[gemery]

2021 is the year for Pepper to switch from a tripoding G Street player and become a Street Touring Hatchback weapon. Here is the faithful steed as last seen in 2020 before going into winter storage.

My plan from a couple years ago was to upgrade Pepper in September 2021, after her second trip to Nationals. Unfortunately COVID-19 cancelled half of last year's season, the 2019 Nationals that would have been her first Nationals, and most likely affect the start of the 2021 season. Rather than mope about what can't be changed, I'm pulling the trigger now.

I wanted to do the build in one fell swoop, however the timing of the upgrade dictated budget constraints, so I'll begin with an "STH Light" build. Scheduled for January, the first phase consists of installing a Quaiffe limited slip differential, JBR front swaybar, front strut brace, and re-installing the stock front struts temporarily while the double adjustable Konis have the spring seats cut off for a Ground Control coilover conversion. The GC coilovers get installed soon after, hopefully before the first scheduled event (which may or may not occur at the end of February... current Oregon COVID restrictions put a maximum of 50 attendees on outdoor events, but if conditions improve, that can become 75 or even 150 attendees). Maybe I'll install the Vortech(*) intercooler I stashed away last year if winter steelhead fishing doesn't distract me.

Later in the year, I'll get more serious about the build, adding two sets of 18x9 rims, a tune, and substituting YCW, Fortune Auto, or Feal coilovers for the GC coilover conversion,.

So, I hear you ask, why the GC coilover conversion if it just gets replaced in a few months? Well, taking lessons from @freakin_elrod, I learned it's worth having a second set of coilovers to use when the primary set is being revalved or sent for servicing every year or two. Plus I already have the Konis, so this is a cheap, reliable, & quick entry to STH, even if it's not going to have the high spring rates one expects one expects of a national-level STH car.

(*) The Vortech intercooler is the only off-the-shelf intercooler that fits with the dreaded active grill shutters in place and the STH rules do not allow them to be removed. Meh, such is life.

Current Build

• 26 Dec 2020 - G Street: Borla cat-back exhaust, Suspension Techniques 2-position rear swaybar, rebound adjustable yellow Koni shocks in rear, custom built double adjustable Koni front struts, 2 sets of Enkei RPF1 17x8 +48 rims, one set of Bridgestone RE-71R 255/40-17 & one set of Yokohama A052 255/40-17 tires.
• 15 Jan 2021 - STH: added upper front strut bar by Massive.
• 21 Jan 2021 - STH: added Eibach front swaybar.
• 6 Feb 2021 - STH: added Quaife.
• 8 Feb 2021 - STH: added race seat.
• 25 Feb 2021 - STH: added Ground Control coilover kit with camber plates (finally!). Have 525 lb/in front & 700 lb/in rear, Eibach front swaybar, ST rear swaybar on stiff. Race wheels are 18x9 Titan 7 +38mm wearing 265/35-18 RE-71R. Street wheels are 18x9 Ground Force +40mm wearing 245/40-18 PS4S.
• 2 Mar 2021 - STH: spring swap to 525 lb/in front & 750 lb/in rear, Eibach front swaybar, ST rear swaybar on soft.
• 15 Mar 2021 - STH: added Wilwood front brakes.
• 25 Mar 2021 - STH: upgraded intercooler to Vortech.
• 6 Apr 2021 - STH: Adapt-X tune by Monster Tuned.
• 16 Apr 2021 - STH: Set ST rear swaybar on stiff.
• 12 May 2021 - STH: removed Ground Control coilovers and replaced with Fortune Auto 510 series. 10k front & 14k rear springs. Swaybars remain same, with rear on stiff. Ride height dropped 3/4" from stock. The 265/35-18 tires on +38mm rims require 5mm spacers to clear spring adjuster on the front struts... long term solution is 6" springs instead of the 7" that were shipped.

 

[freakin_elrod]

Looking forward to your updates and progress with pepper in STH trim!

 

[bobharly]

(*) The Vortech intercooler is the only off-the-shelf intercooler that fits with the dreaded active grill shutters in place and the STH rules do not allow them to be removed. Meh, such is life.

I think you have this all backwards. You should be thankful that Vortech was thinking about you and STH. Every other aftermarket manufacturer abandoned you... But Vortech. They got your back. The backside of your active grill shutters.

