Tuesday, November 28, 2017

Interior Enhancements; Getting Back to the Track

Interior Enhancements

We did a couple of interesting upgrades to the interior of our WRX over the summer, including a new carbon fiber/leather contoured steering wheel, and a inside-trunk pull handle, plus we tried on another new shift knob. We also installed some new shocks, and got the car back out to the race track in the fall.

We've always coveted some of the fancy Japanese contoured steering wheels, but they are hard to get and very expensive. We finally found a supplier that we liked, with a good quality product at a price point that seemed more reasonable. The wheel has a thicker rim compared to the stock item, and there are shaped portions that fit your thumbs and fingers. The top and bottom are finished in carbon fiber, and the 3-and-9 positions are in leather, perforated for ventilation. The frame is cast aluminum, just like the stock steering wheel.

The wheel installs just like a stock one; we carefully transferred over the stock airbag and spoke covers from our stock wheel. The clock spring, steering angle sensor, and airbag module are delicate and easy to damage, so if you choose to do this upgrade, have a trained mechanic install this part.

We really like the new wheel in the car. The fat rim is easy to grip and feels good. The indentations promote a good proper hand position on the wheel, and they feel comfortable. Plus the new wheel looks great. Several people asked us if it was a factory item.

The integration with the stock steering wheel controls and airbag is seamless. You can't really tell which part is aftermarket and which is original, which is the way we like it.

One tiny annoyance on the 2015+ WRX and STI is the lack of any handle to pull the trunk lid down. Many modern cars have a handle you can grab from the inside to close the trunk. We developed a Mach V trunk handle strap that you can attach to the inside of the trunk lid. This prevents you from getting your hand dirty on the soot and grit that sticks to the back of the trunk, plus you don't have to worry about scratching up the rear of your trunk lid. You can install our trunk pull strap on either the left or right side of the trunk lid; if you install it on the right, as we did, you just have to drill a single hole in the trunk liner. Otherwise, there is no cutting or drilling of the metal trunk. It's a small thing, but it makes us happy.

One last interior modification was to try out another new Raceseng shift knob. This one is called Raceseng Slammology. The -Ology shift knobs are all modular, so you can swap out the Delrin covers to mix and match colors or shapes. The Slammology knob features a full rounded Delrin top. We really like the feel of Delrin in the hand -- it's soft and doesn't get too hot or cold. Plus we love the look -- the smooth Delrin contrasts nicely with the finely-machined stainless steel
peeking out at the bottom of the shift knob.

More Suspension Changes

We had a customer with a 2016 WRX STI that found the stock suspension a little too uncomfortable. We ended up swapping shocks with him, so our WRX got STI shocks. The rear shocks are pretty similar in construction, but the front STI shocks are a fancier inverted monotube design.

The ride with the STI struts is a little bit more nervous in daily use, and you feel small undulations in the road surface more than with the WRX struts. This is something we have experienced before driving the STI, and the struts seem to be a big part of the difference in feel between WRX and STI. But the faster the car goes, the better the STI struts seem to work. At high speeds, even over bumpy surfaces, the STI struts show outstanding road-holding.

Track Testing

We haven't been out to the track with the WRX in a couple of years. The last time out, the car was on stock WRX struts, stock sway bars, our Mach V lowering springs, and Hankook Ventus Evo V12 tires. This time, we had STI struts, the same Mach V springs, our Mach V 22mm rear sway bar, and a set of 265/35R18 Continental ExtremeContact Sport tires on our Mach V Wicked Awesome 18x9.5" wheels. One more difference was that although we were at the same track -- Summit Point Main circuit -- the track was just repaved, so we had brand new fresh tarmac.

Photo by Finish Line Productions
The car performed great. Grip was excellent, with higher cornering speeds at any given part of the track. Chalk that up to the tires. The Continental ExtremeContact Sport offers excellent dry grip, and the grip stayed good as the track sessions went on.

With our Mach V lowering springs (yes, the Mach V springs work and fit perfectly well with the STI struts), our 22mm rear sway bar, and the STI struts, the car felt very neutral. It turned in promptly, with only the slightest hint of understeer on high-speed corner entry. On power exiting corners, the back end would step out just slightly. The whole car felt very planted and easy to control, with no unexpected behavior.

One other modification we made prior to track day was to install some DBA XP650 brake pads. These are a brand new product from DBA. The XP650 compound is specifically recommended for track day use. As promised, the pads held up great, with no fade even after 30-minute track sessions. they worked just fine cold, too, which is unlike some track-oriented pads. On the way to and from the track, they behaved just fine and stopped without squealing or creaking.

The only downside to using these as a street pad is the dust. They put out clouds of black dust. Even on the way to the track, the wheels developed a thin film of brake dust, and after a couple of track sessions there was a distinct plume of black dust down the sides of the car and coating the back bumper. That's par for the course for track brake pads.

We haven't yet decided to stock the DBA pads, but we may offer them in the future. Stay tuned.

Products mentioned in this blog post:

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