Drilled rotors

[Mad4Macs]

http://motortrend.com/features/performance/112_0408_corvette_tech/index1.html

The relevent part being "Drilling an existing rotor reduces the surface area swept by the pads and removes mass that would otherwise serve as a heat sink in preventing brake fade, so it's not generally a good idea."

I've always been led to believe that the drilling improves cooling. Does anyone know where the "brake engineers" stand on this?

Also...

"But the new Z51 brake rotor diameters are larger by 0.6 inch in front and an inch in the rear, and they feature smaller internal cooling vent passages so that their mass is actually increased by 2.2 pounds each in front, 1.8 pound each in back, providing plenty of fade resistance, holes or no holes."

If the engineers felt that they had to do this, adding unsprung weight to each wheel in order accomodate drilling, doesn't it sound like they may think that drilling is more cosmetic than beneficial?

[sailsmen]

I have heard several theories, the holes/slots are to release gas generated by the pads that can build up reducing friction, i.e. stopping,and I have heard that w/ modern pads gas is not much of a problem.

There are several approved vendors that can probably answer your question.

[SergntMac]

Ummm...Okay, why not. This topic has come up a few times in the past week, let's have it out again.

Experts...What say y'all? Crossdrilled? Slotted? Both? What's bling and what's performance?

[Krytin]

Ummm...Okay, why not. This topic has come up a few times in the past week, let's have it out again.

Experts...What say y'all? Crossdrilled? Slotted? Both? What's bling and what's performance?

Well there is a definite bling factor involved here! With the absence of anyone doing comparative stops w/tape measure - seat of the pants analysis tells me that the OEM size drilled & slotted rotors I installed stop better than the originals! The added bonus is the pads don't glaze over the way they used to!
My wife is right - I do drive to fast!

[TAF]

Yep...it's all part of the vast "Brake-Bling Conspiracy"...and Brembo, Hal Baer, Ferrari, Porsche, the designers of the new Ford GT and other high-performance car manufacturers and aftermarket companies are ALL in on it. ;)

[Todd TCE]

Reluctanly so am I. It's busisness today folks.

Buy a CNC mill and sell rotors on ebay and tell everyone they will make your car stop better. The kids believe it and of course; everyone loves a bargain!

Truth is drilling rotors pretty well represents ALL of the above comments to a point.

Lighter.
Blingier.
Improved gas venting.
Maybe a bit cooler.
Maybe a bit better water relief.

Downsides exist also;

Faster pad wear.
Dustier wheels.
Shorter life span of the rotor.

Who needs them and who does not?

Open track uses beware. Street users can be just fine. The reason being the heating and cooling properties of the rotor are effected. That 'runs cooler' benie is only as good as it getting hot and sucking cool air over the edges of the hole. This is where the cracks begin. Due to thermal expansion issues. And yes, all drilled rotors have sharp edges. Even the ones with the nice chamfer on the surface as mine do. Nobody chamfers the INSIDE of the rotor so it's only a partial cure.

Be sure the company supplying them has some experience in doing so. The improper drilling can lead to early cracking if the webs of the rotor are hit when drilled. Not good. And btw; the direction of the holes patterns vary by the company who does this. Hole and slot patterns have NO dedicated rotor direction of rotation. Most of the better rotors will be directional however and this is very important for improved air flow. Here's are two examples of a rotor drilled. Note the holes 'flow' in one pattern due to the inner webs.

First is the more common ebay rotor design;
http://www.wilwood.com/Products/Rotors/009-SRP/6bdwg.gif
Universal direction regardless of the hole/slot pattern.

Here is the improved directional rotor with holes.
http://www.wilwood.com/Products/Rotors/009-SRP/12bdwg.gif
Webs dictate a clockwise rotation and the hole pattern run reverse to this.



So, why do all those 'other' cars COME with them if they are so bad? Well, first you're paying mega $ for them and you certainly want the most bling for the dollar. But the other thing to consider is their weight distribution is usually superior to most American cars. Mid engine cars allow for more rear brake and overall better balance/bias numbers. Increasing brake on only one end of the car too much without considering the other end can have a detrimental effect rather than a good one. On the euro cars they can achieve fantastic braking by having larger rotors on both the front and the rear given the dynamic braking involved with the cars weight distribution. On a MM better rear braking can be had with two people in the back seat. The trade off being more mass to stop...

