911 Understeer Issues at Auto-Cross (long)

[SAM DACOSTA]

At the PCA/OCR's Auto X on 12/06/09 at El Toro, I had extreme 'under steer' all day. I constantly adjusted tire pressure (after marking with chalk to determine tire roll or stiffness) all day and never came up with a setting that suited the car. I am driving a 1990 C2, with Kumho V710's mounted. The track temperatures and ambient temperature were relatively cold and I based my 'under steer' problem on the weather. I knocked cones down on all practice runs and it was only on the 2nd to last timed run that I had a clean run without the noticeable 'over steer' issues.

All season I ran cold temperatures of 32 psi (fronts) and 34 psi (rears) but on this day, I went as high 36 psi (front) and 38 psi (rear) just to get hooked up but it felt like I was running on ice all day. Many drivers were complaining of an 'over steer' issue but not sure how many were able to adjust their cars properly to compensate or correct this issue.

Any comments on this would be appreciated as well...

[Flieger]

Some tires such as Advan A048s have very stiff sidewalls and can be hard to read. The tread wears in the center because of the centripetal force at speed. The shoulders show more tread and a good wear pattern, though. You may need to run lower pressures than you think for maximum grip.

[Randy W]

Assuming that an alignment for autocross has been performed, the suspension and tires are fresh and properly adjusted, and the sway bars have been dialed in on a skid pad - then understeer is fairly simple to address. I don't recommend adding weight to the front of a 911 - that just makes it sluggish to turn. You can accomplish the weight transfer needed as you need it with the throttle and brakes. With the above in mind, low speed understeer in a sharp corner is brake bias and brake technique dependent. This is the hardest autocross turn to do right and is the "slow down to go fast" corner. An '84 Carrera has a "safety" brake bias built in which is horrible for autocross. To fix this, move some bias from the front and/or trail brake more. Mid speed sweeper understeer can occur if you have not "set" the car with a throttle lift or light brake just before entering the turn. The goal here in a 911 is to throttle steer the back end of the car after getting it to rotate. Slalom understeer is usually driver technique or shock related - you want the car to dance, and the best way to do that is with throttle or shock adjustments. Driver technique can fix a lot on a 911 except for a car that leans too much or has bad shocks. In the final analysis autocross results are mostly about seat time.

[Grantsfo]

When surface temps are so cold that tires cant get up to proper operating temps you will always have a understeer issue in mid and rear engined cars. Rather than considering wider front perhaps a more narrow rear is an option in those conditions as you are wanting to get more heat into your tires.

new A6 is by far the best solution when temps are down. Anything less will slide around. I have been on older 710's on cold surfaces for AX and they do feel like ice skates.

Tire pressures. I actually go opposite direction than you in the cold. I drop pressures. FOr a couple reasons. I think you can generate little more tire temp with lower pressures and you can use sidewall flex in rear to help rotate the car.

Dont forget to use your driving toolbox either. I drove a road race setup 914 in AX for a couple years and never adjusted my suspension. I just changed my approach. Couple things you can do. Go into turns and drop clutch harder than usual as you enter turn, throw a cheap set of pads on the front for AX, sometimes you can use marbles to your advantage (thats tricky however).

Pete knows his 911 setups so definitly listen to his suggestions. I have some off the cuff thoughts. If you have LSD you might want to put more rear bar on the car. If no lsd perhaps more rear spring or less front bar will help. If you have adjustable shocks adjust rears to full firm on cold days when understeer is an issue. Will allow you to brear rears free more easily.

[SAM DACOSTA]

Originally Posted by Grantsfo

When surface temps are so cold that tires cant get up to proper operating temps you will always have a understeer issue in mid and rear engined cars. Rather than considering wider front perhaps a more narrow rear is an option in those conditions as you are wanting to get more heat into your tires.

new A6 is by far the best solution when temps are down. Anything less will slide around. I have been on older 710's on cold surfaces for AX and they do feel like ice skates.

