We are finally done! This is the final chapter detailing the upgrades we made to our Arctic Cat M7 project sled.
Fabcraft, makers of ultra lightweight mountain rider's trick gadgetry, provided us some fine looking rear axle wheels for our M7. These 8-inch wheels are made of tough, durable new composite plastic and weigh in at a scant 8 ounces apiece. The upper idler wheels, which are 5 and 5/8-inches, weigh in at 4 ounces, not counting the bearings. These wheels provide a significant weight savings over stock wheels and are lighter then most aluminum wheels on the market as well.
Composite plastic is beneficial because it will not hold ice like aluminum wheels where snow and ice will flash-freeze on high-polished aluminum. Furthermore, the wide windows on the Fabcraft axle wheels allow snow to pass through, preventing buildup.
Installing the wheels was simple: pop the caps off the rear axle wheels, speed ratchet out the bolts, slide off each wheel, replace with the new Fabcraft wheels and speed ratchet in each mounting bolt. The Fabcraft wheels do not use Cat's existing bolt caps. Each Fabcraft wheel came with its own sealed bearing.
Next we installed some light ultra-strong chomoly upper and lower A-arms from Spencer Suspension Products (SSP) in Gaines, Mich. Terry Spencer, the creator and fabricator of these A-arms, is a master welder and metal fabricator. Spencer recently joined AmSnow's efforts to build this project sled and has built front-end suspension parts for many Team Arctic racers for snocross, cross-country, ice-ovals and grand prix circuits - pretty much wherever modified sleds compete. We have been more than satisfied with his product.
The A-arms reduced the sled's weight by 7-lbs. For mountain guys, reduced unsprung weight is paramount, and SSP gave us what we wanted - strength with minimal weight. We were not too concerned with the strength of the A-arms because the ultra-strong chromoly is tough even though the walls are thinner than the stock steel A-arms. However, you don't want A-arms that are overly strong. To explain, Spencer discussed shear points for mountain sleds. He says that his A-arms are built for their purpose and are not so robust that they will rip out the bulkhead if you hit a rock or tree heavily. He believes you must balance weight, rigidity and strength.
As we installed the A-arms, Kevin and I both commented on the craftsmanship, and precise engineering. The bushings - which replaced the inner axles - allowed the A-arms to float, but not rock in their mountings.
The upper A-arm is a single unit, unlike the OEM's upper A-arm that consists of two tubes. When installing the A-arms we removed the belly pan, front nosepiece and bumper, hood and airbox. We replaced one side at a time, using the other as a pattern and assured that our torx screws were separated for each removed part due to the differing screw lengths - each has a specific mounting hole. To add some style to the upper A-arms, SSP hot-tacked in a "floating M" to the finish. Our total time to swap out the front A-arms and rear axle wheels was about 3 hours.
One last final install for this project M7, is a Boondocker Liquid Nitrous System. Rocky Young donated this system after the snow dissipated, but we will install it in early fall in time for our first deep-powder rides of next season. The Boondocker system is a 30 horsepower system and when the motor is at peak RPM, we should get 180 to 185 hp out of this machine. That is some serious arm-stretching fun!
Final EFI injector duty cycle settings through the Boondocker Control box:
| RPM | Low | Mid | High | Trim` |
| 3000 | -03 | 00 | 00 | 00 |
| 5000 | 00 | 03 | 00 | 00 |
| 6700 | 00 | 00 | -10 | -02 |
| 7800 | 00 | 00 | 10 | -02 |
| 8100 | 00 | 00 | 10 | -02 |
Each injector duty cycle numerical increment - up or down - increases or decreases fuel flow by .448%.
Drive and driven clutch specs, for 6,000-8,000 feet altitude:
Drive clutch
• 68 gram Arctic Cat weights lightened (ground down) to 63 gram
• Orange/white Arctic Cat spring
Driven clutch
• Team Industries' red/pink
Thanks to Bret Rasmussen, Kevin Allred and Jake Allred for their work, and all the aftermarket companies that provided product for this project.
More info: Fabcraft at 406-777-1200, www.fabcraft.com; Spencer Suspension Products at 810-444-0061