Drive Chain Tech by Capo

slob · 08-02-2011, 06:36 PM

Discussion On The Chain Drive System

The following is applicable to the chain drive as fitted to the S*R series.
The final chain drive, takes power from the gearbox output shaft and transmits it to the rear wheel, under deceleration the load is in the opposite direction.

The gearing ratio is dependent upon the combination of the front and rear sprockets.

The chain pitch is 5/8” (15.875mm) and the width may be 520 (1/4”, 6.35mm) on some S2R’s and 525 ( 7.93mm) on the S4R’s. The chain tension is adjusted by means of an eccentric hub in the rear wheel that effectively moves the rear wheel forward or back ward (this also affects the ride height).

The eccentric position and ride height setting can combine to cause contact with the plastic chain guide fitted to the swinging arm especially at full suspension extension.

Chain alignment is predetermined and controlled by the use of shims between the swinging arm and the engine mounting boss. As designed, the axial position of the sprocket and the shaft is fixed and cannot be adjusted, although it would be possible to adjust the sprocket inboard by shimming between the keeper and the sprocket, the sprocket cannot be adjusted outboard Production tolerances can produce significant misalignment. Chain alignment should be checked and adjusted as necessary

Power is transmitted to the rear wheel via an elastomeric cush drive that is designed to dampen the forces being applied to the drive system, the rear sprocket consisting of 5 rubber bushed bolts, power flows from the outer through the rubber to the inner bolt that is secured to a drive plate spider, The spider is internally splined and is fixed securely to the axial with a 33mm nut.

In order for the rear sprocket to rotate slightly during the cush action, a small axial clearance is provided, this can cause some free play (the proverbial sprocket wiggle).

Ducati uses two types of mounting the front sprocket to the output shaft. The first uses a large nut that tightens he sprocket to the shaft, the second uses a keeper plate.

This describes the keeper plate system.

The keeper plate is splined internally to match the splines on the output shaft and has two holes the secure it to the sprocket with two 5mm bolts. The output shaft has a groove into which the keeper locates

The keeper is slid into position then rotated within the groove until the holes line up with those in the sprocket. This action causes the internal spines of the keeper to oppose the spines of the shaft thus fixing the sprocket to the shaft and fixing the axial position of the sprocket on the shaft. Note that the bolting of the keeper to the sprocket does not tighten the assembly to the shaft, it locates and secures. The bolts serve only to fix the keeper to the sprocket and need only be torqued to the recommended value. They should however be secured by the application of a low/medium strength thread locking adhesive.

The rather loose fit of the sprocket on the shaft and the clearance of the keeper and the groove, combined to allow a surprising amount of movement. This is exacerbated by wear
The keeper is a punched mild steel part, edges are ‘rolled’ on one edge and sharp on the other. Ducati recommend that the rolled edge face the sprocket.

Wear patterns on the shaft and keeper, indicate that movement is taking place between the sprocket and shaft during operation, the contact area is not lubricated. It has been known for the teeth on the keeper to be totally worn away.

Tips.
Check the chain alignment.
Change the keeper each time you change the sprocket.
Don’t over tighten the bolts securing the keeper to the sprocket.
Avoid causing judder in the drive when riding this is bad for the cush drive.
Check the cush drive bushings regularly to see if any have failed and are backing out.
Keep the chain clean, lubricated and adjusted.
Use a torque wrench to tighten the eccentric clamp pinch bolts.

08-02-2011, 06:36 PM	#1
slob . Join Date: Jul 2003 Location: East London Bike: Multiple Monsters Posts: 9,735	Drive Chain Tech by Capo Discussion On The Chain Drive System The following is applicable to the chain drive as fitted to the SR series. The final chain drive, takes power from the gearbox output shaft and transmits it to the rear wheel, under deceleration the load is in the opposite direction. The gearing ratio is dependent upon the combination of the front and rear sprockets. The chain pitch is 5/8” (15.875mm) and the width may be 520 (1/4”, 6.35mm) on some S2R’s and 525 ( 7.93mm) on the S4R’s. The chain tension is adjusted by means of an eccentric hub in the rear wheel that effectively moves the rear wheel forward or back ward (this also affects the ride height). The eccentric position and ride height setting can combine to cause contact with the plastic chain guide fitted to the swinging arm especially at full suspension extension. Chain alignment is predetermined and controlled by the use of shims between the swinging arm and the engine mounting boss. As designed, the axial position of the sprocket and the shaft is fixed and cannot be adjusted, although it would be possible to adjust the sprocket inboard by shimming between the keeper and the sprocket, the sprocket cannot be adjusted outboard Production tolerances can produce significant misalignment. Chain alignment should be checked and adjusted as necessary Power is transmitted to the rear wheel via an elastomeric cush drive that is designed to dampen the forces being applied to the drive system, the rear sprocket consisting of 5 rubber bushed bolts, power flows from the outer through the rubber to the inner bolt that is secured to a drive plate spider, The spider is internally splined and is fixed securely to the axial with a 33mm nut. In order for the rear sprocket to rotate slightly during the cush action, a small axial clearance is provided, this can cause some free play (the proverbial sprocket wiggle). Ducati uses two types of mounting the front sprocket to the output shaft. The first uses a large nut that tightens he sprocket to the shaft, the second uses a keeper plate. This describes the keeper plate system. The keeper plate is splined internally to match the splines on the output shaft and has two holes the secure it to the sprocket with two 5mm bolts. The output shaft has a groove into which the keeper locates The keeper is slid into position then rotated within the groove until the holes line up with those in the sprocket. This action causes the internal spines of the keeper to oppose the spines of the shaft thus fixing the sprocket to the shaft and fixing the axial position of the sprocket on the shaft. Note that the bolting of the keeper to the sprocket does not tighten the assembly to the shaft, it locates and secures. The bolts serve only to fix the keeper to the sprocket and need only be torqued to the recommended value. They should however be secured by the application of a low/medium strength thread locking adhesive. The rather loose fit of the sprocket on the shaft and the clearance of the keeper and the groove, combined to allow a surprising amount of movement. This is exacerbated by wear The keeper is a punched mild steel part, edges are ‘rolled’ on one edge and sharp on the other. Ducati recommend that the rolled edge face the sprocket. Wear patterns on the shaft and keeper, indicate that movement is taking place between the sprocket and shaft during operation, the contact area is not lubricated. It has been known for the teeth on the keeper to be totally worn away. Tips.* Check the chain alignment. Change the keeper each time you change the sprocket. Don’t over tighten the bolts securing the keeper to the sprocket. Avoid causing judder in the drive when riding this is bad for the cush drive. Check the cush drive bushings regularly to see if any have failed and are backing out. Keep the chain clean, lubricated and adjusted. Use a torque wrench to tighten the eccentric clamp pinch bolts.