alternator balancing

[rv8ch]

Is balancing the alternator a thing? The reason I ask is that I have had to add a couple of big washers under my 4" pulley for spacing, and want to make sure I'm not inducing an unnecessary vibration.

[rv7charlie]

It does need to be balanced, but if the washers are a snug fit on the shaft (centered), it wouldn't worry me.

However... having played around with a lot of different automotive alternators, adapting them to a/c engines and to other auto engines, I'd look carefully at the retaining nut, to be sure it still has adequate 'bite' on the shaft threads. Many alternators don't leave a lot of wiggle room for anything other than 'stock' thickness pulleys.

FWIW,

Charlie

[rv8ch]

Thanks Charlie. The 4" Summit pulley is about 3/16" thinner than the original, which is why I added 2 washers close to the alternator, and one close to the nut. There are plenty of threads.

The washers didn't seem like they had a lot of precision since they are cheap hardware store items, thought I'd check on the balancing.

Perhaps I should find a better source.

[hgerhardt]

Find someone with a lathe and turn a pair of spacers out of aluminum, since the pulley is alum too. That way, they will fit the shaft perfectly and no worries about balance. Plus, you could fine-tune belt alignment through spacer thickness if desired.

Heinrich

[Lenny Iszak]

When you are doing your prop balance you can see the alternator peak show up on the vibration spectrum. Make sure you do it on a balancer that can show you the full spectrum.
To find the peak just calculate the rpm from the size of the pulleys. Mine spins at 3.61 x engine rpm.