Whats the best rear brake upgrade for the PP GT's?

[BmacIL]

I'll humbly disagree. These heavy cars want a ton more rear brake. There's a reason the GT350's have a 4 piston caliper in the rear. Mine are 6 piston on all 4 corners including the rears for aesthetics, however the rear piston diameters are greatly reduced to get the correct bias. When you grab a bunch of brake in my car, it feels like it squats instead of a slight nose over. The confidence and ability to stop without effort is amazing and in my opinion much more impressive than big power. The factory PP1 calipers and stock rears on my car performed nothing like the Baer system. Also keep in mind I'm running their least aggressive pads to keep the dust and noise at an OEM level. I know they are crazy expensive, but the result is crazy amazing.

And how's the brake balance at 100% effort on track?

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[Chris Barnes]

Predictable and without any fade whatsoever!

 

[Andy13186]

Predictable and without any fade whatsoever!

So , the only reason you dont want them to be drilled is because you think they may crack and dont give any credit to their lighter weight , better offgassing abilities and looks? Seems paranoid if they havent cracked yet and youve driven hard. Mine didnt even come close to getting surface cracks when doing the rotor seasoning and pad bedding procedures which was like 15 back to back 80 to 10 mph near ABS stops in a row (for the final set, many more sets of less agressive braking), nothing like you would see in any normal driving and most likely not on tracks too, it actually gave me a headache doing it.

 

[BmacIL]

So , the only reason you dont want them to be drilled is because you think they may crack and dont give any credit to their lighter weight , better offgassing abilities and looks? Seems paranoid if they havent cracked yet and youve driven hard. Mine didnt even come close to getting surface cracks when doing the rotor and pad bedding procedures which was 15 back to back 80 to 10 mph near ABS stops in a row

Look man, no one is telling you your baby is ugly. Drilled rotors are MORE susceptible to significant rotor cracks than plain or slotted. It's a damn fact. Holes by drilling create stress risers. Stress risers in the presence of very high thermal gradients and thus thermal strain = cracking. It's basic mechanical engineering.

 

[Andy13186]

Look man, no one is telling you your baby is ugly. Drilled rotors are MORE susceptible to significant rotor cracks than plain or slotted. It's a damn fact. Holes by drilling create stress risers. Stress risers in the presence of very high thermal gradients and thus thermal strain = cracking. It's basic mechanical engineering.

Just searching cracked rotors I found more cracked slotted rotors and plain which I posted, yes there are some drilled ones too. I think its very very unlikely for 99% of people to crack any rotor and I think that means that there is a benefit for 99% of people having drilled and slotted rotors, aka lower rotating mass, better offgassing capabilities, and in most peoples opinion better looks, especially if they only street drive or dragstrip.

 

[BmacIL]

Just searching cracked rotors I found more cracked slotted rotors and plain which I posted, yes there are some drilled ones too. I think its very very unlikely for 99% of people to crack any rotor and I think that means that there is a benefit for 99% of people having drilled and slotted rotors, aka lower rotating mass, better offgassing capabilities, and in most peoples opinion better looks, especially if they only street drive or dragstrip.

Probably because overwhelmingly more people use plain or slotted rotors on track and thus the potential population size for cracked rotors and thus pictures of them is much much higher.

No one's telling someone to not buy them for street, drag usage. People are just saying that the mechanics of the rotor design is such. Please just stop arguing with people about things that are known truths and be happy with the fact that they work for your usage.

 

[Andy13186]

Probably because overwhelmingly more people use plain or slotted rotors on track and thus the potential population size for cracked rotors and thus pictures of them is much much higher.

No one's telling someone to not buy them for street, drag usage. People are just saying that the mechanics of the rotor design is such. Please just stop arguing with people about things that are known truths and be happy with the fact that they work for your usage.

Just trying to let other people know they will most likely work for 99% of peoples usages better than the other options for the reasons I stated..

