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Thread: Drilled and slotted rotors? Reply to Thread
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  Topic Review (Newest First)
02-26-2010 05:31 PM
Riddle You are a touchy one, aren't you?

Again, SAE papers or anything that can be freely published. If you've been doing this for 15-18 years, surely you know of some open source general references?

Even if a super secret slot design gives a competitive advantage, what kind of advantage is it if the company never tells the consumer about it? It is surprising to me that no one anywhere has ever done tests to say, "Yes, our slotted rotors outperformed the basic OEM plain rotors by XX%." Maybe no one has a marketing department...... Heck, no mechanical engineer students have undertaken this as a test for a thesis?
02-26-2010 07:44 AM
FMTRVT Good luck with those SAE papers. Info that gives a company a technical advantage is never going into an SAE paper. Honestly there are lot of science projects that are never put into papers, and companies for the last decade really have cut back not only on presenting papers but attending the events. The SAE Brake Colloquium is held in the fall and you can read through the presented papers list, past and present.

I've been answering brake questions for years starting about 15-18 years ago on a CompuServe forum. I get no money for this and when I worked for a company I never tried to "sell" their products, and if fact mostly here told people to change from it. There is a lot of misunderstandings out there and many companies use this to sell products that don't improve the situation. Just hate to see people spend money when they don't have to. I spent too much time on the computer as it is here and many other forums, so I really don't plan on pulling references for everything I type. Take me at face value or not.

Oh, and thanks for pointing out my error. I meant to say Outback and just typed in WRX since I guess I just pulled the link. One engineer that worked for me in NJ had a WRX and his mother had an older Outback. Non-working hood scoop. Brain fade about a vehicle I really don't care about.

You can always just put me on ignore.
02-26-2010 02:00 AM
Riddle .... which is why I asked for things like SAE papers that can be freely published (well, with a download fee). Heck, at this point I'd be happy for magazine tests. And no disrespect to you, FMTRVT, but I don't know you from Adam, being a noob here and all. Your previous post in this thread seems well thought out, but then you make a big error like saying that a WRX hoodscoop isn't functional. How do I know you know what you're talking about (you undoubtedly do, but without hard numbers to validate, I'm wary of accepting general statements of fact). So, again, if you do know of any links to publishable hard data on the effects of slotting on brake output, particularly in wet conditions, it'd be greatly appreciated. Engineering white papers would be best, but anything would help. I did find this paper but it is more of a survey than an experimental results paper. Perhaps the references will be useful.
02-25-2010 09:24 PM
FMTRVT That goes against my confidentiality agreement with the company I worked for. Or would you rather see me be unethical and violate the law?

This is a common problem for any of us that work or worked in the industry. We didn't pay for the tests or work; we were the employees of a business that owns what was done.
02-25-2010 07:41 PM
Riddle I know he has explained in detail, but I was looking for hard, experimental data to back up his statements.
02-25-2010 10:55 AM
444-4D FMTRVT has explained, in detail, drilled and slotted rotors on SD trucks a few times on this site. Here is the short version. Slots will help if your brake temps get to 800°. The way most people use their truck they only get to about 500°. Use your nose, if you can smell them you would benefit from some slots. If you can't smell them, any benefit from slots is just wishful thinking.
02-25-2010 10:41 AM
AmarilloPSD Just installed EBC 3GD Dimpled and Slotted Rotors with Hawk Pads and Russell Brake Lines, this weekend. Currently experiencing some problems with bleeding, had a problem mounting the Russell lines, still waiting to hear back from Russell's engineer and apparently there is some air trapped in the ABS module. Once I get everything ironed out, I will give a review of what I think.
02-25-2010 12:24 AM
sportbiker929 Got mine from R1 performance and they rock.
02-24-2010 11:55 PM
Pappy19 Drilled and slotted rotors are the only way to go IMHO. Can't go wrong with www.ROTORPROS.net. I had them on my 2002 and they never missed a beat for 80k. Never had one issue; no shutter, no fade, nothing. It was all good. When I need new brakes on my 2008, that's who I'm calling.
02-24-2010 11:06 PM
Riddle Sorry to bump an old thread, but I thought it was a pretty interesting read overall. I just wanted to correct one thing:
Quote:
WRX- you know the vehicle with the fake hood scoop because it sells “high performance”. Like factory cars with drilled rotors.
The WRX (and STI) hoodscoop is very functional - it directs air to the top mounted intercooler, as you can see in the attached picture (the space on the left lets air get down to the turbocharger area).

If you're thinking fake hood scoops "selling performance", I think you're thinking of the 2005-2009 Mustang GTs (I kid, I kid! I still like Mustangs too).