Tire pressures. I actually go opposite direction than you in the cold. I drop pressures. FOr a couple reasons. I think you can generate little more tire temp with lower pressures and you can use sidewall flex in rear to help rotate the car.

Dont forget to use your driving toolbox either. I drove a road race setup 914 in AX for a couple years and never adjusted my suspension. I just changed my approach. Couple things you can do. Go into turns and drop clutch harder than usual as you enter turn, throw a cheap set of pads on the front for AX, sometimes you can use marbles to your advantage (thats tricky however).

Pete knows his 911 setups so definitly listen to his suggestions. I have some off the cuff thoughts. If you have LSD you might want to put more rear bar on the car. If no lsd perhaps more rear spring or less front bar will help. If you have adjustable shocks adjust rears to full firm on cold days when understeer is an issue. Will allow you to brear rears free more easily.

I initially went down in tire pressure with the thought that it would generate more heat, thus enhancing grip but for 4 runs it seemed worse than with the higher pressure. I seemed to need more time to determine the correct adjustments and those I spoke with suggested the higher pressure, since the lower pressure was not working and I only had 4 runs left to get a timed run in.

Thanks for sharing your knowledge, this is an ongoing learning curve for me and I appreciate all the input.

[Grantsfo]

Oh I forgot the biggest one. On cold days always bring a tire warmer along! It will greatly improve everything related to cold tire understeer.

I knew I was going to cold event late last month and recruited a fast co-driver to help keep tires warm - we rocked on the single driver cars. Only guy who beat us was a two driver EVO with huge Hoosier A6's.

[Grantsfo]

Originally Posted by SAM DACOSTA

I initially went down in tire pressure with the thought that it would generate more heat, thus enhancing grip but for 4 runs it seemed worse than with the higher pressure. I seemed to need more time to determine the correct adjustments and those I spoke with suggested the higher pressure, since the lower pressure was not working and I only had 4 runs left to get a timed run in.

Thanks for sharing your knowledge, this is an ongoing learning curve for me and I appreciate all the input.

What do you consider low pressure for a 710? I go as low as 22 PSI in a 2000 lb car when surface temps drop below 70 degrees. I run my race slicks at about 20 PSI with my 2300 lb Boxster when its cold.

[SAM DACOSTA]

Originally Posted by Grantsfo

What do you consider low pressure for a 710? I go as low as 22 PSI in a 2000 lb car when surface temps drop below 70 degrees. I run my race slicks at about 20 PSI with my 2300 lb Boxster when its cold.

I used 26 psi (f) and 28 psi (r). That was my low cold readings ...

[rfloz]

Wow! Like Topsy said "It jus growed."

I will try to respond to everyone's posts, more or less in order. But first, I'd like to address Randy Wells' advice. If Randy says look to your driving, you ought to, and I do, take it seriously. I am well aware my driving can be improved. And, I try each event to learn/improve some aspect or other of driving. My skill level is about mid-pack. I am one of the slower fast guys, or faster slow guys, at the regional level. Kinda half-fast, if you like.

My point is, some things adriver induced and some are car issues. Fo example, when I lock up the front brakes, as I did 2-3 times the past year (once pretty much killing a half worn pair of VictoRacers), that is initiated by a driving error - braking too late and then too hard. But, the fronts only locking up seems to me to be a car issue (for those who mentioned it, this was not only a cold weather situation). If the brakes are going to lock, I think all four, or if in a turn, maybe the inside front, should be involved. But, these are straight ahead braking adventures and the rears don't make a peep. So, my aim in this thread is to maximize the car, while also working on driving.

Also, the tire temps, besides being 25 or so degrees cooler in front, at 150-155 rear and 125-130 front, just seem to cold after 4 runs. Maybe the front/rear difference is a Porsche thing, but the overall temps really seem too cold. I am not the most aggressive driver out there, but I do get some reasonable slip in the tires and I am pushing it hard enough to get the afore-mentioned understeer issues. Maybe driving a bit more aggressively would help with this, but maybe lower tire pressures or smaller tires would help too. I dunno.

