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Discussion Starter · #41 · (Edited)
A more aggressive test drive today with the new street tires (rather than my all seasons). Purposely induced wheelspin in straight lines and exiting corners gave no signs of torque steer. As expected, no rubbing with stock springs. Eibach front swaybar and Suspension Techniques rear swaybar on stiff (equivalent to Eibach rear swaybar on soft) are a nice balance for canyon carving with the stock springs.

245/40-18 Michelin Pilot Sport 4S on 18x9 +40 Ground Force GF07 rims tuck nicely into the fenders without rubbing. Could easily fit 255 width if desired; I won't in order to stay on the good side of fuel economy when street driving.

Edit: When I installed the wheels, it slowly dawned on me they weren't hubcentric, which I confirmed a few days later while swapping back to my all seasons. Seller did not send hub rings with the wheels, so I've ordered a set to reduce from 73mm.

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Discussion Starter · #42 ·
Lightening the Car & the Wallet

It's amazing how expensive lightness becomes. When I loosened the purse strings, it was inevitable; if I can justify X, I can justify Y and then Z, right? Rims, battery, Wilwood brakes, and a race seat have all bled the bank account for the sake of having no excuses other than my driving.

  • Titan 7 rims were probably the most expensive pounds lost and, because 265/35-18 tires weigh so much, I'll be comparing 17" options to see which is most effective. @freakin_elrod might have been on to something by sticking with 17" rims.
  • The MeLe battery box & Odyssey battery were okay expenses. At least I thought so until I added a battery maintainer for the winter and a portable jump starter for travels.
  • 13" Wilwood brakes to remove many pounds from the front unsprung weight is better use of money than the rims. Because many more pounds removed for the money.
  • Then today's decision was which race seat. FIA certified or not? After all, Corbeau makes some nice seats and they're relatively inexpensive because they're not FIA certified. But, just in case, I decided FIA certification has its merits even if autocrossing doesn't consider it a requirement (which would be moot anyways since the seat is on sliders). Still, it is shocking how an $850 seat gets so much more expensive when you add the base and sliders and side rails! Based on the dimensions Jon Lugod had for his Bride seat that fit so cleanly, I selected the Sparco Evo L QRT seat; hopefully I won't grow into the extra width, but it does seem like a good idea to have it for potential codrivers.

If one seat is good weight loss, why not two seats? The left front of the car is heavier than the right by 140 lbs with me in the driver's seat, so removing weight from the left front should make it easier to corner balance. But maybe not since only the battery is in the left front while the seat is just behind the center of gravity.
 

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Discussion Starter · #43 ·
Suspension Case Study

Clifford Moten's STH build braking and turning
Ground Control coilovers with 8k front springs (450 lbs/in) and 10.7k rear rear springs (600 lbs/in) with stock front swaybar and Suspension Techniques rear swaybar, 255 tires on 18x8.5 R716 Option Lab Wheels
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(pic by Robert Killmer from 15 July 2020 post in SCCA STH Class group on Facebook)

What I see is the right front tire staying fairly upright (good), but the car is onto the bump stops in front because of the braking (bad). He is likely running what should be a relatively oversteering rear suspension to get good turn-in under these conditions. You can also see how the rear roll stiffness is still slightly higher than the front. Therefore one would expect that increasing front spring rate to keep the car off the bump stops would be a big overall help, though rear springs and/or rear swaybar would need to be increased for cornering balance.

Ground Control's typical front/rear spring suggestion is 525/600 or 550/650, so Clifford's 450 lb/in in the front is pretty soft and the lowest anyone should consider. On my ST1, that works out to a 2.1 Hz wheel rate and the tires' spring rate knocks the ride rate well below 2 Hz, so there's definitely room for improvement and avoid a crazy stiff ride.

So with my suspension choices, the intention is to try staying off the bumpstops as much as possible under braking and to keep the car from lifting any wheels.
 

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Discussion Starter · #44 ·
Wilwood is getting further behind on orders due to COVID. What had been a Jan 15 estimate has become a Feb 22 estimate. Wilwood is an essential employer in California due to their military contracts. Thankfully this isn't something I need to begin the autox season.
 

