[VAC] Re: Towing With A Manual 5Speed Transmission

[Rick Davis <k8doc@xxxxxxxxxxx>]

The message below was one i posted a couple years ago, for whatever it may
be worth on this subject.

My thanks to Tom Patterson for archiving it as I did not have it here.

Since originally writing this I have gained a bit of towing experience with
the 99 Dodge and am still happy with the choice of the manual. Currently at
210,000 miles.

We also now have four traffic lights in the county instead of 3.  Creeping
civilization I guess.

The key to being satisfied with a manual is the low gear ratio. Some 1/2
ton vehicles and SUV may have a close ratio transmission and be lacking in
the low gear area.

OLD POST
There are many people towing with both types of transmissions, probably
with automatics in the wide majority. 
Here are some of the factors involved based both on my personal experience
with all of them and a lot of reading over the years. Please don't take
this as advocating one over the other as it is strictly a personal choice. 

Years ago all the car manufacturers recommended the automatic.  At that
time virtually all cars and most light trucks manual equipped vehicles had
a 3 speed manual. Because this is no longer the case this old advice is no
longer valid. 

The one major factor that is overlooked in most articles is that the
toughest thing you have to do is get the load moving.  Years ago Wheels
Afield Magazine, now gone, wrote an excellent article and provided the
needed calculations to determine what grade your particular vehicle could 
start on.  Things such as weight, rear end ratio,power and tire size
entered into this. Unfortunately I lost this article somewhere along the way. 

Their Standard was the ability to start your load from a standing start on
a 15% grade. In a nutshell the results were as follows.: 

The 3 speed manual with a typical 3 to one low gear was not sufficient to
do the job. more on this later 
The Automatic could start the load due to torque multiplication in the
torque converter. 
A "real" manual truck transmission with a 6:1 creeper gear could start
anything going, limited only by traction. 

There are other factors as well.  In the 3 speed manual the low gear
situation is marginal but the problem is compounded by an even weaker
reverse gear.  Reverse is when you are most likely to be working the clutch
the hardest such as when parking.  If you stop when you get the first whiff 
of clutch smell chances are the clutch will survive.  It is also likely a
few thousand miles later, just as you decide everything is ok, the throwout
bearing will fail because the heat boiled the lubricant out of it.  I have
towed with a 3 speed and personally experienced these problems. 

I have also had 2 tow vehicles equipped with automatics.  Both performed
well although I did suffer a catastrophic failure of one with no obvious
cause. I was going 20 miles an hour on level ground at the time. I did
experience trouble getting up a couple really steep grades, had the 
torque converter stalled and couldn't get over 20 mph with a 454 engine
equipped vehicle.  None the less I did get there and most of you wouldn't
have been in that situation in the first place.  With the automatic it will
probably be necessary to provide some extra cooling as they can generate 
quite a bit of heat 

Most of the current crop of trucks will have either a 5 speed or 6 speed
manual available. These will have a good strong low gear in the 6 to 1 area
and an overdrive.  The extra gear on the 6 speed should fill in the hole
that is usually apparent between direct and the next gear down.  These 
shift easily and smoothly, much bettr than the older 4 speeds that were a
real workhorse but noisy and hard to shift. 

Overall I personally feel that too big a deal is made over rear end ratio.
I have been all over the west with a 1/2 ton pickup with a 400 cu in engine
and a 3.05 rear gear towing a 29 ft Airstream. I have also had 3.73
equipped vehicles and one with a 4.10.  I felt the 4.10 made for the engine
running at too high an rpm on the road. Of course with an overdrive
equipped vehicle this will not be as bad. Probably 3.73 is a good
compromise choice for most of us. 

>From a load starting standpoint the automatic user might want to go one
choice lower (numerically higher) than the manual user.
Other factors of course are simply based on personal preference as either
works well. 
I personally have two manual shift equipped tow vehicles, a 84 6.2 liter
diesel chev (non turbo) with the older 4 speed manual and 4.10 gears. A
gear Vendors over /underdrive was added a few years ago to fill in the
holes between gears and reduce engine rpm on the highway. Prior to that
change the truck was less than satisfactory. 

The other vehicle is a 99 Dodge turbo diesel with 5 speed manual and 3.54
gears. I have limited towing experience with it with my own trailers, but
have done some towing for a transporter which included some trailers far
heavier than the Airstreams.  So far it has performed perfectly and is 
rarely out of overdrive. 

Please keep in mind that  I am not trying to make a case for any particular
transmission or vehicle.  I live in a rural county with ony 3 traffic
lights.  If I had to drive every day in downtown wherever I might have
automatics. 

Rick Davis  1602 
54 Safari 
69 Ambassador 
70 Globetrotter 
Amateur Radio  K8DOC 
NSS 14876 


     
Rick