Out of curiosity, why Quaiffe? I'm trying to differentiate differentials... (yes, I did that...)

 

[gemery]

Out of curiosity, why Quaiffe? I'm trying to differentiate differentials... (yes, I did that...)

The LSD choices that I'm aware of are clutch pack (OS Giken), torque biasing gears (Quaife), and slightly different torque biasing gears (Wavetrac). Clutch packs and Wavetrac offer the ability to provide power if a driven wheel leaves the ground and they can be tuned, so they're probably better than a Quaife for competition. The Quaife will just give you wheelspin when a wheel leaves the ground, just like an open differential, and there's no choice in biasing levels, so it's not tunable. However, the other part of the equation for a street-driven car is the desire to avoid maintenance and a Quaife is the leader in maintenance-free operation.

Fortunately we have a couple FoST mitigations for the Quaife's competition weakness. First is adjusting/designing the suspension so it doesn't lift a front wheel. Second is using a Cobb-based tune so traction control reduces power if wheelspin is detected. And finally we still have the FoST's e-diff, weak as it is, applying brakes when it detects wheelspin. Listen to @freakin_elrod's 2020 autox videos to hear how little wheelspin these mitigations provide and he doesn't even have an LSD.

This begs the question of whether an LSD is needed. I believe the answer is yes, because it keeps the e-diff, the brakes, from activating. That reduces brake temperature and allows more power to turn into acceleration rather than heat & brake dust.

My preference is to never touch the differential again after it's installed, thus the Quaife. At least it is my preference until I find I can't tame the wheelspin and decide I need a Wavetrac.

 

[bobharly]

Listen to @freakin_elrod's 2020 autox videos to hear how little wheelspin these mitigations provide and he doesn't even have an LSD.

This begs the question of whether an LSD is needed. I believe the answer is yes, because it keeps the e-diff, the brakes, from activating. That reduces brake temperature and allows more power to turn into acceleration rather than heat & brake dust.

Oh, an LSD is definitely needed. The brakes are totally over used. No, I have noticed that many users like MFactory, which as far as I can tell is the same as Quaiffe and cheaper. Clutch plates are out for me, since I don't want to maintain it. And while Wavetrac sounds cool, it's overkill for me. I'll never take it out again, so having it adjustable would be a waste on me. I'm just not ready to spend the money or pull the trans out.

Where do I find @freakin_elrod videos? And do you post videos too? I always enjoy the pictures you post up of Pepper. I wish I had a photographer that good. Then I could count how many cones are trapped under the car...

 

[freakin_elrod]

We post most of our auto-x vids in the auto-x forum Show off your autocrossing ST!

 

[gemery]

Why choose to prepare for STH when classes like DSP, SMF, and the new XSA allow more freedom for modifications?

In DSP, like STH, you still can't correct roll center height on a lowered car, no significant weight removal, and additional engine mods are pretty much limited to a lighter flywheel/clutch. Wheel width is unlimited, you get to run Hoosiers, and fender flares are allowed. The FoST's competitiveness isn't going to come alive with those allowed mods (DSP is faster than SMF despite SMF allowing more mods), especially not against the class-dominant Mazda RX-8. Sure, you might be able to win a drag race, but you'll be lost in the curves due to a higher center of gravity.

Allowed mods in SMF are pretty open. Roll centers can be corrected, weight can be removed, big turbos are allowed, engine swaps are allowed, Hoosiers are allowed, aerodynamics are allowed, all the competitors are also fwd, and on paper it's still a slower class than DSP. So what's not to like? Well, like the competitive cars in the class, a fully prepared FoST will not be particularly pleasant to drive to/from events and I don't want to trailer a car. The FoST is a tad large compared to the older Honda Civics, CRXs, and MINIs that populate the class, but if you really want to go nuts on a FoST build, this is the place to compete.

Like DSP, XSA is a bad idea for a FoST since the rules are similar to SMF, but the competitors are not limited to fwd cars. Your big turbo FoST on 200 treadwear tires is not going to be competitive against a talented driver in an awd Mitsubishi Evo (or Nissan GTR or Subaru WRX) pushing 450 bhp... and that 450 bhp has been turned down from much higher because multiple builders have found they can't make use of any more power in autox even with awd. Most XSA competitors have not yet awoke to this reality, but eventually they will.

