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I'm still confused about why some of you guys are needing such large cambers. I have 1800 track miles on my car, of which the first 1200 were taking it somewhat easy and the last 600 have been driving the car reasonably hard. With -2.0 cambers and everything else stock and hot pressures around 30/31, the wear on SC2 is fairly even, the grip is still good, and the car feels fairly balanced. A local pro racer who has the car and has tracked it (and loves it) even suggested the leaving the cambers stock (-1.5).
Maybe adding substantial camber with this car generally throws things out of whack and counterintuitively results in worse tire wear and handling?
FWIW, given that it's a GT3, my approach with this car has been to keep it as stock as possible, making changes only to address obvious and significant problems as they come up.
Joe. I think thats the thing. Something has to give when you are going this fast with no other real compromises. For your the MPSC2 were giving four hard track days before the fronts were wearing through. For most others its been 6-8. But then Ive seen you drive and you are not watching the grass grow! I think you dialled in camber first to handle tyre wear, then changed tyre compound and now tire brand. But along the way you increased castor, then now back again using LCA inserts and washer.
I think perhaps its better to run -2.5 F+R camber/0.9.?? castor and live with the consequences. These IMO are simply 5 track days to a set of MPSC2 tyres. Also a new inner front guard liner and/or push the existing inside bracket back a bit so it doesn't rub through. This way you get your fast lap times, compliance, confidence and predictability. Lets face it the brakes and pads seem to last very well on this car and quite frankly I for one never thought Id get any more than 5 track days from a set of these Cup tyres - the fact they last so long has been a revelation to us all and we all went in budgeting on them lasting less time! Soon there will be Nitto and other brands supplying 20" alternatives for Dot Rated and we will have cheaper tyres to burn on the track that may be stickier and last as long or longer. If you are to experience with you set up perhaps look at removable rear Crawford aero with custom front lip (I already have an old spare you could have if I want so far away - Im sure it wouldnt be hard to graft some extension on this). Maybe some wider front and rear rubber.
Just some ideas.
Thanks, Macca. It's tough to nail down the culprit at this point. It will take a few tries to figure it out too since I can only test a new setup on track.
Originally Posted by Macca
Mech33. This is where Im at. We took it as far as we could (results below). The castor moved out as you would expect but so far it hasnt caused any significant wear on the liner after 5000 miles on these settings.
Some guys have been seeing 9.x caster straight from the factory. Perhaps caster is the culprit here. I'm set at 8.3 right now. Maybe add back in a degree? The car was 10.x of caster when the liner rubbed.
Originally Posted by Manifold
I'm still confused about why some of you guys are needing such large cambers. I have 1800 track miles on my car, of which the first 1200 were taking it somewhat easy and the last 600 have been driving the car reasonably hard. With -2.0 cambers and everything else stock and hot pressures around 30/31, the wear on SC2 is fairly even, the grip is still good, and the car feels fairly balanced. A local pro racer who has the car and has tracked it (and loves it) even suggested the leaving the cambers stock (-1.5).
Maybe adding substantial camber with this car generally throws things out of whack and counterintuitively results in worse tire wear and handling?
FWIW, given that it's a GT3, my approach with this car has been to keep it as stock as possible, making changes only to address obvious and significant problems as they come up.
Who knows what the real deal is. This is the problem with people trying to go off of other people's setups. What works for one guy won't necessarily work for another because there are so many variables. The intent was to keep the car as stock as possible and address problems as they come up. Our first setup was the best in terms of handling (-2.7/-2.4) Nspec MPSC2, but the 10 degrees of caster ended up rubbing a hole in the fender liner, which I felt was a problem that needed to be addressed...
There's a lot of mystery with setting up this car. Remember Randy Pobst saying that the car oversteered like mad? They softened the sway bars fully, which helped, but it still oversteered? On the other hand we have members here that find the car understeering like mad and have sway bar settings on full stiff....
There's a lot of mystery with setting up this car. Remember Randy Pobst saying that the car oversteered like mad? They softened the sway bars fully, which helped, but it still oversteered? On the other hand we have members here that find the car understeering like mad and have sway bar settings on full stiff....
Seems that nearly all journalists who've tracked the car - some of which are excellent drivers - have been happy with the car's behavior, and presumably the cars have had stock setup. Then add that my local pro racer suggests keeping it stock alignment, and the implicit recommendation from Porsche to keep it stock, and I'm thinking that stock should be the baseline, with tire wear issues being the only likely good reason to deviate.
