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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.
Yup, those rear tires look exactly what my cup2 looked like on my .1 even with -2.4 camber. It's the way the cup2 wear. I remember a while back someone from europe was running -3.5 in the rear, but that seems crazy to me.
If you switch to a different brand of tire it won't wear like that. I'm betting -1.8 won't change the wear pattern, but confirm and let us know.
Originally Posted by TRAKCAR
My 0.02c
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.
Agree with you. It's cup2 thing.
Also agree that messing with the camber too much doesn't help and might be detrimental. It definitely doesn't make the car faster as most people would think
You're getting more usable life out of R7 over the cup2?? The one time I tried R7 on the GT4 they were only good for 2 days.
Yes, amazingly enough it looks like I will get 4 hard days out of the R7.
They lose their crazy glue after 6 sessions but we got the temps very even across the tire and wear is very even.
More testing Tuesday and Wednesday.
Wesnesday is my 4th day.
After Wednesday I hope to have my permanent setup
We’re close already!
Yes, amazingly enough it looks like I will get 4 hard days out of the R7.
They lose their crazy glue after 6 sessions but we got the temps very even across the tire and wear is very even.
More testing Tuesday and Wednesday.
Wesnesday is my 4th day.
After Wednesday I hope to have my permanent setup
We’re close already!
The tread will last, but doesn't the grip fall off hard after 2 days? I was a couple seconds slower than cup2 and Re71r after the 3rd day
They never fell off to fresh MPSC2 pace.
Im only on my second set but will be doing proper data testing, so stand by another week and I’ll be able to confirm.
They never fell off to fresh MPSC2 pace.
Im only on my second set but will be doing proper data testing, so stand by another week and Ill be able to confirm.
Man, I must have done something wrong with my set.... You'll have to tell me what your method once you get it all figured out
Ok, I was able to test out the 1.8 Negative Square setup... and have to say I'm SUPER impressed... ran 4 sessions during today's 'auto-x' event... for a total of 20 or so laps. The tires definitely seem to 'come in' after lap 1... and probably start to fall off a bit by lap 4. I can see why Porsche put a new set on for each attempt at the Ring!
I ran the morning session with just ESC off... TC on. And then I ran the afternoon sessions with everything off... which was fun... but frankly not any faster.
I also was able to get the Porsche Precision Track app to work, which was neat to see it work so well. I've posted a video below... of about 3 consecutive laps. As well as tire photos (which are large) to get your feedback after two 'full days' worth of track time. So you could call the images, comparable to 'one complete weekend'. Notice, it has whether the car is oversteering or understeering, as well as wheel spin/slip.
I ended up starting the morning at 27 front 29 rear... and just left them there. I used 'chalk' on the sidewalls... and the fronts are spot on... the rears... are just slightly going over... but Joe to your point... I don't think I'm going to chase that... it's ever so slightly over and wearing so evenly, but I'd like your feedback after seeing the tire pics below.
^^^^^ See?!?!? SCCAFORUMS...is more proof what I’ve been saying that the 991 cars especially on MPSC2 tires don’t not want massive camber and low tire pressures. 991 cars are different than past 911 Porsche’s.
I just got back from COTA this weekend in my car. The car performed well. I was running consistent 2:26's and a PB of a 2:25.
Tire wear was very good. However - I am running a more aggressive setup than what others are noting.
I noticed more roll on entry than the .1 car had for sure. The front likes to really dig in and set fast. I am running both bars neutral. For COTA - I think it would be faster to run a stiffer front bar and run middle or even soft bar rear. This would allow the car to go deeper into the brake zones and trail brake more, then allow the rear tires to put the power down sooner. I am headed back in April so we'll see if that proves true.
I'd almost say the car feels like it has a softer spring rate up front than the .1 car did. That would lend to a bigger front bite with slow movements and allowing the car to set. This could be why it's turning in so much better.
Ok, I was able to test out the 1.8 Negative Square setup... and have to say I'm SUPER impressed... ran 4 sessions during today's 'auto-x' event... for a total of 20 or so laps. The tires definitely seem to 'come in' after lap 1... and probably start to fall off a bit by lap 4. I can see why Porsche put a new set on for each attempt at the Ring!
I ran the morning session with just ESC off... TC on. And then I ran the afternoon sessions with everything off... which was fun... but frankly not any faster.
I also was able to get the Porsche Precision Track app to work, which was neat to see it work so well. I've posted a video below... of about 3 consecutive laps. As well as tire photos (which are large) to get your feedback after two 'full days' worth of track time. So you could call the images, comparable to 'one complete weekend'. Notice, it has whether the car is oversteering or understeering, as well as wheel spin/slip.