As I mentioned above, I have been expirimenting with trail braking into slow corners. It works quite well when I get it right. When I get it wrong, it is pretty lurid. More practice. I will definitely try to be more conscious of what I am doing in the sweepers. I have played with throttle steering some, but probably need more practice here also to get a "set". For those of us new to the Porsche car, having had "never lift" drilled in by well-meaning souls, it taks a leap of faith to do more than barely ease off the gas at speed. Yet more practice.

On to setup, described in detail above, it is biased toward auto-cross almost entirely (Added info, it has been corner-weighted and is w/in 2# of 50/50 on the cross weights with the driver in the car. Of course, the right/left balance is not so great, like most Porsches, I am told). The current tires are good 710s, but I have not had the opportunity to use a skid pad to set up the sway bars (not easy to find and for whatever reason, eventmasters seem loathe to set aside space, even in the sea of asphalt that is El Toro). I shall try to find a venue for a reasonable size skid pad.

I just hate the idea of adding weight. I went through some effort to knock off 200+ pounds. I am removing more rear weight and will only add weight to the front if I need to ballast for class rules or to expiriment. Later on, I will make a list of things to try and the order to try them in. As noted above, I am stuck for now with the fairly new shocks/struts I have - re-valved, but unadjustable, Bilsteins. When the budget allows, that will change.

Anyway, thank you for your advice. I will try to put it to good use.

[Evan Fullerton]

Since you have a turbo flared car, I would go big on the front tires to cure the understeer as well as making sure the car has enough rake. The Kinningers are running 275 front and 315 rear 710s in a 17" size on the SMURF car. Previously they had run a 245 in the front and apparently the 275 works better for them. From my engineering books tire grip increases by the delta in width raised to the .15 power. While this is not a lot it may be enough. Additionally, at some point if you are still having understeer, reducing rear grip is the only option as Rad has found with his Ferrari. This can be done with a smaller rear tire or stiffening the rear suspension either through a sway bar adjustment or larger springs/t-bars.

Rake is also important. If the car is too low in the back there is not enough weight on the front for turn in without the use of left foot braking or heavy trail breaking (hard to do at autocross speeds with out lockup which ruins it as the coefficient of kinetic friction is much lower than static and does not load the front as intended). Changing your driving style can also play an important roll as slow in fast out tends to mitigate understeer.

Tire temps are also a factor but the 25degree delta you observed is negligible. I also think that excessive scrub radius does not cause understeer. It does have some downsides such as higher steering effort and kickback but I was running a negative offset wheel on my old 914 and did not experience any added understeer. Some or more toe out in the front will also decrease understeer as well as build more heat in the front. If it was terminal understeer though, now is not the time for subtle changes. If you can turn it into a larry oversteering beast you will know that your adjustment worked and you only need to dial it back a little.

My $0.02
Evan Fullerton

[rfloz]

SteveW - Yes, the spindles are de-cambered ,as well as raised. Some, including Chuck Moreland, aren't fans of de-cambering the spindles as it seems to make the scrub radius worse. Oh well, it did geve me plenty of camber. And, I can probably get another .5 degrees if I need it. The tire temps across the tread seem to indicate I am pretty close to ideal at -2.6. Maybe a bit more as some people say the inside edge should be just a bit warmer than the outside for maximum grip. I stopped at -2.6 for now for the reasons you mentioned -contact patch on braking. Lower tire pressures may help this a bit.

I'll look for you at the next event re a chip or e-mail sooner if the exhaust gets done before then.

petevb - While a stock 3.2 may be a largish lump, it's not exactly a powerhouse. The 245/315 tires allow the car to be pretty low - 24 1/2" to the front fender lip, 24 3/4" to the rear IIRC. I have to watch traffic humps (the bane of suburbia). I have pretty good wheel well clearance with just a tiny bit of rub in the right rear and the left front. Certainly, I cannot go any lower with these tires (and torsion bars).

