NOT Another...Yes...another auotx build thread

[kcbrown]

I suspect that it's a way to maintain a little understeer under the lower lateral-g cornering that should cover any reasonably sane street driving without resulting in much heavier understeer out toward the limit. That the car then gets progressively "less tight" the harder you drive it as the LLTD effects become a relatively bigger part of the picture. The larger rear tire also dials in a little extra cushion against random right feet that don't understand the concept of throttle modulation as well as they should.

None of this makes any sense to me.

The Roadrunner engine makes more power but less torque than the Coyote, and the torque curve isn't as flat as that of the Coyote, either. If there's any car that needs the extra cushion against lead feet, it's the base 5 liter Mustang, not the Boss 302.

The engineers could have simply tightened the suspension all the way around and gotten the same understeer behavior out of the Boss as they get out of the GT. Whatever reason they had for putting bigger tires out in the back, it must not have been to maintain understeer. After all, between the Boss and the GT, it's the GT, and not the Boss, that you want more understeer characteristic in, since it is going to be a far bigger seller and, thus, a greater liability risk.

No, I suspect it was to make it possible to get on the throttle earlier on corner exit and/or to make that more effective, and the larger rear bar and heavier relative spring rates are being used to, as much as reasonably possible, maintain the relative neutrality of the car. After all, the target audience of the Boss 302 (and especially the Laguna Seca) is people who want to drive the car on the track, and as a group those people will tend to be better, more capable drivers than those who buy the GT.

At the very limit it may well be pretty close to neutral (though we don't know anything about such matters as whether any leading throttle was being used or only maintenance throttle).

Other reviewers have suggested that with the Boss/LS there is a greater handling balance sensitivity to how hard any trail-braking is being done. That at least sounds consistent with trying to balance an understeer effect with an oversteer effect, given that the two effects do not necessarily increase at the same rate with respect to lateral-g.

That makes a lot of sense.

 

[csamsh]

There's also the stupid answer...they gave it a staggered fitment because of the looks, and to sell tires.

 

[Mountain]

None of this makes any sense to me.

The Roadrunner engine makes more power but less torque than the Coyote, and the torque curve isn't as flat as that of the Coyote, either. If there's any car that needs the extra cushion against lead feet, it's the base 5 liter Mustang, not the Boss 302.

The engineers could have simply tightened the suspension all the way around and gotten the same understeer behavior out of the Boss as they get out of the GT. Whatever reason they had for putting bigger tires out in the back, it must not have been to maintain understeer. After all, between the Boss and the GT, it's the GT, and not the Boss, that you want more understeer characteristic in, since it is going to be a far bigger seller and, thus, a greater liability risk.

No, I suspect it was to make it possible to get on the throttle earlier on corner exit and/or to make that more effective, and the larger rear bar and heavier relative spring rates are being used to, as much as reasonably possible, maintain the relative neutrality of the car. After all, the target audience of the Boss 302 (and especially the Laguna Seca) is people who want to drive the car on the track, and as a group those people will tend to be better, more capable drivers than those who buy the GT.




That makes a lot of sense.

From what I understand in reading the BOSS 302 book, the engineers actually added more understeer into the LS over the regular Boss. There was no detail that I found as to why, but I think I have an idea why more understeer was added to the Boss in general.

The Boss is supposed to be a track car, right? That is the whole basis around it. It's easier for the average car entusiast to control a car that is understeering rather than oversteering. Understeer was added to the Boss to make it safer to drive it on the track. If pushed hard, the understeer can teach a average drive how not to push their car or what dangers may lie ahead if they do. You put the car into a corner with too much speed, it understeers, and naturally an average driver would try to slow the car down and control it. An understeering car doesn't look cool or feel right. If the car were to have a tendancy to oversteer, I bet you the average driver will try and be a hero and control the car (drift) or just plainly lose control of the car. Oversteer is fun and looks cool or it can scare the shit out of you and, when that happens, mistakes are made.