I ended up starting the morning at 27 front 29 rear... and just left them there. I used 'chalk' on the sidewalls... and the fronts are spot on... the rears... are just slightly going over... but Joe to your point... I don't think I'm going to chase that... it's ever so slightly over and wearing so evenly, but I'd like your feedback after seeing the tire pics below.
Hey Dave, sorry for the delayed response. Been busy and forgot to respond!
It looks like a square camber setup (even front and rear) is what the factory wants and works well with the car
That rear tire wear on the outer edge is exactly how it wore on my .1 even with -2.4 camber. I agree I wouldn't chase it any further. It's a cup2 thing. If you ever try a different brand tire it will wear evenly.
Originally Posted by mdrums
^^^^^ See?!?!? SCCAFORUMS...is more proof what Ive been saying that the 991 cars especially on MPSC2 tires dont not want massive camber and low tire pressures. 991 cars are different than past 911 Porsches.
Yeah, it's a hard thing for many people to believe, I used to be one of them, but I agree with you.
I just got back from COTA this weekend in my car. The car performed well. I was running consistent 2:26's and a PB of a 2:25.
I noticed more roll on entry than the .1 car had for sure. The front likes to really dig in and set fast. I am running both bars neutral. For COTA - I think it would be faster to run a stiffer front bar and run middle or even soft bar rear. This would allow the car to go deeper into the brake zones and trail brake more, then allow the rear tires to put the power down sooner. I am headed back in April so we'll see if that proves true.
Love the .2 so far.
- Chris.
I couldn't agree more... I had told myself after my first event... it seemed like the car could use less rear bar (increase rear bite) and more front bar (again to help tighten up the rear). I didn't want to make too many changes at once, so stuck with the minor adjustment to camber. Based on how much I saw the 'rear' rolling over (body roll)... I would be more inclined to just stiffen the front bar first. But I could see the car liking both adjusted, to your point... stiff front, soft rear.
Originally Posted by orthojoe
Hey Dave, sorry for the delayed response. Been busy and forgot to respond!
It looks like a square camber setup (even front and rear) is what the factory wants and works well with the car
That rear tire wear on the outer edge is exactly how it wore on my .1 even with -2.4 camber. I agree I wouldn't chase it any further. It's a cup2 thing. If you ever try a different brand tire it will wear evenly..
Thanks Joe, no worries. Yes, agreed... I'm going to leave it at 1.8 square, 'if' I were to chase the rear... I could see it possibly liking 2.0 negative. But the front at 1.8 is clearly more than enough based on the chalk markings.
Originally Posted by R.Deacon
Sccaforums
When u r using the P Precession track app is the video recorded via
The phone?
Yes, it syncs via your cars wifi to your phone, and uses the phone's camera to record the image. You can also do all sorts of data analysis as well. I will typically quickly reference what max speed achieved was for the fastest laps, G's, max rpms in gears etc...
I purchased an 'AmazonBasics Windshield Smartphone Mount' for $15, and it seems to work just fine.
I just got back from COTA this weekend in my car. The car performed well. I was running consistent 2:26's and a PB of a 2:25.
Tire wear was very good. However - I am running a more aggressive setup than what others are noting.
I noticed more roll on entry than the .1 car had for sure. The front likes to really dig in and set fast. I am running both bars neutral. For COTA - I think it would be faster to run a stiffer front bar and run middle or even soft bar rear. This would allow the car to go deeper into the brake zones and trail brake more, then allow the rear tires to put the power down sooner. I am headed back in April so we'll see if that proves true.
I'd almost say the car feels like it has a softer spring rate up front than the .1 car did. That would lend to a bigger front bite with slow movements and allowing the car to set. This could be why it's turning in so much better.
Love the .2 so far.
- Chris.
Hi, Chris. Could you define your "more aggressive" setup? Thanks!
Hi, Chris. Could you define your "more aggressive" setup? Thanks!
Tire wear after a day at COTA looks very even. I did not bring my pyrometer so I have no data points to show what temps looked like across the tire. The settings felt very controllable at speed.
Again, I would have been faster had I made a bar change with the car, increasing on the front and potentially softening the rear. I went back to my data and ran a 2:22 during the happy hour. I also had a predictive lap on that session of a 2:18. I think with a bar change I could get under 2:20 with my car which would be a milestone for me at COTA.
Man, I must have done something wrong with my set.... You'll have to tell me what your method once you get it all figured out
Apologies if someone else mentioned this already.
I run R7's on my race car. They are very temperamental compared to most others that I've used, don't know why. Try running them at a little higher pressure than you would on most tires and be easy on the initial heat cycle. I wore a s front left out in 4 heat cycles and then blew up another one after 2 heat cycles. Back to pressures, I will typically run a Pirelli slick at 32 hot and the same size R7 I will run at 34-36.
01-26-2018, 11:45 PM
