My STX 09 autocross future and questions

[Norm Peterson]

Edit - never mind


Norm

 

[Whiskey11]

EDIT: Just saw your edit! Yeah, no STU love for Mustangs below 5.0L I wish I could as it would be far more attractive and might make a little more sense. I could get away with it locally if I asked the STU competitors (although some are sticklers so maybe not).

 

[jayel579]

It's probably time to come up on spring and dampers both. But remember that one of your goals at the time with the setup was that it was comfortable on the street. Well, KW's are pretty comfy considering what you've now grown into wanting. Give you the higher rates you are after, and independent double adjustment too.... plus that nice lifetime warranty and the ability to cornerweight the car too.

Well right now I see two glaring issues beyond overall grip in the car. The first is the lack of throttle oversteer without upsetting the chassis.

Right now, trick shocks and super stiff springs are an absolutely low priority.

I have had a couple of conversations with Sam about this; STU/STX versus ESP for my car as well. I believe what Sam has suggested with upgrading your dampers is key though you have set this as a low priority. I am racing on a set of KW Clubsports (linear rate spring) with Sam's bars on RS3s and I can say that the car is an absolute dream to race right now. On the street, it’s tolerable but this it is not my daily driver. I am constantly adjusting the shocks, writing down every setting, to see where the car runs best. Car ran like a top at Watkins Glen about a month ago, it was fantastic. I had a friend of mine co-drive my car this past weekend and he found the car very easy to drive. I also had two top level FS drivers (Don Slevin and Ron Bistrais) in the car with me during the day.

My car is not completely done prep wise but given the ST classes, I don’t think the issue with our car is not handling or power but weight. Just cannot get our cars down to the E36/46 weights. Might come down to right course, right driver at the National Level for the car to win but I am bringing a whole another argument into the mix here. The more I have driven my car this season I believe that ESP is the best direction. You also said you are still junior in your experience, so tightening the nut behind the wheel will be the cheapest/hardest improvement for the car. Keep driving, keep racing, you’ll get there in time. Just be deliberate with the steps you take in the development of the car.

 

[Sam Strano]

It's genuinely a shame that you had problems with your car and Ford wouldn't or couldn't take care of you. One of the many reasons I always recommend avoiding 1st model year cars or when they make large changes in the drivetrain.

A little birdy told me that your FRS/BRZ (I can't remember which you bought) might be getting prepped for Autocross duty instead of the Vette? I'm not sure I put much faith in that little birdy as he drives an Evo. That is always exciting! I do hope you return to the Pony Cars someday!

My FR-S is my daily driver. It's got ST parts on it, and I'm going to screw around with it in St Louis in a few weeks *IF* that event happens, but it's FAR from a full build. Not sure I will do a full tilt build on it, it is my means to get around and I don't want to make it suck for that.

I just traded my Z06 on a Grand Sport because I've learned (or rather confirmed) that the gearing just can't be overcome with a C6 Z06. I'm pretty committed to Corvette for right now. But I always think about an ESP S197. I drove one I setup two weeks ago, first run outran any run I put down in the Corvette. And when ESP is on (meaning Mark Madarash, Dave Ogburn in my old Camaro, and myself because we've each done this, nobody else has) it can outrun SS.

 

[Justin_H]

My thoughts are these:
Fixing the handling so you like how the car drives should be your first step. Since you're not ready to lighten your wallet for big $ shocks and stiff springs, just raise your rear roll center until the car becomes a bit loose, then adjust the rear bar until you're happy.

A better diff will help if yours is shot, but rebuilding the stock one is cheap and easy, and can easily last a season with multiple drivers, assuming those drivers know enough not to plant their right foot if they get one wheel peel. A torsen style diff will change the handling somewhat, loosening the car up more with power application.

Dropping a few pounds will help, but only a little. I used to take passengers regularly when I autocrossed, and a 200 lb passenger in my sub 3000 lb SM Mustang would slow me down somewhere around half a second on a ~60 second course. It'll make less difference in a heavier car.