Perhaps it's worth spending some time trying to adapt to the car, rather than adapting the car to the driver? I do sense that this car involves a bit of learning curve for most people (including drivers coming from prior gens of 911). For example, there are multiple ways to overcome understeer, and IMO part of the fun with any 911 is implementing them (though of course a car that understeers badly needs to be fixed, no reason to live with that). As far as tire wear, after prematurely destroying some expensive tires in the past, I've developed a better sense of when I can ask more of the tires vs when it's time to back off a bit, and of course 'overdriving' isn't generally faster even though it might seem like it.
Thanks Joe, any possibility to add picture in picture?
Harry's laptimer allows for that.
Not that I can see. You are stuck with just the camera view on the phone.
Originally Posted by Manifold
Seems that nearly all journalists who've tracked the car - some of which are excellent drivers - have been happy with the car's behavior, and presumably the cars have had stock setup. Then add that my local pro racer suggests keeping it stock alignment, and the implicit recommendation from Porsche to keep it stock, and I'm thinking that stock should be the baseline, with tire wear issues being the only likely good reason to deviate.
Perhaps it's worth spending some time trying to adapt to the car, rather than adapting the car to the driver? I do sense that this car involves a bit of learning curve for most people (including drivers coming from prior gens of 911). For example, there are multiple ways to overcome understeer, and IMO part of the fun with any 911 is implementing them (though of course a car that understeers badly needs to be fixed, no reason to live with that). As far as tire wear, after prematurely destroying some expensive tires in the past, I've developed a better sense of when I can ask more of the tires vs when it's time to back off a bit, and of course 'overdriving' isn't generally faster even though it might seem like it.
Nearly all except for one. Pobst. He clearly stated that the car was setup like a drift car. I don't 'think' that my latest laguna video looks like I'm over driving the car, maybe I'm wrong?
Actually, now that I think about it, I rode with my buddy's 991 GT3 running MPSC2 and the exact same alignment setup that I had prior to the caster bushing being installed and his rear end was definitely more planted than my setup. He was powering out of corners much harder in a way where if I tried the same thing, the back end would step out. Maybe it's the caster, but shouldn't pushing the wheels back rather than forward give you more understeer, which is what I want?
Forget it. I clearly don't have a clue when it comes to suspension setup. I'll talk with my shop and have him figure it out.
On my recent Nurburgring outing I quizzed the RSR guys about setup, wear, and " issues" with their 2 GT 3's. Their cars spend 90% percent of their time on the Ring or SPA. The one I drove had 33 k kilometers. The car felt and drove well with no issues and stuck like glue.
Re camber, factory.
Re break pads and rotors , factory. Obviously, they have been through several sets of pads and rotors.
No issues with CL's although their coating was well worn.
Tires, factory Michi's.
In essence they drive the car as Porsche set it up as they said Porsche essentially engineered the car on the Ring.
Other observations, front shocks wear quickly in a pure track environment.
Engine is oil level critical, as we all seem to be discovering. Some oil consumption is normal.
Joe - I am in the same camp as Manifold in wondering why some GT3 owners are running such large cambers. I'm running -2.2 front and -1.8 rear. Toe and castor are factory spec. Car feels planted, and tread wear is mostly even. This varies with the track. I'm a fairly aggressive driver, and can keep up with everything on the track except the well driven Cup cars.
Just another data point for all. I don't claim any expertise in setup matters.
Nearly all except for one. Pobst. He clearly stated that the car was setup like a drift car. I don't 'think' that my latest laguna video looks like I'm over driving the car, maybe I'm wrong?
Actually, now that I think about it, I rode with my buddy's 991 GT3 running MPSC2 and the exact same alignment setup that I had prior to the caster bushing being installed and his rear end was definitely more planted than my setup. He was powering out of corners much harder in a way where if I tried the same thing, the back end would step out. Maybe it's the caster, but shouldn't pushing the wheels back rather than forward give you more understeer, which is what I want?
Forget it. I clearly don't have a clue when it comes to suspension setup. I'll talk with my shop and have him figure it out.
In two cars that appear identical but are behaving quite differently, I'd look at things like:
- Are the tires really the same (eg, N0 spec vs K1)?
