[Guest]

I'm seriously looking at getting these rotors.... what are the pros/cons to these rotors and are they worth the money?

 

[Guest]

Drilled Rotors are a big NONO! A small number of people on this forum have cracked their drilled rotors during heavy braking.

Slotted rotors are merely unnecessary, as opposed to 'warned against'.

Drilling and slotting were conceived when brakepad construction and compounds were inferior to today's. At high temps, old pads would release gases that interfered with pad-to-rotor contact. Slots and holes gave the gases a way out, allowing maximum frictional contact.

This isn't a problem today, provided you select the right brakepads.

Fact is, the stock GM B/D-body rotors are barely adequate for police pursuit duty, which is why they came up with the 9C1 Brake Cooling Package. Unfortunately, the brake cooling fins cause high-speed handling issues.

If you have concerns about brake cooling, read this. 5Damns is the simplest solution, but more is possible.

 

[Guest]

So just keep the rotors and go with something like a ceramic brake pad?


Oh, and the slotted/cross drilled rotors look bad ass.... is there any OEM type rotor that has a 'flashy' look but still performs like stock?

 

[Guest]

My personal experience with slotted rotors is quite the opposite. I actually have them on my car, so can actually tell you how well they work..

Extra braking power = YES
Keep pads cleaner = YES
Better stopping in the rain = YES

Ask anyone that has slotted rotors, and they LOVE them... Ask anyone who doesn't have them, and they don't like them...

I have two 9C1's.. One with slotted, one without. Both have the brake bolt mod, and both have either PF pads or Raybestos brute stops. The car with the slotted rotors stops much better on hard stops. It also has Valvoline synthetic brake fluid in it too, compared to regular fluid in the other car, but I doubt that makes much of a difference in a panic stop.

Must be the cadnium plating......

As far as gassing, my front PF's smelled like a methane refilling station yesterday when I had things apart for service.

 

[Guest]

Exactly what is "quite the opposite" of "merely unnecessary"? I guess I forgot to say "they can't hurt", which, I suppose, is barely a recommendation?

Frankly, I'd love to know which is more important to braking:
Slots
Pad Choice
External Cooling Provisions

'cause it's obvious which one gets noticed more.

I'm simply uninterested in the easy questions, or their answers.

Now that I've established that I - and possibly only I - care more about undebatable function, rather than tastes which can't always be accounted for ...

Sparty, how sure are you that the higher boiling point of Valvoline Synthetic Brake Fluid doesn't have something to do with superior panic stop performance? The longer the panic stop, the more every component's thermal capacity comes into question.

Your slots are outward, not inward, right?

 

[Guest]

Heh.. I'll re-word that. The slots help, therefore I find them necessary.

I installed the rotors per installation instructions. L on left side, and R on right side. Never paid much attention to the direction. I think they are sideways.

I mainly installed them on my car for function, not looks. It all had to do with function, including the valvoline synthetic fluid.

Oh, with my brake setup, external cooling provisions are unnecessary IMO. This was verified at Waterford, MI road racing. Zero brake fade all day long. 90mph - 20mph in a heartbeat. It's awesome watching the brake dust form clouds behind the car.

I think if you were to try slotted rotors some day, you'd be impressed by the results. But you'd need to drive the car hard in order to recieve all the benefits of them.

 

[Guest]

I don't understand the claims of better braking in the rain. I have always found the tire to be the limiter there. Maybe it is because of the crappy 9C1 dams that direct water onto the rotor?

As far as

So just keep the rotors and go with something like a ceramic brake pad?

Ceramics are good pads but performance is not their key attribute, what they are good at is being quiet and the dust is colored so that it is not very noticable. Just because something is new and more expensive doesn't make it better, neither does the parts store jockies word. On this forum most of us are enthusiasts that is why we are here, we are looking for different things than the average driver. The quiet and low dust visibility properties of ceramic make them an upgrade for the average person, for us we want performance first to get that we are likely to tolerate a little noise, slightly more dust, maybe lesser rotor life, or slightly less cold braking in order to gain maximum bite in other conditions.

Personally I like the AutoSpecialty blank rotors with the Performance Friction 6144 pads(guess there was a recent PN change and I don't know what the new one is). These rotors are a good choice for when the stockers need replacing and have thicker cheeks and directional cooling vanes between the cheeks. I actually had a caliper hang up on me and it didn't warp these beasts.

The biggest braking improvement you can make to an Impala or 9C1 is the stealth bolt mod, it should be done before you worry about the front. GM used the same proportioning valve as the drum cars so the rear discs do not work properly in normal braking just under hard stops. With the age of these things new lines are comming to the point of being maintenence so an upgrade to braided can help as well.