If you're willing to drive far enough, you can get in some more events this winter. No idea how far that would be for you- when I was heavy into autocrossing, I used to drive 250+ miles one way for winter events. Coming home often got interesting.

Justin

 

[dontlifttoshift]

Put more tire on it, use up every bit of that 265 rule, and keep driving. Adjust what you have. Run roll center to the top, run it at the bottom, set the shocks on kill and see what they do, camber bolts might get you closer to where you want to be, but most of all seat time, seat time, seat time. We live between Chicago and Milwaukee and carry dual membership. There are at least 4 smaller clubs that also host events here. Get seat time anywhere you can.

My wife and I run our '12 in STX. We routinely get beat. These cars are heavy by comparison and to run on 265 tires.....they are just not enough. I stay in STX because its low cost, this is my hobby, I think it is yours too, enjoy it.

It was explained to me like this,

1. Driver
2. Tires
3. Shocks
4. Everything else

All number 4 does is make it easier on number one.

 

[Whiskey11]

My FR-S is my daily driver. It's got ST parts on it, and I'm going to screw around with it in St Louis in a few weeks *IF* that event happens, but it's FAR from a full build. Not sure I will do a full tilt build on it, it is my means to get around and I don't want to make it suck for that.

I just traded my Z06 on a Grand Sport because I've learned (or rather confirmed) that the gearing just can't be overcome with a C6 Z06. I'm pretty committed to Corvette for right now. But I always think about an ESP S197. I drove one I setup two weeks ago, first run outran any run I put down in the Corvette. And when ESP is on (meaning Mark Madarash, Dave Ogburn in my old Camaro, and myself because we've each done this, nobody else has) it can outrun SS.

I knew not to trust that little birdy!

My thoughts are these:
Fixing the handling so you like how the car drives should be your first step. Since you're not ready to lighten your wallet for big $ shocks and stiff springs, just raise your rear roll center until the car becomes a bit loose, then adjust the rear bar until you're happy.

A better diff will help if yours is shot, but rebuilding the stock one is cheap and easy, and can easily last a season with multiple drivers, assuming those drivers know enough not to plant their right foot if they get one wheel peel. A torsen style diff will change the handling somewhat, loosening the car up more with power application.

Dropping a few pounds will help, but only a little. I used to take passengers regularly when I autocrossed, and a 200 lb passenger in my sub 3000 lb SM Mustang would slow me down somewhere around half a second on a ~60 second course. It'll make less difference in a heavier car.

If you're willing to drive far enough, you can get in some more events this winter. No idea how far that would be for you- when I was heavy into autocrossing, I used to drive 250+ miles one way for winter events. Coming home often got interesting.

Justin

The diff was rebuilt about a month ago with the standard clutch packs so it's "fresh" in a matter of speaking. It has two events on it, one on asphalt and one on the Nationals concrete (running the West Course). I realize it's easy to rebuild, but dealing with it falling off every season with daily driving and autocrossing and the winter is going to get expensive and annoying hence why I want to switch to something that wears out over the course of decades rather than a season and should be consistent from run to run.

I don't run with passengers when I have actual competition showing up and at this previous event I had zero passengers because I actually had a competitor (prepped [according to the owner] Integra Type R which I narrowly beat) worth running against. I've in the past taken rides on the first run but rarely after that.

I live in Omaha Nebraska. 250 miles in the winter just lands me into more winter and most regions around here in less than a day's drive are done after the first week in November or so. I would have to travel pretty far South to find regions still going. Not to mention the fact that the car is going back to stock (ish, the D-Specs are staying on because I busted the hex head off a stock strut) for winter and obviously the Star Specs are coming off. I'm not sure it's practical to do much traveling for autocross in the winter!

 

[dontlifttoshift]

All else equal, something like 3/4 second per minute. No idea what the compound change might add beyond that.

Not questioning you, just the concept, so is this accurate? I am assuming you got to this number with some really cool math but can I consider this to be a good rule of thumb? Also, is it linear, could a person expect a 2 1/2 second reduction by going to 315s?