Which leaves STH as a good place for a lightly modified FoST. Even though the top competitors in the class are awd, they're crippled by the rules with a maximum tire width of 245 and the inability to add an LSD (fwd cars, like the FoST, are allowed 265 width and an LSD). Nationally, the Honda Civic Si and Volkswagen GTI have shown that the rules are reasonably balanced between awd & fwd, but with STH being new as of 2018, fwd cars have not been proven at Nationals. @freakin_elrod and @oinojo have done their parts for proving the potential of the FoST. Since STH gives you popular options like tunes and a better intercooler and a limited slip differential and 9" wide rims and coilovers and racing seats and brake mods, the car can still be a delight to drive to/from events and the wallet is happier.

 

[gemery]

Leaving the High Rollers Behind

We're all well aware of how much body roll the FoST has and that the body rolls more at the front than the rear, thus there is rear wheel lift, tripoding, and much peeing on cones. It happens so much, rain or shine, that the rear tires show no wear because they're in the air half the time.

So lowering the car to drop the center of gravity will reduce body roll and that improves cornering, right? Yes, a lower center of gravity will improve cornering, but, with McPherson strut suspensions, body roll gets worse as the car is dropped and that hinders the tires finding more grip!

How much worse can it be? Well, you gotta measure the suspension, find roll centers and then measure how much the distance between center of gravity and the roll center increases. Then you take the results with a grain of salt because measurements are never as precise as we'd like, but at least you have a better idea of what's going on. Fortunately, I did that for you... you can either repeat the exercise (please do, I'd like some verification!) or just trust that I've got the gist of what's going on.

For the first 1" drop of center of gravity, the moment arm increases by 1.7". The second 1" drop increases the moment arm by another 1.8". If you want to compensate back to stock body roll after lowering 1", you need springs or swaybar that are 7.63% stiffer. If you want to do so after lowering 2", the springs or swaybar need to be -15.82% stiffer. So it's not quite a linear relationship, but close enough that it doesn't matter. The fact that other McPherson strut cars have a similar ratio when lowering means I'm probably in the ballpark with the measurements.

Alternatively, one could put a spacer block under the ball joint to correct the roll centers. Unfortunately, that is not a legal modification in STH (or DSP). Another method to correct roll centers would be to move the suspension mounting points up and use struts/shocks with a shorter shaft, which is also not a legal modification in STH (or DSP). Fortunately, though, it doesn't matter much because we want to reduce body roll well below stock, so we're going to have springs & swaybars significantly stiffer than stock, stiff enough that 15% stiffer is a small fraction of the anticipated total of 400% stiffer. But I had to go through this exercise to know that.

The eagle-eyed & suspension-minded among you will notice that 2" of lowering puts the roll center below the ground and the internet says don't do that! Relax a bit... that happens with a stock FoST anyway, every time you use the brakes hard when you enter a turn. Haven't heard or experienced anyone blowing up as result, though we all know lowering 2" is a bad idea anyway because we'd be running on the bumpstops, right?

One last comment is that I tried finding the roll centers when the body is in roll. Ugh, that attempt did not go well and I have no clue what I did wrong. Hopefully I can revisit it. Again, people drive and even compete with lowered FoSTs without being hindered by where the roll center moves to. And roll center movement can't be any worse than what I've already experienced in G Street competition!

 

[gemery]

Leaving the High Rollers Behind, part 2

Back in late 2012, when the FoST first started showing up at autocrosses, any DOT tire was allowed. That was what I knew & loved, so returning to autox in 2018 after a 12 year absence, it was a bit of letdown to find that Stock, er, Street (Crap, they changed the name when I wasn't looking, too?) now had to run on 200 treadwear tires. However, for FoST drivers, it was probably a good thing because Hoosiers on a stock suspension can lead to...

173 S3 (GS) Bicycle Run (2-Wheeling) - 2013 Toledo Pro, Left, SCCAGoPro - YouTube​

Gordon Maciulewicz had that "moment" while driving Christopher Grayson's FoST. Hoosier's can pull 1.35G under the right (or wrong) circumstances, so it's no surprise to me that he bicycled. Top HS FiST drivers have moments like this often enough (and a couple turn turtle) on 200 treadwear tires, so I'm glad they don't have access to Hoosiers these days. I bicycled a Subaru Justy in 1994 while entering a slalom and I'm not eager to revisit the experience!