Really, why would Ford go through all the trouble to develop a special, track oriented car and give it such soft spring rates up front compared to the rear? The car has adjustable dampers, so it wasn't for ride comfort... and again, it's supposed to be a track oriented car, one they openly made compromises for in respect to normal product, like the GT. The GT500 runs front springs 200-260 lbs/in [and 180-200 lb/in in the rear] depending on the year and package, so there goes that ride comfort thing again (I understand the engine weighs more; Boss is 135-150 lb/in; 148 for the Boss and 137 for LS).

I think the staggered setup is there for rear wheel traction. 1. for those who just mess around the car in a straight line (people who buy the car for the novelty) and 2. to help put the power to the ground on corner exit (how many average drivers do you think try to apply throttle too early or apply too much coming out of a turn?). Thicker sway bars over the GT were added to the rear to match the wider, stickier tires in the rear compared to the front and keep the goal they had for balance of the car's rotation.

 

[Mountain]

Terry and Norm are saying the same thing I am.

To anser your questions again, think of it like this. The oversteer comes from combination of the spring rate setup and the tire/wheel size setup. The change in the rear sway bar is just something added to fine-tune the amount of understeer. That's the most basic way I can put it.

 

[Norm Peterson]

None of this makes any sense to me.

"Less tight" the way I intended it to mean = less understeerish, and this is more or less circle track terminology. As used in that sense it's not really about specific suspension firmness. Does that help?

"Understeer" as you observe it while driving is the summation of several effects that don't have to remain in the same ratios to each other as the lateral g's increase.

The Roadrunner engine makes more power but less torque than the Coyote, and the torque curve isn't as flat as that of the Coyote, either.

Since you wouldn't be using all of the available torque when you're rolling into the throttle as you unwind the steering on corner exit, the difference between the 380 and 390 peaks is meaningless. If anything, the shapes of the torque curves is more important as this goes to predictability. Probably depends on what kind of driver/driving we're talking about, though (see "Otherwise . . .", later).

The engineers could have simply tightened the suspension all the way around and gotten the same understeer behavior out of the Boss as they get out of the GT.

When you tighten the suspension all around, the components of understeer due to front and rear wheel cambers change . . . both in relation to each other and to the total. I'd expect that these camber effects taken together (but separate from everything else) are progressive and oversteerish as roll is reduced. Hence you'd need a slightly more understeerish setup in terms of alignment/tire sizes/wheel widths/spring and bar rates just to remain in the same place.

It's kind of a modern-day Gordian knot where even though a brute-force expedient approach like revising the distribution of roll stiffness will "work", like cutting the knot with a sword they really aren't true or full solutions.


Otherwise, we're saying about the same thing with respect to handling balance sensitivity to the throttle. Just that we're looking at different people and different situations, some random hoon on the street vs an experienced track rat shooting for a personal best lap time or a competitor gunning for position and series points or contingencies. As far as any street-legal car is concerned, Ford would have to consider folks in the first group and probably have to assign priority there. Off-road only models like the FR500 series cars, probably not.



FWIW, I agree that we're trying to approach RP's driving and evaluation skills. To varying degrees of success, I'm sure.


Norm

 

[csamsh]

18x11 Forgestar F14 fitment photos and build update:

Read first, then pictures.

SO, in case you haven't noticed, my Forgestars came in, and they have 315/35/18 V710's mounted on them. They fit great, look great, weigh great, and I couldn't really be happier.

In other news: I also got a Cobra Suzuka GT seat and G-Force 6-point harness installed:




I had really been doing things the hard way. If I could start again, I would do seat first, then everything else. Now that I am solidly connected to the car, everything is amplified. Shifts feel different, I can feel the suspension working, understeer and oversteer are more clearly defined, as is body roll. Changes to shock and tire settings are incredibly obvious now. THAT BEING SAID- I would not daily drive THIS seat. There are other ones out there though (Imola GT?) that would probably be fine. I ended up going with the G-Force harness because the Schroth supplier had somewhat of a mixup in getting parts to Terry @ Vorshlag. Oh well, maybe something to do for the future.

