It was 6:30 a.m. and I was already up and getting ready to leave. It wasn't for work - I'm usually not awake until 7:30 a.m. on workdays. I also didn't need to grab or prepare lunch. I did grab a couple of items, though, my helmet and my second car key - the track key (TracKey), for the first day at the track this summer. The local track - Atlantic Motorsport Park (AMP) - is about an hour away. I filled up the car and a 10 litre gas tank and headed to the track.
I arrived shortly after 8:00. The last time I was at the track before then was the last weekend of August, 2012, and I have been counting down the weekends since then. Once I arrived at the track, saw the line up of cars and heard a few idling engines, it seemed like it was only last weekend that I had been there last.
Now let's get to the important stuff - the car. I've had the car on the track before. Initial impressions were excellent. I bought my car "used" with 230 miles on the clock, so I had no say in the options and, unfortunately, it didn't come with the Recaro seats and Torsen differential. Nonetheless, the Boss 302 is excellent on the track. It's one of those cars that shrink around you when you push it. It feels eager and willing. The car I had before was a less powerful, lighter car (under 3,000 lb). Once I strapped into the Boss, I felt the extra heft and wondered if suspension wizardry could make up for it and did it ever! Unlike my last car, which was a light car (good) and felt like it on the track and on the road, the Boss feels like a great GT car on the road, especially in the price range, but it's a different story once you take it to the track.
When I took it to the track last summer for the first time, I started slow. The first few laps, I decided to take my time to learn the car and get comfortable with it.. but the car kept asking for more at every corner, turning in and pulling out of corners with ease. The more I pushed, the lighter it felt. Lap after lap, I started getting quicker and more impressed with the car. Understeer is practically non-existent. Turn in is impressive and unless you are trying to come into a corner too fast, you won't miss an apex by going wide. When you do go wide, it's simply the momentum of the car carrying it through the corner, not the front tires losing traction and dreadfully screeching for mercy. The back end can come out but it's very easy to catch. The excellent Alcantara wrapped steering wheel gives you plenty of information about what the tires are doing, especially for a car with electric power steering. It's neutral and well balanced. It has little body movement and plenty of grip and power plus good manners at the limit. What more could you ask for?
Plenty, as it turns out. As is the case with any automotive enthusiast who likes to modify, reasons that, to you, are logical and justifiable will always pop up in your head as to why you should modify. When I bought the car, I told my wife "Honey, this is more expensive than our previous car but I won't spend any money on modifications like I did with the other car. This is set up perfectly." I was wrong. I meant it at the time, but I should have known better. This wasn't my only mistake, though. Unfortunately, I did what I always advise people not to do - I made more than one modification at a time.
Firstly, the differential. I figured I would make it as good as it could have been straight from Ford before I change anything else. The standard Traction-Lok limited slip differential (LSD) is a great unit and it comes with carbon fibre clutch plates for added durability but the performance of the Torsen is on a different level. The same stands for the seats. The standard seats have great support and comfort but they are no Recaros (I don't know how good the Recaros are on long trips, though). I haven't got to upgrading the seats because they cost nearly $3,000 new and I am willing to buy used but I haven't been able to find a good used set. I did upgrade the differential, though, and decided on the OEM Torsen - the same unit that comes standard on the Boss 302 Laguna Seca and is optional on the Boss 302. It has a torque bias ratio (TBR) of 2.7 which puts it mid-way of gear-based limited slip differentials. I picked it because:
1- I was assured by Ford Racing and Torsen that the unit was developed with the Boss in mind and durability was a huge factor (you actually can't order that unit from Torsen, only Ford Racing or Ford Racing vendors)
2- Too high a TBR, and the car would start to push/understeer and I don't want that, especially for a short, technical track like AMP. Too low a TBR would make a small difference over the standard differential. 2.7 seemed just right.
Next on the list came a Watt's link. I went with the Fays2 Watt's link because, at $650 (from Strano Parts), it was several hundred dollars less expensive than alternatives, quality was top notch and it had the widest range of rear roll centre adjustability (7-positions). I also heard great things about support from Strano with parts installation and adjustment so I figured I couldn't go wrong. Unfortunately, I did have some installation hiccups along the way but they were quick to respond and get the issue resolved.
