<VV> Thrown Belt

[corvairduval]

 I see you have not heard of the problem with Clark's C5790 belts. Drove me nuts for years trying to find why I kept shredding belts. I sandblasted all the pulleys, changed belts (but always used the C5790s I had on hand) but the problem continued. 

On the forums I found people talking about the issue and the common denominator was C5790! All the people using other belts had no issues. They were using mostly the industrial size 3V560. Available from Gates and other manufacturers. Supposedly Clarks has changed suppliers. I'm buying 3V560 now. They are wrapped, and thin enough to fit deep in the pulleys, just like the original GM belts!
And yes, you should be able to just turn the alternator (generator) pulley with the belt properly tensioned. Over tensioned will wear the fan, alternator and idler bearings. 
Frank DuVal
    On Wednesday, October 9, 2024 at 03:18:46 PM EDT, Steven J. Serenska via VirtualVairs <virtualvairs at corvair.org> wrote:  
 
 

Here's my contribution to traffic.

I had work done recently on my 1965 Monza 110/4spd.  While the shop was 
doing other things, I asked them to replace the fan belt.

After i got it back, I drove the car for a few weeks with no issues.  
Then, during 70-80mph drive home, it threw the belt and I had to pull 
over.  I didn't have the right tools in the car, so I got a tow home.

I replaced the belt myself using that handy bent wrench that Clark's 
sells.  I had read on a forum somewhere that, when the belt is 
appropriately tensioned, you should just be able to turn the alternator 
with a single finger.  I bought a replacement belt and tightened it to 
that level and was on my way.

I took it on another high-speed drive this past weekend of about 60 
miles each way.  When I arrived at my destination, I could hear 
something squealing and opened the engine compartment and checked.  The 
fanbelt hadn't been thrown but it was loose and slipping.  After 
everything cooled down (about an hour), I checked and the tensioner was 
still firmly bolted into place exactly as I had left it.  My only 
conclusion was that the belt had somehow expanded although that didn't 
somehow seem right.  I loosened and moved the tensioner, tightened 
everything up, and drove home.

When I got home, there were no noises but I checked the belt anyway.  It 
was loose again.

I got a steel rod and was able to use it to pull the tensioner back.  
The belt was tighter than I had gotten it in the past but I could still 
turn the alternator.  When I backed into the garage, the car began 
making a whirring noise, not unlike the noise of the flying car in the 
Jetsons cartoon.  I read somewhere that the whirring could be coming 
from the alternator due to an overtightened belt.

I suppose my next task is to loosen it a bit but I'm afraid of taking 
another long, highway speed drive and having another issue.

What other things should I do or check out?  The belt that's on there 
now was purchased a few years ago from Clark's.

Thanks in advance for your help.

Steven J. Serenska
Bristol, RI


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