 

[Norm Peterson]

Not linear. Think [width ratio]^0.15.

It came from somebody who works at the OE level.


Norm

 

[dontlifttoshift]

Forgive me Norm, I don't understand

[width ratio]^0.15.

I try to keep up with the smart kids but I'm just a weldor.

 

[Whiskey11]

Yeah I'm not sure I follow the math there at 245 I got like 2.82 or something like that and at 265 I got 2.31. What that means is beyond me! I'm sure Norm can explain (and I hope he does so I don't have to go try and find the maths on Corner Carvers) and I look forward to that response!

Anyway, I started reverting the car back to stock for winter and got the opportunity to weigh some things. My Stock 18x8.5 Bullitts with 245/45/18 Dunlop star specs weigh in at 52.5 lbs (scale is accurate only to the half pound). According to TireRack the 245/45/18 Star Spec weighs 29lbs. This puts the OE 18x8.5's at 23.5lbs each giver or take half a pound (I am going to err on the side of caution and go to 24) which I didn't think is too bad for an OE wheel. It's certainly not as nice as 19.7lbs each for the TSW Nurburgrings but they also didn't cost me as much to upgrade to when I bought the car!

The Fays2 Watts link weighs in at 29lbs. I didn't weigh the individual arms to measure the increase in unsprung weight but I'll try that tomorrow. I don't expect it to be a whole lot. Certainly a lot less than the Whiteline unit adds.

I also measured the 25mm Strano Rear bar with hardware at 16lbs. I have no idea how that compares to other bar's on the market but it isn't that heavy. Heavier than the stock bar, but no idea by how much.

I also measured the stock spring, shock and GT500 mount set up and IIRC it was 23lbs. I will re-weigh this tomorrow when I pull the D-Specs/Steeda Sports/Steeda HD plates and see what they weigh. I'm assuming more because I'm like that!

Also, PHB's suck. After a year of driving with the Fays2 Watts, going back to the stock PHB is a huge difference. I don't like the feeling at all. It feels like the back end is loose (it's not, I triple checked to make sure) but it moves around under the car in bump. Absolutely disconcerting. I know that in my uphill battle in STX that every pound counts but the 12 pound addition over the rear axle for the Watts link is more than made up for in the feel of the car and provides one more tool for tuning the rear suspension.

 

[Norm Peterson]

[Width Ratio] raised to the 0.15 power. Keep in mind that this is at best an approximation.

Sort of like square root, which would be the 0.5 power, except it's a smaller effect.

What this basically means is that small tire width changes aren't all that productive until you need to find pretty small differences in time.

Easy enough to do on a calculator or in a spreadsheet but I wouldn't attempt doing the math for even one tire width comparison with only pencil and paper.

Norm

 

[Whiskey11]

Thanks for the explanation Norm. I think 3/4 of a second is a safe assumption for time reduced from going from 245/45/18 Star Specs to 265/35/18 Star Specs but supposedly the RS3 is that much better than the Star Specs. Add in the fact that the Star Specs are being discontinued atm and TireRack is having a closeout sale and that means the ZII is around the corner.

A part of me REALLY wants them because of the fact that I keep hearing that the RS3's soft sidewalls are really disconcerting. Maybe I'm just over thinking the tires and should just get the RS3's and "be done with it." I guess I want as much of an advantage as I can get!

So I'm curious, Norm, since you mentioned STU in an earlier, edited post. Do you think that this car on 285's can make it into the trophies and potentially win? All of the allowances are the same in ST so all that is changing is the wheel and tire size. STU's fastest time on the West course was a 60.428 vs the 61.318 in STX although the PAX combined time at Nationals was very close with 130.901 in STU vs 130.784 in STX so STX was "faster" this year when looking at the top guys anyway. The end goal is the same but the PAX is harder for STU (.841) than STX (.822). Just bench racing STU vs FS (.825), if the FS PAXed time was 60 seconds (raw time of 72.727), in STU trim I'd have to run a 71.344 to even PAX the same as an FS car. Possible? I don't know, I wouldn't think so given the power of the Purple crack.

