Project #YAE92 M3: Part 6 – Roll, Stop, & Stick

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Here you see the rear toe arms and rear sway bar end links from SPL Parts as well as our spring & shock setup from BC Racing. What you can’t see in this photo are the SPL Parts upper control arms and traction arms. We are still using the stock lower spring perch and stock lower trailing arm at the moment, but SPL Parts does have plans to develop these as well. Also note the eccentric lockout washers from SPL Parts used to eliminate the possibility of unwanted changes in rear toe from the stock cam bolts. In the rear we can now adjust camber, toe, squat, toe steer, and ride height.

Wheels are another important part of a vehicle’s setup. They should be strong, light, appropriately sized, well made, and damn good looking. We’ve nailed all of those with our new wheel setup from BC Forged Wheels. Just like their coilovers, their new line of wheels is also made to spec. You can choose your diameter, bolt pattern, offset, style, and color for the perfect fit and finish. (For those who follow our social media and our racing, fear not, these are NOT the wheels we had fail on us during our last race). The only thing you’ll need are the right tires, and the right tires for us happen to be the Achilles GS-328 race slick. These race slicks are non-DOT meaning they don’t have to stick to the strict guidelines of being a highway legal tire. That means no grooves whatsoever, a true racing slick giving maximum contact patch. We’ve found that these tires give not only superior grip to others we’ve raced on in the past, but also superior sensitivity to operating temperature making it a very drivable tire whether setting qualifying laps or maintaining a comfortable pace in the middle of an endurance race. Despite the better performance, they are also showing exceptional wear characteristics and tire life allowing us to do 3-4 stints on them during our endurance races.

 

Our BC Forged RS43 wheels are light, strong, and straight sexy. Custom specs allow us to get exactly what we need out of them. 18×10” with +25 offset all around.

For sizing, we’ve gone with the 27/65-18 which translates into a 270mm wide tire, for those not used to the Achilles sizing. We’ve paired them with an 18×10”+25 BC Forged RS43 wheel on all four corners. For wet weather conditions we run the same wheels, but wrapped in the Achilles 123S tire, the same tires used on their top level Formula Drift cars. While we could groove the GS-328 slick with the same 123S tread pattern for a softer wet weather tire, there’s a reason we choose to run their much harder off-the-shelf 123S instead. Everything we do for this car revolves around the 25 Hours of Thunderhill race which is run in December. Temperatures are generally in the 30s-40s overnight at this race which is very cold. When you add rain into the mix, things become very cold and it is incredibly hard to keep temperature in your tires. The 123S street tires have a much lower optimal operating temperature than the GS-328 which actually translates to better performance under these extreme conditions.

 

The Achilles GS-328 non-DOT racing slick is the real deal. To us, it’s the only choice when considering performance, cost, and availability. Squared shoulders and no tread provide maximum contact patch.
The Achilles 123S is one of the best performing tires in Formula Drift and our choice when it comes to wet weather racing. Since the 25 Hours of Thunderhill is run in frigid cold temperatures, the lower operating temperature range of a DOT street tire like the 123S is more ideal than a running a grooved GS-328 race tire in the rain.

Last, but certainly not least are the brakes, an incredibly important part of any race or track car. We consider brakes not only to be a performance modification but also a safety device so when it came to choosing a brake kit we were very picky. We actually turned down brake manufacturers that were willing to give us brakes for free simply because we knew that this is one area where we were not willing to compromise or “test” anything new. We are endurance racing and our brakes need to perform flawlessly for 25 Hours straight. Our lives literally depend on it, which is why we paid tons of money for the best; AP Racing brakes, and not their street performance stuff either, their true motorsports brake kit. The stuff you can only get exclusively through AP Racing’s US distributor Essex Parts Services, Inc. These brakes come from the same division of AP Racing as the ones you see on all the top level Daytona Prototypes and LeMans Prototypes. The AP Racing Competition Brake kit we run on our car shaves 10.5lbs of weight off each corner and grossly outperforms the stock brakes. For brake pads, we run Hawk Performance DTC-60 and DTC-70 compound race pads. If you’re curious on how well this setup works, in the 2014 25 Hours of Thunderhill we went the entire 25 hours on the same set of brake rotors, but as a precaution, we changed our brake pads after 14 hours of racing while still having around 40% of life left in them.

 

Our AP Racing Competition brake kit sheds 42lbs of weight over OEM and when paired with the Hawk Performance DTC brake pads we could have theoretically lasted nearly the entire 25 Hours of Thunderhill without changing the brake pads. Although, as a precaution we changed just the brake pads 14 hours into the race and they still had roughly 40% of life left in them.

Although we are completely satisfied with our current setup, there’s always room to grow and evolve. We have some very exciting things coming our way for 2016 including a new complete replacement billet single lug hub setup and a switch to AP Racing’s newest endurance centric Radi-Cal brake kit. The new brakes will allow us to run 1” thick Hawk Performance brake pads which should enable us to make it through the entire 25 Hours of Thunderhill without a brake change!  Until then, we will continue to push and develop our current setup through the toughest form of sports car racing!

 

SOURCES:

 

Yost Autosport

BC Racing Custom Coilovers

Achilles Motorsports

SPL Parts

Essex Parts

Hawk Performance

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