Project Update for May 23, 2012: We've done a bit of work to the car since the last update, and had another autocross to test changes before the Lincoln "Spring Nationals" event this weekend. Let's get right into the new stuff.
One of the changes we had planned to delve into if the car seemed to be ESP competitive was proper race tires. The defacto R compound DOT tire in SP is a Hoosier A6, but we had been doing well with a Kumho V710. The Kumhos have plenty of life left but work better as a road course tire than in autocross, so we pulled the V710s off of the 18x11/18x12 Forgestars and ordered some HoHos...
Go Big or Go Home!
Looking at the 2012 Hoosier Tire Listing for the A6, the obvious choice up front is the 315/30/18 size, which has 11.8" of tread width and 12.5" of section width. The problem is the height, which is only 25.6". That's short for this car, and even with our "tallest Ford made for it" 3.31 rear gear ratio, this height shortens the speed range in 2nd gear significantly. The goal is to at least be able to reach 70 mph in 2nd, and with the relatively short 2.43 ratio in 2nd, this means we have to watch rear tire height closely. When we ran STX last year (*twitch! shudder!*) we saw noticeable improvements going from 265/35/18 tires to a taller 265/40/18 size, which softened the rear ratio and extended 2nd gear speeds a noticeable amount.
The real goal for me is to avoid EVER having to go to 3rd gear in an autocross run (which inevitably means another downshift to 2nd), as the up/down/up shifts cost so much time. Gear the car right, including tire height, and you never leave 2nd. This 5.0L engine has torque everywhere so even if it doesn't have as much "snap" at lower speed corners it still has "more than enough". So, all that said...
I picked a pair of 345/45/18 Hoosier A6 tires for the rear and a 315/30/18 for the front. The 345 is the biggest 18" tire Hoosier makes in the A6 and has 13.25" tread width, massive 13.9" section width, and a big 26.8" tire height (the stock tires are 27" tall on this car). That's a 14" wide rear tire... the same relative size that CP cars use. This tire height allows for an insane 77mph top speed in 2nd gear at 7800 rpm, and 75mph at 7500 rpm. No more 3rd gear in a parking lot with this tire, ever.
Trying to fit a 14" wide tire under factory sheet metal car sounds insane... and went against my own better judgement as well as the recommendations of others. But I've taken some leaps of faith on this build using the "bigger is better" mentality that have paid off already. The car was also experiencing enough wheel spin in slow speed autocross corner exits with the 315mm Kumhos that I was willing to give this larger 345 mm wide tire a chance out back. Of course this tire would never fit up front without major fender surgery, so I went with a non-square 315F/345R combo - again, against my own recommendations. We had to space the 12" rear wheels outboard another 10mm to have the same clearance to the rear swaybar and inner fender structure as the 315 had on the same wheel as before. It was a gamble but I tossed the dice, hoping we could make them fit.
Yea, not a chance. These things are redonkulous. HUGE. So now the rear tires needed more spacer and protruded past the fenders a solid 1/2 inch, which I dislike both aesthetically and functionally. First, it widens the rear track, making the differential work that much harder and making slaloms/transitions that much more difficult to navigate. Secondly, it adds a potential rub point at the outer fender lip itself, if there is enough roll movement in the rear of the chassis to let it roll over and touch the tire. I was hoping that this wouldn't be a problem, and with a known amount of axle movement in cornering it could even tuck under the fender lip on the outer tire in turns. I also hoped the stiffer 275#/in rear and 550 #/in front springs (installed when we put on the Motons a week earlier) would keep the roll down enough to keep the rear tire away from the outer fender lip.
Other prep this week before this SCCA autocross was a swap to the rear spoiler (wing isn't legal in this series/class), and we could uncover the hidden SCCA stickers (something NASA requires). I didn't even add any fuel to the car from the last event - we loaded it into the trailer Thursday night and it sat there until the race on Sunday.
This next autocross would tell us a lot about this round of changes...
