Carbon Cub Denso alternators

[Cactus Charlie]

If you have a Carbon Cub with a Denso alternator take a close look and the crankcase mounted hinge attachment bracket next time the cowling is off.

I found that the alternator moved when I checked belt tension. I found free play between the alternator mount lug and the crankcase attach bracket. All slack should be eliminated from this attach point by proper section of shim washers but mine had not been correctly assembled and the alternator lug, shim washers, bolt, and the bracket had been fretting.

I took the alternator and crankcase mounting bracket home for closer inspection. I machined a spacer from 6061 bar stock to replace the ill fitting shim washers. Today I got it back on the aircraft and the alternator is now rigidly attached.

Photos later. I left my camera in the hangar.

 

[Cactus Charlie]

 

[Neal]

Seems like quite a gap. Something missing from the install? I'll have to look at mine next time the cowl is off.

 

[Cactus Charlie]

The photo is with the machined spacer installed. There is no gap. It was machined to be a light interference fit.

 

[Neal]

I was implying before your spacer. Did something possible break and release from the original install?

 

[Cactus Charlie]

The spacer replaced 3 shim washers with thicknesses 0.127, 0.127, and 0.125 inch. With those shim washers installed I measured 0.012 inch gap. Some of that gap was caused by fretting but the fretting was caused because there was a gap when initially assembled.

If you have a gap you will be able to spin the shim washers with your finger without dismantling anything.