krisa9977

Yes, you are thinking correctly.

skippyBKR

Yes - it was my first track day with the car, so I was keeping it simple with all 4 wheels the same pressure. I found the car "squirmed" around too much with the lower pressures.
But happy to take ideas on a stagger F v R.
I'm doing a back to back tyre test in 2 weeks Dunlop v's Michelin (all new tyres with 2 sets of same rims). I'll start a new thread with results if anyone is interested in the results - I've probabably polluted Orthojoe's thread enough here, sorry!

MaxLTV

So you got me confused now - you are suggesting increasing rear camber AND softening rear bar. Or did you mean softening front bar?

Mech33

So many conflicting recommendations!! -2.7F/-2.4R, or -3F/-3R, or -3F/-3.6R... ugh

krisa9977

Yes, I'm suggesting increasing rear camber AND softening rear bar. On my 997GT3 I had rear bar in hard or medium position with more front camber then rear . 991GT3 is totally diffident because of rear active steering. You can setup 997GT3 to be neutral throughout entire corner, but I was not able to do the same with 991. It can be neutral on corner entry, but oversteer at mid corner or undesteer at entry and neutral at mid corner. I found that second choice is better, because you can be on throttle sooner with faster exit speed.

But you need to understand, that alignment settings is very individual for each track, driver and driver style. If those settings work for me it doesn't mean that they will work for you!

Ducati1199

I'm no expert on car tires but certainly for bike tires at track conditions you'd always run the front lower than the rear. Manual also states not to exceed f/r pressures by more than 7.1 (or 7.3 psi can't remember off hand) with door sticker pressures of 29/33 psi (I have dunlops too). I'm not saying it's right or wrong but you would have been close to manuals stated max pressure on front tires.
I ran a track day with Joe last Friday and was running 31/35 hot. He took the car out and said it felt fine on stock set up - that was good enough for me!! Ambient air temps in the 90-95F range in the afternoon.

orthojoe

Let us all know what you think of this setup, Peter!

I had the opportunity to drive MPSC2, Dunlop sport maxx race, and TrofeoR on 991 GT3s this weekend. Here are my thoughts:

1) MPSC2 and Dunlops are very similar, IMO. I'm looking forward to mounting a set of dunlops on my GT3 next. Dunlops require 2-3 psi higher pressures than MPSC2.
2) TrofeoR seem to handle hot weather better than MPSC2. In cool weather, they grip equally. In hot weather, the TrofeoR maintain grip better
3) MPSC2 'talk' to you more than TrofeoR and break away more progressively. To me, I get more confidence that way and prefer the MPSC2 characteristics over the TrofeoR
4) The low running pressures for TrofeoR turn into a pain for track days. You start off with pressures as low as 22psi cold. This means you need run quite a few laps until pressures rise a bit higher before pushing it because those starting pressures are too low. With MPSC2, you just do one warmup lap and you're good to go.
5) maxLTV has mentioned this before, but the sidewalls of the MPSC2 are apparently weak. I found this out myself this past weekend after I hit a tall berm and blew out the sidewall. Another GT3 owner has told me the same thing has happened to him as well after dropping a wheel off.





This is what my tire wear looks like after 250 miles at thunderhill (roughly 2 track days). Obviously not even wear, but I like how the car feels at this point. Although, my hunch is that it's because of the tires and not the alignment.

Rear tires have less wear than the front with MPSC2. It's the opposite with TrofeoR


Front tire has outer edge wear still with -2.7 camber

TRAKCAR

So far so good, after today and tomorrow at Spa I will take another close look at tire wear.

Mech33

Hey Joe, you ever have the end links of the sway bar get loose on you after adjusting to a different slot? I moved mine to full stiff in the front before the last event and on the drive home it was rattling around. I had it torqued down pretty well, too...

It looks like there is some sort of thick paint coating on all of the bar and holes except for the OEM center hole, so when you move the bar to the stiff setting, the nut crimps down on some thick paint that can work its way loose again over time...

Did you guys clear the paint off of the bar when adjusting?

MaxLTV

Interesting. I had 2 days on my last set (Thunderhill and Sonoma, both rather hot days), and my fronts look better (-2.8 camber) - more even wear and in general more tread left, but my rears look a bit worse and are close to the wear bars. I was lighting up rear in some places in Sonoma though. So now my fronts and rears seem to wear at the similar rate, but different pattern.

It's funny that most of us had our PBs back in winter/spring. I do not think it's just the heat.

orthojoe

Yes, this has happened to us as well. We re-torqued it a second time and now it is solid and didn't loosen after the last track day. Make sure you are using that Torx socket to stop to bolt from spinning when you tighten down.

I think wear pattern can also vary depending on which track. Thill seems to really kill the outer edges. Maybe it's those long, high speed sweepers or maybe I just drive faster at thill.

If it's not the heat, what do you think it is? Maybe the winter rain cleans up the track and the surface grips more during the early part of the year?

MaxLTV

I think it's probably dust/oil film on the track surface. I've read a rumor about change in MPSC2 compound, but I strongly doubt that it's true. And you and some others had slower times on other tires. Looking forward to some rain, just not during a track day.

mikymu

wow, that's a really blunt berm. I doubt any tire will survive that hit. I will pass along the pic to Thunderhill CEO and see if they can do anything about it

orthojoe

Another update:

1) I replaced both front tires with a new pair of MSPC2 after I blew the one tire. Took the car to Laguna seca on Saturday. The rears have 3 days on them at this point and look like they only have one more day to give.

2) Love the cup2 tires. I managed a faster lap time with the cup2 over the TrofeoR at Laguna Saturday with the confidence the tires gave me

3) Installed the rear AP rotors. It might just in my head, but the car seems more stable under braking. The ferodo DS1.11 pad really do require less pedal effort than I'm used to giving. It's taken me several track days to get used to not slamming so hard on the brakes and engaging abs all of the time.



4) I don't think I'm going to mess with my alignment/setup anymore. Very happy with how the car behaves. I let a pro take the car out for several laps and he agreed that the setup was perfect. Just a touch of understeer, but manageable with some throttle control, which is what I was aiming for and felt the car was doing as well. The pro racer told me he drove another 991GT3 recently that was totally unstable and way out of whack. I don't know what kind of settings that car had.

5) My best lap at Laguna Seca on Saturday was a 1:38.4. Theoretical best for the day was 1:37.5. Video below. For whatever reason, the microphone picked up the noise difference when the GPS switch closes and re-opens the exhaust valves much more clearly this time around. As I exit T6, you can hear the exhaust get louder again on it's own. I've never been blacked flagged once for sound at Laguna

Macca

Great update Joe. Just for sake of clarity given the length of the thread could you re iterate your current geo settings you are happy with?