 

[Guest]

You have to define 'improvement' or 'better braking' first. To some this means more torque, to others longer operating ranges.

If you want more 'power' then that means torque. And that only comes from pads. Higher Cf is the key. Rotors will not change that. (stock size we're talking)

If you want extended operating temp ranges the cop rotors with the directional vane castings will aide in that by providing a bit more cooling effectiveness.

Slotting will mearly enhance what is there. Decent pads seem better, better pads work to the full potential.

The down side often is that said zoomy pads on said zoomy rotors genterate even MORE heat! All the while providing the torque you are after but coming with greater heat saturation.

Ultimately the only long term solution is more rotor. Both larger for torque value and thicker for thermal capacity. Does everyone need this? Probably not. But it's pretty much how it works.

 

[Guest]

From Baer's web site:
What are the benefits to Crossdrilling and Slotting?

In years past, crossdrilling and/or Slotting the rotor for racing purposes was beneficial by providing a way to expel the gasses created when the bonding agents employed to manufacture the pads began to break down at extreme temperatures. This condition is often referred to as “green pad fade” or “outgassing”. When it does occur, the driver still has a good firm brake pedal, but simply little or no friction. Since this normally happens only at temperatures witnessed in racing, this can be very exciting!

However, with today’s race pad technology , ‘outgassing’ is no longer much of a concern. When shopping for races pads, or even ultra-high performance road pads, look for the phrases, “dynamic surface treatment”, “race ready”, and/or, “pre-burnished”. When these or similar statements are made by the pad manufacturer, the pad in question will likely have little or no problem with ‘outgassing’. Ironically more pedestrian pads used on most streetcars will still exhibit ‘outgassing’, but only when used at temperatures normally only encountered on the racetrack.

Although crossdrilling and/or slotting will provide a welcome path to expend any gasses when and if they develop, it is primarily a visual enhancement behind today’s often wide-open wheel designs.

Crossdrilling offers the greatest gas relief pathway, but creates potential “stress risers” from which cracks can occur. Baer’s rotors are cast with crossdrilling in mind, from the material specified, to curved vanes, behind which the holes are placed to minimize potential crack migration. Slotted surfaces are what Baer recommends for track only use. Slotted only rotors are offered as an option for any of Baer’s offerings.

 

[Guest]

Yup, most of us in the business pretty much agree to what the real value of all this is on a rotor today. You'll find pretty much the same info on a Stoptech or Brembo page finally too. In fact you'll find a lot of your better pads are in fact slotted.

Funny how things change...a few years ago you would not have found such honest comments from many in the business. I swore off drilled rotors back in 93 when I started building kits only to have other suppliers come up with such techno-bs about cooling, better braking, 'fire slots' and any other wiz bang terms people could come up with. They often left out the part about cracking rotors...that part came later. Trying to stop an SHO on 10" drilled rotors. LOL Yea, sure those are what you need... more holes!

I put this on my web page many years ago after I caved in and began to offer drilled rotors. If I didn't I'd have never survived as of course everyone else pushed them. People are learning finally. Sometimes at costly expense however.

>>>Q: I noticed you said drilled rotors are an option, why do you not recommend them? Even Porsches use them, but I’m told they’re better because they are cast into them.


A: Drilled rotors aside from the minimal weight savings offered, don't do as much to enhance the kits performance as some people like to believe. In fact they can cause more harm than good. The drilling of the rotor is to mainly remove the gas/particle build up developed by the friction materials against the rotor surface more than cool the iron. Problem is that when the air rushing through these holes is significantly cooler than the rotor temperature we begin to develop thermal stress cracks in the iron. These start as small crack, but over time become larger and can lead to major cracking problems. While the outer surface of the hole is chamfered to help this, the inner area of the center vaning is not. For this reason TCE offers gas slotting as a performance option. This is to help 'vent' the pad and create a self cleaning effect of the pad as the rotor passes over it. Keep in mind that either of these, drilled or slotted, will lead to faster pad wear and more dusting. As for the Porsche rotors being cast; that’s a myth. They are drilled like all others, and given the completely different weight bias of a rear or mid engine car the requirements of the brake system differ then that of most FWD applications also.<<<

 

[Guest]

wow, a lot of info on these

Thanks guys


I think I'll probably get them. I could use the extra stopping power....

To me, it seems like with these 22's, the car does not want to stop like it did with the stocks

 

[Guest]

Forgive me, then you've competely missed the point. No stock sized rotor with or without holes, slots, dimples, or gold plated is going to give you "more stopping power". It just doesn't work that way.

