GMC Western States

 Tech Center Number 33 - June 1, 2001

Emery Stora

From our Technical Vice President

We had some excellent seminars at our Emerald Desert 2001 Spring Rally in Palm Desert, CA.

Monday - 03/19/01

Timken Bearings - Marty Schlotshauer
Our first presentation was by Marty Schlotshauer who is the Western Regional Manager for the Timken Bearing Company. His talk was on the operation and maintenance of bearings on the GMC but mainly on tapered roller bearing sets as used on our wheel bearings. He stated that the bearings may be removed, cleaned, repacked and reinstalled; however, they must be examined closely for any signs of pitting, spalling (deposits of metal or missing metal) and overheating if being reused. Brown staining is all right but if there is any blue discoloration, which means overheating, the bearings must be replaced. Always use the same parts together. Do not mix the bearing race from one side of the motorhome with the cone from the other side. If one part is bad, discard the whole bearing assembly.

A question came up about one or more suppliers indicating that they had a special "culling" out of bearings from Timken and that no other Timken bearings should be used. Marty indicated that the company had "Set Numbers" (Set 23 for the GMC front wheel bearings) and then within a set number they might have additional "Assembly Codes" and, on special order, "Inspection Codes" for special requirements. Inspection Codes are usually done only for very large customers that order in the tens of thousand bearing sets. In the case of our front wheel bearings, Set 23, the Timken factory once had two Assembly Codes: 904A1, which was .0060 (6/1000's of an inch) axial clearance. This was used for the Tornado automobile, and Assembly Code 904A2 which was .0095 and used on the GMC motorhome. Five years ago, Timken discontinued the 904A1 and now only produces the 904A2 (they will also work in the automobile), so all number 23 bearing sets manufactured by Timken are satisfactory for use in the GMC, no matter whom you buy them from.

Timken never had any Inspection Codes for this bearing set, and they have never "culled" out any bearing sets for any dealer.

Marty warned that some resellers could still have older stock in their warehouses, so you might still buy a set that has the .0060 spacing. A set that I purchased recently had the marking ". 0095" hand etched into the side of the spacer. If you find that, you'll know for sure that you have a suitable set for the GMC.

Please note that .006 clearance sets might work just fine in some GMC motorhomes. Both the steering knuckle and the hub have a +/- tolerance when it is made. But if your motorhome happens to have the smallest allowable size hole in the knuckle and the highest allowable diameter of the hub, when you press the bearing onto the hub and put it into the knuckle, it might be squeezed so much that a .006 clearance bearing set might bind and overheat causing premature bearing failure, whereas the .0095 clearance set would not be too tight even in the worst case.

He also warned about purchasing bearings manufactured in China and some other countries as Timken's tests show that they are generally inferior in their metallurgy and machining.

The subject was asked regarding which grease to use and he deferred to the manufacturers of lubricants saying that Timken only recommends using a high quality grease and that since there are so many different applications we should either follow GM's recommendations or that of the grease manufacturers. This was followed by several members recommending using synthetic grease such as Mobil 1 or Amsoil.

If anyone has technical questions that they wish to ask Timken, you can call Jim Lee or Rod Hodge at 330-471-6666.


Living on 12 Volts, A GMC Guide - Henry Davis
Henry, a Western States member from Santa Cruz, CA gave a superb presentation in which he reviewed different electrical requirements due to various styles of camping -- from full hookups to "hardcore" boondocking, and he reviewed the types of equipment that might best fit various styles. He covered batteries, charging, loads, wiring and troubleshooting. He had a total of 48 slides, which we are planning to put onto the GMC Western States Web page for reference by our members. For those of you who do not access the Internet, let us know if you need a copy. His sections on battery selection and maintenance and his information on troubleshooting are a valuable addition to any GMCers library.

Tuesday - 03/20/01

Interior Concepts - Jim Bounds of GMC Co-op, Orlando, FL
Jim generally spoke about repairing, maintaining and upgrading the interior of the GMC. Members asked many questions about insulating, carpeting, headliners, sound systems, window coverings and a wide variety of other topics. Jim said that he enjoyed our rally so much that he is looking forward to coming to our Mariposa, CA rally in September.

Onan Trouble Shooting - New Information - Duane Simmons
Duane updated his information on the Onan Control Board Operation and added quite a bit of trouble shooting information. His updated handout will be added to our web site. Again, if anyone needs this information and does not have access to the Internet let one of us know and we'll mail it to you. Duane is an old pro at his presentations, and he again did an excellent job. There were many, many questions from the members as the Onan operation and maintenance seems to be a major concern for most owners.

Wednesday - 03/21/01

GMC Height Adjustment/Wheel Alignment - How to fix it, and what to do, made simple. - Claude Brousson
Claude gave a first class presentation including both rear air bag and front torsion bar adjustment and Rear Wheel Alignment. When he was finished with this rather complex task, he had us all convinced that it really could be made simple and many of us are looking forward to trying his methods. His handout is very well designed and quite a complete guide.

