<VV> Shop Manual, Corvair Basics Manual, VV

[Dennis Pleau]

In '70 I had a '63 102/4sp and worked at a Union 76 Station.  The station
had a strand tension gauge so I used it to tension my fan belts.  I
tossed/broke a lot of belts.  In my 16 year mind, I was sure I wasn't
putting them on tight enough so I started putting them on tighter and still
had a lot of belt problems.  I then started using a crow bar to get them
even tighter and broke one of the ears off were the generator bolts went
through.  After welding up the ear, I don't remember a lot of problems after
that but I was still replacing a good number of belts.  I bought a '70
Maverick in '71 and my Corvair became my fun car.  It was much more
enjoyable to drive than the Ford, but the Maverick had AC.  I sold the
Corvair in '74.  

I bought another '63 102/4 in '84.  Joined CORSA and Valley CORSA (now
Silicon Valley CORSA) and learned the proper way to tension belts and
started getting years out of belts rather than the days or week I got when I
was in High School.

dp

-----Original Message-----
From: VirtualVairs [mailto:virtualvairs-bounces at corvair.org] On Behalf Of
Jim Simpson via VirtualVairs
Sent: Friday, September 04, 2015 2:50 PM
To: Virtual Vairs
Subject: Re: <VV> Shop Manual, Corvair Basics Manual, VV

I do have a strand tension gauge (from the late John Moody) and trust me,
the shop manual specifications are WAY too tight!  If you do actually use a
strand tension gauge and tighten a new belt to 75 lb tension, make sure you
have a spare -- you'll be replacing the fan belt soon.

The 50+ years of accumulated wisdom and experience of Corvair owners (as
opposed to the original engineers) has shown that a somewhat loose belt
works best.  As pointed out in the Corvair Basics manual, just tight enough
so you can just barely turn the alternator/generator with your fingers is
about right.  I measured that as somewhere around 15 - 25 lbs tension
depending upon how well calibrated your finger might be.

I did a little research to see how Chevrolet came up with the recommended
tension and as best as I can find, they used the formulas published by the
drive belt manufacturers such as Gates.  If you make some assumptions as to
loads and RPM, you come up with numbers like 75 lbs tension in order to make
sure that nothing (fan & alternator) is slipping at high RPM.  I suspect
that this high tension specification is one of the reasons why Corvairs
developed a reputation for short fan belt life.  That and the high
rotational inertia of the early steel fans and generators.

The collective experience is that it's better to allow some slippage.

Jim Simpson
Group Corvair



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