If you want more 'power' you need either;
Larger rotors
More piston area
Better brake pads
Stickier tires

Or a combo of them.

On the other hand the proper mix of one or more of the above can net you rewards. The Baer kits, Moveit kits or my own TCE kits offer the right mix of how to achieve this. While each may have its own pros and cons the concepts are the same. Other than a change to high friction pads, there is nothing you can bolt onto the car now that will change brake torque.

 

[Guest]

... with these 22's, the car does not want to stop like it did with the stocks

Are you surprised?

Your present wheels are obviously not lighter, and probably heavier than your previous wheels. Problem is, it isn't static weight, like a sound system, but rotating weight.

I don't know the equations, but every additional pound of rotating weight is being multiplied by both the fact that it's spinning, and the fact that it's further out.

In other words, if you got a set of 17" wheels that weighed as much as your 22"ers, your braking would improve.

Your braking would also improve if you got a lighter set of 22"ers.

The same goes for acceleration, which is why most drag racers use lightweight 15" wheels - and in some cases, lightweight brake components.

Todd, do you have the equations?

 

[Guest]

Well, the braking isn't too much worse but I can feel it. As far as the weight of the rim? They are not too much heavier. They are aluminum and surprisingly light weight, relatively speaking

Now, I do need some new brake pads, that's for sure as well and I do have some dead weight in the car such as the sub box in the trunk and of course my fat ass doesn't help

 

[Guest]

If you want more 'power' you need either;
Larger rotors
More piston area
Better brake pads
Stickier tires

Todd, I have to disagree with the above statement. So we will have to agree to disagree.

If I use your ideology as rule of thumb it would lead me to believe that dirty tires wouldn't affect the stopping distance on a vehicle.. Think of the tire as the rotor, and the road as the brake pad. If they are muddy, they will slide over the pavement. So do I stay with muddy tires, or clean them off so that I can stop better?

The same applies for the rotors. As has been proven, under hard braking the pads can produce dust and gassing. The slots act as wipers to help keep the area between the pads and rotors clean. Under normal every day braking the slots are not needed, though they do provide a more uniform pad surface. Once you get into performance use, is where they will help the most. I have also noticed improvements in the rain, as well as other members on the forum.

I have read independant magazine articles where they actually did testing on slotted rotors and they DID help stopping distance. The first test was to just swap to slotted rotors. Then they swapped to better pads. And swapped pads again to those used for racing. Each time they showed a positive improvement in braking ability.

 

[Guest]

No formula for the wheel weights. Your speaking of the MOA or Moment Of Inertia. The reverse of that achieved with a lighter flywheel for example.

As for the slots, I don't disagree with the benefits of adding slots to rotors. However they do not increase brake torque or power. The math is the same never the less. What you are doing is keeping the pad in its proper state and allowing the gasous particals to vent. This is in turn 'enhancing' the pad or simply making it work as it should.

We'll agree that a boundary layer builds between the pad and the rotor. The slots (or holes) vent this. But the total torque value (for measuring purposes) has not changed. You'd be correct to say that pad efficiency is diminished by not having a vented surface.

To use your own example; The P Zero tire doesn't work well in the mud, but the maximum tire torue it is capable of (its AA rating perhaps?) is not measured in the mud. So it's performance is not improved on a clean surface- only what it is intended to be.

Depending upon the brake pad compound and or the pad supplier you may find less gasous build up on some than others. And good real performance pads are slotted too, thus negating the value of rotor slots.

One of the down sides to the use of the slots is this lack of boundary layer. This in turn can boost the rotor temp as well. That's why production cars get crappy pads- they fade. Put in a good set of pads and they don't fade, they bite, then the temps go up as a result of the energy expended, now you shift your problems from the pads- to the rotors.

It's a bit of a semantics thing I guess, and I'm not agianst the use of gas slots in any way. I only mean to point out that slots do not produce more power or torque.

I'm with you all that adding a good pad, slotted rotors and braided hoses produces the best "Brake Enhancement" you'll get. The problem later becomes the elevated use raises the bar for other parts.

 

[Guest]

Does that mean I should start running BFG muds on my car?

 

[Guest]

... the weight of the rim? ... not too much heavier

Same weight, smaller wheel = better braking and acceleration.

Same weight, larger wheel = worse braking and acceleration.

Like Todd said, moment of inertia.

 

[Guest]

Yes that's correct. When I change over to my summer tires on the truck I have to re-adjust my right foot braking pressure.. The extra rolling resistance of those 33" tires compared to 30" tires is a big difference and adds a lot more work to the brakes. Plus it's covering more distance in a shorter amount of time which also causes the brakes to work harder in order to stop the vehicle in the same amount of time.