how to install your crazy mountain extreme belt drive system

Pull the suit coat off a late model Crazy Mountain Xtreme muscle sled. Poke your eye down its belly and take note of a blower looking device that drives the big track up a slope.

Mark Hoffman of Clyde Park, Mont., owner and designer of the exotic CMX mountain sleds and belt drive unit, known as the Crazy Mountain Xtreme Drive System (CMXDS), markets the belt drive system for other makes and models. Hoffman's goal with the belt drive system is to reduce rotating mass/weight and to increase drive efficiency. Drive efficiency is increased by 15-percent.

Here, in a nutshell, are the how-to instructions to install a CMXDS on a Polaris RMK. The method is similar for other brands and models. Before completing this, bone up rear suspension and chain case removal, rear suspension installation track alignment and tightening. Have a shop manual nearby for your sled or, at least, a photocopy of these needed instructions.

Hoffman, recommends the installation be done by an experienced mechanic, fabricator, or snowmobile tuner. But if you must do it yourself, here's our step by step outline.

Essential tools you will need, beyond the normal, are: air body tool (miniature Sawzall), rivet gun, emery cloth, drill and drill bits, C-clamps, red Loctite, DOT 4 brake fluid, general shop tools.

1. Remove hood. Your choice. This makes working around the sled easy and this protects the hood.
2. Roll sled on left side, or elevate sled on a body lift, such as a Mar-Lift.

NOTE 1: Suggest lifting sled on a body lift that will let the rear suspension float. If working on the ground, know the sled will be tipped from side to side numerous times; place carpet on the ground next to the belly pan for the sled to rest on when on its side.

NOTE 2: Steps 3 through 7, and 48 and 49 require an OEM shop manual instructions, or prior experience/knowledge.

NOTE 3: Complete steps 3 through 7 in reverse order after the CMXDS installation is complete; take note of removal sequence.

1. Remove rear suspension.
2. Remove brake caliper unit.
3. Remove chain case cover.
4. Remove sprockets, gears and chain.
5. Remove back chain case cover.
Fit drive side plate to bulkhead - with top shaft in stock location.

Note: Belly pan and footrest area will need to be trimmed for dropped and rolled CMX drive system.

1. Using a drill or a hammer and chisel, remove rivets that prevent plate from sitting flat against the bulkhead.
2. Use 3/16-inch drill bit to align plate on bulkhead.
3. Clamp CMX plate to bulkhead and drill 5/16-inch mount holes.
4. Using the air body cutting tool, cut bottom shaft hole and slot through bottom to match CMX plate.
5. Ensure sprocket idler/tensioner sliding nut is in the slot on backside of CMX drive plate.
6. Permanently install CMX drive plate by installing the mount bolts.

Install clutch side plate

1. Using a drill or hammer and chisel, remove rivets keeping plate from sitting flat against bulkhead.
2. Using the air body or equivalent, trim bottom of footrest mount as needed.
3. Use alignment holes in bulkhead to locate plate.
Note: Top shaft on the clutch side drops 1/32 of an inch from stock location; this is to maintain belt alignment.

Temporarily install top shaft

Note: Use drill bits as an alignment tool to verify offset by placing the proper size drill bit between jackshaft and bulkhead from side to side.

Note: As close to the side as possible, the drill bit on the drive side should be 1/32" larger than the one on the clutch side.

1. Using the air body tool and a drill, cut and drill new holes in BH to match plate, top and bottom.
2. Install clutch side plate by riveting in place to bulkhead.

Install top shaft and bearings

1. Ensure drive side bearing is fully seated in plate by scanning the plate's backside.
2. Tighten 5mm socket head pinch bolt at top of plate.

Note 1: Do not over tighten pinch bolt, or premature bearing failure will occur.

Note 2: Do not tighten setscrews on clutch side bearing at this time.

3. Place red Loctite on set screws.
4. Tighten clutch side set screws, top shaft and bottom shaft after the rear suspension is installed.

Install track shaft

1. Set track in tunnel in preparation for installation.
2. To install track shaft, remove 5mm socket head pinch bolt and window retainer; the window in the bottom of the plate will drop out.
3. Ensure clutch side bearing and flangettes are loose on drive shaft with locking collar toward drivers - do not tighten at this time.

Note: The clutch side bearing will bolt up on the inside to the bulkhead.

4. Install drive shaft by sliding the shaft's flat side in the slot on the CMX drive plate.
5. Slide shaft toward clutch side.
Note: If needed, tap the shaft to seat the drive side bearing in the plate.
6. Bolt up the clutch side flangetts.
7. Lift clutch side of track shaft to top of hole and tighten bolts.
8. Ensure drive side bearing is seated through visual inspection.
9. Install window and pinch bolt.
10. Tighten pinch bolt.

Note: Do not tighten setscrews on clutch side bearing at this time.

11. Place red Loctite on set screws.
12. Tighten clutch side set screws, top shaft and bottom shaft after the rear suspension is installed.
Install bottom sprocket

1. Ensure brake disc is on sprocket prior to installation.
2. Place red Loctite® on aluminum nuts.
3. Install and tighten aluminum nuts that retain bottom sprocket.

Install CMX billet machined, 4-piston brake caliper

1. Ensure brake pad is in caliper prior to installation.
2. Place red Loctite on three titanium mount bolts.
3. Route steel braided brake line against CMX drive plate and retain brake line to plate with clamp and screw.
4. Install Wilwood master cylinder and connect brake line.
5. Use DOT 4 brake fluid and bleed brake.

Install idler and top sprockets

1. Place belt on bottom sprocket prior to installing idler and top sprockets.
2. Place red Loctite on titanium set screws.
3. With belt in place, install top sprocket to hub with six titanium socket head cap screws.
4. Install idler sprocket.
5. Before tightening idler retaining bolt, tension the belt by prying on the idler spindle and then tighten the retaining bolt.
Note: This belt runs fairly tight. Use your judgment when tightening.

Install protector cup

Note 1: Best practice is to bolt cup on, thus allowing easy removal and maintenance.

Note 2: The footrest on the drive side needs to be blocked off so that snow and ice cannot get into drive system. Complete this by installing a thin aluminum or plastic plate.

Install rear suspension

1. Using the OEM shop manual, install rear suspension.
2. If track shaft moved down and back , then move rear suspension down and back in matching distance.

Note: After rear suspension is installed, Loctite® and tighten jackshaft bearing and track shaft bearing setscrews.

Once the CMXDS is installed, verify that the exhaust system has enough clearance to the drive system, if not add a heat shield.
If needed, or if desired, add reinforcement to the drive side footrest by attaching a brace from the outboard footrest and trailing arm attachment area forward to the bulkhead in front of the CMXDS.

For more information about this belt drive system, contact Mark Hoffman at Crazy Mountain Motorsports, 406/686-4921.