Texas Region Autocross # 3 at TMS
We're trying to make as many of our local "Texas Region" SCCA events this year as we can, and using each event as a test session. Amy was out of town on business this week, so I ran this event by myself. Hey, maybe I could win this time! Just like the autocross a week before, this event was set-up in the same sealed asphalt "Bus Lot" at Texas Motor Speedway, with the same course designer, but this time with the SCCA region running the show. This is my favorite group to autocross with - they put on an excellent event, every time. Well organized, great courses, good competition, great announcing (except when they let me do it, ha!), and final results are posted within hours. Things run smoothly, safely, and consistently. Its no coincidence that our Solo REs are also the event masters for the 2012 Solo Nationals - Jen and Brad Maxcy. (Jen whipped some ass on Sunday in their STX BMW, beat Brad, and PAXed right on my tail in Heat 1, with Brad 3rd in PAX for the heat)
Here are the event particulars:
- Pax Results: http://texasscca.org/2012_solo_results/tr12_3_pax.htm
- Class Results: http://texasscca.org/2012_solo_resul..._final.htm#ESP
- Course Map: http://vorshlag.smugmug.com/Racing-E...0/O/course.jpg
- In-car Video for Run 1
- In-car Video for Run 2
- In-car Video for Run 3
- In-car Video for Run 4
- In-car Video for Run 5
The results don't tell the entire tale, of course. This is where I begin my excuses. So, as I've said before, this TMS site currently has construction happening right at the edge of the lot surface, with Jersey barriers holding back a mountain of fine, silty dirt from the lot. Every time it rains (which has been often here lately) it washes this dirt/mud mix onto the surface of the lot. So early drivers get to clean off the driving line, mid-day drivers get a cleaner line with some added track temperature, and afternoon drivers tend to see the cleanest line but the most track heat. If its a cooler day the afternoon runs are quickest. If its a warming day the mid-day drivers are fastest. That last scenario happened on this day - 2nd heat drivers were fastest by a good margin. It helped that our top National drivers ran that heat also!
Left: Run #1 was quick. Right: Run #5 was my fastest
I ran in the first heat along with about 1/3rd of the 109 racers. The first run in Mustang was with the stickers still on the tires, but that didn't seem to slow the car down at all. On that run I had trouble with braking in all of the higher speed stopping zones (super hard pedal - no power assist?) but put in a respectable run. My 2nd through 4th runs were either slower or not much better, with continued braking problems. My 5th run I finally adjusted my braking zones back significantly, went slower into most turns, and dropped 3/4 of a second from my first run. It wasn't pretty but it was faster. This was the only 42 second run of the heat and put me #1 in PAX for that 1/3rd of drivers as well.
This was short lived, as Heat 2 drivers put in some phenomenal times and I dropped to 18th in PAX. There were two significant problems in my runs, and one "missing" problem. Well, other than my regularly crap driving, which goes without saying. The first car issue was a broken vacuum line from the JLT oil separator that was added in 2011. This part helps catch oil residue coming from the heads (that would normally pump back into the intake manifold) caused during high RPM use (7800 rev limit? Yea, that qualifies!). The problem was this JLT kit it came with plastic fittings and inflexible plastic vacuum lines that are prone to breakage.
After my first run it I opened the hood and the catch can lay there askew, with the line or fitting obviously broken. I grabbed some zip ties an secured the unit but with this line wide open I was losing vacuum. A-ha! This is why I was losing brake booster assist after any long straights, hence the hard pedal. Eureka! I've been complaining of this issue at autocrosses for many months, back into 2011, so there's no telling how long ago this fitting cracked (see below for "the fix").
Another issue was, as you can see above, the tire rub (then tire smoke) shown above. The 345/45/18 rears were both taller and significantly wider than the 315/35/18 Kumhos, and rubbed at two locations on the inside of the chassis - on the body at the forward section of the frame rail where it curves outward and on the rear swaybar. I would turn in, the car would take a set, where the axle would slide over and the tire would move relative to the rim, and the inner sidewall would start to "catch and release" the rub points - hop hop hopping through the long turns. This caused enough rubbing that it would smoke heavily. I kept an eye on it but there was little I could do other than drop out or keep going. I kept going.
So I had miscalculated a bit on the 14" wide rears. They need to go out another 1/2" and then they'd look like Bubba going to the Drag Strip. We have the rear ride height compromised enough as it is for extra clearance and Amy said a firm "NO!" to flaring the rear of the car. So... when this set is gone we'll switch back to the 315 and tuck it all under the rear fenders. Again, I'm a fan of a narrow track for autocrossing, and this is very much "not narrow" at the moment.
