[kenpeterson]

I haven't seen anything recent on this topic in the forums, so forgive me if I am asking for something repetitive. I have the motive power bleeder and the Porterfield pads in hand. SS brake lines are on the way. I have visible uneven wear on my rotors, so they will need to be turned. My question is, if they are out of spec for turning, and I need new ones - can I get some recommendations? Pelican has no-frills basic Sebros for $81 each and Zimmerman coated & cross drilled for $133. Are the Zimmermans worth the extra $50? Especially with the good Porterfield pads? The car is a weekend driver and I don't race it.



tnx

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[flash]

i am running the zimmerman cross-drilled - reasonably pleased with them



you can get them cheaper online - there is a company pretty local to us that sells them - do a search here and you'll find the link

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[williamoss]

I have a general question about cross drilled rotors. Why are on our cars are the fronts rotors crossed drilled but the rears are not. Also why are the rotors drilled with round holes while newer vehicles as in the boxters or 911's have slots as opposed round holes?

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[flash]

they aren't like that stock - standard cars are solid all around - M030 cars have holes all around



aftermarket rotors are drilled - factory rotors are generally cast with the holes (as is the case of the M030) - casting the holes alleviates most of the cracking issues



slots do an even better job, but are more expensive to do, wear pads faster, and can make noise, especially with harder pads than used on OEM applications

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[hryden]

I wouldn't suggest spending the extra money for cross-drilled on a weekend non-track event car unless you just want the look. Zimmerman makes a non-cross drilled rotor for our cars as well that is usually in between the 2 you listed price wise. My car is primarily a track car and I didn't find the cross drilled rotors made much difference at all. I actually ended up taking them off prematurely because of extensive deep cracking. I run solid zimmerman's now with Hawk racing pads with no rotor issues. For a street car, I don't think cross-drilled or slotted rotors really make much difference. The brakes usually won't generate enough heat even in spirited driving to take advantage of the improved cooling / heat dissipation. I've found pad selection to have a much bigger impact. Just my 2 cents.

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[flash]

where i find the advantage is in wet weather - the cross-drilled rotors do a better job than flat ones in controlling water



as for cracking, i now a lot of people have complained about this - i attribute that to a driving difference - even on the track i have had no issues with cracking - but, i use a street pad (porterfield R4-S) and not a track pad - also, having driven a momentum car for so long, i learned to throttle steer and late brake, and consequently don't use the brakes as much as most people, so they don't get hot enough to crack



when i have to change my rotors, i'll likely go with exactly what i have now

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[banditsc]

I got mine here, it's the place Flash was eluding to. http://www.r1concepts.com/porsche-968-1994-exc.htm

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[Cloud9...68]

"having driven a momentum car for so long, i learned to throttle steer and late brake, and consequently don't use the brakes as much as most people, so they don't get hot enough to crack"



Amen to that. I like to adhere to the great Fangio's response to a reporter's inquiry as to the secret of his success as a race driver: "More gas, less brake." My brakes are barely hot after completing a track session. I never understood the wisdom of whomping on the brakes at the last possible moment and greatly upsetting the balance of the car. Smooth, gradual application and release has always worked best for me.



Now, a competitive event where you're trying to pass under braking might be a different situation, but for street driving, and occasional DE/track day activities, I agree that rotors from a reputable manufacturer, either solid or drilled, will work fine. Zimmerman and Brembo both make very good rotors at a reasonable price. I guess what I'm getting at is that the brakes aren't one of the 968's weak points, so I see little sense in spending a lot of money on fancy aftermarket rotors, let alone calipers, unless you plan to go racing.

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[rxter]

I also had the drilled/slotted Zims with Porterfield R4S pads. The pads were great - very low dust. With my worn pads and stock rotors I definitely noticed fade during spirited driving (no racing). The new setup gave me great performance with no fade. They did growl quite a bit during braking, which caused some odd looks from the right-seater from time to time. To do again I would go with the solid zinc-zims and R4S pads.

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[968TDG]

My current brakes have been squealing for a few months now. I have the R4S pads ready to go on the car, but I'd prefer to change the rotors at the same time. Flash, do you have any brake noise from the drilled rotors or is the noise Rxtr was talking about more likely due to the slots?



Phil

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[banditsc]

I have slotted only with the R4S pads and haven't had any brake noise from them.

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[flash]

nope - none from mine either



lol - it's probably just his windscreen

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[pure&simple]

>>> My brakes are barely hot after completing a track session. I never understood the wisdom of whomping on the brakes at the last possible moment and greatly upsetting the balance of the car. Smooth, gradual application and release has always worked best for me.



If that's the case, then you might not be using the full capabilities of the car. Not saying that's a bad thing, since nobody wants an off-track excursion, just that you could be going faster. The fastest way around the track is to go from full throttle to full braking at the last possible moment with as little time spent in transition as possible. And then, to trail off the brakes gradually during turn-in. AND doing that smoothly without exceeding the available traction of the tires, which is the difficult part. If the balance of the car is upset by excessive dive under braking, that could mean too much front brake bias or a soft suspension.



Furthermore, the more time your foot is on the brake pedal, the more time the pads are in contact with the rotor, and the less time your brakes have to cool. So it is best to get the braking done quick and get off the brake pedal.