Woman's Expert Panel
Later that morning, we had a panel chaired by Dege Lowry. Also on the panel were Judy Cherry, Irene Davis and Marilyn Roland. They answered many questions from the audience on the operation and driving of the GMC and gave examples from their own impressive experiences. The audience was well attended by both male and female members.

Thursday - 03/22/01

On Thursday we tried something a bit different by breaking into several smaller groups, each with a group leader so that many different topics could be covered. Unfortunately, I was unable to go to them all so I don't have good coverage on what topics were discussed. I do know that brake boosters, auxiliary vacuum pumps, rear disk brakes, electrical inverters, wheel and tires, GPS systems, use of computers in the motorhome while on the road, and Darren Paget's wheel stabilizers that prevent tires from coming off in the event of a flat or blowout were among the topics.

This was followed by an Ask The Experts Panel comprised of Denny Allen, Chuck Aulgur, Zay Brand, and Duane Simmons. This continues to be a very popular session. The audience asked many questions and hopefully many people had their problems solved or were given a good start by the advice of our panel.

This is a great thing about our Roundups. The willingness of people to help one another with diagnosing and repairing problems could be seen everywhere. Henry Davis was spotted at several motorhomes with his Volt-Ohm-Meter in his hand checking out electrical problems (free, of course!), and there were quite a few people helping me when I discovered a broken rear shock and when I had to replace a house battery that had a bad cell. Dave Lowry really gets around on that electric cart of his - he seemed to be everywhere passing out his usual sage advice. Al Chernoff was seen frequently passing out parts from his rolling parts warehouse - extra air bag, 12-volt solenoid, electric fuel pump, fuses, and just about whatever else anyone seemed to need! If Al didn't have it someone else seemed to. Thanks to Frank McQuilliams for the loan of a Bilstein shock. I was able to get back on the road right away. I just can't recall where I've seen this many great people in one place. I, like most others, always seem to get more out of it than I put into it. I am really looking forward to our next rally at Mariposa.


Rear Bearing Adjustment
Since we have covered Timken bearings, I would like to point out that they have an excellent Website with a lot of information on it. Go to They have much information on cleaning, packing with grease and adjustment of bearings. In particular, their detailed method of using a dial indicator to adjust the rear bearings to .005 inch clearance is especially good information.


What Tools and Spare Parts Do You Need

I have been asked this question several times so I decided to write it all down. Even though I carry a lot of tools I still don't carry as many as some GMCers that I know.

My tools consist of a Plano Tackle box used as a toolbox. By removing my original "Buzz Box" and replacing it with a StatPower charger mounted on the back wall and rotating the electrical switch panel to the left side wall, I am able to store the tool box in the compartment that held the original charger.

The top compartment and the four-compartmented drawers of the toolbox hold the following:

Crescent Wrenches - three sizes
Vise Grips (two sizes)
Needle Nose Pliers (two sizes)
Electrician's pliers
Side Cutters (two sizes)
Channel lock pliers
Screwdrivers - 3 sizes of flat, 3 sizes of Phillips and a set of tiny screwdrivers
½ inch drive torque wrench - up to 200 lb-ft
½ inch drive socket wrench
½ inch drive flex handle
½ inch drive socket set 3/8" to 1-1/4"
½ inch drive extensions, 2", 6", 12"
½" drive spark plug socket
½" drive 1-1/2" socket for front axle nut
½" drive deep socket set
½" drive "U" joint
½" drive to 3/8" drive adapter
3/8" drive torque wrench - in lb-inch.
3/8" drive socket wrench
3/8" drive socket set 12 point 3/8" to3/4"
3/8" drive socket set 6 point 3/8" to 3/4"
3.8" drive spark plug socket
3/8" drive brake caliper hex socket
3/8" drive socket extensions
3/8" drive deep sockets - 3/8" to 5/8"
3/8" to ¼" adapter
3/8" drive "U" joint
¼" socket set with extensions and "U" joint
¼" drive screwdriver handle
1 set of combination wrenches
1 set of box wrenches
Various open-end wrenches
Wire terminal crimper
Wire stripper
Magnetic pickup
Gasket scraper
Medium pipe wrench
Teflon tape
Black electrical tape
Small funnel
Feeler gauge
Fuses, switches
Wire ties
Piece of chalk
Razor knife
Carpet knife
Jack knife
Golf tees (for blocking vacuum lines)
Measuring tape
Distributor wrenches
Mirror on wand (for viewing parts of engine, etc.)
JB Weld
Dielectric compound
Small file
Hex wrench set
Flare wrenches (3 - with six sizes)
Torque bit sockets
Stubby screwdrivers
Putty knife (2)
Chisels (2 sizes)
Pin punches (1 small for distributor gear)
Center punch
Small tubing cutter
Miniature hacksaw and blades
Small wire brush
I can also fit into the compartment a hammer and an electric drill with drill and screwdriver bits.