I am starting to see a consensus that my tire pressures are too high. Lowering the pressures will be one of the first things to try, I love freebies. Also on my list of things to play with are stiffening the rear sway bar (that one is somewhat adjustable) and/or swapping the 22mm front out for the stock 20mm. Maybe some combination will find the "sweet spot".

The spindles are raised (33mm) and de-cambered and a bump-steer kit has been installed. I will definitely try more toe out. More camber can wait, as you suggest.

Brakes - I am a little puzzled by your recommendation to use a higher friction (softer?) pad up front. Wouldn' that increase front lockup? Likewise with using a prop valve to lessen rear brake pressure? I'm not disagreeing, just not seeing how this would work.

M&K - yeah, I am not hoping for a lot more power, but those with an SW chip and a two-out M&K seem to at least break even and the pre-muffler actually seems to give a few ponies. And, it will be lighter.

I am taking more weight off the rear and will avoid taking more off the front (however tempting some things may be). I am pretty close to class limits on weight, so a lot more off the rear will necessitate some ballast. Of course, if I get there, any ballast will go in front. My car is a bit tail heavy as I have taken a fair amount of easy pickings off the front and am just getting serious in back. As you know, past a certain point, weight loss gets very expensive. So, baby steps.

Finally, yes, these things really squirt out of the corners. My old Mustang would light up one tire if the LSD was weak and spin both even when it was working unless I was careful. None of that now.

911st - Well, the shocks are supposed to be for auto-cross, but as noted elsewhere, the Bilstein re-valve guru, Jim French, has passed away and the new guy appears to be an unknown quantity. I gots what I gots for now. They are fresh and no leaks have sprung up, so, they may not be ideal, but they should be serviceable. I hope.

I am re-thinking all the alignment settings. Certainly more toe out in front, maybe a bit more camber and possibly a bit less caster. I'd like to try one at a time in the order above, but that pushes costs up. I probably should get back to doing some of my own alignment.

If adjusting my present (21mm) rear bar stiffer seems to help, then, yes, I will try an even bigger one. I kow the softer spring/harder sway bar vs harder spring/softer sway bar debate will rage on long after I am dead and gone, but I tend to come down on the latter with sways as a tuning device, less as a spring medium. I know with the Mustang spring (and wheel) rates get really high on the more competitive cars. Obviously very different cars, although both have the less than optimal McStruts in front.

Okay, dinner break. I shall return.

[rfloz]

Alrighty then, back to work.

Max - Love your demo tape. Even though it looks like he was locking up the rears, I get it now.

I'll be at the New Years run unless it rains. Last year the water and ice on the way up to Angeles Crest was a bit too, um, interesting for me on the R tires.

You really need to bring your beast out to an auto-cross when ever you have a break from school. It is huge fun to be able to run full bore with no worries about cops, other cars or hard objects lying in wait.

petevb (& Max) - I pretty much agree and I guess the question I have is - what is the right balance for tire stagger? With my wheels, I can run from 225-275 in front and 275-315 in back. I prefer 710s to A6s and so not all the steps in between are available. My thinking at present is that a smaller tire in front (and maybe also in back) than the current 245/315 combo will get the tire temps up and thus get better traction despite the tires being smaller.

I have a picture of my car at Streets of Willow and the inside front is barely touching the ground even with an instructor in the car.



And, I wasn't really pushing the car that hard as it was my first time there. So, I gather trying stiffer rear and/or softer front on the sway bars will likely lead to improvement. As mentioned, the shocks will have to wait a bit.

911st - FWIW Jack O's car is more track oriented and so transitions are less of an issue. Also, with 245/315s, which I grant is a bunch of stagger, the rears are still getting more heat in them. In auto-cross we almost never get tires up to the optimum temps except for some of the street tire classes (think Azenis). But, the closer we can get the better.