 

[Norm Peterson]

Look man, no one is telling you your baby is ugly. Drilled rotors are MORE susceptible to significant rotor cracks than plain or slotted. It's a damn fact. Holes by drilling create stress risers. Stress risers in the presence of very high thermal gradients and thus thermal strain = cracking. It's basic mechanical engineering.

This ^^^

I used to do a fair amount of thermal transient analysis to determine what the thermal effects due to rapid temperature changes were likely to be, relate that to estimating the fatigue life of the part being analyzed, and either qualify the part for its intended service or make some changes and try again. The only real difference between what I was analyzing (nuclear power plant piping and related components) and brake rotors here is what the parts look like.

Even a nicely contoured cast hole introduces some amount of stress intensification, and there's no guarantee that plain rotors as cast can't have stress intensifications of a different nature. One of the reasons why - as crude as it is - we have the 'fingernail test'.


Norm

 

[Norm Peterson]

My guess for why the GT350 gets 4-piston rear calipers has more to do with uniformity of pad to rotor contact pressures.

I'll humbly disagree. These heavy cars want a ton more rear brake. There's a reason the GT350's have a 4 piston caliper in the rear. Mine are 6 piston on all 4 corners including the rears for aesthetics, however the rear piston diameters are greatly reduced to get the correct bias. When you grab a bunch of brake in my car, it feels like it squats instead of a slight nose over. The confidence and ability to stop without effort is amazing and in my opinion much more impressive than big power. The factory PP1 calipers and stock rears on my car performed nothing like the Baer system. Also keep in mind I'm running their least aggressive pads to keep the dust and noise at an OEM level. I know they are crazy expensive, but the result is crazy amazing.

The harder you brake, the LESS rear brake you want. Obviously you want enough total braking potential for the car, but beefing up the rear braking alone in an attempt to bring total brake capacity up is the wrong approach unless rear braking really is way out of whack.

In today's world, it's easier to believe that there might be a little too much rear braking given that rear brakes are also responsible for such things as traction control, hill start assist, and stability control. Easy enough to let the ABS sort it all out even though it means that on the way up to ABS intervention the rear wheels are being overbraked.

Overbraking the rear wheels could well be what's giving you that feeling of 'squatting' as opposed to nose-diving. Just that even though you're braking a good bit harder than what street driving normally requires, you're not yet into the ABS or particularly close to the car's ultimate braking capability with however much brake you're grabbing.


Norm

 

[Norm Peterson]

I think its very very unlikely for 99% of people to crack any rotor and I think that means that there is a benefit for 99% of people having drilled and slotted rotors, aka lower rotating mass, better offgassing capabilities, and in most peoples opinion better looks, especially if they only street drive or dragstrip.

I know what you're getting at, though I'd be a bit careful about recommending drilled rotors for those who live in mountainous areas. Or use their car for early-morning newspaper delivery (an incredibly hard use as far as brakes are concerned).

That 99% - I'm willing to stipulate to your number at least for the purposes of this thread - isn't going to be particularly concerned with offgassing (far less of an issue these days than it was in the 1960's), and the minimal amount of mass removed has only a negligible effect on either rotating or unsprung mass that they're never, ever going to notice. At best these days, drilled might help a little when you're driving in a heavy rain.

The only reason people go for drilled rotors these days is appearance, and that's mainly for its connection with what racers used to do (with these snazzy drilled rotors my car looks more like a race car now). This has reached the point where aftermarket brake rotor suppliers expect everybody to prefer drilled rotors (been there; the guy on the other end of the phone call had trouble believing that anybody would actively prefer plain rotors . . . true story).


Norm

 

[Ewheels]

I'll humbly disagree. These heavy cars want a ton more rear brake. There's a reason the GT350's have a 4 piston caliper in the rear. Mine are 6 piston on all 4 corners including the rears for aesthetics, however the rear piston diameters are greatly reduced to get the correct bias. When you grab a bunch of brake in my car, it feels like it squats instead of a slight nose over. The confidence and ability to stop without effort is amazing and in my opinion much more impressive than big power. The factory PP1 calipers and stock rears on my car performed nothing like the Baer system. Also keep in mind I'm running their least aggressive pads to keep the dust and noise at an OEM level. I know they are crazy expensive, but the result is crazy amazing.