I was wondering if anyone has come across anything like the SAE paper referenced above, except for slotted rotors. I'm not interested in the cross-drilled look, but am curious to see if there are any hard experimental data on the effects of slotting rotors.
01-09-2010 05:20 PM
WHB
Quote:
Originally Posted by Matt0987 View Post
Also, who is to say, generically, that aftermarket products are better than OEM. I would guess that there are those that are. And those that aren't. I am sure cost plays a factor is what OEM products are used as well as safety. That is why we have Lincolns and Fords. Our pocketbook determines what products are put on which product line.
I didn't mean to come across as saying "all aftermarket rotors are better than Ford rotors." I think that benefits seen by certain aftermarket, drilled rotors are more likely a result of other factors (such as metallurgy, thickness, cooling vanes, etc.) than the fact that the rotors have holes in them.
01-09-2010 02:39 PM
klhansen
Quote:
Originally Posted by Matt0987 View Post
Now, according to FMTRVT, who seems to have some experiance with these things...
D'YA THINK!!

When Jack talks (types) about brakes. I listen (read). Everyone else would be well advised to do the same.

He has years of experience with braking systems on multilpe vehicle types. He's earned the title of "TDS Brake Guru" in my book.
01-09-2010 02:18 PM
bb79ranch I hate to keep adding fuel to the fire on which is better, there will always be a down side in the non-believers eyes. I have used three different types of rotors on my truck. First were the stock ones which were on the truck when I purchased it used so I can't attest to their treatment, but they were shaking when brakes were applied. I replaced the factory units with top of the line Raybestos (from Carquest)all the way around these rotors were over $150 each IIRC and probably another $100 or so for semi-met pads. I replaced alot of parts dealing with the brakes before these rotors were installed(all slide pins, calipers, brake lines and evacuated the fluid), then torqued all the bolts including lug nuts to spec. and ended with burnishing the pads to the rotors. I allowed about a week before towing anything to give the brakes time to bed-in, even with all the above treatment the shaking returned at about the 60 day mark to say the least I was pissed. I didn't want to spend another $700 on the same parts that failed so my only option I could see was drilled and slotted. I researched, took advice for and against then weighed my options, I found Rich at Rotorpros.com and he gave me a 6 month warranty against warping or cracking(it is a year as of now) plus I got all four rotors with Posi-quiet low dust pads delivered for $350 I bit the bullet and haven't looked back since. I know the solid undrilled rotors turned a bluish color from the heat of my braking, still today after over two years my drilled/slotted haven't as of yet approached this bluish tint from the heat. I know they (D/S) don't heat fade like the stock or aftermarket solid rotors do. I have been keeping tabs on the pad life and I will admit the pads do wear a little faster because of the slots but with over 40k miles they still have half the friction material left. I'll also admit that these D/S rotors I purchased aren't top of the line, some say the cryo rotors are better or a certain pad is better I'm sure there is better but at what cost to benefit raio. I am sorry for being longwinded, I just wanted to give the results on what I've tried good or bad and with 6 vehicles with these D/S rotors I can attest to their advantages over stock/replacement rotors. I don't mean to sway your decision to or from these rotors, all I know is they work very effectively for my needs at a cost that is very economical to my wallet. I hope this helps in any way. WHEW! Todd
01-09-2010 01:16 PM
Matt0987 It is my understanding that the slotted eat the pads up faster so in the future I plan on staying away form the drilled/slotted. How much I do not know. 1%. 10%. 50%. I have not read.

Now, according to FMTRVT, who seems to have some experiance with these things, when you get down to it there is a lot of variables based on pad compositions and the composition of the metal the rotors are maunfactured of. And, as WHB suggested, whether they are drilled or fabricated with the holes w/out drilling. That must be an interesting process.

Also, who is to say, generically, that aftermarket products are better than OEM. I would guess that there are those that are. And those that aren't. I am sure cost plays a factor is what OEM products are used as well as safety. That is why we have Lincolns and Fords. Our pocketbook determines what products are put on which product line.

Either way, from what I have read, when you buy your rotors (solid, OEM, slotted, aftermarket, or drilled) and pads you need to keep an eye on them just as you do the level of oil in the engine.

And, just as you can get differeing opinions about which oil is best, Amsoil or Rotella (Or Rotella Vs which version of Rotella for that matter) you will get varying opinons on which rotor manufacturer and pad manufacturer and the variables from each one.

But, too, if it weren't for all of these variables these forums would get pretty boreing!
01-09-2010 10:52 AM
444-4D
Quote:
Originally Posted by WHB View Post
In our application, though, I think the "benefit" of drilled rotors is that aftermarket parts are simply built better than the Ford pieces. I think a high-quality, aftermarket solid/slotted rotor would do just as well if not better than a drilled or drilled/slotted rotor would.
What about an aftermarket rotor is "built better"? Why do you think a solid/slotted rotor would work better on a SD?
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