Bringing it back to brake rotors, my OEM (non-M030) brakes are just barely sufficient for the speed I carry on the track given the weight of the car. A couple of years ago, I lost brakes completely at Summit Point Shenandoah (which is notoriously hard on brakes) when my pads glazed and fluid boiled. After that, I had RSBarn put in some brake ducts to channel cool air to the brakes and I got full race pads from Cobalt Friction instead of track/street combo pads. Still, I find that drilled rotors (especially worn ones) don't have quite enough heat sink capacity. I use the regular OEM Porsche rotors that are not drilled or slotted with good results.



Edit: just noticed that you don't track the car. As mentioned above, if you are looking for pad longevity stay away from slotted. If it were me, I'd stay away from cross-drilled, but I recognize that not everyone seems to have problems with these.

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[bombfactory]

I have drilled front rotors on my car, installed by a PO. I think they're Zimmerman but I'm not sure. No issues with noise, cracking or wear, but it bugs me that on one side - can't remember if its left or right - the hole pattern is going the 'wrong' direction (kinda like turbo twist wheels turn the 'wrong' direction on one side of the car), indicating the rotors are universal and not a specific left and right. Call me a poser cuz I know I don't need drilled rotors for the performance, I just like the look :-)



Does anyone make standard size 968 drilled rotors that have the 'lots of holes' drill pattern of the M030 rotors? Mine have about half as many holes as this:





   

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[judge]

I'm so envious of the choice you guys have in the USofA!! Here in AUS it's virtually impossible to get anything other than OEM rotors and they are hugely expensive. I'd happily go to one of the online stores, pelican or paragon for example, but the shipping costs are prohibitive because of the weight.



I'm going to need new rotors soonish, so has anyone in AUS any ideas or links, or has anyone else any suggestions?

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[Eric_Oz_S2]

[quote name='judge' timestamp='1311307468' post='113011']

I'm so envious of the choice you guys have in the USofA!! Here in AUS it's virtually impossible to get anything other than OEM rotors and they are hugely expensive. I'd happily go to one of the online stores, pelican or paragon for example, but the shipping costs are prohibitive because of the weight.



I'm going to need new rotors soonish, so has anyone in AUS any ideas or links, or has anyone else any suggestions?

[/quote]



Shipping from the US is very expensive. I got the Sebro rotors from Design911 in the UK - shipping was much cheaper. I use them extensively on the track with PFC97 pads and they don't seem to be that different from the OEM ones. I get some cracking, but it seems this is fairly common when used on the track. I wouldn't use cross drilled discs for this reason.



Eric

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[Tom030]

The O.E. M 030 rotors are directional, two different part numbers.

~tom

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[Cloud9...68]

"The fastest way around the track is to go from full throttle to full braking at the last possible moment with as little time spent in transition as possible."





I'll try that when I get my car back, with its extensive suspension mods, which should firm things up quite a bit. I found that the approach you describe with my car in its current (now former) condition resulted in way too much dive and general pitching and rolling and waiting for things to settle to be fast.





I'll also keep an eye on pad wear and rotor condition. So far, I've had no issues with any sign of cracking on my Zimmerman cross-drilled rotors, and the Porterfield RS4 pads are holding up great.

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[flash]

i disagree about "the fastest way" - i have found that it can actually be faster to not go as fast as possible going into a turn, and rather to back off a touch, and have the car settled going in, so as to be able to be on throttle all the way through the turn - it depends on the car, and the track, but on short tracks, it really works - i barely use the brakes at all on those, and have always done very well



i know the pca guys like to teach you to go full on and then brake full on, but i think that comes from the disasters in doing anything else in a 911 - those same guys are stuck on rules too, which limit how you can set up a car - they won't allow you to set your car up so it can beat a 911 - also, if you drove like i describe, you would be pissing off the guys in the 911s for 2 reasons - first, because they would think you were holding them up on the straights, and second because they couldn't figure out how you were lapping them in spite of that



my instructors taught balanced driving, and not "go fast brake hard" - they taught us to feel the weight of the car and "surf" the corners, using the steering wheel and the throttle, not the brakes, the theory being that any energy spent on braking took away from acceleration - but, then too we were talking about very different cars, which were much lighter



i still drive that way though, and it continually results in people asking me if my brakes lights work



you have to drive the way that is safest for you though, and momentum driving and power steering takes a LOT of time to master, and should not be done in a group of cars, but rather on private track time

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[Cloud9...68]

My experience so far is pretty limited, but I have to say, I completely agree with Flash on this one. It seems that sudden motions, such as stomping on the brake and the accelerator, will inevitably upset the balance of the car, which will cost you time waiting for things to settle. My PCA instructors taught the "on-off" method of never combining braking and turning, and it drove me crazy - too much on-off, herky-jerky motions. So far, I much prefer what Flash describes as "surfing" through the turns, applying the brakes a touch early and not quite so aggressively, trail braking, then easing off them earlier in the turn, allowing for transition to the throttle earlier. This seems to allow me to carry more speed through the turn, and once I got the hang of it, my lap times dropped dramatically. But this was all on a very short (0.7 mile), highly technical track, with the car in what I would describe as a "firm street" tune. I'll definitely experiment with different methods going forward; maybe there's a happy medium somewhere. But no matter what, I find it hard to dispute the "smoother is faster" theory.

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