continued from above
We also switched the 2.5" ID x 200 #/in Hyperco rear springs to a longer 2.25" ID x 175#/in rate Hyperco, and I machined the AST rear ride height adjusters (made for 60mm and adaptable up to 2.5") down to fit the 2.25" ID springs. Problem was there's not a lot of lengths or rates available in 60mm ID or 2.5" ID, but TONS of choices in 2.25". We do this on all sorts of cars when the choices move us to the smaller ID spring. The 2.25" spring is lighter, but costs more than 2.5" or 60mm, and we usually stock and sell 60mm Hyperco springs if possible (most AST struts are made to fit 60mm springs). We have played with no less than 5 different rear springs in the past few months and we finally got a winner in a softer rate with the 2.25" ID that works with the new rear shocks, rate and lower ride height. A lot of trial fitting went into this. Long story short - we now have 3 different rear spring length/rate packages that should please a wide range of the autocrossers and track guys, and we're trying more front rates as well.
The new lightweight
WedsSport TC105N 18x9" ET50 wheels arrived from Vivid Racing this past week. I immediately weighed one wheel, and at 17.4 lbs on our scale it came in only 1/2 pound more than the claimed 16.9 lbs, which is better than normal for claimed weights, from our experience. With their high prices its easy to understand the confusion, but upon inspection I noted that the WedsSports were simply a one-piece "flow formed" wheel (like D-Force, SSR, some BBS and others) and not a "forged wheel" as some folks like to think. I mounted the 265/35/18 Toyo R1Rs to this set for the coming autocross weekend and weighed them together; the wheel and tire package came in at a scant
43.1 lb per corner.
Putting these pricey WedsSports on for the first time was a pucker moment - the spokes only cleared the Brembo front caliper by about .040". It was a close one but it works, and we've run with wheels this tight to this caliper in the past. It definitely fits inside the stock fenders with
inches to spare - this is definitely
NOT HellaFlush.
For an autocross car I prefer a narrower track width, as this makes the car easier to navigate (and faster though) a tight slalom and allows the rear differential to work more efficiently. For road course use I'll let the track width push wide as you please, well, hopefully without disrupting aero (which will if the wheels push out past flush).
The wheels are fairly simple but very well made looking, and look damn good on the car, and so does the now lower rear ride heights. We tried these heights on 150#/in rear springs (and even 1/2" higher) and it bottomed the shocks (and nearly touched axle to frame) too often on the street, so we're scratching that one off the list of rates we recommend. The 175#/in rates worked well for daily driving and autocross both, and we're VERY happy with the performance improvements. You'll see this in the autocross pictures in my next post - its finally squatting well under acceleration (from the new ride height + new spring rate + new shock length + new piston and valving).
This WedsSport+Toyo package is now
13.8 pounds lighter per corner than the
56.7 lb OEM 19x9" wheels and tires, and remember: this is both rotational and unsprung mass. That's... just HUGE. We could possibly get the front rotors 10 lighter, too. We'll get the lead out of this Pony Car, by damn! The 18x9" Enkei FP-01s are still mounted with the 265/40/18 Yokohama AD08s (and
weigh in at 48.2 lbs, or 5.1 pounds heavier than the Toyo/WedsSport combo) which we'll test back to back with the Toyos at an upcoming test day, and we'll share what we learn here.
We also had AST-USA put in some more compression in the base valving in the front struts, which was very noticeable and more matched the new rear shock valving added earlier. We weighed the AST + Vorshlag + Hyperco bits from the front suspension while it was off, and AJ cleaned up the rear of the chassis which had been covered in rear axle lube (new aluminum catch can and bracket parts are here and will be installed soon).
Costas asked what changes were in store for this coming autocross on Sunday, which he was scheduled to co-drive the Mustang in. I rattled off that we had new rear spring rate (450F/175R) and lower ride heights (14.5" F&R), new front strut valving, new adjustable and stiffer front swaybar. New cold air and SCT tune, with probably +35 whp if not more, a new rev limit 600 rpm higher, lighter 18x9" WedsSport wheels with a slightly narrower track width, and went from the taller Yokohamas at the last event to shorter and stickier Toyos. We also had planned on running 10 psi more tire pressure front and rear. "So... not so many changes?"
Race write-up is next...