Tuesday, November 24, 2015

Improved Shifting, New Exhaust Note

The Mach V WRX is sometimes last in line for modifications, since we keep pretty busy modifying customer cars, but we were able to perform some more modifications since my last blog post. We installed a new Kartboy short shifter, Kartboy shifter stop, and and lovely Raceseng knob to top everything off.

The Kartboy short shifter is an interesting part. As you probably know, the WRX uses a cable shifter mechanism, which is a departure from the old lever-actuated shifters in previous WRX models. The shift lever operates a counterweighted pivot on the underside of the car, and the Kartboy shifter is a shorter version of that pivot. Unlike some of the competing short shifters, the Kartboy unit is itself counterweighted, which gives a nice feel and sense of mass to the shift motion. And since you asked, it IS compatible with the OEM Subaru short shifter available from the dealer.

Up on the inside of the car we installed a brand new Kartboy shifter lock, which limits the left-right travel of the shift lever, further tightening up the throws on the shift lever. There are other versions of this kind of part on the market, but most are made of metal, which can lead to some noise when the shift lever contacts the stop. The Kartboy unit is made of a high-strength glass-filled nylon, which is almost completely silent when the shifter contacts it. (Kartboy banged on it with a hammer to test its impact strength. It survived.) Our prototype part was black, but production parts will be yellow.

Finally, with all these improvements in the shifter action, we thought the top of the lever deserved an upgrade in the form of a nice shift knob. We chose the Raceseng Topologi, which has a massive stainless steel core with an outer layer of Delrin. We installed the red Delrin sheath for now, but might switch colors later -- the parts just thread together, so we can swap out whenever we want.

Shifter feel after these changes is light years from the feel of a stock car. The throws are short and weighty, and you can feel click-click when the lever is going from gear to gear. It takes a bit more effort to push the lever around, but it's a welcome trade-off for the improved feel.

One final modification we made to our WRX lately is to install a Cobb cat-back exhaust. I can't say enough good about this system. It fit up perfect to the factory J-pipe, it looks great, and it sounds terrific -- it's got a good growl under acceleration, but at idle it is just a pleasant murmur. It took us a while to get one for our own car, though, since demand for the new system outstripped Cobb's manufacturing capabilities at first. The supply situation has finally improved, so the systems are readily available now.

Parts referenced in this post: Kartboy 2015+ WRX short shifter, Kartboy 2015+ WRX shifter lock, Raceseng Topologi shift knob, Cobb 2015+ WRX/STI cat-back exhaust.

Friday, February 6, 2015

More Brakes!

When we last left our hero, he had taken the 2015 WRX to the race track for a HPDE event, and found the stock brakes...not really up to the task.  The car stopped fine, but the system quickly overheated, resulted in boiling brake fluid and a soft pedal.  Even before that, the pedal feel was kind of mushy and didn't provide very solid feedback.

As you probably know, the higher-spec STI comes with larger and better Brembo fixed-caliper brakes.  I decided I'd retrofit those to my WRX. Since the car shares the same basic platform, and the WRX and STI have the same 5x114 bolt pattern starting in 2015, the parts would easily swap over.  Black Brembo calipers from the 2008-2015 STI will bolt directly on. Even the earlier gold Brembo calipers from back before 2008 will bolt up; the rears just need an adapter bracket.

I sourced some used gold Brembos from a 2004-2007 STI from our local JDM importer, Virginia JDM Motors.  I got them powder coated blue, partially because they were a little dinged up, but mostly because I just wanted them to look different.  I grabbed an STi brake rotor/pad/lines combo kit that we sell, and the aforementioned adapter brackets, and bolted it all up.

Our rotor/pad kit also came with our Mach V stainless steel brake lines.  Stainless lines don't flex under pressure like rubber lines do, which makes for a more solid pedal feel and better feedback under hard braking.

The STi brakes have larger and more massive rotors, but the aluminum calipers weigh a good bit less -- the entire swap removes almost four pounds of total mass, and weight is removed from the calipers (where we don't want it) and added to the rotors (where we do want it).  The result is very solid pedal feel, and vastly improved ability to survive hard use like our track day sessions.  Plus, the brakes definitely stand out under the wheels!

Note that the stock 2015 WRX wheels will not fit over the large Brembo front calipers.  You'll have to run some different wheels, or use at least a 10mm wheel spacer in the front.  Our 18x9.5" Wicked Awesome wheels have plenty of clearance, so that wasn't an issue for us.  (In fact, we could put a much larger brake kit under those wheels, if we wanted...)

Products mentioned in this post: Mach V complete brake pad/rotor kit; Gold Brembo adapter brackets; Mach V 10mm wheel spacers.