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I just got back from Race Technik in Tempe, Factory alignment was:
BEFORE
1.5 Negative Front
0 Toe Front
10' Positive Caster
1.5 Negative Rear
3mm Total Toe In
AFTER:
We decided to leave everything the same, except increased front camber just slightly to Negative 1.8. After this weekends, event, I'll check tire wear and see if it needs more, but for 80% street and maybe 20% track... I didn't want the car to not be as enjoyable around town.
After my first event, I believe the 1.8 negative in the front is more than enough, no tire roll over whatsoever and tire rare was great. However... 1.5 was not enough in the back (IMO) and I'll be looking to bring that to match the front, or possibly even 2.0.
I'll have them measure ride height/rake numbers when I bring it back in.
Thanks for the update, what pressures were you running? Your track looks pretty flat, at our regional tracks like Barber, Pitt-race, Putnam, Mid-O, NCM, etc.....we need a significant amount of camber to avoid destroying tires.
Always interesting to see how setup varies between tracks.
After my first event, I believe the 1.8 negative in the front is more than enough, no tire roll over whatsoever and tire rare was great. However... 1.5 was not enough in the back (IMO) and I'll be looking to bring that to match the front, or possibly even 2.0.
I'll have them measure ride height/rake numbers when I bring it back in.
Best Regards,
Dave
Thanks for the report. Are you on cup2?
At least on the .1, the outer rear edges on the cup2 tires (only the cup 2 tires) always wear. I wouldn't chase that too far (I tried and failed). What will happen is that the front tires will be gone and done before the rear tires anyway. The only question is if the new n1 tires have more usable heat cycles than the n0 and if you can keep running the rear tires and just swap out they'll fronts without a big drop in Performance. It was painful throwing out good looking rear tires in the .1 n0 tires.
What hot pressures were you running? I also think that I used to run pressures that were too low, so that might have contributed.
Thanks for the report. Are you on cup2?
At least on the .1, the outer rear edges on the cup2 tires (only the cup 2 tires) always wear. I wouldn't chase that too far (I tried and failed). What will happen is that the front tires will be gone and done before the rear tires anyway. The only question is if the new n1 tires have more usable heat cycles than the n0 and if you can keep running the rear tires and just swap out they'll fronts without a big drop in Performance. It was painful throwing out good looking rear tires in the .1 n0 tires.
What hot pressures were you running? I also think that I used to run pressures that were too low, so that might have contributed.
Do you think the problem on the outside wear on the fronts on the 991 GT3 was due to the same issue as the GT4 (front springs being way too soft)? I found that going to the stiffer Swift spring package really helped with the outside wear on my front tires.
Anyone know what the front and rear spring rates are for the .2GT3?
Thanks for the update, what pressures were you running? Your track looks pretty flat, at our regional tracks like Barber, Pitt-race, Putnam, Mid-O, NCM, etc.....we need a significant amount of camber to avoid destroying tires.
Always interesting to see how setup varies between tracks.
Originally Posted by orthojoe
Thanks for the report. Are you on cup2?
At least on the .1, the outer rear edges on the cup2 tires (only the cup 2 tires) always wear. I wouldn't chase that too far (I tried and failed). What will happen is that the front tires will be gone and done before the rear tires anyway. The only question is if the new n1 tires have more usable heat cycles than the n0 and if you can keep running the rear tires and just swap out they'll fronts without a big drop in Performance. It was painful throwing out good looking rear tires in the .1 n0 tires.
What hot pressures were you running? I also think that I used to run pressures that were too low, so that might have contributed.
Mvez/Joe, I kept dropping pressures as the day went on. I started at approximately 29psi front, 31 psi rear... but was seeing the car get to 38psi front (HOT) and 42 psi rear (HOT). So on the last session of the day, where I was only able to get in 2 laps, I had adjusted the pressures to go 36psi Hot front, and 38psi Hot Rear.
I'll take pics of the tires when I get back home, but the wear was extremely mild, and flat across the tire. I was impressed, compared to many of the images I'd seen posted before.
Joe, I was on the Factory Cup 2's... with about 300 street miles on them.
