Rules get more open, min weight goes up by 100 lbs, tires get bigger:
Amazingly, these new wheels & tires are 7 lbs lighter per corner than the much smaller 275s! There's something to be said for good wheels- the Real Racing Wheels with huge Hoosier slicks are just 42 lbs each.
| Specifications | ||
| SM | CP | |
| Weight w/o ballast | 2957 | 2771 |
| Distribution w/driver | 54.5/45.5 | 53.4/46.6 |
| Total tread width | 38" | 52" |
With the first event about a month away, I began the conversion from SM to CP. While there are many changes that can be made, the one essential change is to switch from 275/40-17 DOT tires to big slicks. Besides having more grip, the minimum weight drops by 200 lbs when using 16" wheels. Adding this much rubber is going to require some serious fender work, so I borrowed my friend Mike's plasma cutter to make the work go quicker. Click on any picture to see a bigger version in a new window. You might need to maximize your browser to see it properly- just press F11 if you're using Internet Explorer.
Rule #1 when using the plasma cutter is to make sure what's behind what you plan to cut isn't going to catch fire when hit with liquid steel- that's a pretty tall order. Much of the interior had to come out to do the rears:
I still caught a few things on fire. After a few hours I'd only completed one fender, although the car was now 69 lbs lighter.
The rear fenders required an inner and outer cut, leaving a big hole to fill:
With no interior bits in the way, the next few fenders would go much quicker. The only bad part is the gas tank & its filler nozzle are awfully close to where the cuts had to be made. That was a little nerve racking, but with some water soaked towels and careful aim I got the rear done without blowing up.
On to the front where the wheels move a lot more due to the steering. To get the clearance right, I loosened the coil overs to allow easy collapse of the front suspension with this simple rig:
Now I could easily simulate the whole range of suspension travel and steering so I won't run into trouble later on course.
Checking the clearance after the initial cut:
This is as tight as it gets:
Inside the clearance is tight, but everything fits:
When I originally flared the fenders about 2" to clear the 275s I went a little too fast on the passenger side and creased the fender:
That mistake was easily removed with the plasma cutter. Here are the main strips of metal removed from the front fenders:
The front bumper and supports are only 23 lbs, but that's weight 2 feet in front of the front wheels so removing it really helps the weight distribution. Just remove the front fascia...
While it's off, may as well remove the lights, that's another 8 lbs. I'll have to put some covers on, but they weigh less than a pound.
The dash and heater core are just extra weight and in front of the middle of the car, so they'll have to go...
After all that work, the car weight is 2771 lbs with a full tank of gas, with 53.9% or 1493 lbs on the front wheels. From SM, that's an amazing 140 lb reduction on the front wheels, and 50 lbs on the rear. Minimum weight is 3050 lbs with my 5.7 liter engine, and if I put all the weight on the rear wheels I'd be at the class maximum of 51% rear weight. There are a few more things I can do to reduce the weight further, like gut the doors, remove more carpet and sound deadening material, and swap the glass for lexan.