In short the average driver is not going to experience substantial braking improvements in a drilled rotor (this has zero impact on brake torque calculations) nor are they likely to experience massive failure unless they are a heavy track user where high temps are the norm. Bottom line; buy what you wish unless you have specific needs. *Your mileage may vary as everyone has different opinons on this it seems.

And of course I'm happy to help meet your needs either way.

[sailsmen]

Thanks Todd! :up:

[03SILVERSTREAK]

Reluctanly so am I. It's busisness today folks.

Buy a CNC mill and sell rotors on ebay and tell everyone they will make your car stop better. The kids believe it and of course; everyone loves a bargain!

Truth is drilling rotors pretty well represents ALL of the above comments to a point.

Lighter.
Blingier.
Improved gas venting.
Maybe a bit cooler.
Maybe a bit better water relief.

Downsides exist also;

Faster pad wear.
Dustier wheels.
Shorter life span of the rotor.

Who needs them and who does not?

Open track uses beware. Street users can be just fine. The reason being the heating and cooling properties of the rotor are effected. That 'runs cooler' benie is only as good as it getting hot and sucking cool air over the edges of the hole. This is where the cracks begin. Due to thermal expansion issues. And yes, all drilled rotors have sharp edges. Even the ones with the nice chamfer on the surface as mine do. Nobody chamfers the INSIDE of the rotor so it's only a partial cure.

Be sure the company supplying them has some experience in doing so. The improper drilling can lead to early cracking if the webs of the rotor are hit when drilled. Not good. And btw; the direction of the holes patterns vary by the company who does this. Hole and slot patterns have NO dedicated rotor direction of rotation. Most of the better rotors will be directional however and this is very important for improved air flow. Here's are two examples of a rotor drilled. Note the holes 'flow' in one pattern due to the inner webs.

First is the more common ebay rotor design;
http://www.wilwood.com/Products/Rotors/009-SRP/6bdwg.gif
Universal direction regardless of the hole/slot pattern.

Here is the improved directional rotor with holes.
http://www.wilwood.com/Products/Rotors/009-SRP/12bdwg.gif
Webs dictate a clockwise rotation and the hole pattern run reverse to this.



So, why do all those 'other' cars COME with them if they are so bad? Well, first you're paying mega $ for them and you certainly want the most bling for the dollar. But the other thing to consider is their weight distribution is usually superior to most American cars. Mid engine cars allow for more rear brake and overall better balance/bias numbers. Increasing brake on only one end of the car too much without considering the other end can have a detrimental effect rather than a good one. On the euro cars they can achieve fantastic braking by having larger rotors on both the front and the rear given the dynamic braking involved with the cars weight distribution. On a MM better rear braking can be had with two people in the back seat. The trade off being more mass to stop...

In short the average driver is not going to experience substantial braking improvements in a drilled rotor (this has zero impact on brake torque calculations) nor are they likely to experience massive failure unless they are a heavy track user where high temps are the norm. Bottom line; buy what you wish unless you have specific needs. *Your mileage may vary as everyone has different opinons on this it seems.

And of course I'm happy to help meet your needs either way.Thanks-Thats the clearest definition so far ...

[Todd TCE]

Here's one of my favorite ones.

And then here's one of my most 'laughable' ones.

[SergntMac]

Thanks for your informative post, Todd TCE, now I know who to call for the straight up 411 on brakes.

[John F. Russo]

Well there is a definite bling factor involved here! With the absence of anyone doing comparative stops w/tape measure - seat of the pants analysis tells me that the OEM size drilled & slotted rotors I installed stop better than the originals! The added bonus is the pads don't glaze over the way they used to!
My wife is right - I do drive to fast!

The following statement was from a recent previous thread called "Slotted/Drilled Rotors".

"I having my second set of Baer rotors [slotted and drilled] replaced despite the fact that I had reported earlier that the hard braking did burn off the accumulation on the rotors. It did help temporarily but the vibration was still unacceptable when braking from above 50 mph. I am getting another free set of rotors from Baer. Two other MM's have had the same problem, but only once. I am the only one in the Kenny Brown family that has had two sets of brakes (also the only one who has had a tramsmission replaced).

