So I have noticed that the past few times it has rained, my brakes feel weird and make a grinding noise when I'm braking. I was planning on getting new pads and rotors soon anyway, so what would be the best pad/rotor setup for a DD with 100k. I was thinking about the strano brake package with the hawk HPS pads and the ATE rotors. Anyone have this setup on there DD that sees rain?

 

Anyone else have this problem in the rain, or is it just me?

 

There is nothing about wet weather that should cause a grinding noise. Can you see how low your pads are? You may be close to the backing plate if you are hearing grinding along with decreased stopping power. Please see the links in my sig for current pricing on Powerstop rotors/pads.

FYI crossdrilled rotors perform better in wet weather than blanks. The benefits are quite significant under moderate pedal pressure. Under high pressure the difference is less apparent but still better than blanks.

 

I was wanting to stay away from the drilled rotors b/c i have heard that they crack. Thats why i was asking about the ATE slotted rotors. Are slotted rotors better for wet weather, or should i just go with blanks? Like i said its my DD so i will be seeing rain, snow, sleet, ect. and want my brakes to preform in all conditions. Plus i might be taking my car to the track a couple times a year.

 

its not uncommon for rotors to get light surface rust, even just sitting overnight. the pads will clear the rust right away when you use the brakes. does it continue after the first couple of stops?

 

Yeah it does it every time i brake in the rain, but the brakes are fine durring dry driving. My pads are getting a little low though, but i was just confused why they did it in the rain but not when it was dry. Like i said above though i think im going to get new Hawks HPS pads and rotors, but not sure what rotors to get

 

Here it is in a nut-shell. Drilled rotors have less surface area for the pads to contact. Also rotors are heat sinks which absorb and help pull heat from the pads. The less mass, the less well it works as a heat sink. And finally, drilled rotors are just that, blanks that are drilled with holes. What else that your life depends on would you start banging holes into and decreasing the structural integrity of?

Drilled, or slotted rotors for that matter will not magically make for better stopping in the rain. The rotors get wet, period regardless of whether or not they are blank, slotted or drilled. Here's the deal, you most likely have crappy pads.

Rotors are priced based on how they are built. Cheap rotors are cheap, I have cheaper rotors--but not bottom draw ones. ATE's are premium one piece replacements, only better are Racing Brake rotors which are far beyond your needs (but great for those running tracks with the directional vanes). I have other options too, but 99% of the time the ATE's do it all, fit, work, are tough, look good, stay looking good.

 

Any rotor can crack from thermal shock, drilled, slotted or blank. Drilled rotors inherently have more stress risers which makes them more susceptible to cracking from thermal shock, however chamfered and cast drill holes have helped mitigate those issues. Drilled rotors lower pad temps through improved convection heat transfer which is enough to keep them from experiencing thermal shock (in most cases, racing conditions are a different story, but we are talk about your DD here).

The primary benefit of a slotted rotor in a street application is pad deglazing, not gas evacuation like most seem to think. I have no test data on slotted only performance in wet weather so I won't comment on it. I'm not trying to sell you on either drilled or slotted as being superior, they both have their pro's/con's.

 

I've only got one thing to say regarding heat and temps....

*IF* drilled rotors ran cooler as is claimed--you can bet you'd find them on racing cars, especially fast heavy ones that murder their brakes. You don't, and that's because they don't actually run any cooler. Because if they did why wouldn't they use them on cars that have brake cooling issues, especially when also consider they are losing a bit of rotational and unsprung mass at the same time.

Rotors shed heat by absorbing is and then the airflow through/around the rotor cools the rotor itself. Drilling holes in the vanes disrupts the airflow through the vanes much like having your window open disturbs the air around the car itself.

We clearly have different opinions. It's up to these guys to decide what makes more sense. I also sell PowerStop, and I know all about their claims of 150+ degrees cooler... But really, a little common sense is all it takes. In fact the company who first started with drilled rotors was Porsche, in the 1960's. And only on Hillclimb cars as a way to shed mass. The road-racing cars didn't get drilled rotors, and Hillclimb cars aren't hard on brakes since the runs are short and, you know... uphill. They could afford the trick....