Weekend autox events:

Saturday- Camaro vs. Mustang challenge @ Texas Motorplex in Ennis, TX

So this was an event that was conceived on some forums/Facebook or some such. It was a one-off Ford vs. Chevy "showdown" that was to consist of drag racing and autocross, with a Ford-powered team and a Chevy-powered team. The cars would get a couple passes and then be organized from slowest to fastest, with heads-up drags happening, Ford vs. Chevy, all the way up the time sheet, for points. Kind of a cool idea. The sky didn't agree. As far as I can tell, drag racing was canceled. At least, it wasn't going when I left.

Autox- we had a small-ish lot, 350'x350', with two lightpoles in the middle of it. Terry managed to set up a pretty fun course anyway, less than 30 seconds, no slaloms, nice and safe for all the people for whom this was their first time ever being timed while turning.

Anyway-first time out with 315's, so a nice test'n'tune perhaps. I made five runs, was the only non-Terry Fair car to get into 23's, and packed it up. I HATE changing tires in the rain, and the sky was threatening. There were some guys who made 30+ runs. People had a good time. This was not your regular SCCA bunch- people were doing burnouts on their street tires coming to the line, saving their spins with donuts, etc. Maybe not the safest/sanest practices around, but hey.

First impressions from the big tires: I need really different pressure and damper settings. The word of the day was "understeer"

Sunday: Oklahoma SCCA SoloII #8, Oklahoma City, OK

So I like doing these events because we get so many runs. Usually 8 or 9, and the courses can be long/fast. I was initially worried when I showed up in the morning, as about half of our parking lot was un-coned, and the rest of it was a tight thing made by a Miata driver. I joined in on the "let's open it up a little" chant and we put some high speed offsets and s-curve portions in, and, together with the two monster slaloms, it was actually a really fun course, with times in the 40s-50s range.

Today was the real test'n'tune I guess, and you can see my times drop as I made changes. Here's a table: (fyi, shocks are adjustable in 12 increments, with 12 being the most rebound, and 1 being the least). I started where I left off running 275/35/18 BFG R1's.

Run: Tires: (F/R) Shocks: (F/R) Time: (s) Comments

1- 33/32 - 6/9 - 46.707+1 - Undriveable. Loose on corner entry, pushy on exit, not stable mid corner. Coned due to understeer.
2- 32/31 - 6/9 - 45.517+1 - Marginally better. Felt a little better mid corner, more grip in general, still not good. Coned due to drifting in a slalom.
3- 31/30 - 7/9 - 43.136+1 - Much better. Less understeer at corner exit, better balance in corner, still loose on entry. Car still tough to handle. Coned due to head up ass.
4- 31/30 - 7/9 - 44.085 - Left settings alone to get a clean run "in class." Clean, but slow.
5- 30/29 - 7/9 - 43.165 - Same time as run 3, but more control, still loose on entry. Still understeers on exit.
6- 30/28 - 7/9 - 43.348+1 - Finally good mid-corner. I think 30/28 may be the numbers for V710's. Coned due to lapse in concentration.
7- 30/28 - 8/9 - 42.621 - Now we're getting somewhere. No more understeer at exit! Feels great. Still a tick loose on entry.
8- 30/28 - 8/8 - 42.129 - This run felt GREAT. I wish it wasn't the last one. Not really driven at 10/10ths though (as with all the runs today) as I was not sure what the car would do when I turned the wheel. This was good for 6th in raw time.

So...a 4.5 second improvement, all with shocks and tires. THIS is why having good shocks is good. The adjustments make very obvious and very impactful changes. I attribute my newfound tuning abilities mostly to the seat. Instead of bracing against the door and center console while one-handing the wheel, I have the extra concentration available to actually feel what the car is doing in the corners. I think there might have a been a 41.0 out there today if I had started with the good setup. Ah well...next time. Now I know where to start, until next time anyway, when everything will be different. Ha.

