can and the antilock modulates the pressure to all the wheels. Makes me wonder when some smart guy will develop an antilock brake kit for Gen 1 Mustangs.

Hornman
You  are correct without the ABS no way I would have been able to hit the brakes as hard without sliding right into the deer. I have had newer cars with ABS but drum rear brakes. It just felt like it stopped faster than those cars were able to, of course with the adrenaline flowing from the panic of almost hitting the deer my perception could have been a little off.