[VAC] Re: Vintage tow vehicle (1972); update

["Harvey Barlow" <harveybarlow@xxxxxxxxxxxxx>]

No, no change.  I assume that is a typo in the front GAWR.  Those figures
support the GVWR.  Are you certain of the 8100 # rating?  I don't remember
3/4 ton trucks of that era being rated in excess of 7500 #.  GVWR is
normally less than the total of front and rear axle ratings.  But it is not
important, your truck has the maximum weight ratings offered and is a solid
platform for towing or hauling.

> >likely to be equipped with the old C-6 automatic transmission which was a
> >tough transmission.
>
> I just picked up a original shop manual so I could figure out the ID
> codes.  If I am reading it correctly, I have a C-4 Automatic transmission.

I was fairly certain that a maximum rated 3/4 ton Ford with 390 engine would
have had the C-6, the most rugged transmission offered at the time, but that
is nothing to worry about either.  The C-4 was also tough, just not as tough
as the C-6.  With clean fluid and filter towing a medium-sized Airstream it
should provide good service for a long time if it is in good shape when you
begin towing.

> >There are two more bits of information that would be helpful in offering
an
> >opinion as to how much trailer you can tow.  What is the rear axle or
> >differential ratio?  You should be able to find a code on a tag on the
> >driver's door frame.  The letter-number code can probably be deciphered
by a
> >Ford dealer and it is probably still the same code in use in '90s era
Ford
> >trucks.  My guess is it is a 3.73:1 but it could be a 4.11:1.  Either
will
> >be good for towing but not for fuel mileage.
>
> I am new to this, but it looks like it is 3.54.1  Could this be correct?

Yes, that may have been an optional gear ratio but less common.  The truck
could have been equipped with a 3.54:1 gear set in the interest of improving
fuel economy.  In those days, overdrive transmissions were not available.
The 3.54 gear slightly reduces hill climbing ability and load starting power
on a steep grade but it will be adequate with the trailer range we are
talking about.
>
> >The other relevant factor is tire size or, more precisely, diameter.
Those
> >trucks were originally equipped with the old style bias ply 7.50x16 8 or
10
> >ply tires.  They were a pretty tall tire which reduces the effective
final
> >drive ratio.
>
> The tires on it are tall. They are LT 235/85R 16 M/S
>
> Would this be a good size for the truck if I were towing a trailer?
>
Yes.  That tire is the modern radial equivalent of the original equipment
7.50 x 16 tires and probably keeps your speedometer reading in the ballpark.
The tires installed on your truck are far more efficient, long wearing,
better handling, etc. than the original and are the correct choice for your
application as long as they are 8PR (eight ply rated) or even better, 10PR
(ten ply rated) and my guess is they are. The weight capacity of each tire
will be molded into the side wall.  In 10 PR they are rated at 3000 #.

> >Having said all of that, if you want to maintain adequate performance
with a
> >safety and performance margin as you said (and I agree), my
recommendation
> >would be to limit your gross trailer weight (including propane, water,
> >clothing, food, personal items) to around 6000 pounds.
>
> OK.  Assuming the above new information I have posted does not change that
> number, I'll use it.
>
> >Airstreams of similar lengths became heavier in each decade.    If you
are
> >seeking a trailer of the same era as your puller, i.e. a '71 to '72 for
> >example, a 27' Overlander (or smaller) would probably make an excellent
> >candidate.
>
> If I wanted to restore (not go completely nuts, but bring a Airstream back
> to it's original look) are 1970's models easier to find equipment for,
than
> say, the 1960's?

Yes.  I would guess that Airstream built and sold more of the '70s units as
RVing became more common and many of them are still in daily service.  Lots
of list members own and travel with '70s vintage units.  Some of them look
so good that unless you are fairly knowledgeable about Airstreams, you won't
know they are 30 years old.  Lots of them have also ended up in salvage
yards and will give up their parts.  '70s trailers are very similar to
current production trailers in many ways and most of the appliances and
parts can be replaced with similar components from '90s or even Y2k
trailers.  Some adapting may be necessary but you are certainly not going to
end up with an unrepairable orphan if you buy a '70s Airstream.

Harvey