Fortunately I've not heard of any upside down FoSTs, but I can tell you that they pull 1.2+G on 200 treadwear tires and both inside wheels will be off the ground (barely). Here, let me demonstrate.

Knowing that Pepper weighs 3300 lbs in GS trim and pulling 1.2G in the above pictures and the transferred weight is 1650 lbs, I used this equation to estimate the average center of gravity height as 25.5 inches.

CG height (inches) = Transferred weight (lbs) * Track width (inches) / (G-force (G) * Total weight (lbs))​

200 treadwear tires are capable of pulling 1.3G. At least that's what I've seen from a top CAM competitor. Rearranging the above equation and playing with the center of gravity and track width, you discover that increasing track width via wheel offset that fit under the fenders barely moves the G-force needle (1.21G), whereas lowering 2" takes you to 1.3G before the inside wheels lift off the pavement. Now we probably shouldn't lower 2" because we run out of suspension travel and my numbers may be off, but I think I've amply demonstrated why lowering the FoST is important.

I'd also like to point out that the inside wheels lifting off the ground do not involve roll center heights, spring rates, or any other thing people consider for suspensions. It's all about track width and center of gravity and how much cornering G-force is present. With a high CG car with lots of body roll, it is possible to dynamically roll over, but I'm comfortable that is outside the FoST's capability, particularly when lowered and stiffened for STH.

Summary: lowering the car is necessary to achieve higher cornering G-force by keeping the tires on the ground and stiffening the suspension is necessary to keep the tire contact patch at its best for more grip due to McPherson struts.

 

[Slangwhanger]

Had a focus st roll at the Dothan, AL area autocross a few years back. Unsure of the mods but it was on 200tw tires. Only vehicle that has ever rolled there lol.


Sent from my iPhone using Tapatalk

 

[gemery]

At the bottom of the first post, I added Current Build and will update it as parts are installed.

 

[gemery]

Pepper is abusing me! I'm installing the front strut brace and managed to drop a heim joint into her bowels. It's like having a puppy that swallows anything & everything before you can stop them.

Won't be time to retrieve it before the incoming rainstorm (will last more than a week) and my frustration is to the point where I'll do stupid things, so stowed everything. Just going to have to wait for the next dry spell. What are the odds on whether Ground Control will ship parts before there is dry weather!

 

[gemery]

Naturally Ground Control notifies me that they've shipped stuff mere hours after I mention their name ;-) So that leaves differential shims & all those bolts from Ford needing a shipping notification.

 

[beretta96]

...and my frustration is to the point where I'll do stupid things, so stowed everything...

So I’m not the only one?! 😂

 

[gemery]

So I’m not the only one?! 😂

No, definitely not!

I feel it is worthwhile to know oneself well enough to take breaks when that feeling appears and the consequences are above normal. Fortunately I'm retired, not relying on Pepper for transportation, and can direct my energies elsewhere.

 

[gemery]

Ordered yesterday... FedEx. Sigh. My experience with UPS is soo much better.

 

[gemery]

Too Much of a Good Thing?

It's straight forward to calculate the ballpark for spring rates because ride quality suffers if you go too stiff and the automotive literature will tell you that people don't like more than 2.0-2.5 Hz. You're near the top of territory with 14 kg/mm (or 800 lb/in) rear springs and to maintain ride quality (aka "flat ride"), subtracting 10% for pitch movements from the rear frequency puts the front spring rates in the 10 kg/mm (or 550 lb/in).

An even lower spring rate in the front would be more ideal for ride quality, but then there will be more nose dive when braking into corners which puts the suspension on the front bump stops (increased spring rate) which creates understeer... happens all the time with a stock suspension and is why you can't use more than about 80% of the braking capacity when autocrossing a stock FoST.

The front-to-rear spring rate difference, however, means you definitely want a larger bar in the front to provide extra roll resistance. Especially because we know our lowered car has reduced roll resistance in the front. Again, it's pretty easy to calculate which swaybar & spring combinations have the desired balance. The rear swaybar is going to be mild, unlikely stiffer than the Strano or Suspension Techniques bar on stiff. The front swaybar will be at least the Eibach or Cobb, conceivably even the JBR, to keep the body roll to a minimum.