The front grip/ tire wear / wear pattern I couldn't be happier with. It was the rear, and not necessarily the 'outside tread wear' per say, it was the 'rolling over' of the sidewalls (and I definitely had plenty of air ) so I'm thinking it's just not enough camber.in the back.
just wonder if going from 1.5 to 1.8 will be enough or if I should just go to 2.0? My concern with going with 'too much' rear camber, is losing the straight line acceleration, as it was wanting to spin the tires on corner exit already with just 1.5 negative.
Do you think the problem on the outside wear on the fronts on the 991 GT3 was due to the same issue as the GT4 (front springs being way too soft)? I found that going to the stiffer Swift spring package really helped with the outside wear on my front tires.
Anyone know what the front and rear spring rates are for the .2GT3?
I actually tried running stiffer front springs on the .1 GT3. The tire wear was pretty even, but unfortunately, it didn't result in any more tire life...
Originally Posted by SCCAForums
Mvez/Joe, I kept dropping pressures as the day went on. I started at approximately 29psi front, 31 psi rear... but was seeing the car get to 38psi front (HOT) and 42 psi rear (HOT). So on the last session of the day, where I was only able to get in 2 laps, I had adjusted the pressures to go 36psi Hot front, and 38psi Hot Rear.
I'll take pics of the tires when I get back home, but the wear was extremely mild, and flat across the tire. I was impressed, compared to many of the images I'd seen posted before.
Joe, I was on the Factory Cup 2's... with about 300 street miles on them.
The front grip/ tire wear / wear pattern I couldn't be happier with. It was the rear, and not necessarily the 'outside tread wear' per say, it was the 'rolling over' of the sidewalls (and I definitely had plenty of air ) so I'm thinking it's just not enough camber.in the back.
just wonder if going from 1.5 to 1.8 will be enough or if I should just go to 2.0? My concern with going with 'too much' rear camber, is losing the straight line acceleration, as it was wanting to spin the tires on corner exit already with just 1.5 negative.
Best Regards,
Dave
Dave, I don't think even going to -2.0 will solve the issue. I ran -2.4 on my .1 and the outer edges on the cup 2 would still wear quickly while the rest of the tire still looked almost new. I did discover that it was only a problem with the cup2. When I ran dunlops, trofeoR, and RE71R, I would not get the same outer edge wear like I saw with the cup2.
Dave, I don't think even going to -2.0 will solve the issue. I ran -2.4 on my .1 and the outer edges on the cup 2 would still wear quickly while the rest of the tire still looked almost new. I did discover that it was only a problem with the cup2. When I ran dunlops, trofeoR, and RE71R, I would not get the same outer edge wear like I saw with the cup2.
Gotcha, thanks. I need to show you some pics... I'm not sure I 'wore' unevenly... it's more the car was 'rolling over' the sidewall, even at 40PSI hot rear?
Gotcha, thanks. I need to show you some pics... I'm not sure I 'wore' unevenly... it's more the car was 'rolling over' the sidewall, even at 40PSI hot rear?
Best Regards,
Dave
yeah post some pics and i'll see if it looks similar
yeah post some pics and i'll see if it looks similar
Joe, here's all 4 tires, side view and top view. I'm going to auto-x the car tomorrow... so we'll see how that goes. I've added a hair more negative camber to the rear,, now running 1.8 negative on all 4 corners.
Have a look at the front and rear, they look pretty good to me, but appreciate your thoughts. The rears were rolling over (as you can see) even up at 40psi Hot. I checked the pressures cold... and I'm running 27/29... do you think that's about right? Or should I add/subtract any? I've put white chalk on all 4 for tomorrow's event... to get a bit more data.
They are not rolling over, that’s just how the MPSC2 are built, no?
More camber makes the car slower and your tires won’t last much longer because the outside edge will chunk and cord no matter what you do.
Never got 5 days out of them, but they slow down after 12 sessions anyway.
The best solution I found is different tires if you want to make them last longer.
after 18 sets of MPSC2 I switched to Hoosier R7.
For grip, anything over 32PSI hot is too high.
I’m aiming for 28F and 29R for maximum Laptime.
this takes hard braking and careful warming up the tires while staying of the curbs because you have to start very low.
In humid Florida tires go up a lot, so last week with morning temps almost freezing we had to go out around 18-20 PSI.
This forum is all fu@ked up, no idea why pictures is so large and on top of this Post but those were Sebring cold start temps.
01-15-2018, 05:52 PM
) so I'm thinking it's just not enough camber.in the back. 