I drive back and forth to work at highway speeds and don't brake very much.
Ben O'Connor at Baer can't figure out what has happened, I do have a good dealer who set the brakes the first time. I'm going to read the instructions on the braking break-in procedure myself and make sure that I am not doing anything wrong.

Regardless, how could I have done anything wrong in breaking-in the new brakes both times if they worked well for 10,000 to 13,000 miles each time and then all of a sudden have a serious wheel vibration problem?

What will the Baer Claw system do for us? What a price!!"

1. The last sentence was in reference to SergntMac's statement regarding his recent interest in the "Baer Claw" system. I was asking him a question that he can now answer if he wishes.

2. Also, I would entertain any comments about my problem.

[SergntMac]

John, I'm not sure what your question to me is here, so, I may still miss the mark.

Regarding your problems with the Baer brakes from KB, I don't know enough of your symptoms/complaints to comment on that, and I'm not an expert anyway. Outline it one more time and maybe Todd TCE can detect the problem?

I agree that it is unusual to warp two sets of high performance rotors in so brief a time, but it can happen. Are you over-torquing the front wheels?

BTW, you're not the only KB-MS owner to break a tranny, I have too. In fact, it's become a common issue now, and since KB does not modify the tranny in any way, I consider it a shortcoming of the Marauder that has been addressed.

My brakes are in good shape today, I have no complaints, and want only to improve rear braking power. I'd like to see a BaerClaw kit for my rear that improves braking performance, and matches the front too. My front brakes were the first built for the MM by Baer back in 2002, and from that came their front "BaerClaw" kit for our MMs. However, mine are not crossdrilled, and I don't recommend that option.

While crossdrilling surely looks cool, and I want my MM to look as cool as everyone else's, I believe that crossdrilling rotors combined with the way we drive our MMs in real life, can lead to other problems. I think this is what Todd TCE was pointing to ^ there. Crossdrilling has its benefits in hard racing applications, but longevity isn't a concern in those applications. A warped rotor probably goes unnoticed, or, is considered an acceptable side effect covered in the budget. Slotted is sufficient performance at my level, and sufficient bling for me as well.

I've also read other comments where it was noted that SEMA has a rationale for crossdrilling. I agree, and they should. SEMA exists to support aftermarket manufacturing and sales and they should have a rationale for every product under their flag. If they didn't have a justification for crossdrilling, however sound it may be, they would not be doing their SEMA job. Like it's been said here, there is a business side to this, and everyone involved expects to make money. Sometimes, the sales pitch overwhelms the science? SEMA is here to underwrite quality, maybe safety issues as well, but practicality is the customer's business.

[cyclone03]

2. Also, I would entertain any comments about my problem.


John I'm no expert but here's a thought...

Back in what seems like a lifetime ago a good friend of mine race AMA Superbikes.A brake pad manufactor came around with a new set of pads that promised to solve every brake problem you could think of.

The new pad did work as advertised but it gave of a huge amount of dust at the end of the fastest strates.So much so that the calipers required cleaning after every weekend because of the build up.

One week we didn't do the job and near the end of one race the brakes started "pulsing",friend pushed on figuring he warped a rotor.Back home we went over everything and nothing was bent or out of spec.Everything cleaned up,new (same) pads and all was well.

So I wonder if after 10000 or so miles you may be getting brake dust build up around the piston bores causing them to lightly drag by not retracting all the way?Your mechanic when replacing rotors cleans it all up puts in new pads and off you go until the build up,ah,builds up again.

But being most Baer stuff looks a lot like Corvette stuff one would think it would tolerate "normal" driving.

Just a thought.

[Todd TCE]

2. Also, I would entertain any comments about my problem.

If you tire of the replacements and the costs, assuming you work past whatever help they offer you for it, I offer a two piece replacement kit for this package. Pretty popular seller to the Mustang crowd too. And SHO.

