<VV> Alternator Pulley Grip

[goofyroo at excite.com]

>>>>>IF it is the belt slipping, wouldn't you be able to detect by at least one of 3 means?
1. Smell it?
2. Hear it?
3. See it? (excessive wear).
AND, if it REALLY is slipping - then why? Bad bearing in the alternator?
Let me ask you this? Does it have the correct "Corvair" fan on it? If not, THAT could be your problem.

Good questions, all.  The working theory is belt slippage due to mismatch of belt and pulley.  The belt is aftermarket (boo, hiss) and probably a tad wider than the stock/vendor belts.  As I'm using the original Corvair generator pulley, that mismatch may be just enough ...

... in combination with the fact that the Corvair belt arrangement puts only about 1/3 of the alt pulley in contact anyway.  Like you, I doubted the slippage theory because I've heard/smelled AC compressor pulleys slip and it was unmistakable.  However, this may be just enough slippage to diminish output, unlike an AC situation where the compressor isn't turning or turns very, very slowly while the belt screams around it.

My local alt rebuilder - in the business 25 years - hasn't seen an alt put out low voltage unless the belt was slipping.  This is the second alt on the car to show this symptom, which suggests the problem isn't in the unit itself.

I do have a magnesium ('64) fan on the car, if that's what you're asking.  The alt pulley is early Corvair, too, so it has a cooling fan built into it.

Finally, the belt is showing wear earlier than I would have expected.  Which suggests heat build-up either causing, or caused by, the slippage.

That's my story until proven otherwise.  Belts on order.  I'll follow-up.  Thanks to everyone who've put their mind to this for me.

Michael Smith
Dallas

----- Original Message ----- 
From: <goofyroo at excite.com>
To: <JVHRoberts at aol.com>; <virtualvairs at corvair.org>
Sent: Saturday, May 21, 2005 3:00 PM
Subject: Re: <VV> Alternator Pulley Grip

> I don't know how to check the alternator's temp, or know what its range 
> is, but heat is definitely a factor here. The voltage drop begins after a 
> couple of miles' driving, sooner as it's hotter outside.
>
> Whether it's the belt/pulley/alt being affected, I'll have to work through 
> one at a time. The previous alt did the same thing, so I'll start with the 
> belt. Maybe a narrower one will grip better, or I need a wider pulley.
>
> Michael
>
>>>>>How hot is the alternator getting? The regulators in those things have 
>>>>>a negative temperature/voltage coefficient. If it gets REALLY hot, 
>>>>>it'll get fairly low. If you got a fried diode, etc., the alternator 
>>>>>can overheat.

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