Big Dog Belt Drive


The Big Dog Belt drive updates your 2005-10 Balance Drive BDM to an open belt drive from the closed wet primary system. Having an open belt drive is one of those traits of a cool chopper to a lot of us out there riding. The mechanical nature of an open belt whippin’ in the breeze gives that element of nostalgia that is so popular in the V-twin dominated world we all love. We agree and tried to build on that cool factor with some modern day engineering. Our 2.4″ wide belt rides on stainless steel pulleys. We used larger 14mm teeth and an outboard support design to add as much strength as possible. Our 12 plate clutch design will handle up 120 ft-lbs of continuous use right out of the box.  Our 1 piece clutch basket design, will deliver years of reliable starting that we all come to expect these days. Not being happy with a product that just works great, we pulled out our design pencils and did our best to add the same level of aesthetic style to complement the strength of the mechanical design.


- Stainless steel pulleys
– One piece steel clutch basket
– 2.4″ Wide proprietary belt
– Billet machined aluminum outboard support (dog bone) and pulley covers
– Available as a 0″ or 1/2″ offset configuration

- Backed by a 2 yr limited warranty

Big Dog Belt Drive Kit Contents, Polished

BDM Belt Drive, Kit Contents. Black Anodized & Polished


– 28 tooth stainless steel pulley up front and a 43T stainless steel pulley in the rear
– 1.58 pulley ratio yields a 7% increase in torque to the rear wheel
– One piece 66 tooth 1045 steel ring gear
– 2.4″ Wide proprietary belt with 14mm teeth
– 12 plate clutch pack holds up to 120 ft-lbs of continuous use while the tight tolerance clutch baskets all but eliminates the ‘neutral clutch rattle ‘ most belt drives suffer from
– Billet 6061-T6 aluminum outboard support and pulley covers
– Motor plate and edge guard are machined from 6061-T6 billet plate stock
– Comes standard with outboard support and a show polished finish.
– Available as a 0″ or 1/2″ offset configuration


As shown below left, is a used aftermarket clutch basket, made from Aluminum. As you can see, after time, virbation of the clutch pack inside the basket wears grooves in the flanks of teeth. Anyone who has wrenched for at least one riding season, has seen this phenomenon in the flesh. These wear marks when they start, cause clutch disengagement issues, shifting issues and trouble finding neutral. When they get to be as bad as this picture, you have to replace the entire basket at your expense. The wearing of the clutch plates into the basket, and the belt into the pulleys is why we designed our belt drive with 1045 steel pulleys. The same material we used on our secondary drive pulleys. Also pictured is a common aftermarket belt (on the bottom) with 8mm teeth, our 14mm tooth belt is just above it. The larger tooth size has more meat to it, and thus can hold more force per tooth. If a 14mm tooth belt size can drive the supercharger on a 500ci Top Alcohol Dragster motor, your bad ass Big Dog will be just fine.

Belt Drive Clutch Basket, Aftermarket vs BAKER

Belt Tooth Comparison, BAKER vs Aftermarket

Big Dog Belt Drive, Cutaway


PN Description Fitment
BD-BDM-0 No Offset, Polished 2005-2007, 300mm Tire Models
BD-BDM-0-08 No Offset, Polished 2008-2010, 300mm & 330mm Tire Models
BD-BDM-1/2 1/2″ Offset, Polished 2005-2007, 250mm Tire Models
BD-BDM-1/2-08 1/2″ Offset, Polished 2008-2010, 210mm & 250mm Tire Models


Big Dog Compensator Style Outer Primary

If you have a Big Dog model that has a compensator on the motor and your outer primary looks like the one on the right (outer primary has a cover on the motor side) you will need a new motor nut to install the belt drive. BAKER PN DSSC-180


Installation Instructions

BAKER Big Dog Belt Drive Installation Instructions: Click Here

BAKER Big Dog Belt Drive Addendum : Click Here


Big Dog Belt Drive Installed, 2008 K9

Big Dog Belt Drive Installed, 2008 K9, Front View

Big Belt Drive Installed, 2007 Mastiff, Top View

Big Belt Drive Installed, 2008 K9, Drivetrain


Big Dog Belt Drive, 2007 Mastiff, Up Close

Big Dog Belt Drive Installed, 2005, Pit Bull

Big Dog Belt Drive Installed, 2010 Bagger

Big Dog Belt Drive Installed, 2010 Bagger, Side View


Big Dog Belt Installed, 2007 Mastiff



BAKER DRIVETRAIN| 9804 E. SAGINAW, HASLETT, MI, 48840 |1-877-640-2004| 517-339-3835 | FAX: 517-339-4590 @2012 BAKER INC