 

[dontlifttoshift]

Are you legal in STU being under 5.0?

S​

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treet Touring Ultra (STU)​

Audi
S4
BMW
135i
3 Series (E90 chassis, incl. M3)
(2006-10)
M3 (E36 chassis) (1995-99)
M3 (E46 chassis) (2000-05)
Chevrolet
Camaro (over 5.0L)
Ford​

Mustang (over 5.0L)

Plus, those damn STIs.....

 

[Whiskey11]

Are you legal in STU being under 5.0?


Plus, those damn STIs.....

No I'm not. My question is if there is a legitimate cause to request the car be reclassed where it could be competitive and if STU was that location or if STX represented the best place for one to run. Right now the PAX factor is saying STX is the more realistic option but the two classes are very close in times despite the 285 wide tires.

 

[Justin_H]

I don't run with passengers when I have actual competition showing up and at this previous event I had zero passengers because I actually had a competitor (prepped [according to the owner] Integra Type R which I narrowly beat) worth running against. I've in the past taken rides on the first run but rarely after that.

Hey Whiskey, I didn't mean to say you run with passengers, I was just trying to give you an idea about the time savings from dropping weight. It helps, but once you get beyond the wheels and heavy stock seats the $/second gets very expensive.

Justin

 

[Whiskey11]

Hey Whiskey, I didn't mean to say you run with passengers, I was just trying to give you an idea about the time savings from dropping weight. It helps, but once you get beyond the wheels and heavy stock seats the $/second gets very expensive.

Justin

Yeah I hear ya on that! I'm more or less planning for the future as I already know I wont be able to afford to max the car out any time soon.

 

[cito]

Fair discussed the STU versus STX issue in his blog (or whatever), and he seemed to indicate that the time saved by adding wider tires (which they tested) would not be enough to make it any more competitive than it was in STX. I am not sure why the SCCA decided that the car has to be in one or the other, leaving it in both would do nothing to upset the apple cart in terms of the current competitive cars in each class.

 

[Whiskey11]

Fair discussed the STU versus STX issue in his blog (or whatever), and he seemed to indicate that the time saved by adding wider tires (which they tested) would not be enough to make it any more competitive than it was in STX. I am not sure why the SCCA decided that the car has to be in one or the other, leaving it in both would do nothing to upset the apple cart in terms of the current competitive cars in each class.

I think the SCCA wanted to address the issue for cars that were competitive jumping between classes (IIRC the RX8 was one of these vehicles) so they decided to make the decision to kill class hopping entirely. The decision certainly didn't help or hurt the Mustang at all. I would be interested to see a car prepped to the ST limit go head to head on 265 and 285 tires and see where it would have done better at nationally before making the decision to condemn basically every Mustang except classics and the GT500 to STX. I'll have to go re-read Terry's build up posts back when he was running STX to see if I can find that post about STU vs STX. At best it's relative to his car's prep at the time. I do think his 2011 would stand a better chance in STX now then it did when he jumped to ESP with the watts link, better shocks/struts and spring rates and all that jive. It would be at least more indicative of what the chassis is capable of. Despite my pleading he has made the sane choice to let the notion that the car is capable of trophying die and I don't fault him for that as he seems to be doing much better in ESP then in STX!

More or less I'm just griping that there isn't any Street Tire place to play for the Mustang outside of RT and ST where limitations on tire width and rim width or both really keep this Pony car down. Part of the reason I'm staying in STX for a while is because I DO enjoy that challenge so I plan on at least trying to make it work. Maybe by the time I get all the way there I'll be able to afford to test the 265 vs 285 theory and see if it genuinely is better for the Mustang in STX vs STU.

 

[jayel579]

I am not sure why the SCCA decided that the car has to be in one or the other, leaving it in both would do nothing to upset the apple cart in terms of the current competitive cars in each class.

You're trying to figure out how the SCCA thinks? Don't ever try to read a rule book, they change their minds like the wind