Wider track can give you a bit more grip or Gs too though. Although marginal, it can add up.

 

Yep, if only I had a pyrometer Joking aside, I should have paid closer attention to your sig, as you're much more experienced than I am at this. But still, even my fairly trackworty RE71R tires at the wrong pressures felt exactly as you described the feeling of poor street tires, just crunching and marbling through a corner with irresistible oversteer as the rear held on like superglue. Almost in tears at Lime Rock Park turn 2....

PS: how did you get into the Barber instructor gig? I instruct with the usual car clubs (BMW, Audi, PCA, HOD).

 

What are your alignment settings?

 

Yes,.... but.... the only truth is what the car actually does in your hands.... in other words, the pyrometer is great for getting you close, but how the car performs, given your style, power, and alignment will give you the truth. For example, when you enter a turn, you are supposed to accelerate... hit the gas. When you do this, the weight of the car is transferred to the rear tires and lessens on the front. More weight = more traction. Less weight = less traction. So.... if your engine is powerful, you will get understeer from a lighter front end and heavier rear. If your car is less powerful, you will get less understeer. So it all depends ..... ultimately, you want a neutral drift (aka slip) out as you exit the turn. For that, you just have to experiment.

Said another way, you may want less optimal grip in the rears... achieved at the track by tweaking your pressures.... due to sub optimal something else like an alignment. Once you are out at the track, tire pressure is about the only thing you can tweak as you typically can't change your tires or alignment. Although a really good driver can feather the throttle and "throttle steer". Throttle steering is manipulating the power to tweak the weight transfer from front to rear thus changing over/understeer. Most amatures should not be dicking with this because you can get into trouble really fast.

Peace
Bruce in Philly

 

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I started getting this really badly after a bunch of track weekends on the same tires.... my tires (factory Michelins) would heat up and then turn to grease (the fronts). My instructor said the tires have heat cycled too many times. I was really disappointed because the car never did this and it really ruined the fun I could have. Maybe the OPs tires are just too old like mine were?

Peace
Bruce in Philly

 

Been around them and knew those guys for years Started racing karts in the late 70s and wheel to wheel SC/924/944s in 83 when I turned 16. Hate to date myself. I stopped racing about 10 years ago, but was pretty serious in both open and closed wheel from mid 80s to early 2000s.

 

Thanks, but read down a bit. I am already throttle steering, on maintenance throttle and using throttle inputs to keep the car on the road at its limits. I am not on a race track hard accelerating out of an apex. Lol, these are places such as long somewhat decreasing radius exit ramps where throttle inputs either way are very subtle.

I can also generally get fronts to grip while on throttle and simply a series of small quick back and forth turns of the steering wheel sufficient to get the fronts to bit, but small enough not to unsettle the car. Lol, I don't recommend this at home. I have seen your videos. I like! and I drive on a track and at the limits with super busy hands as well. I like to think I am at 10.5/10ths!

 

I am assuming stock since this is a CPO car granny driven by a little old doctor before me. I used to set up my 997s with GT3 settings with zero toe and will do this with the GTS as well except I won't run GT3 camber until I come up with a solution for the rear wheel tuck..

Correct me if I am wrong as it has been about a year since I dealt with a 997 alignment, but doesn't all C2, S, C4S and GTS come out of the factory with around 3 to 5 toe. They do this to make the car more stable and less likely to swap ends. Run it at zero and the car drives much better IMO.

 

I used to teach my students very early on how to throttle steer and use maintenance throttle properly. It is an easy concept to learn if correctly taught (instructor in car and through demonstrations in instructor's car) and helps students improve car control rapidly. Pyrometer just helps you dial in the pressure so you have maximum tire contact patch at all time. You are correct, the end verdict rests with the driver and technique!

 

Yes, stock alignment has front toe in. If the car was never aligned (and it sounds like it wasn't, based on the history you're providing), do you think it would be worth throwing it on the rack? I bet all the numbers are in the red. My 997.2S came new with horrible understeer. I ended up lowering the difference in camber between front and rear to 0.5 degs, changing front toe to 0, and adding a stiffer rear sway bar. I also played around with all sorts of tire pressures before landing back at 33/37 cold. Oh, and front/rear shock stiffness also matters (adjusted on a DSC module). If you've got the tire pressures where they should be, and you're still not happy with understeer, perhaps there's something else going on.

 

The TPC DSC module would be another great idea for this car as it's a 10 minute plug and play swap since the 997.2 already has the 3-axos accelerometer built I to it.

Doug, you are also correct that the factory alignment settings include rear toe in as well as front toe in. It's the rear toe setting that is also partly to blame for the terrible rear tire wear. With your driving experience, dial a bunch of that back out. The car will drive better and your tires will last 50% longer in the back.

 

I will totally throw it on the rack real soon. I have a great little shop within 2 miles from me that is super cheap and does excellent alignment work.

My car did go through CPO process about a year ago and 8,000 miles before I purchased. I was somewhat assuming that the CPO process would include an alignment, but could be wrong there.

I will post up my before and alignment specs soon. May try and get it done tomorrow if they have an opening.

 

I keep reading about the DSC and will likely look at that this weekend. Seems like it gets very positive feedback from those that have it.

 

My driving coach always is careful to first blame the driver and then the set up (I have heard "is it you or the car?" about a million time). Are you sure you are braking and apexing late enough to get it rotated enough where there is very little turning to be done? Sometimes with enough slip angle, little to NO steering input might be needed at mid corner to corner exit. Watch closely the GT cars vs other cars and the line is a bit different being rear engine vs mid engine. The front end is going to be lighter given the engine in the back (but im sure you know this). Going from an M3 to the 911, I have changed the way i drive the car, especially cornering. Also, the Pzeros to me, suck. in fact, my brother through his away, even though there was over 5/32 tread left, to get the 4s, which was an immediate upgrade. He felt as though the zero was OK, when new, but dropped off very quickly and with lots of tread left.

outside of that, i'd check tire pressures, and camber first.

EDIT: just read further down, sounds like you know what your doing, driving wise. I'd caution the GT3 aligment specs. I did this, loved how the car felt, but my rears insides were shot in only like 3k miles do to the camber and toe. but if it is a track only car, that might be a bag thing.