Anyway- to anybody contemplating a better seat- DO IT.

I'm not sure yet if I enjoy driving in STU or ESP more. I'll give ESP another few weekends, then I'll decide for next year. Street tires are fun. It's EASY to push the car and the feedback is great. I don't have to take a second set of wheels. Arrive and drive. On the other hand, you go fast with race tires.

I can get all four of my 18x11's in the car, but it requires me to remove my trunk latch, insert tires, and re-attach latch. Also, two tires will not fit in the backseat without removing the seat backs, which is technically a CP move. Will anybody care regionally? I doubt it. Then again, I don't have a ton of respect for rules, and I don't really care what people do when money is not on the line.

 

[Jucostud]

Hahaha lol at burnouts and donuts... Wonder who that guy was
. Can't wait to get new tires/wheels and get my suspension fixed so I can go again.

 

[csamsh]

Hahaha lol at burnouts and donuts... Wonder who that guy was
. Can't wait to get new tires/wheels and get my suspension fixed so I can go again.

Yeah no idea...probably somebody who was REALLY mad at his tires.

Come out to TMS on Sunday and check out the road course autox. They won't let you drive since you haven't done 3 events but I'm sure you could catch some rides.

 

[NDSP]

Yeah no idea...probably somebody who was REALLY mad at his tires.

Come out to TMS on Sunday and check out the road course autox. They won't let you drive since you haven't done 3 events but I'm sure you could catch some rides.

Are you going to drive to the event on your Hankooks and then switch to your Continentals on site? If so, might you be willing to "rent" your hankooks? I figured I'd float that out there, no worries if it isn't something your interested in doing.

 

[csamsh]

Are you going to drive to the event on your Hankooks and then switch to your Continentals on site? If so, might you be willing to "rent" your hankooks? I figured I'd float that out there, no worries if it isn't something your interested in doing.

No I'm driving down on my stock wheels. I don't like to put road trip miles on the rs3's if I can help it.

 

[2013MustangGT]

I have done TMS before, small track (interior track), but fun. The one and only time I was there was a 2011/12 Mustang GT went into the wall while trying to negotiate turn 1. His rear rotor cracked and he lost control.

 

[csamsh]

I have done TMS before, small track (interior track), but fun. The one and only time I was there was a 2011/12 Mustang GT went into the wall while trying to negotiate turn 1. His rear rotor cracked and he lost control.

That sucks. The event Sunday is actually an scca autox. They put cones out on the track.

 

[Sky Render]

Hash marks only go on the driver's-side fender!

 

[csamsh]

Hash marks only go on the driver's-side fender!

Normally I would agree with you. I have an OCD sense of symmetry. It's killing me to not have matching seats

 

[2013MustangGT]

Normally I would agree with you. I have an OCD sense of symmetry. It's killing me to not have matching seats

I was going to get two Suzuka GT seats because I wanted them to match. However, Terry suggested I use the Imola seat for the passenger side to save money. He took both of them out of the box and they looked good together. Just a thought for you in the future if you want both seats to be race seats.

 

[frank s]

Hash marks only go on the driver's-side fender!

I thought it depended on which side of the track the pits were on?

 

[Jucostud]

Somebody got the donuts from the autoX action on camara

 

[csamsh]

I thought it depended on which side of the track the pits were on?

Emergency crews needed to know where the driver was in case of a wreck, and with some things being LHD, they put them on the driver's side.

Teams varied colors though between cars to tell drivers apart coming into the pits though.

 

[Vorshlag-Fair]

Our photographer Brandon got some great shots of Mark's Mustang at the Saturday "Camaro vs Mustang" autocross event:









He was the fastest Mustang or Camaro in the official results. Nobody else was close. He had the new 315mm R compounds and 18x11" wheels working well!

More pics and video: http://vorshlag.smugmug.com/Racing-Events/Camaro-VS-Mustang-100513/

Cheers,

 

[ArizonaGT]

NICE