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Discussion Starter · #45 ·
Seat, sliders, & side brackets arrived today in two boxes. The base is backordered, expected to ship by the end of this week.

The Sparco EVO L QRT is none too wide because I fit comfortably snug. I was hoping for a little more wiggle room, for potential codrivers. For reference, I fit in the FoRS Recaros just fine, but not the FiSTs. "Really, I'm not THAT wide, not yet!" LOL
 

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Discussion Starter · #46 ·

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Discussion Starter · #47 · (Edited)
Quaife is installed. No serious testing yet due to weather, but I can tell it's working. Among other things, better mpg noted in the rain. My custom double adjustable Koni front struts are finally modified with the Ground Control coilover sleeves, but had to shorten the sleeves. Still plenty of range to drop 1.5". [edit: er, maybe 1.375"]
 

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Discussion Starter · #48 ·
Ground control coilovers with camber plates placed on modified custom Koni double adjustables originally built by ProParts. Normally the coilover sleeve is 3" long, but to avoid disassembling the struts, I settled for grinding off the stock spring seats and trimming the sleeve flush with the top of the strut. This left 1-3/8" for dropping while still having full thread engagement. Probably not quite enough for 1-1/2" drop even with the 525 lb/in springs (vs. 550 lb/in if you've not removed a little weight) Ground Control sent with the kit. Center nut should be tightened to 18 ft-lbs using a dial torque wrench; clickers can over/undertighten in this critical area. The mounting studs use OEM torque spec.

Not included in Ground Control's kit were the helper springs with coupler that I added. The helper springs keep the spring seated when the strut extends. Missing in the pic are the bump stops.

Remember this is not intended for my primary coilover set, rather as something to help me dial in the rear spring rates & swaybars and be a backup coilover set when the primary ones need to go in for maintenance/changes. The primary set will likely be installed early April if they arrive in March.

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Discussion Starter · #49 ·
Spent the afternoon assembling the Sparco Evo L seat, sliders, and seat base. Without pictures/instructions, at each step, if there was a way to assemble it wrong, I found it. Think I disassembled it 4 times. I'm disappointed that the base & sliders weigh 15 lbs, so the hoped for weight savings will be minimal. Will swap seats tomorrow morning.
 

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Discussion Starter · #50 ·
It took me all afternoon today to finish this?!? Well, yes, between one thing and another. Needed T50 torx bit to remove seat belt clip from old seat and then needed grade 8 bolt/nut to fasten it to the Sparco, so 2 trips to town. It's a bit higher right now compared to the stock ST1 seat lowered all the way, so I'll be dropping this a notch or two. Otherwise fit is perfect.

I'll have to figure out how to hook up the seatbelt in use wiring to avoid acknowledging the error message at start-up. Some other minor detail to finish, like threading the seatbelt through the hole or just installing a harness... don't know, but for now the seat is installed and it ain't coming out any time soon, LOL.

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Couple of finger-widths at the wings.
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Better-than-stock clearance of the center console.
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Generous door clearance.
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And a rear view of the very shiny fiberglass finish. The green reflection is a tarp on the ground outside and the white reflection is a rag on the seat. Oops, my sleeve slipped into the frame, too.
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Discussion Starter · #52 ·
Oh my. Let's start guessing what he's going to lose first in his big seat crack. I go first.
I found a pen when I pulled out the stock seat, LOL.
 

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Discussion Starter · #53 ·
I like her!

Went for a test drive after adjusting the seat one notch down on the seat which makes it like the stock ST1 seat fully lowered. This is the middle round hole on the Sparco QRT-R side rails. If you're tall and need more helmet room, the bottom hole will do wonders for ya. To give a little rake to the seat, the forward slotted hole is next to the top. Fits me very well, I'm very comfortable.

Climbing into Pepper is more of a head-first operation now. Still working out the best exit procedure.

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On my test drive, it was notable how much the Quaife is pulling me out of corners without wheelspin. Yes, with the Michelin PS4S tires in 44F weather, I could still get some wheelspin and traction control would engage. She is still on stock springs, Eibach front swaybar, & ST rear swaybar on hard, so still deliberately set up to understeer. Fantastic turn-in with that front swaybar, even with what should be a numb toe-in alignment.
 

