Boss Hoss ZZ4 Alternator Belt Squeal

[The Mindless Philosopher]

Probably preaching to the choir here, but just in case anyone needs it; I specified ZZ4 because I do not know how other BH models are configured (serpentine belt? different frame? Different alternator placement?):

Boss Hoss ZZ4 alternator belt squeal/chatter...

Symptoms:
- Alternator belt squeals upon initial start
- Squeal persists until load is applied (put into gear and/or twist throttle, or begin riding)
- Black sooty powder on alternator (front and back) and on bracket and wire(s)
- Glazed appearance on sides of alternator belt

Other possible symptoms:
- Faint burning odor
- Mild drop in battery voltage due to insufficient charging, characterized by hard initial start and easy subsequent starts, repeating the cycle after sitting overnight

Root cause:
(Inherent in the BH frame design) distance between crank shaft pulley and alternator is too short (limited adjustment space), creating problems with the contact area of the belt in the alternator pulley groove, due to available product selections. "Close enough for government work" i.e. "the belt fits" is not necessarily sufficient. It not only needs to fit into the pulley groove, it also needs to hug it firmly.

Other (possible but not always present) contributing factors:
- Misaligned pulleys (alternator/crank shaft)
- Warped pulleys
- Chrome plated alternator pulley (overly slick surface contributing to slippage)
- Rusted alternator pulley (rough, overly abrasive surface damaging belt)
- Cracked/damaged alternator mounting/adjustment bracket (especially hidden cracks on the back-side)

Remedy (as with any alternator application, whether BH or otherwise):
- A belt with sufficient surface area for belt-to-pulley contact (#1 consideration with the limited adjustment space)
- Align pulleys (shim alternator pulley if necessary)
- Clean pulley surface areas (remove rust burs or other surface abnormalities)
- Replace alternator pulley if necessary
- Proper tension on alternator belt (be careful not to over-tighten)


That said, I have yet to find the "perfect" belt, so I can't make a good recommendation. Finding one that fits over the crank pulley and reaches the alternator without being too long, is challenging enough (usually a lawn mower belt), much less finding one that has adequate surface area (wide enough and deep enough). Most are too narrow and sit too low in the groove, or are too wide and shallow and sit too high.

I thought I might have a winner with a Gates Racing 9325HD V-Belt, but no. Even so, the toothed belts seem to work best.

So far I am getting by with the one that's on it, but I didn't keep track of what it is, and it's not printed on the belt.

I don't know if there is a custom Boss Hoss alternator pulley out there, or an aftermarket GM pulley, with a narrowed, shallower groove better suited for thinner automotive belts or lawn mower belts?

[Puff]

My 2001 ZZ4 has the v-belt pulley.
I use a NAPA 7312 V-Belt.
To install it, I have to remove the
alternator a bit, just to get the belt
in-place, then reinstall the alternator.
Not difficult. The belts DO stretch,
as you well know.
If it squeals a bit, or if the voltmeter
drops a bit, I readjust the belt.
They do wear out after awhile, so I
carry 2 replacement 7312's in my
saddlebags.
A slight inconvenience, but we can
all turn a few wrenches when needed.

[The Mindless Philosopher]

I replaced about 7 until I found one it wanted to live with for a while. It kept throwing them until I stopped using the flat non-toothed type.

I'll keep that NAPA 7312 in mind.

[V8Bikers]

Have you considered upgrading to the later model (I think started in 06 ?) ribbed belt setup? A fairly simple job after removing radiator. You will need a torque wrench that goes to about 250, which I believe the crank pulley needs to be. I would use a new bolt as well. Both pulleys should be easy to source. On the several bikes I have had this setup on there have been no issues.

[The Mindless Philosopher]

Haven't considered. Wasn't aware until the replies here. Thank you both for the info.

[knockdolian]

I have foun the v belt to be better than toothed belt so far. As for fitting, undoing the to radiator mount and lifting the radiator slightly to clear the bottom mount. It will pull forward enough to get the belt on