More aggressive in the rear. 11 is more aggressive..

 

Thx John,

so the stock ABS of the 6TT needs more clamp force on the rear with the 997 PCCB Gt2/3 brake calipers?
I dont understand this. The 997 bias is totally different to the strock bias and even though the rear must brake more?
Wouldnt it be better to use the non PCCB Version of the 380 mm Calipers, which do not swop the bias as much to the rear like the PCCB version?

Right now i do run the stock 6TT 4 piston caliper with 350mm at the front and the 997 GT3 MKII at the rear. Can i use the same pad front and rear?

Phew...lots of ????

 

The street ABS has very low lock up threshold. Even with the larger rear 997TT/GT2/3 calipers it helps to use a more aggressive pad as it increases straight line braking and I found it to help with initiating rotation under hard trail braking. I always ran PFC 8F/11R with R compound tires with the OEM ABS using 997GT3 front calipers (with the smaller pistons) and the larger 997GT3 rear calipers. I can not speak for how the balance would be with street tires but I would imagine the same.

When I switched to a Motorsport ABS, I had to reduce the friction of the rear pads as the car had a profoundly increased tendency to oversteer when trail braking aggressively. This was due to the much higher lockup threshold and slip angles allowed by the Motorport ABS. Under the same conditions, the street ABS has already reduced rear brake pressure significantly.

Long story short, with the OEM ABS, even with the larger rear calipers, I found a more aggressive rear pad to be beneficial. Hope that makes sense..

 

 

Guys just some updates, I have ended up using Pirelli slicks as follows

285/645/18 on 10"rims fronts in medium compound
325/660/18 on 13"rims rears in hard compound (13" are a bit too wide for 325s)

Car runs really great, fast as hell and turns like a race car, front track is like +9cm or so and +16cm in the rear, total is 203cm or so, thats very wide like AMG GT-R wide, idk if you have seen the youtube video of shmee150 comparing the 991.2gt3 with amg gtr and the amg was like a lot wider.
Speed wise car lost at the same boost like 5mph on the main straight due the huge wing in the back, maybe canards, wider body, tires etc

As Geometry I am running only -1.8 Camber in the back and grips like HELL, more Camber made me loose a lot of grip in the straights, other that this low value of rear camber, I am running "regular" settings for a track oriented car

I was able to improve my record on the local track using lowest boost (0.9bar) by 0.7seconds driving still in the comfort zone, not pushing too much, with higher boost and more aggressive driving I am sure will come some even better times maybe 4-5 seconds or so, had so little time to get out and drive her and this doesn't make me happy at all. Car is really fun but already maybe a bit too much track oriented for me as having straight pipes and race braces etc, I am considering even moving to a 991 TTS with light mods as might be a better choice for me now, my life changed a bit as having 2 kids and not so much time to spend, by the other hand car is so beautiful, exciting experience to drive each time, maybe even a keeper for lifetime, I have spent so many hours and put so much emotion into this car, what should I do?! I have sold my E36 race car and posted the GT-R also for sale... The cars I might consider are : 991.2 TTS or 720S. Can these be a replacement for me, or I will really miss my wide 996 and 1200hp GTR ?

Anybody moved from a track oriented 996tt to 991 TTS or 720S? Seems all new cars are considered a bit too boring, on the other hand still not very tempted to try 991 gt3/rs idk why

 

Fadi- I’ve had a few 6TTs, Radical, GT3, GT350R and recently picked up a gorgeous and sorted 997.2TT with every option. I out a few track bits into it, but will keep it a very nice dual duty car. I have not driven the 991TTS and hear they are even better/faster than the 7.2s. Maybe keep the 6tt and luck up a. Ice 7.2TT(S) and have best of both worlds?

 

Huh..yeah... I might keep it and sell only the GTR, 991.2 TTS with some mods, guess will follow 99%. Btw I have considered at some point the RS3RS or even the v8 Radical after I have been in the right seat with one of the guys from official Radical Test Team or so (former) and actual Porsche driving school, car was just impressive for me, still to dedicated track car and afraid going to use it just 2-3times/year maybe

 

I can tell, that the 380mm + 7Gt3 mk2 PCCB Calipers wont fit under OZ alleggeritas in 18" wheel. Guess i will stick to the little 6 pots...and 350mm.

 

I have a VERY tight fit with same exact calipers on my 18" rims

 

 

In search of more brake bite, i guess i go for giro discs all around in 350mm and 6gt3 6-pots and 7gt3mk2 4-pots in the rear, which i already have.

Guess i need a better pad with more initial bite. pfc 01 and 08 is best with giro discs?

 

That's what I am using as pwdrhound recommended
Comparing oem 996tt calipers on 4x350mm Giros with 996tt pump and Carbotech XP20 with the new setup 7gt3mk2 all four on 380+350 giros and pfc 01/08 the difference is night and day.

It is true that car has way better aero and bit lighter over the winter, I have been at hungaroring last week and was overbraking all the time in the straight line, really perfect brake setup for me, even without 997 pumps.

Just as a comparo, on low boost 1.1-1.2bar or so I could keep up with the new 991.2 gt3 (really quick for N/A in the main straight), I was on slicks and those on Cup2s, could easily brake better then the Gt3s, way better..

 

I have switched to a Li-Ion battery design some Aeromotive application, using 2/3 tank and 5Liters of meth in tank car weighted 1434kg - 3161 lbs

Guess will remove some more weight as having FIA fire fighting system installed, two seats, full interior, maybe even the cage.. and will try to get my record lap, hope to be as close as possible to a CUP car level, let's see

Might also switch from Pirelli 285DM/325DH slicks to Yoko 250/320, just testing which is better perfoming, Yoko rear runs wider and might fit better 13" wheels

 

Hi Fadi,


thx for the info and your experience. I will go the Girodisc way cause the tight fit of the 380mm scares me and the loss of significant weight thrills me. :-) I will lose lots of unsprung mass when switching from 350mm factory to giros. For sure 1,5 kg up to 2 kg or even more per disc. So 6 kg or 8 kg reduced unsprung mass is equivalent to 42 kg or 56 kg car weight (1kg unsprung mass = 7 kg weight). That is insane.

Thats hugh. The handling of the car will get better.

 

I did read some old posts and i changed my mind.

First i wont get the giros or brembo discs legalized over here. Second, the 6GT3 caliper wont change the braking force, since my front 4 pot calipers already working with 350mm discs and 3rd my mech told me to move on to the 380mm.

So i bought the adapters and i will buy the PCCB calipers. Since the 991 TT steal rotors fit plug&play there shouldnt be a problem to get this legalized.