I installed it with a lower rear roll centre position (3rd from the bottom). The closer the rear centre is to the car's centre of gravity (in this case, higher upwards), the less roll the car will have. With no change to the front roll stiffness, less rear end roll means better turn in - the same effect as going with a stiffer anti-roll bar. While that's great (and it is something that I want), I'm not a professional race car driver so I wanted to make sure the car won't be too tail happy before I move the roll centre further up. After a few trials, I ended up 2 positions higher, 3rd from the top.
Last but certainly not least came wheels and tires. They actually came first in terms of order of installation. Some of you may remember my first post (An unfortunate first post.. or is it?) where I was (happily) forced to upgrade wheels and tires earlier than I had planned. The car comes stock with 19" x 9" wheels in the front and 19" x 9.5" wheels in the back wrapped in Pirelli PZero tires - 255/40/19 in the front and 285/35/19 in the back. The wheels weigh about 32/33 lb. each. I bought 18" x 9.5" TSW Nurburgring wheels in gunmetal grey shod in 285/35/18 tires all around.
I wanted to go with lighter wheels all around and wider in the front for a little more rubber to improve (the already excellent) turn in. The new wheels weigh about 22 lb. each so they save about 10/11 lb. per corner. Additionally, the drop in wheel diameter from 19" to 18" means two things; a whole car and centre of gravity drop of 1/2" and the effect of gearing up the rear end by 3.9%. I.e. the drop in wheel size, from the drivetrain's perspective, is equivalent to going from the stock 3.73 gears to 3.87 gears. There are no gears that I know of that are available in this ratio but if there were, they would have the same effect. Now, I was told by many that there's no way I could feel the difference from the drop in weight or diameter but I actually noticed some improvement. But then again, it could all be in my head!
Track impressions this year after the modifications were even better. The Torsen provided a huge traction advantage coming out of corners. I was able to come back on the power a lot sooner and roll into the throttle more quickly than last year. It was appreciated the most at the corner exit of corner 2. As you can probably figure out from the track map, corner 2 is the slowest corner on the track. If you're in a hurry coming out of it (as you should be) in a car with any appreciable amount of power, you get nothing but spinning if you can't modulate the throttle. In a car like the Boss with the standard LSD, you can use very little throttle, which can be frustrating after a few laps. With the Torsen, speed starts to build up a lot more quickly while exiting a corner. You still can't go full throttle past the apex at every corner, but it is a whole lot better.
And thanks to the Watt's link, it takes more to upset the rear axle now. The track is on the bumpy side so it makes an even better case for itself on this track. Although you can notice and appreciate the Watt's link on the road, it's a whole other level on the track, especially on the back "straight" (between turns 6 and 7) were bumps were very unsettling at higher speeds. Between the lighter wheels and decreasing rear end roll, the car feels much lighter on its feet, even more willing and eager to slow down or change direction. I can carry more speed going in and around corners, which is even more impressive when considering what tires I ended up buying.
The tires I bought - Continental ExtremeContact DW's - are actually supposed to be slightly less sticky than the stock Pirelli PZero's. Since I daily drive my car as long as the weather allows (about 8 months out of the year), I went with the Continentals because they have much better tread rating and they are better in the wet (it rains often here) and in cooler temperatures. The Michelin Pilot Super Sports give up a little tread life and comfort to the Continentals but they are still a lot better than the Pirelli's and are supposed be best in class in terms of performance. They are a lot more expensive than the Continentals, though, so I couldn't afford to buy them at the time since I was buying wheels along with them. When it's time to replace the Continentals, I will be trying the Michelins.
Despite the slight drop in ultimate tire grip, the car had better turn in and braking, higher corner speed and more rear traction, all point to the improvements that the modifications made. Overall, I couldn't be happier with the outcome and I'm looking forward to the next weekend at the track, which will be with the local BMW club - BMW Club Atlantic. Make sure to check back for updates!
Note: The pictures were taken last year at the track so they show the stock wheels and tires. I apologize that they're low res - the gentleman who takes pictures at the track posts low res versions on his website for free and I couldn't buy the high res pictures because I had spent all my money on the car!
this was a very informative article. thanks very much
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