For $225 shipped, you get two alum hats and the ordering specs for the rotor for this set up. For the MM I'd have to dbl check the stud circle and likely bore the hats to your needs. No charge for it. From there you place your order for the rotors and rotor finish of your spec (slots, holes etc) and order the hardware to your spec also (SHCS's or NAS etc.). **I supply you the spec sheet and ordering info for both as well as the suppliers. Same supplier I and many of the 'BBK' guys use for our own needs.

The reason for the sub contracting of the hardware and rotors is that this set up is used on different OD where the Vette rotor is cut to anywhere from 12 to 13". So there's no way I would want to stock them! Exepct to pay $125-135 per rotor plus shipping, bolts of $8 to $25 for NAS ones. They are all non floating design. They are a heavier construction to the Vette rotor also from what I'm told.

Total package will run you about $500. BUT, the benefit is later replacement of the rotor is only $125ea.

The root of your problem may stem from either poor pad choice, or binding caliper sliders. I certainly look at this first. Then if you run out of help with the good folks over there and wish to pursue something else let me know.

* Can't believe we managed four pages on this over at Corner-carvers! Sheese! I had to go digging for the pic.

[SergntMac]

But being most Baer stuff looks a lot like Corvette stuff one would think it would tolerate "normal" driving. Just a thought.
Bingo, Lance, my replacement pads for the Baer kit are Corvette parts.

[Marauderman]

Bingo, Lance, my replacement pads for the Baer kit are Corvette parts.
...........Dang!!!! Thanks Mac! I didn't know that---will keep that in mind when replacement time comes for mine..thanks again.. ps. loved your smokin tires pic at Indy..way to go man!!!......Tom

[pacammer]

I put drilled rotors on my DTR for the bling. However, my 65 Cobra and 72 Pantera which I race, Opps, "high speed tour with, on a race track", have Wilwood solid vented rotors as do all NASCAR vehicles. Better strenght, heat performance, and pad wear. The use of my DTR MM makes bling over function possible.

High speed touring is a little story my insurance carrier and I share.

Gary

[Krytin]

Regardless, how could I have done anything wrong in breaking-in the new brakes both times if they worked well for 10,000 to 13,000 miles each time and then all of a sudden have a serious wheel vibration problem?


2. Also, I would entertain any comments about my problem.

Cann't say for sure what you're encountering - I only have about 5k miles on mine. I was very careful to avoid high speeds during the first 150 miles so i wouldn't find myself making any panic stops - after that is back to driving like a jerk (only kidding!). The only high speed phenom I have is a barely detectable hum when making hard stops from above 60mph. I'll keep an eye on mine for anything else abnormal and post it if/when it happens!
Good luck with your's, I hope you get it straightened out. Todd @ TCE knows his stuff - we spent close to an hour on the phone one evening and the man knows brakes!

[John F. Russo]

Cann't say for sure what you're encountering - I only have about 5k miles on mine. I was very careful to avoid high speeds during the first 150 miles so i wouldn't find myself making any panic stops - after that is back to driving like a jerk (only kidding!). The only high speed phenom I have is a barely detectable hum when making hard stops from above 60mph. I'll keep an eye on mine for anything else abnormal and post it if/when it happens!
Good luck with your's, I hope you get it straightened out. Todd @ TCE knows his stuff - we spent close to an hour on the phone one evening and the man knows brakes!

Thank you for your help.

I know for sure I did not make any hard stops for the first 150 miles in both instances.

I'm getting another set of free Baer brakes and making sure that my dealer (Wall's Lincoln Mercury, a great shop) follows the written bedding procedures religiously.

[John F. Russo]

John, I'm not sure what your question to me is here, so, I may still miss the mark.

Regarding your problems with the Baer brakes from KB, I don't know enough of your symptoms/complaints to comment on that, and I'm not an expert anyway. Outline it one more time and maybe Todd TCE can detect the problem?

I agree that it is unusual to warp two sets of high performance rotors in so brief a time, but it can happen. Are you over-torquing the front wheels?

BTW, you're not the only KB-MS owner to break a tranny, I have too. In fact, it's become a common issue now, and since KB does not modify the tranny in any way, I consider it a shortcoming of the Marauder that has been addressed.