I agree, and I think others above do also, that stiffer in the back and/or softer iin front will help. So, that's one of the things to try. Unfortunately, the first PCA auto-cross here isn't until March, so I amy have to go slumming with my old SCCA bunch who start up in January in order to start the great expiriment.

Less caster is on the list of things to play with. FWIW, my corner weights are good for the cross weights (2# delta). Even lthough the LF is 37# higher than the RF, both front tires seem to both lock up at the same time (at least in straight line braking). Even so, I may put the battery in the smuggler's box if I put the Odyssey PC680 in the car. While that takes some weight off the front, it does shift it to the right a bit. Of course that means the sross-weights will need adjusted. Sigh.

Ducman - Yes, trail braking helps a lot in the really slow turns. But, as we both have hearned, it can be tricky. More practice will help, but I am hoping a better balanced setup will help too. We shall see.

Sam - I suspect your car is a good bit heavier than mine (2550 w/o driver) and so higher pressures are probably correct. How much higher is an open question. In the cold, all bets are off.

I tried 1 psi lower to no real effect. I probably should have tried more to see any real change - good or bad. It was a frustrating day. If I only had my issues on very cold days, I'd be a lot less concerned. Mine seem about the same - warm or cold.

That probably isn't much help, but, hey, misery loves company.

Grantsfo - If I read Sam's post correctly, his issues were probably due to the cold while mine seem to be present hot or cold. I have always heard lower pressures help in the cold and I probably should have let some more air out. I ran A6s for a while and never got to like them. Kumhos are just a better fit for me, although I never ran the A6s in very cold conditions.

Of course, as Randy W so deftly pointed out, driving has a huge impact in auto-cross. On my car, and probably Sam's, once you put the car in second, it stays there for the rest of the run. So, not a lot of clutch action. Certainly trail braking or even abrupt throttle lif going into slow turns helps. I know I need more practice with this.

My car has LSD, not sure about Sam's, more rear/less front bar will be tried.

Sam - I have tried lower presures on warm days (24/28 IIRC) and it didn't "feel" good so I put them back up to 28/32 f/r. I suspect I need to try this again to be sure it's not faster, even though the car is slower to react and "squishier". You may want to experiment with this too. With PCA OCR's 12 run format, at least there is some time for trying different settings. At SCCA events we get 3 runs and sometimes you can pay for three more.

Grantsfo - A tire warmer would be excellent! However, they would need to be trained in the vagaries of the 915 for my car. Sam at least has a decent transmission.

22 psi! Yikes! What in your opinion is a ballpark figure for a 2500# 911?


For some of those following along, you may not be aware that Randy W, JP (or at least his son) and petevb have been auto-crossing a long time at a very high level. I don't know the auto-cross bona-fides of the other contributors, my bad, and you may well be in that league. But I am certainly am not and I really appreciate the input of everyone, experts and novices alike.

In any event, thanks to all. BTW, if I sometimes seem to be disagreeing or questioning in my tone, it's because I am trying to learn. It certainly isn't any delusion of greater knowledge.

[J P Stein]

Whel lift....my God, we can't have that....

[HarryD]

Originally Posted by J P Stein

Whel lift....my God, we can't have that....

Gosh, without some wheel lift how would I avoid the cones!

[911st]

Not much tire stagger in those pics!

Again, A 911 has 50% more weight to control in the back.

That is equal to about one full front wheel and one and a half rear wheels of equal size.

With a lot of stager one is going to have to keep the other front wheel on the ground or the front is going to wash out with a lot of tire stager. This will take a lot of rear spring/bar which this car dose not have and require giving up some of the rear hold. That is ok as the rear should have plenty with such large rear tires.

Yes, 911's do have an issue getting heat into the front tires compared to the rear. In theory the heat difference would make us want to go to relative smaller front tires to get them to temp. If one has a solid chassis with little flex and where the front can be softened to get both front tires to work like the rear tires, this might work. I suspect doing this would make the car more sensitive to throtle and braking inputs as the weight shifts.