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Discussion Starter · #54 ·
A Few Words About the Mainstream STH Cars

Audi TT, awd

600 lb/in front, McPherson strut
900 lb/in rear (motion ratio of about 0.7), divorced spring multilink.
3290 lbs with driver, 59%/41%
Ride height -1"
-2.8 deg camber front
-2.0 deg camber rear
Notes: Difficulties with access to the front strut adjusters due to small hole. Cross-weighting was 50.5/49.5. Being awd, limited to 245-width tires. Engines seem to blow when tuned. 30-35 mpg on the highway. Clutches wear fast.

VW GTI, fwd
425 lb/in, 9k, 600 lb/in front [mild, medium, extreme], McPherson strut (motion ratio of 0.97)
750 lb/in, 14k-16k, 1200 lb/in rear [mild, medium, extreme], divorced spring multilink (motion ratio of 0.642)
Ride height -1" to -1.25"
300-310 HP, 350+ ft-lbs (per Jason Vehige current owner of car built by Brian Flanagan and is for sale as of yesterday)
Notes: Difficulty obtaining enough negative camber like the ST, is easy to fall into reverse camber curve when lowering, high cg like the ST, tire rubs possible, clutches wear fast in manual transmission, DSG automatic transmission is possibly quicker in autox after some programming, a turbo blew & differential bearings died in the ex-Flanagan car.

Honda Civic SI, fwd
600 lb/in front (secondhand hearsay), McPherson strut
900 lb/in rear (secondhand hearsay), divorced spring multilink
Notes: Clutches slip even in stock form, 38 mpg driving to events(!), tough to get more negative camber.

Subaru WRX, awd
8-10k front, McPherson strut
8-10k rear, McPherson strut
340 HP
Notes: Engines blow, balancing with swaybars is finicky & necessary to keep away wheelspin and understeer. For some reason, the WRX guys have stayed away from the 12k/12k setups that the STI drivers are using in STU & ASP.
 

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Discussion Starter · #56 ·
I like her more now!

The Ground Control coilover kit with camber plates is finally installed after many various delays and frustrations. I'm only about 3 weeks behind schedule in that regard, with the autox season starting for me in two days. Have driven all of about 60 miles... in the rain. Consequently, I do not know what the limits are, but I've really enjoyed the glimpse I've had and she gave me lots of confidence!

Ride quality is fine at 525 lb/in front & 700 lb/in rear. It's certainly no worse than stock, possibly better. It is a little different than stock and I probably need to give the front Konis another half turn of increased rebound.

Wilwood brakes install and a corner weighting are scheduled for March 15. I have autocrosses scheduled every weekend between now & then. Expect to install the lightweight battery and possibly the intercooler before that appointment.
 

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Discussion Starter · #57 ·
What a joy!

First autox run on the new setup resulted in a 270 degree snap spin in the first corner, LOL. Thankfully was due to being rushed, so rear tire pressures were absurdly high rather than a miscalculation. A couple more runs got the pressures dialed in: 33F/31 R. Driver got in the ballpark after a few more runs, but there is still more time to lose as I adapt to a car that responds so well.

Once tire pressures were corrected, it confirmed my spreadsheet is giving me the right numbers <whew>. Inside rear wheel is lifting a little mid-turn, but not in a slalom. Busy instructing and then 9+ fun runs, I totally forgot to take a pic!
 

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Discussion Starter · #58 ·
Adjustments

Today's competition proved that I'm very close to where I should be after the upgrades. Making some adjustments may or may not find me the last 0.2 seconds that will put me where I expect to be, though I can also get there just with driver improvement.

I dropped rear tire pressures another pound so I have a little headroom if the pressures build up during a run, so now using 33F/30R. Decided turn-in is a little lazy, so plan on a touch of toe-out, like 0.1 total. Also will swap in 750 lb/in rear springs and put the rear swaybar on soft. Going to drop the rear ride height 1/4" from its current location. Front struts need maybe a half turn more compression and I'd have done that at that track, but didn't have a longnose Koni knob.
 

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Discussion Starter · #60 ·
A few more gratuitous pics after washing. These are the street tires, 245 Michelins on Ground Force 18x9 +40 rims.

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