- Are the tire pressures and temps the same? As we know, tire pressure gauges can differ by as much as several psi?
- Is the alignment really the same? Good idea to cross-check with a different shop. I know of a shop that thought 1 deg 30' equal 1.3 degrees ...
- Something going on with PTV+ not working right?
My experience has also been that many shops - even those dealing with race cars - lack solid expertise with suspension setup, but may not want to admit that (even to themselves), so best to choose a shop very carefully. I've gone through many events trying to get my 997S dialed in after putting in new shocks and other suspension components, working with a generally reputable shop, and it's still not there ...
Joe - I am in the same camp as Manifold in wondering why some GT3 owners are running such large cambers. I'm running -2.2 front and -1.8 rear. Toe and castor are factory spec. Car feels planted, and tread wear is mostly even. This varies with the track. I'm a fairly aggressive driver, and can keep up with everything on the track except the well driven Cup cars.
Just another data point for all. I don't claim any expertise in setup matters.
I'm confused as well. If factory camber is -1.5, I'm really confused as to why the pros are supposedly saying to leave that alone. I don't know of any car that is being tracked hard that does well with minimal camber like -1.5. That really makes no sense to me. The factory gives you the ability to adjust camber aggressively for a reason, and AP highlights that ability when he was interviewed on the GT4. I'm fairly certain that if I decrease my negative camber, outer edge wear will get worse, not better. It might just be the track layout we have here in norcal. I was running -2.8/-2.4 on my boxster spyder with NT01 tires, and that car was setup perfectly.
In two cars that appear identical but are behaving quite differently, I'd look at things like:
- Are the tires really the same (eg, N0 spec vs K1)?
- Are the tire pressures and temps the same? As we know, tire pressure gauges can differ by as much as several psi?
- Is the alignment really the same? Good idea to cross-check with a different shop. I know of a shop that thought 1 deg 30' equal 1.3 degrees ...
- Something going on with PTV+ not working right?
My experience has also been that many shops - even those dealing with race cars - lack solid expertise with suspension setup, but may not want to admit that (even to themselves), so best to choose a shop very carefully. I've gone through many events trying to get my 997S dialed in after putting in new shocks and other suspension components, working with a generally reputable shop, and it's still not there ...
My buddy is on original OEM N spec MPSC2
Tire pressures are definitely a potential issue here. I haven't figured out what the ideal pressure setup is for the Trofeo R. Maybe someone who has experience with these tires can chime in.
My buddy had his car aligned at the same shop as mine.
One thing to should clarify: It's not like the car is currently way out of control. It's a subtle issue, but subtle enough where it affects my confidence and ability to power down.
The set-up is always track dependent, where I run with -2.3 you will wear out the right front outside edge of the tires. I went much more aggressive to try and arrest the wear. I am now running -3.1 RF and -2.7 LF. The rear camber is -2.3 and the car is planted.
This is my front tire wear after 2.5 track days. Camber -2.3 all the way around.
I'm confused as well. If factory camber is -1.5, I'm really confused as to why the pros are supposedly saying to leave that alone. I don't know of any car that is being tracked hard that does well with minimal camber like -1.5. That really makes no sense to me. The factory gives you the ability to adjust camber aggressively for a reason, and AP highlights that ability when he was interviewed on the GT4. I'm fairly certain that if I decrease my negative camber, outer edge wear will get worse, not better. It might just be the track layout we have here in norcal. I was running -2.8/-2.4 on my boxster spyder with NT01 tires, and that car was setup perfectly.
The track can definitely make a difference as far as the optimal camber, though I've now driven my car fairly hard on three quite different tracks (two more coming soon), and it felt good on all of them.
-1.5 sounds low to me also, and I have to think that it's meant to accommodate a lot of road use (rather than optimized for the track), but with the all the variables that need to work together - tires, tire pressure, tire temp, alignment parameters, suspension geometry, spring stiffness, damping, bushings, etc. - maybe this car doesn't need as much camber as many others? Though I'm at -2.0 now, I'm considering going to -1.5 when I put on the next set of tires, just to see how the car compares when alignment is all at factory specs. My vague recollection is that car didn't feel quite as good on the road when the camber was increased from -1.5 to -2.0 (but I never tracked it with -1.5).
05-25-2015, 08:43 AM
