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I had my alternator belt flip over at an autocross last weekend. Anyone else ever seen this?

Belt was on the fan and alternator pulleys, just as it should be, but the teeth were facing outward. It had flipped itself inside out! Tension was good. Adjuster bolt still tight.

Discovered this after the motor had started cutting out and finally stopped on course. The cause for that was the electrical connections coming off of the starter motor. Those connections include the power supply to the CDI box. So the engine quit due to no spark. The nut had backed off and fell off. (User error on that. Could'a swore I'd torqued that nut...)

My theory is that, as the electrical connection was shaking loose, the engine was cutting in and out, and the torque variations from that process caused the fan belt to jump around enough to flip over. But that's just my theory.

Anyone else had any experience with a problem like this?


Andrew Blyholder

back in the 90's we used to club race a 4 cylinder
it too, would throw the belt
high rpm, and especially if there was ever a missed shift where the motor would rev very fast....

the real problem is likely a worn pulley that doesn't "grip" the belt as well as it should.

I've seen them flip
and more commonly, I've seen them just throw off

but here is a cheap thing to try.
take a new belt.
put it into a zip lock bag
soak with with wd40 or some lubricant of your choice
let it soak a minimum of over night.
dry it off with a rag
and install, but not too tight.

what happened for me: if the motor rpm was really high or something occurred that may throw off the belt, the belt will then just temporarily slip...

the slip is enough that the belt doesn't throw off

give it a try
if it doesn't work, your out a 5$ belt
but I've seen it work!

I've seen it happen & found that the alternator bracket was fractured at the pivot end so never got proper alignment. The bracket is a weak design IMO...welded it up & OK now...
Alignment caused this for me. i had powder coated something and increased the size by a fraction.

I suspect yours is just belt stretchable and high RPM operation though...
Thanks for the good suggestions. I'll try all solutions!

Alternator bracket is sound, and I carefully shimmed it to get the alt. pully exactly in plane either fan, so I don't think alignment is my problem.

I too have experienced throwing the belt off on minor miss-shift over-revs. Flipping inside out, however, was a new trick for me.

I have a good selection of used (but not worn out) belts in my parts collection. Pulled them out. They have an amazingly large amount of variation in width, vee taper, and length. All presumably considered a "stock" 914 belt by their manufacturer. But who knows what configuration is optimal?!

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