Porsche runs a lot of stagerwith there new car with something like a 235/305. However, I suspect we do not have the chassiss stiffness, the set up, nor geomitry to make this work as well on an old 911.

We seem to work better w a near square three wheel set up. That is setting it up with less wheel stager and a stiff front so one front wheel is in the air is easier and might be more forgiving.

I do not know if we can expect AutoX to warm up the tires much. Especially the fronts. Lower air pressure, non shaved, and or softer compound are other things to look at to get some heat in the fronts. I think w autox one just has to get soft enough compound tires to make them work. If was possable to put softer compound in the fronts, that might help to.

I used to know a guy that ran a mostly stock 70 911 w SC flairs and a 2.7E motor. He was the national SCCA champ severl years in I think A mod against a lot of big cars w a lot of tires. He ran 225's front and rear on I think 8 & 8.5" rims. AutoX 911's just do not need to have much stager it would seem.

Now a higher HP car like a Turbo might be a different story.

----

I just would try stiffening up the rear w big rear sway bars.

Sorry for being redundent.

Again, I am not an expert on this and still have a lot to learn.

[911st]

Camber thoughts.

On this suspention with this car we should see about 4 to 5 deg of lean. I suspect this style of tires need about 1 deg of inclination to do there best work. That is a total amount of camber compensation we need of about 5 to 6 deg.

With lifted spindles if my info is correct we should see as much as 2 deg of camber gain in the front with compression, depending on ride height. If the car is set at as static camber setting of -2.75 that is about 2 plus 2.75. Add to that a little for the camber gain that comes from all the caster we run and that is about 5 degs total if camber compensation built in.

If you can keep the front flat your camber setting could some where from "ok" to about one full deg short of how much neg camber needed. If you are lifting a front wheel, it probably could require even more more static camber to reach its ideal.

Taking temps at an autoX is probably not going to help. One would have to do it on a skid pad. Temps on road race tires when set up right will often be 10 deg hotter on the inside of the tire I hear.

Check out the heavily modified Porsche AutoX racers at the track. They often have more neg camber in the front than the rear and it looks to me like a lot more than one would expect. (Look at the white autoX car above. Note the lack of stagger and how the front has more neg camber.)

De-cambering the front spindle is not a big deal on a normal body car. More of a deal on a turbo body car w stock wheel widths. Wider tires lessen this.

The only other way to go to get more camber would be to add big camber boxes so the strut can be pulled in closer or to lengthen the A arm (or offset ball joints).

Somthing else interesting. Stiffening up the rear can reduce the need for more static camber in the front and alow the front to gain on two levels. More inside front tire doing the work and the outside being at a more ideal angle.

[Randy W]

Originally Posted by 911st

I used to know a guy that ran a mostly stock 70 911 w SC flairs and a 2.7E motor. He was the national SCCA champ severl years in I think A mod against a lot of big cars w a lot of tires. He ran 225's front and rear on I think 8 & 8.5" rims. AutoX 911's just do not need to have much stager it would seem.

That was Dwight Mitchell who drove in ASP back when early 911s were competitive in that class. Great driver.

I don't run with any stagger either. The front do not get as warm as the rears - but that is never going to happen anyway in a 911 that is driven hard at an autocross. Some tire lift is also inevitable especially in a stiff 911 that has a cage or keepers on the front suspension.

To autocross a 911 well requires intuitive driving techniques that are gained by years of practice. A lot of these are actually counterintuitive so that's why they are so hard to learn. I wouldn't say you are using one end of the car at a time - but with a 911 it sometimes feels that way! To rotate the car on corner entrance or in mid slalom you are always transferring weight to the front to aid grip there by either using throttle lifts or a light tap to the brakes. Left foot braking allows for both as needed. To steer the car through the corner you are using the throttle much like you would use a rudder on a boat. Steering corrections need to be made a little before they are actually needed. All the time you are trying to drive as smooth as you can and not disrupt the car's balance - it ain't easy! Rather then throw more money at a car that has the fundamentals right, I always recommend more autocrossing. Ride with a hot shoe, then take them as a passenger and learn as much as you can. Then practice, practice, practice. The learning curve can be frustrating, but eventually it will come and it will feel great.

