continued from above
Wait... Track Events???
Yes, track events. I am breaking my own, very sensible rule of no longer tracking this "still too new" car yet again. It just rolled 10,000 miles today, so I guess the new has worn off!! Hehe. I'm going to try to hit several NASA Time Trial events this year in the Mustang - I just had too much fun driving it on track with the extra grip and new horsepower in December. Due to the massive restrictions of the base classing that NASA levies against this car, I'm moving it out of TTB, skipping TTA completely (I added up 64 points of mods from aero, shocks and tires alone!) and slipping right into TTS (8.7:1 pounds per hp) - which is a simpler power-to-weight class. It probably won't do well against the modded Corvettes and other creations that show up in TTS but at least I won't be counting every point, taking 4 points for having no OEM wing, 2 points for the stock brakes, etc, etc. I could literally build an STX classed autocross car, still on street tires, that was up into TTS class on points alone. I know I know... those are the rules for TT, but I'm just going to bypass all of that and go have fun.
With the 315mm Kumho gumballs, the current 430 whp, and the added aero bits in store we might not be
that slow, but who knows until we track it? I'm ALWAYS fast when bench racing!
The car is under the power-to-weight limit with 3650 pounds (with driver) and 430 whp - but only just. I'll have my dyno chart and classing work sheet ready at the next NASA event, in case I screw up and stumble upon a competitive set-up. Bad part is that I'm missing the first two NASA Texas events, due to scheduling conflicts, which sucks (MSR-H and MSR-C). I'm not happy about this AT ALL but these two were unavoidable. I will be at the April TWS event and should have two more track test days before TWS (TK2K12/GSS and Pro-Touring/HHR). NASA Texas has 9 events planned this year in this region so we could have plenty of chances to go have fun in TTS.
315/35/18 Tires on 18x10 D-Force
If we're running in TTS we could use wider tires, right? We also had several S197 Mustang autocrossers ask if we knew if 315mm tires would fit the car on our new D-Force 18x10" wheels. I had my doubts about using a tire that wide on "only" a 10" wide wheel, but I gave it a try. Ordered a set of 315/35/18 Kumho V710 R compounds to see...
This set actually came free from Kumho - our spoils from winning the $2011 GRM Challenge (and our E30 V8 is
on the cover of the next GRM mag!). So yesterday I took one of the 18x10s and mounted one of the 315mm Kumhos, which is shown above. It looks a bit squeezed on the wheel, to say the least. For me, I'd want an 11" wide wheel for a tire that big, or maybe an 11.5". But for some autocrossers, this is fine (look at some of the crazy squeezed stuff Stock class guys do). Today we stuck them on the Mustang, starting with the front and using a 5/16" spacer we had...
Monster room up front, both inboard and out, with
this 5/16" spacer. It would work with as little as a 1/8" spacer, but to be safe I'm going to recommend a 1/4" spacer when using this massive 315mm tire up front with these wheels. If you stick with a more sensible 275 or 285mm tire it still needs no spacer on these wheels, front or rear.
Checked them at full lock, room for days. Now this is with -3° of camber up front, but that's not much in my book. That's what we use for the street on this car. Now on the rear it wasn't as ideal, but still "
good enough for auto-x" in most people's eyes. So I would say "these tires fit" but I won't be running these 315s on a 10" wheel. Stick with 285s or smaller, as those tires fit the 10" wheel width properly - no squeeze.
I'm now pulling the 315mm test tire off the 18x10s and re-mounting the 275/40/18s. Damn, we need a tire machine here at Vorshlag. It would pay for itself in one racing season. On the prowl for a deal. So now I've got these massive tires with no wheels to use them on. So... once we get the panhard and upper control arm on later this week we'll measure for 18x11 front and 18x11.5" rear 3-piece wheels. Forgeline, CCW, something. These should fit with fairly different offsets front and back. Can't let these tires go to waste, and it sure would make for some monster TTS grip.
Rear Suspension Fixes - Quick and Dirty
Our first autocrosses for the Mustang are in early March, with a track event in mid-February, so we've got some new rear suspension bits to install and test before then. I feel that much our our low speed traction problems in this car center around the compromised rear suspension geometry. When you lower the car with this 3-link rear suspension the pinion angle on the axle gets out of whack.
Solid axle RWD cars have so many limitations when compared to an IRS set-up that the SCCA Street Touring rules give the stick-axle vehicles all sorts of leeway, and we're going to finally attack these issues. We did a lot of looking, thought about making our own stuff, then looked at the calendar and bought the Spohn Performance's upper control arm and panhard bar as a stop-gap solution. Their adjustable length upper control arm allows us to adjust the pinion angle properly at the lowered ride height. The adjustable panhard bar lets us center the axle relative to the car, when lowered. Each piece features their optional "Del-Sphere" joints , which allow for high angular movement without bind or noise, at least on paper. These are basically giant spherical joints made inside forged steel ends with Delrin material surrounding the steel ball joint. They are rebuildable - we bought the tool to do that. Seems like a neat little joint that could give you the best of a rod end but without the metal-to-metal street nightmares. Once these new arms are installed we will set the pinion angle for our lower ride height and do some before and after acceleration data logging. I'm hoping for some help in 1st and 2nd gear for STX use -
keep hope alive!
Non-NASA Track Events?
The first event of the year we're trying to make is Feb 17th at Harris Hill Road in San Marcos, being hosted by Pro-Touring.com. It includes an autocross, speed-stop event, and a timed track day, with a trophy for the combined winner? At least -
we think so. Details are sketchy at the moment, but it looks like fun. The problem is they have one rule - tire treadwear limit is 200 - which rules
out damned near every tire we have for the car (all four sets of our ST legal stuff on hand is 140-180 treadwear).
The Dunlop Star Spec tires are 200 treadwear and I've had great luck with them on track before (in the EVO X, at April 2010 Tire Test we did, the December ChumpCar event, and my 265/40/17 rears that I've barely used in this car) and there are two other 200 TW tires that could be fast for this series (they use the Optima Challenge rules), including:
Falken RT-615K (275/35/18 @ $275 or 295/40/18 @ $300) and the
Nitto NT05 ($275/35R18 @ $213, 275/40R18 @ $202, 285/35R18 @ $223, 295/35R18 @ $243). I don't really want to spend $800-1200 on tires to run for
one event (and they'd be pretty much useless for anything else other than street use - which I have the fresh 275/40R18 RE-11s for), so I might beg/borrow/steal a set. So if any of you have some
fresh 275/35/18 Dunlop Star Specs or any of these other tires in the sizes listed you'd like to
loan me for 2 days, please speak up!
(I have a line on some 275 Dunlops, but they are anything but fresh) In a pinch I might use that pair of 17x9's and 265s we have for the rear, but I'd really like something wider in 18" that we could put on the D-Force 18x10s.
We've still got some work to do before then, including the brake cooling, the Spohn parts, and some rear aero. Anyone have a good used 2010-up Mustang trunk for sale?? I'll post up with an update when we've tackled that stuff. We plan on a before/after test of 2nd gear acceleration on a control set of tires (probably the 265/35/18 Hankook RS-3) when the Spohn parts are installed.
More soon,