Suspension Tuning and Maintenance Series:

 Linkage & Bearings

The modern Off-Road motorcycle incorporates a very sophisticated suspension system.  An infinite number of tuning parameters including springs, oil volumes, valving, and hi/low adjusters front and rear allow these suspension to be tuned to track, rider, and riding styles.  An often neglected area of the suspension is the linkage, swing-arm, steering, and wheel bearings.  Thrashing through mud conditions, dry dusty conditions and cleaning with high-pressure water reeks havoc with these delicate bearings.  A regular routine of cleaning, inspection and repacking the grease will allow the suspension to work properly.  Failure to maintain these bearings can lead to improper performance, costly failures and even sever injuries.  This letter will discuss the role of these components, installation and maintenance techniques.

Bearings incorporate three parts, two stationary surfaces and one moving surface.  A lubricant (grease of oil)  forms a cushion between the surfaces.  When the bearing assembly moves, the lubricant absorbs the energy and prevents meta-to-metal contact.  As the lubricant breaks down, is washed away or dirt enters the bearing additional friction occurs and wear is introduced.  This mechanical looseness is sometimes referred to as “play”.  Additionally dirt or other foreign substances can mar or scratch the bearing surface causing a performance loss.

Motorcycles generally incorporate four bearing types.  Needle bearings are used in linkage systems and swing-arm bearings.  Spherical bearings are used where multidirectional forces are needed such as upper and lower shock bearings.  Ball bearings are generally used for wheel bearings.  Tapered roller bearings are used in the steering stem.  Seals are used to keep dust, dirt and water from entering the bearing.  Grease fittings are not generally used due to design limitations.  Special tools are necessary to replace some bearings, but generally servicing only requires disassembly, cleaning and repacking with water proof grease.

The maintenance requirements vary with the type and amount of riding conditions (dry or muddy).  New motorcycles should be inspected and serviced prior to the first operation and regular inspection and maintenance schedule adopted.  Use good waterproof grease and proper torques and adjustments employed.  Follow the service procedures outlined in the OEM service manual.  This will allow the motorcycle (and suspension) to perform as it was intended.

• Inspect the linkage system, swing-arm, steering stem and wheels for excessive play and adjust or repair as necessary.

• Replace the wheel bearings and seals on a regular basis.   Adopt a regular maintenance schedule.

• Never spray water directly at the seals, this may drive dirt into the bearings.

C-Cycle Suspension Service

16 West High St. East Hampton, CT 06424 - 860-267-1710 – www.Ccycle.com