Synopses of the Technical Documents
Engine
and Transmission - - -
Rebuilding that Motor
Larry Weidner, whose GMC coach features a 500 cu. in.
Cadillac engine, weighs in on what he has learned and
observed over the years about rebuilding engines. Though
careful to stress he’s providing only his opinions, the
article is quite powerful and worthy of reading by all
owners. View/download
the article.
Rebuilding the Olds
Engines
Jim Bounds responds to an email detailing the work done
at the Cooperative Motor Works with Jasper rebuilt
engines. Jim provides an overview of what needs to be
considered when taking on such a project. View/download the
article.
Throttle
Body Fuel Injection Upgrade
Ray Swartzendruber provides an excellent overview of the
throttle body fuel injection system. What is covered is
generally applicable to most TBI systems, but while
putting particular emphasis on how it applies to the
engines of the GMC Motorhome. The file contains the 77
slides and notes from Ray’s original presentation.
View/download the article.
Fuel Injection for the GMC
As Richard Waters writes, “This is about how a not very
experienced, ‘shade tree mechanic’ figures out how to
install Fuel Injection in his GMC Motorhome. This
presentation is for those non-engineer/professional
mechanic types that want to install TBI.” Don’t be fooled
by the disclaimer, Waters provides lots of photos and
pointer in this 171-slide presentation while crediting
may other members of the GMC community who also provided
advice. The fous of Waters’ project is the installation
of a kit from Howell Engine Developments, Inc. View/download
the article.
Steering,
Suspension and Towing - - -
The GMC Motorhome Steering Box
If the steering on your 30-year-old GMC is getting
a little too loose then this informative document is for
you. Don Wirth gives details on the Saginaw power
steering box. He tells how to identify the proper style
used in the motorhomes, how to disassemble it and the
proper way of adjusting it. View/download
the article.
Saginaw
Steering Boxes
In a reprint from Hemmings Motor News, author Jim O’Clair
goes over some of the virtues of the venerable Saginaw
equipment used in so may GM vehicles. An important thing
to remember when interchanging Saginaw gearboxes is to
use your original pitman arm and idler arm, if possible,
to maintain the proper steering geometry. Ken Henderson
highly recommends this article. View/download
the article.
Steering Column Upgrade and Repair
Are you interested in having a more modern steering
column with the dimmer, cruise control and wiper switch
on the turn signal stalk? If so, this detailed article is
for you. Richard Sowers provides images and notes in a
step-by-step format for doing a complete job. View/download
the article.
A GMC-specific Toad Brake System
Fred Veenschoten provides an overview of the different
types of brake systems for a towed vehicle (toad) before
detailing how to build a VIP System (variable,
independent pressure system). Controlled by the driver’s
foot, the toad brakes can be applied independently of the
coach brakes or in conjunction with the coach brakes.
View/download the article.
The Power Level Air Suspension from the Top Down
The Power Level system was the standard system in 1973
through 1976 GMC coaches. Rick Denney's article presents
the Power Level system starting with its basic theory of
operation and proceeds from there to troubleshooting and
leak detection and repair strategies. Many of the
principles in this article also apply to later
Electro-Level systems, but the article does not attempt
to address that more complicated subject. . View/download
the article.
Suggestions for
Installing the QuadraBag System
Bill Brown offers practical and helpful suggestions for
installation of the new QuadraBag system for the rear
suspension of our GMC coaches. The system, designed by
Jim Bounds and Jim Kanomata, has many advantages of the
original single-bag system developed by GMC. The document
is based on Bill’s notes and observations from installing
a new system on his personal coach.
View/download the article.
Miscellaneous
Auto Issues - - -
Guide to Final Drive Ratios and Tire Size Information by
Brand
Don Brown provides a handy table for evaluating the
difference from original specs for a combination final
drive ratios and tire sizes from Michelin, Goodyear and
Bridgestone.
View/download the article.
The Forgotten Ammeter
An Ammeter measures the direction and quantity of
electricity flowing through it. It has been replaced by
the voltmeter. In pointing out how the ammeter has become
the forgotten gauge a vehicle, Frank Folkmann tell the
proper way to install one as well as the two wrong ways.
View/download the
article.
GMC
Motorhome Electrical System from the Top Down
The electrical system of the GMC is fairly simple when
considered as a system, but it’s easy to get lost in the
details. We work on those details, and sometimes miss an
understanding of the system as a whole. In this document
Rick Denney lays out the system as a whole so that GMC
owners can see how the details fit into the big picture.
View/download the article.
NEW:
LED Tail
Lights Connected by Tail Light Bulb Base
Interested in upgrading the tail light/turn signals of
your coach with LEDs? Tom Whitton tells how to adapt a
trailer light kit from Harbor Freight for use in the GMCs
lense. Tom shares with you his secret of repurposing the
standard bulbs wiring the LED set into the bulb base.
View/download
the article.
All
Around the House - - -
The Wonderful World of Type II HVAC Systems
It began with one question: “Why is my dash airflow so
bad?” In a well-documented and photographed procedure
Mark Wall tells how he greatly improved the stock system
in his pre-1977 Motorhome. In the process he rerouted
ductwork, added vents and installed a second
evaporator. View/download the
article.
GMC
Motorhome House Electrical System: Troubleshooting,
Maintenance and Safety
Don’t be fooled into thinking this document is a repeat
of the one listed immediately above. In this document
filled with illustrations, Bob Hendrickson takes the
reader through the processes involved in troubleshooting
and maintaining the house electrical system of the GMC
Motorhome with an emphasis on safety. View/download
the article.
Water
Quality and Sanitizing Issues
Frank Folkmann provides a common-sense guide with regard
to water quality, it's safety and sanitizing issues.
View/download
the article.
Horizontal
Installation of the Atwood Furnace
Ray Swartzendruber shares his experience and insight into
installing an Atwood furnace in a horizontal rather than
angled orientation. He gave this presentation at Elkhart
in 2004. Note that the typical installation is made to
line up with the angle of the outside panel where it is
installed. Ray’s method saves space and yields extra
storage capacity as well. View/download
the article.
Operating
and Troubleshooting the Suburban Dyna-Trail Furnace
Though John Nicholls will be the first to tell you he’s
not an LP gas technician he does provide some good advice
in this article about the Suburban furnace in many
coaches upfitted by Coachmen. The reader should take note
that he/she is responsible for making your own
determinations as to validity and applicability of the
information presented.
View/download the article.
Etc. -
- -
GMC Maintenance and Friends Application
Database developer, Byron Songer, has made available his
standalone application for tracking maintenance and
upgrade information for owners of TZE coaches. The user
can provide information on work done as well as line item
costs. On the friends side the user can keep a listing of
GMC friends, see where they live in a Google map or view
a related website all within the application. The log of
maintenance work can be printed or previewed. Download
file for Macintosh. Download
file for Windows.