The one problem that was missing was... the traction control faults and steering feedback shudder. WTF? This is a mystery but I have noticed that the more wheel spin we see the more problematic the steering is and the more faults we trigger. With 345mm rear A6s and a fresh LSD out back there was dramatically less wheel spin. This is good, because both the OEM replacement and the FRPP race re-programmed steering racks (M-3200-EPAS, $1249) are on national back-order until June 23rd. We found one in the country after calling dozens of places, and they were saving it as a spare for their GRAND AM race team. Wouldn't sell it to us for any amount of money. So... we cross our fingers and hope this steering rack and traction control fault issues take a hiatus. :/
We had been running with -4.0° front camber and I also noticed several pics showing the outside front tire loaded up at almost vertical, and not positive camber. Again, we're not using too much negative, and could even use a hair more possibly.
Updates After The Autocross
In preparation for the upcoming 4 day weekend of racing in Lincoln we knocked out these updates and repairs. First up was replacing the hoses/fittings and improving the mounting of the JLT oil separator.
Ryan made the bracket out of aluminum and bolted it to open flanges on the valve cover, then bolted the catch can to that. He had one of our vendors make the lines and fittings and buttoned that up quickly. Looks like how it should have been from Day 1 - I knew better than to let that aluminum can hang from plastic hoses and fitting. Its funny how these obviously poor parts can come back and bite you in the ass... no idea how long this has been broken. Hopefully I'll have a better brake pedal from now on!
Next up was the catch can installation for the rear differential fluid overflow problem we've been fighting at track events and even some autocrosses since day 1. Remember the fiasco this year from TWS, with oil spewing onto the rear tires? The little vent cap thing in the RR axle tube is a joke, and oil can and will come spraying out when it gets hot - and it will get hot at a track day. I bought this billet catch can and mount in mid 2011, and we finally got around to installing it. The factory vent was removed and a new fitting and custom made lines were fabricated by our hose vendor (who's a good friend of mine). Ryan bolted the catch can to the rear seat bulkhead and routed both the vent line from the axle and the "overflow" line from the catch can through a factory grommet in the trunk floor, on the driver's side just behind the back seats. Fixed!
Some wider spacers were procured and the 18x12 wheels and 345 tires went more outboard, and look just terrible. If we could massage the inner fender areas we could make this tire fit, but that's a big no-no in the SCCA, so out goes the wheel. With a custom swaybar (legal) and 45 minutes with a sledge hammer (not), these wheels would tuck inside the fenders. GRR.
Last up was foglight opening "grills". We had a customer's Boss 302S race car in the shop this week to do some suspension set-up work and we saw several great ideas on the car, including how they mounted the wire mesh grills in the foglight opening. These are functionally necessary to keep rocks and balled up tire rubber from hitting the evap core or radiator fins when lapping the Mustang behind other cars. The lower grill opening is also wide open from the factory and the evap fins on our car are already smashed up a good bit, and starting to happen behind the now missing foglights.
Ryan took the tighter stainless mesh material we picked up a few weeks back and made some round sections slightly larger than the foglight openings, then painted them black. Then he drilled a series of VERY small holes around the round rear openings in the grill. Last he tied stainless safety wire thru these holes to hold it in place, just like how the 302S does it. Sometimes seeing something done simply makes a solution so obvious. Looks good, functions great, no more smashed cooler fins. The grills are almost invisible at this rez above, but clearly visible in person or in higher rez pics.
Oh yea, the under-trunk carpet was reattached so we'd be extra-legal for the upcoming dual SCCA events.
Many Upcoming Events
There are several competition and track day events we have planned in the near future for our Mustang test mule. This weekend in Lincoln is the SCCA "Spring Nationals", with a ProSolo Friday-Saturday and a National Tour Sunday-Monday. After that we have a weekend off, followed by 3 straight weekends of racing in June:
- May 25-26, SCCA Lincoln ProSolo - ProSolo autocross
- May 27-28, SCCA Lincoln National Tour - Autocross
- June 8-9, Optima Face Off at the HOT ROD Power Tour - Autocross + Speed/Stop + Time Trial track event (ECR + Ball Park at Arlington)
- June 14-15, Mid-American Ford Meet, track event (Hallet Motor Racing Circuit)
- June 23, Five Star Ford Track Day (ECR)
Looks like we have a busy month of testing ahead. Click any of the links above to find out about coming to watch or to enter any of these events. We'll have the Mustang at all of them listed above, and we will give ride-alongs on any run we take, if they allow it. Just bought a special set of 200 treadwear tires for the Optima event, we'll be running the big A6s in Lincoln one more time, and the 315 Kumho V710s for the other two track day events at ECR. I'll talk more about each of these events in future thread updates.
Trailer is loaded, 11 hour tow to Nebraska tomorrow...
Cheers,
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