 

Per the stop-tech white paper, "brake torque is directly proportional to Piston Area, System Pressure, Friction Coefficient and Effective Radii and is not affected by pad area".

The the effective area of friction is only as large as the brake pad. At any given moment in rotation there are only a couple holes under the pad. Compare that loss of surface area to the surface area lost when a pad is chamfered.

True rotors are essentially heat sinks, their primary form of energy dissipation is through radiation. The next equally important avenue for heat dissipation is through convection (airflow). The amount of mass that is lost from drilling a rotor can easily be maintained by increasing mass in other parts of the rotor (if the manufacture finds it worthwhile or necessary). When you compare the loss in material of a couple ounces of mass versus a rotor that weights 30lbs, the loss of radiation capacity is at best insignificant. Additionally the loss in radiation heat transfer (again, inconsequential) is more than compensated for through increased convection heat transfer ability due to the added airflow between the vanes.

A drilled rotor that is machined properly will be no more prone to catastrophic failure than any other rotor under real life conditions (putting it on a brake dyno and subjecting it to insane loads beyond the realm of anything you would see in real life is a different story).

Actually they do (not magically) , that was the point of my first post since the OP seamed pretty concerned with wet weather stopping. I do agree it sounds like his pads are crap. And it hasn't been mentioned but do you know when the last brake maintenance was performed? If ever? It really sounds like your getting down to the baking plate which is extremely dangerous and can lead to catastrophic failure. You should inspect the pad wear asap.

Agreed, you get what you pay for. There is a considerable markup on certain brands based solely on their name. Others, you are paying for the R&D that goes into them. Big brake kits, move out kits etc are a whole 'nother story. $$$$$$

 

Can you back up that claim with any proof? I can take it the opposite direction (which doesn't hold anymore credence than your claim), why do Lambo, Ferrari, Lotus, Porsche etc drill their rotors?

Drilled rotors do serve a purpose in certain forms of racing most notably WRC. It is the high speed cars that cannot use them due to the extreme temperature swings they are subjected to. Road racing and super speedway (nascar) are too demanding an environment for a drilled rotor to remain in tact for the duration.

Again, proof of this theory? I hear it a lot but never any evidence to support the claim.

As important as common sense is as a character trait, to me, hard data (which I have sitting on my desk in front of me in the form of an SAE Technical paper) blows common sense out of the water in engineering. I'm not an engineer but I have read plenty of articles and papers written by engineers to have an informed opinion. I'm not trying to push anyone either direction, just posting what I know to be factual so the consumer can make an informed decision. I know who you are and your background in racing and believe me I respect that! We can have differences of opinion, that's the catalyst for discussion and learning, exactly what this forum is for!

So after all I have typed you would think I run drilled rotors on my C5 right? I dont! But I definitely believe they have their place for certain applications.

 

Thanks guys for the replies. You have all helped a lot. I think im going to get the ATE's and Hawks HPS pads. I saw that Sam Strano has this package on sale. I'm sure i will be ordering them soon enough

 

Fair enough... Those companies you mentioned, don't run drilled stuff on their competition cars. When they have actual competition cars. Why do the street cars run them? Well, cause they are cool? Hell I don't know, for the same reason they can get away with charging the price of a whole car for Carbon-ceramic brakes when it's not like stock 911 GT3 or F430 brakes suck to start with (and certainly don't need to be upgraded by oh, 99.85% of the posers that run them).

Do have proof that drilled rotors don't run cooler? Other than having seen a set of drilled vs. non-drilled (same brand) rotors on a car with temperature paint? No. DBA rotors--another brand I sell puts TSP on their 4000 and 5000 series rotors. I have a customer that has run both slotted and drilled 4000's on his car, and the temperature paint showed the same maximum heat results. FWIW, YMMV, etc.

I personally don't think drilled rotors have much use beyond looking cool. I have found that slotted rotors do help with wear and grooving as the dirt can be swept out vs. getting bedded in the pad and wearing the rotor.

Thank you for the frank discussion Adam.

 

Well said, anytime!