And there's the snag. Will a stiff front swaybar be too stiff for awkward one-wheel bumps, like when you cross railroad tracks at an angle? Will it contribute too much to wheelspin? The automotive literature acknowledges these are risks, but I've found only empirical guidelines: Front wheelspin, head tossing side-to-side, and a tendency for the front end to wander are all symptoms of a front swaybar being too stiff. But I've found no calculations to help get me in the ballpark.

So I'm guessing that percentage of spring rate added by the swaybar is the correct parameter to play with. A stock FoST has 48% of the front roll resistance coming from the swaybar, so it seems that if the JBR bar on hard is only 35.4% of the front roll resistance with anticipated spring rates, then it should be satisfactory.

The tuning plan, therefore, is to start out with an Eibach front swaybar and switch to the JBR bar unless unwanted symptoms develop. This also means rear swaybar and/or spring changes to match any front end changes.

 

[gemery]

I wanted to do the build in one fell swoop, however the timing of the upgrade dictated budget constraints, so I'll begin with an "STH Light" build. Scheduled for January, the first phase consists of installing a Quaiffe limited slip differential, JBR front swaybar, front strut brace, and re-installing the stock front struts temporarily while the double adjustable Konis have the spring seats cut off for a Ground Control coilover conversion. The GC coilovers get installed soon after, hopefully before the first scheduled event (which may or may not occur at the end of February... current Oregon COVID restrictions put a maximum of 50 attendees on outdoor events, but if conditions improve, that can become 75 or even 150 attendees). Maybe I'll install the Vortech(*) intercooler I stashed away last year if winter steelhead fishing doesn't distract me.

Later in the year, I'll get more serious about the build, adding two sets of 18x9 rims, a tune, and substituting YCW, Fortune Auto, or Feal coilovers for the GC coilover conversion,.

Already there are changes in the plan. As mentioned in the previous post, I'm starting with the Eibach front swaybar instead of the JBR. I've decided against the TB Performance front strut bar due to the lower cowl trimming required and am getting one from Massive since the Mountune are no longer available. An FSWerks lower front stress bar has been ordered. I'm not convinced of the strut/stress bars' utility, but until I try them I won't know.

Unexpectedly, the budget constraints disappeared over the New Year's weekend, a month earlier than I anticipated. Consequently, I ordered two sets of 18x9 rims, one set for the street(*) and one set for competition. In the spirit of dealing with only one change at a time, the tune will wait until after the suspension is somewhat sorted. I'm now eyeballing weight reduction items: battery, driver's seat, and front calipers.

Waiting for stuff is annoying. Can't do x-y-or-z until a-b-and-c arrive, so not much is getting done right now and then there will be a short burst of action and we're back to waiting. Differential shims will arrive Friday. Race Ramps arrive Tuesday, a week from today. Coilover kit has not yet shipped. So next week will see a small flurry of action and then a pause and we'll cycle through that at least one more time for the coilovers. If you're ordering things out of California, be aware that COVID-19 & stimulus money purchases are slowing deliveries. Brexit & UK lockdown are having similar effects if you need something from over the pond. At least tires from Tirerack, with warehouses in Washington & Utah, are rapidly serving the west coast, so I'm waiting for the rims to arrive before buying tires.

(*) Groundforce GF07 in silver, +40 offset. Originally I thought the street set would be 17x8, but upon checking Michelin Pilot Sport 4S prices, I discovered that the 245s are cheaper in 18". No, I don't need 18x9 to use 245s, but I like the GF07 appearance, so chalk this choice up to vanity. 245s have worked well for my street tires as a compromise between grip and fuel economy on the 18x8 premium wheels. My current Michelins have survived 91 autox runs and about 20,000 miles, but are closing in on the wear bars, so I'll probably retire them a bit early rather than transfer them to the new rims. I'll still have my winter tires, Bridgestone all seasons, on 17" rims.

 

[gemery]

Speed costs money. How fast do you want to go?

Not everyone is willing to spend for a no-excuses STH autox build. Even I balk at springing for the next levels in suspensions (MCS or custom Penske) because I do have my limits & priorities. So how much would a 95-97% build cost? What are the essentials when starting from scratch?