My brakes are in good shape today, I have no complaints, and want only to improve rear braking power. I'd like to see a BaerClaw kit for my rear that improves braking performance, and matches the front too. My front brakes were the first built for the MM by Baer back in 2002, and from that came their front "BaerClaw" kit for our MMs. However, mine are not crossdrilled, and I don't recommend that option.

While crossdrilling surely looks cool, and I want my MM to look as cool as everyone else's, I believe that crossdrilling rotors combined with the way we drive our MMs in real life, can lead to other problems. I think this is what Todd TCE was pointing to ^ there. Crossdrilling has its benefits in hard racing applications, but longevity isn't a concern in those applications. A warped rotor probably goes unnoticed, or, is considered an acceptable side effect covered in the budget. Slotted is sufficient performance at my level, and sufficient bling for me as well.

I've also read other comments where it was noted that SEMA has a rationale for crossdrilling. I agree, and they should. SEMA exists to support aftermarket manufacturing and sales and they should have a rationale for every product under their flag. If they didn't have a justification for crossdrilling, however sound it may be, they would not be doing their SEMA job. Like it's been said here, there is a business side to this, and everyone involved expects to make money. Sometimes, the sales pitch overwhelms the science? SEMA is here to underwrite quality, maybe safety issues as well, but practicality is the customer's business.


Thanks for the response.

1. I'lll make sure that the dealer doesn't overtorque the bolts
2. I may be interested in the Baer "Claw" system once you can determine the availability.

[SergntMac]

Thanks for the response. 1. I'lll make sure that the dealer doesn't overtorque the bolts. 2. I may be interested in the Baer "Claw" system once you can determine the availability.
Ummm...If you own a Kenny Brown Marauder S, you own a BaerClaw front brake system now. It comes with the KB build, eh?

[Todd TCE]

Here are some clips from another thread on another forum to help educate folks.

****************************** *****************
Topic Title: are rotors directional?

Yes, rotors CAN be directional. These however are not from what we know of them. A directional rotor is based SOLEY on it's venting properites and 'sucking air' through the middle. They have casting webs to enhance this. These are most likely 'straight vane' rotors and are universal. Direction of the rotor has absolutely nothing to do with surface treatments. i.e. gas slot, holes, dimples etc.

****************************** **********

You'res will run in either direction. But if it makes you feel better turn them around... but if you think somehow you'll know the difference, nada. As the directional rotor uses the reverse pattern it does so to try and put a hole in each of the vane cavities. The hole pattern on a straight vane rotor can (and often does) run the other way when drilled. I'm going to try and compile a folder of different patterns and such for a more complete reference on some of this. If nothing else it makes one think a bit about some of the comments made. (and I'm now up to 14 patterns)

****************************** ***********
UPDATE:

I hit upon something I'd thougth of the other day and did not take time to look into closely until building a kit today for a customer who ordered drilled rotors.
By now you know (I hope) that the direction of the holes does not dictate a rotor rotation direction. With this in mind I reviewed patterns in drilled rotors and noticed a common element; non directional rotors, or straight vane ones, can have the hole pattern in either direction and vent nearly all the vanes inside by doing so. However, if you put a hole sweep of four holes in the same pattern as the inner vanes of the rotor you may wel vent only one of the passages. Now...when you 'reverse' the hole pattern into the curve vane rotors you introduce a port to nearly every passage. (depending upon the number of sweeps drilled of course)
So, straight vane: either way.
Curve vane: counter pattern is more effective pattern.

****************************** ***********************
NOW ONTO THIS THREAD> I liked this one.

****************************** ***********************
Topic Title: Another Ebay rotor question...

As the old saying goes "You get what you paid for.", in this case, I'm looking at 4 different rotors being sold on Ebay for the same price. Each offers a different photo, all look relativly the same from said photos so I'm to believe a few of them are the same thing. The descriptions are pretty much alike as well, highlighting the key buzz-words and talking about crazy real-life implications of these rotors. And for the price of one name brand rotor I can get all 4...so it's worth a shot.

Now this set I've seen asked about on the board to which they got pretty good reviews. Haven't heard of any warping or horrendious performance issues, and with his feedback these would be my first choice.

