Friday, May 12, 2017

Changing Shoes and Improving Cornering

My WRX has been a faithful companion over the last year or so, just trundling around, carry people and parts, hauling me to and from our track store and our main office, and I haven't had much to report. It's been reliable and trouble-free, and getting around 30 mpg. I have swapped on a couple different sets of wheels, though, plus I added a new Mach V rear sway bar.

One of my all-time favorite wheels is the TWS Motorsport T66-F. TWS is a Japanese company that makes forged wheels -- it's one of only three companies in Japan that does. I actually went to the TWS manufacturing facility in Toyama, Japan, last summer. Forging aluminum results in a lighter, stronger wheel compared to traditional casting. The 18x9.5" T66-F is incredibly light -- more than six pounds lighter than the stock 17" wheel that came on my WRX, even though the TWS wheel is 1" larger in diameter and 1.5" wider! Of course they clear STi Brembo brakes, which is important since our WRX has been retrofitted with them.

I paired a set of 18x9.5" T66-F wheels in Gunmetal color with a set of 265/35R18 Michelin Pilot Super Sport tires. The Pilot Super Sport is one of my all-time favorite street tires, and combined with the super-light TWS wheels the car felt like it had limitless grip and a feeling of being light on its feet. Plus, the wheels looked amazing! We got tons of positive feedback about the way the car looked with this wheel set on it.

I would have kept those wheels on the car forever, but a customer took a liking to them and the TWS wheels went out the door. It was getting to be winter, so I swapped on a set of our own Mach V Awesome wheels, which are 17x9". For tires I chose Dunlop SP Winter Sport 3D, sized 245/45R17. The ride was suddenly quite plush, what with the additional 1/2" of tire sidewall, plus the softer winter tire. But unlike some of the previous winter compound tires I have run, the SP Winter Sport 3D was no slouch in terms of dry traction. I even drove in a winter autocross on them. (The Summit Point Refrigerator Bowl series, since you asked. Sponsored by Mach V Motorsports!) The sad part of putting on the winter tires this year was that we got almost no snow. Maybe next year we'll get some deep stuff and I can have some fun.

The last wheel I tried out was a new one that we just got in. As you probably know, the new 2018 WRX STI has a larger front brake package, which requires the wheels to grow in size to 19" diameter. The Focus RS also comes with 19" wheels, too. I figure we'd better get ahead of this wheel trend and start selling some 19" Subaru-fit wheels, so I ordered up a set of Linea Corse 818 wheels wheels in a massive 19x10" size. These wheels didn't quite clear the Brembo brakes on my WRX, so I put a thin Mach V 3mm wheel spacer in place between the front wheels and the hubs.

I installed Continental ExtremeContact DW tires in a 265/30R19 size. That tire size is a bit narrow for the 10" wide wheel, so the tire looks a little stretched on the wheel, but I didn't think a wider tire was going to fit under the fenders of the WRX. The result looks AMAZING, but the tire-to-fender clearance is very tight. I didn't drive the car hard enough to really test fender-to-tire clearance, but it looks close. I didn't plan to keep these on my car long-term, and I wanted to keep the wheels in nice enough shape to re-sell, so I took them back off after taking some glamour photos. With some coilovers for a stiffer ride, and some camber to get the tires to tuck in a little more, I think it could be a usable setup for street use. 

Finally I went back to my original wheel/tire setup, the 18x9.5" Mach V Wicked Awesome wheels. The summer tires I had on the car before were pretty used up, so I installed a fresh set of 265/35R18 -- this time I chose the brand new Continental ExtremeContact Sport. This is a tire I was introduced to at the SEMA show last November. Continental had a ride-along event where you could get driven around a little track layout in a sporty BMW with a pro driver at the wheel, performing massive smoky drifts. Although none of the Continental staffers said it to me straight out, I gathered that the ExtremeContact Sport is a direct answer to the excellent Michelin Pilot Super Sport. Indeed, my experience so far is that it has all the great traits of the Michelin tire -- very high dry grip, excellent wet grip, relatively low noise, decent wear -- at a lower price. As I write this the PSS in my preferred size costs $222.97, and the ExtremeContact Sport in the same size is $181.55. That's almost 20% less expensive.
One more modification I did was to bolt on a new Mach V rear sway bar kit that we developed. This is a 22m rear sway bar kit that comes with polyurethane bushings plus a set of reinforcement bars to strengthen the sway bar mounts. The bar is 46% stiffer than the stock 20mm part. (Pro tip: Sway bar stiffness increases with the fourth power of the bar diameter.) The bar makes the car feel more neutral in corners and, combined with our Mach V lowering springs, the cornering attitude is nice and flat. I am happy with our kit because it is complete, coming with everything you need, including the reinforcement brackets, for a good price.

Products discussed in this post:
TWS Motorsport T66-F 18x9.5" wheel
Mach V Awesome 17x9" wheel
Linea Corse 818 19x10" wheel
Mach V Wicked Awesome 18x9.5" wheel
Mach V 22mm rear sway bar kit