Fmlywgn

I have had my 99 1500K Suburban for 6 weeks now, and I have to replace the rotars. Had the drums turned and pads replaced 2 weeks ago, but the rotars are too far gone to turn (apparently previous owner replaced pads, but never turned rotars).

I have been looking at all of the options for replacement rotars, and have seen some of the "slotted" designs out there that supposedly promote cooler brakes, therefore extending brake life (?).

My question is this; are any of these fancy rotars any better than a pair of factory/OEM rotars for half the price?

McGuireV10

For regular street driving, no, you just need regular OEM rotors.

Slotted and/or cross-drilled rotors do permit hot gasses to escape but they're really only applicable to racing applications. Just to give you an idea of the difference between street and track conditions -- I've instrumented the racing brakes on my Viper and in regular street use they might hit 350 degrees (that's a momentary peak temp) under hard braking for street conditions. At the race track they occasionally peak at 1200 degrees. Granted a heavy truck will put a lot more heat into the brakes, but still nothing that would warrant slotted rotors.

If you're concerned about high-temperature performance, the best place to start would be running better-quality fluid, and flushing and replacing your brake fluid on a regular basis (every six months isn't unreasonable).

Fmlywgn

Thanks Mc. I don't do any racing (not to speak of anyways). I do quite a bit of mountain driving, and downhills can get those brakes heated. I don't exactly have a pocket full of money to blow, so I think I'll just go OEM.

Thanks again

McGuireV10

I've dragged some pretty big trailers through the mountains over the years, and hi-temp fluid is well worth the money if you ever have soft-pedal problems. The number to pay attention to is the "wet boiling" point. The dry boiling point is kind of an abstract figure that never occurs in real life. Motul is a great brand. (There are better ones like Castrol SRF in particular, but they get very expensive, and are really aimed at racers.)

350Suburban

Sorry to say, but brake fluid rating has nothing to do with why your rotors are being warped. Unless you have a broken line or piston brake fluid never even touches the rotors. GM trucks and SUV's are made of good quality, heavy duty parts in the body, frame, suspension and everywhere else. Unfortunately this means that the suburban you drive is extremely heavy. GM, although make outstanding products, didn't exactly put brakes on the suburbans that got the job done. In other words, they're too small. Upgrading to bigger brakes takes a lot of money and a lot of time. My burb warped brakes just like yours is doing so I put a set of severe duty brake rotors on it. These are slotted rotors that help dissapate heat by releasing gas caused by the friction between the pad and rotor. They work beautifully but they are significantly higher in price when comparing them to OEM. The money you will save in between rotor replacement is well worth the cash spent up front.

McGuireV10

Er... he didn't say they were warped, and nobody said fluid "touches the rotors".

With regards to fluid, I specifically said "if you have soft-pedal problems" which is going to be his first indication that his brakes are getting too hot, which is ALL that slotted rotors will help with. If you're not running hi-temp brake fluid, I guarantee you aren't getting into the temperature range where slotted rotors are going to help. Brake fluid that meets the basic DOT specifications will boil long before you have the kind of gas buildup that requires a slotted rotor.

Did you just put new rotors on it, or did you actually upgrade to bigger brakes? Typically when somebody says "bigger brakes" the starting point is bigger calipers and braided steel lines. Larger diameter rotors are a cheaper route, too, if you can find a relocation bracket for your stock calipers. Slotted rotors are really only going to help under the most extreme conditions, and they're generally the last step in upgrading a braking system, otherwise every tow truck, every semi, and lots of other vehicles would be running them since they're the cheapest part of the braking system to upgrade.

I'd bet money that most of your improved braking that you attribute to your slotted rotors is actually due to nothing more than having installed new stuff on an older truck.

350Suburban

Neither did he mention a soft pedal situation yet you gave him a way to fix that. I just voiced my opinion as to what helped my suburban, no need to jump my case. Fmlywgn did say that his rotors were turned to nothing by the previous owner. You turn rotors because they get warped. I put severe duty rotors on my 97 about 2 years ago and haven't had to touch them since.

McGuireV10

Sorry, I didn't mean to come across as jumping your case, I was just discussing the points you raised.

You turn rotors because they get grooves and/or they form a lip around the inner and outer edges. You replace them when they're too thin to turn.

It's still a bit controversial in racing circles, and probably unheard of outside those communities, but most major brake companies will tell you that brake rotors don't warp. If you have some time, this writeup on the StopTech website, for example, is an interesting and well-written explanation behind this assertion. Warping such a dense, heavy piece of metal would require temperatures that would set your entire vehicle on fire. The short explanation is that it's almost always uneven pad material deposition.

I mentioned soft-pedal because it's the first indication that you need to address brake temperature problems, which is what slotted rotors are intended to alleviate. Since he asked about slotted rotors, and they are not the best place to begin addressing temperature problems (unless you're planning to throw a few thousand at it and upgrade the calipers and lines, too) I felt it was relevant to explain diagnosis of and first-steps to correct brake temp problems.

In any case, he probably has more than enough information now to make a decision.