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Drawings
1997 © Triumph Motorcycles Limited. |
Alternator Shaft Bolt |
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The top drawing shows the side of the alternator that goes into the crankcase. The four blade impeller is attached with a bolt. This bold has been known to shear or loosen up. Triumph found that the specification for the bolt had been changed without their knowledge which lead to the failure. This failure was not wide spread. |
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| The next drawing shows the alternator without the impeller installed. Should the shaft bolt holding the impeller in place shear or loosen, the impeller begins to move on the shaft. As a gap develops between the metal shaft and metal impeller surfaces a rattle, which usually disappears as the engine rpm's increase, will be audible. | |||
| The rattle will usually appear at idle and disappear just past 2k rpm. Putting an electrical load on the system at idle or very low speed, such as applying the front or rear brake, will cause the impeller to settle down on the shaft and the rattle to disappear. Should the bolt head shear it can be launched about the cush drive housing. That is a noise you won't forget. Eventually the rattle will increase in volume and be audible at higher speeds. Lowering the engine idle can also increase the rattle. | |||
| Triumph had issued Service Bulletin #185 which covers the original problem. If your bike is still under warranty take it to your dealer. The Haynes Service & Repair Manual indicated that there are no replacement parts for the alternator so if you are out of warranty the complete alternator, impeller, bolt and two washers may need to be replaced at your expense. | |||