[911st]

Yes! Dwight in ASP. It usually took a 3.5 914-6 with pro built hight butterfly RSR-MFI w huge sticky meats and a national pro level driver to beat him for TTOD at local events in that little 911 w no oil cooler and about the smallest brakes Porsche ever put on a 911.

[rfloz]

Originally Posted by Randy W

That was Dwight Mitchell who drove in ASP back when early 911s were competitive in that class. Great driver.

I don't run with any stagger either. The front do not get as warm as the rears - but that is never going to happen anyway in a 911 that is driven hard at an autocross. Some tire lift is also inevitable especially in a stiff 911 that has a cage or keepers on the front suspension.

To autocross a 911 well requires intuitive driving techniques that are gained by years of practice. A lot of these are actually counterintuitive so that's why they are so hard to learn. I wouldn't say you are using one end of the car at a time - but with a 911 it sometimes feels that way! To rotate the car on corner entrance or in mid slalom you are always transferring weight to the front to aid grip there by either using throttle lifts or a light tap to the brakes. Left foot braking allows for both as needed. To steer the car through the corner you are using the throttle much like you would use a rudder on a boat. Steering corrections need to be made a little before they are actually needed. All the time you are trying to drive as smooth as you can and not disrupt the car's balance - it ain't easy! Rather then throw more money at a car that has the fundamentals right, I always recommend more autocrossing. Ride with a hot shoe, then take them as a passenger and learn as much as you can. Then practice, practice, practice. The learning curve can be frustrating, but eventually it will come and it will feel great.

I saw Dwight Mitchell drive that car at a Cal Club event many years ago. Very, very fast. I never dreamed I would be driving one.

I seem to recall an Excellence article featuring your #51 car and you were running a 245/275 setup IIRC. Have you gone to a no stagger setup since (it was a while back)?

While the fronts wouldn't get as warm as the rears due to the rears carrying more of the load and power application, especially with no tire stagger I would guess, I don't have a good idea what that difference should be. Nor do I have a good grasp of what temps 710s ought to show when auto-crosed hard. Somewhere between the factory engineer's ideal of 190-200 and the 145-155 I am seeing (at the rear) I imagine.

Thanks again for the driving tips. These cars are certainly "interesting" to drive. I went into this worrying about controlling the rear end and find myself having issues with the front.

I have gone for runs with some of our better instructors* and have seen them doing things, e.g., trail breaking, that I am putting to use. But, I have also seen their cars turning in better and holding the front end in line better on the sweepers and have not detected any driving techniques that I am not using. Of course, that could be my failure to perceive what is going on.

FWIW, I have gone through a couple of the EVO schools and have (finally) put "looking ahead" and "go slow to be fast" (in the tight stuff) to good use. I am hoping your 911 specific techniques will help me build on that.

Thanks again for the input. It is appreciated.

___________

* - Not all our instructors are by any means expert. They are so desperate they even made me an instructor. Which, by the way, is a great way to learn. Seeing what students are doing, right or wrong, is very instructive for the instructor as well.

[J P Stein]

While I agree that a very good driver can overcome a poor handling car, why should he & what would he do with a car that handled well?
Heroic driving is fun to watch and but very hard to do consistently.....beyond most, me thinks.

A balanced car is a lot more fun to drive and your butt time will translate to any well balanced car. I have seen Evo School instructors flummoxed by a poor handling cars......going slower than the owners. Put these same folks in a balanced car and they will lay waste to an owner that has been driving the car for years. Nothing personal, that's their job.