Yet another set listing the same benefits. Nothing new from the first.

These are a little different. For just $40 more I can get them plated in black or bronze. Only reason I'd go for these is because of that option so I could get black. But it's not the deciding factor here.

Finally, these guys here. Again, nothing new or descriptiong in the ad to set these apart from the rest...

I guess I could just go for the person w/the best feedback, or cheapest shipping (but at this savings why?). But basicly I'm looking for some insite if anyone knows a friend or has experience w/them. I'd like to place the order tomorrow or Saturday.

****************************** *************************
Let's take a minute to really talk about all the rotors on ebay today. I'll put it simply for you: Kids buy bling and love a bargain. There, I've said it.

I'll wager that 99% of these are the same blanks. How can this be? In todays world of production anyone with modest funds can purchase a CNC machine and pump out 'performance rotors'. What makes a 'performance rotor'? Well, let me tell you; it's not how many holes it has or what color it is. What's behind these fancy web pages, or who is behind them and where? For all you really know it's one shop spitting out the same rotor from (insert country of origin here) and selling them through different sites.

Why would one be better than the other? It's not. If they fit your car in stock fashion; they are the same rotor! Why, how? The only real issue I'd look for in a stock rotor being 'better' is if said rotor is directional (and we aren't arguing about the diretion of the slots or holes- on a standard rotor it doesn't matter). Do any of them list rotor weight? How about air gaps? Maybe wall thickness?

Bottom line; buy the ones that tickle your fancy or wallet. With decent pads and ss hoses they are all going to perform the same; Acceptable. And that's cool. Just don't expect the buzz words of one to suddenly have you braking at the one marker.

****************************** *********************
I know these aren't going to be some hidden gem that will out perform rotors that are $200 each. But they are probably a tad better than OE and they do add a nice look to the car. I'm not getting these because of the "look", but if I can get something that works a bit better than stock I'll go for it. These are in much better shape than my current setup, and they don't cost too much coin so it's not like I'd be pissed if these were to be junk in a year or two.

****************************** *********************

Don't mis understand my comments; I'm not saying there are not some minor enhancements in the use of such rotors. Just not significant improvements and most certainly not any difference between the ones you linked from what we know of them. A blank's a blank's a blank at this price level. I doubt there is serious grain structure or nickel content difference for example to justify one over the other.
****************************** **********************

[John F. Russo]

Ummm...If you own a Kenny Brown Marauder S, you own a BaerClaw front brake system now. It comes with the KB build, eh?


I just checked with David Frey at Kenny Brown. He did confirm that I do have the BaerClaw system.

I keep learning from the best here at mercurymarauder.com.

Thank you.

I've changed my car bio below already.

______________________________ _____________________
2003 Dark Blue Pearl 300B (Canadian) w/Light Flint (reversed
traction control, mini spare, trunked 6 disc CD changer,
clock-in-the-radio, heated front seats/mirrors, hood light)
-Born 12/10/02; converted new then used 2/28/03
-23,000 miles
-18.5 mpg at a steady speed of 80 mph, one tank of gas
-Stock transmission (upgraded with Performance Automatic
clutches and band after stock tranny failed in 8,800 miles)
-Wheel locks (Ford); godshead valve stem caps
-Badgeless front grille by “Zack”
-Zaino waxing; RainX
Kenny Brown: 6th “Signature Series” conversion (450 hp) Born
3/28/03 (first drove it)
-Vortech supercharger (3 to 7 psig boost)
-377 RWTQ
-4.10 gears
-14 in. BaerClaw front brakes, two piston, slotted/drilled rotors
-MMX Driveshaft
-Precision, triple disc, P/N469018-3 Precision, triple disc, P/N469018-3
-Ford Racing Stud and Girdle
-Pirelli P-Zero Asimmetrico (front 255/45ZR18 99Y; rear
255/50ZR18 102Y)
-Dead pedal
-FordChip
-3/4 of a coil from each front stock spring removed to produce
the “same” effect as an Eibach spring
-Ground clearance: 5 in.
______________________________ ___________________________
1961 Ford Galaxie, 2 dr. Club Victoria, 390CID, 375hp, 4 barrel (gone)