You're only supporting my point. You're telling me you did the caliper upgrade for aesthetic reasons, not for performance. Which is fine, but don't try to convince people your aesthetic upgrade was for performance reasons.

You said your car feels like it squats now under braking. That is not exactly ideal when an already front-heavy car brakes and all the weight transfers to the front of the car. You want more braking in the front. Adding more brake in the rear gets you a diminishing effect.

"Least aggressive pads" for "an OEM" feel. This further tells me performance is not your priority. Street driving will never push the limits of any system of the car. Saying these brakes feel amazing while driving on the street quite literally means nothing.

 

[Chris Barnes]

Not for OEM feel, but to keep dust and noise down as this is primarily a street driven car. I really have never claimed this car is a max effort road race car, just a fun car that does everything fairly well. No need to get so freaking argumentative, I was simply sharing MY experience on this car as well as others I've had this same brake system on. Good luck Sir.

 

[Radiation Joe]

I don't have a horse in this race.
I'd just like to point out that people on this forum seem to argue points that are, for the vast majority of conditions, completely esoteric.
Are cross-drilled rotors more susceptible to cracking? ... Yes, They are. Will it affect the durability of even some track rat 3 weekend a month HPDE car? Probably not. I personally prefer the lighter, better cooled cross drilled rotors, but won't use them because I don't like the sound they make on the street. On the track they are just another consumable item. Replace when cracking begins to bother you. By the way, BMW and Audi both put cross drilled rotors on factory high performance street cars.
And I might as well chime in on the cult of caliper piston counters. The best braking car I have ever owned had single piston calipers on all four corners. Could I have improved the brake feel slightly with $7000 worth of PFC brake components? ... Yes. If I had the money to burn on $7000 worth of PFC brakes, I would have done it.
And that's another point to be made. If someone has the resources to spend money on parts that make them happy, then let them do it. Don't put them down because you wouldn't justify their decision for your situation.

I'll take my soapbox home now.

 

[Andy13186]

I don't have a horse in this race.
I'd just like to point out that people on this forum seem to argue points that are, for the vast majority of conditions, completely esoteric.
Are cross-drilled rotors more susceptible to cracking? ... Yes, They are. Will it affect the durability of even some track rat 3 weekend a month HPDE car? Probably not. I personally prefer the lighter, better cooled cross drilled rotors, but won't use them because I don't like the sound they make on the street. On the track they are just another consumable item. Replace when cracking begins to bother you. By the way, BMW and Audi both put cross drilled rotors on factory high performance street cars.
And I might as well chime in on the cult of caliper piston counters. The best braking car I have ever owned had single piston calipers on all four corners. Could I have improved the brake feel slightly with $7000 worth of PFC brake components? ... Yes. If I had the money to burn on $7000 worth of PFC brakes, I would have done it.
And that's another point to be made. If someone has the resources to spend money on parts that make them happy, then let them do it. Don't put them down because you wouldn't justify their decision for your situation.

I'll take my soapbox home now.

Personally I love the hum-down sound of cross drilled and slotted rotors. Unless I get pad squeak which I dont think is related the the drilled holes.

 

[luc]

Just searching cracked rotors I found more cracked slotted rotors and plain which I posted, yes there are some drilled ones too. I think its very very unlikely for 99% of people to crack any rotor and I think that means that there is a benefit for 99% of people having drilled and slotted rotors, aka lower rotating mass, better offgassing capabilities, and in most peoples opinion better looks, especially if they only street drive or dragstrip.

Yes, for all the drivers that don’t track their car, those 99%, cross drilled rotors are a non issue
By the same token, those 99% don’t need to “improve” their brakes since they don’t track their car
...form over function....

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