$1500 - Coilovers w/front camber plates
$ 700 - M-Factory LSD
$ 200 - Differential install kit (extra shims can be resold, so -$50 after install)
$1000 - Vortech intercooler (sorry, no other choice here)
$ 650 - Downpipe, catted
$ 950 - Exhaust
$ 450 - Eibach front & rear swaybars
$ 500 - Tune (wild estimate)
$1100 - Rims, 18x9 offset +45 to +38
$ 950 - Tires, 265/35-18 w/mounting & balancing

$8000 total

Yes, still scary. Fortunately some of you who might pursue the 95% goal have already purchased some of the gear and/or are good at finding deals. Unfortunately, we're in the territory of "but I could have bought an RS for that money" if you started with a new car. And how much more does a 99+% build cost?

$ 320 - Odyssey battery in MeLe box (weight loss)
$1532 - Willwood 13" discs & calipers (weight loss priority rather than braking performance)
$4255 - Titan 7 TS-5 rims, 2 pairs (lightest I'm aware of, 2 pairs for backup set of tires)
$1200 - Better set of tires
$1000 - racing seat(s) with sliders (weight loss)
$ 410 - front upper & lower strut bars, rear upper strut bar
$ 320 - helper springs w/couplers
$3500-8000 - Better coilovers
$600-5000 - data acquisition, cameras, etc.
$300 - corner weighting

What you quickly realize with a no excuses build, even if you're careful about spending the money, is that rims quickly become a significant part of the expense, with the coilovers being second unless you have deep pockets. This is no different than a GS build, except that the best (lightest) rims are bigger & thus more costly. I found 4 sets of rims to be "just right": 1 set for winter transport, 1 set for 3-season transport, and 2 sets for race use. The race sets let you have one fresh set of tires and one set of tires that are past 50% worn. The fresh set is used for rain (tread depth!) and important events while the older set is used until they're dead.

 

[bobharly]

Speed costs money. How fast do you want to go?

Not everyone is willing to spend for a no-excuses STH autox build. Even I balk at springing for the next levels in suspensions (MCS or custom Penske) because I do have my limits & priorities. So how much would a 95-97% build cost? What are the essentials when starting from scratch?

$1500 - Coilovers w/front camber plates
$ 700 - M-Factory LSD
$ 200 - Differential install kit (extra shims can be resold, so -$50 after install)
$1000 - Vortech intercooler (sorry, no other choice here)
$ 650 - Downpipe, catted
$ 950 - Exhaust
$ 450 - Eibach front & rear swaybars
$ 500 - Tune (wild estimate)
$1100 - Rims, 18x9 offset +45 to +38
$ 950 - Tires, 265/35-18 w/mounting & balancing

$8000 total

Yes, still scary. Fortunately some of you who might pursue the 95% goal have already purchased some of the gear and/or are good at finding deals. Unfortunately, we're in the territory of "but I could have bought an RS for that money" if you started with a new car. And how much more does a 99+% build cost?

$ 320 - Odyssey battery in MeLe box (weight loss)
$1532 - Willwood 13" discs & calipers (weight loss priority rather than braking performance)
$4255 - Titan 7 T-R10 rims, 2 pairs (lightest I'm aware of, 2 pairs for backup set of tires)
$1200 - Better set of tires
$1000 - racing seat(s) with sliders (weight loss)
$ 410 - front upper & lower strut bars, rear upper strut bar
$ 320 - helper springs w/couplers
$3500-8000 - Better coilovers
$600-5000 - data acquisition, cameras, etc.
$300 - corner weighting

What you quickly realize with a no excuses build, even if you're careful about spending the money, is that rims quickly become a significant part of the expense, with the coilovers being second unless you have deep pockets. This is no different than a GS build, except that the best (lightest) rims are bigger & thus more costly. I found 4 sets of rims to be "just right": 1 set for winter transport, 1 set for 3-season transport, and 2 sets for race use. The race sets let you have one fresh set of tires and one set of tires that are past 50% worn. The fresh set is used for rain (tread depth!) and important events while the older set is used until they're dead.

And lets not forget that the money bleeding never really stops. You always want something else and you are never really done...

And I'll say one more thing. You truly love Pepper. You have analyzed other competitive cars and the money you are investing. Despite the aging platform you are sticking by her side.

Keep posting this stuff. I'm learning a lot and enjoy your thoughts.