since 1940

Alternator bracket breakage. Lycoming Engines

74324 Lycoming alternator bracket

1. Insufficient torque on mounting bolts.

2. Excessive engine vibration.

3. Excessive clearance between the mounting bracket and the lugs on the alternator. Clearance should be less than .004 inch. Install shims per Lycoming Service Instruction 1270A.

 

Lycoming engines with Prestolite alternators - shim with 76534 shim there is .004 max clearance between bracket and bushing. Each shim is .005 inch thick. Shims are about $4.00 each from Lycoming.

4. Worn alternator bushings.

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