Under the front dinette seat I have several small boxes containing (listed in no particular order):

Timing Light
Extra distributor cap, rotor, pickup coil, coil & ignition module
Holley TBI throttle position sensor and 2 fuel injectors
Oxygen sensor
Gasoline filters (2)
Warner front bearing puller & OTC puller
Two #23 Timken Front wheel bearing sets with seals
Thermostat w/ gasket
3/8 & 5/16 gas tank hose (2 foot each) with brass splice connectors and clamps
Vacuum hose (2 sizes)
Brake caliper repair kit
Spare Onan control board & rectifier
Soldering iron (pencil type) & solder
Heat shrink tubing (3 sizes)
Two small jumper wire sets
Battery jumper cables
Volt-ohm meter
12-volt test light
110-volt test light
Exacto knife set
Tire air gauge
Bubble level
Brass air fittings with nylon glands for air bag lines
Fuel pressure gauge
Exhaust donut
Exhaust manifold gaskets
Steering wheel puller
Brake pad set (for both sides)
Measuring dial caliper
Extra CV boot with clamp
Vacuum pump tester
PCV valve
Graphite lube
Form-a-gasket #2
Ultra blue silicone sealer
Permatex weather strip adhesive
WD40 spray oil
3-in-1 oil
JB Weld epoxy
Super glue
Lubriplate white grease in tube
Electrical terminals (crimp on) wire nuts
Copper and steel wire
Electrical wire (small rolls - three sizes)
Duct tape
Misc. Screws, bolts, nuts, clips
Misc. Plumbing fittings & connectors
Hose clamps
Masking tape
Seam sealer
Grease gun and Mobil 1 grease
Spare sparkplug set
1 spare sparkplug wire
HEI ignition test tool

In a plastic crate mounted under the front next to the battery, I carry:

1 gallon of antifreeze
5 quarts of oil
1 quart of brake fluid
1 can transmission fluid
1 oil filter
1 funnel with extension hose.

Now to many this may seem like a lot of things to bring along, but I have found that I can repair or at least get most things running again in order to get from the boondocks to civilization. I think the most important spare parts to carry are the distributor parts. I have added to this list over the last 20 years and have used about everything on it at one time or the other while traveling.

I have seen others carry electric impact wrenches, air operated tools, pop rivet guns, water pump, starter, alternator, etc; but since my wife has limited me to these two spaces, I have found the tools and parts I carry sufficient for my needs. Now, the other extremes are to either carry a gun to put it out of its misery or just a cell phone and a credit card!!!!

If anyone wants to submit their suggestions for tools or parts to carry, please let me know and we'll publish the ideas in the next newsletter.

Hope to see many of you at Mariposa in September

Emery Stora, Technical Vice President

Proposed list of vendor activities
For the Mariposa Roundup Fall 2001

As an addendum to the vendor paragraph shown in the main part of the newsletter, the following list has been furnished by Jim Bounds:

Windshields installation and re-sealing
Early style window felt installation
Late style window rubber gasket installation
Window re-bedding
New style "T" slider side window installation
Leak testing and resealing
Door re-curve and repair
Electrical systems check and repair
Macerator installation
Chassis lube and rear pin lube
Brake systems inspection and repairs
Rear suspension inspection & repair (no bogie pin replacement at the rally, though)
Front suspension inspection and repair
Front wheel bearing replacement
Tire truing and balancing
Ragusa accessories installation
Roof vent installation
Body side molding installation
Rectangular headlight installation
New style tail light kit installation
Fiberglass bumper cover, wheel flares, visor installation
Generator repairs and demos
Dash refinish / recover
Headliner replacement
Dash Radio replacement
Window blind and valance building and installation
Cruise control installation
Differential swap
Outer CV boot replacement
Emergency engine (or whatever) repairs
New owner "what's that?" demo
"How do I?" for the ladies
Open Q &A for any other related topics

Some of these services would take longer than others and some would not lend themselves well for a demo seminar but many could be if there is member interest. If members already have equipment that they wish to have installed or are buying from another vendor that doesn't wish to install at the rally, you can also check with Jim Bounds on the installation.


GMCs on the Internet

For those of you using a computer and accessing the Internet, there is now a tremendous amount of information on modifications, maintenance, parts sources, etc. for the GMC motorhome. Besides maintaining the GMC Western States Site at one of our members, Billy Massey also has his own site with a lot of good GMC information. It is called Bdub's Place and is
Gene Fisher, another GMCWS member, has amassed an amazing amount of information on the GMC. It can be found at
Gene lists many links on his site. A lot of them are GMCWS members and others are GMC owners from across the USA. The following information was copied from Gene's site:

PERSONAL GMC WEB PAGES  Jolene's GMC  Mark Andreasen  Mike Beaton  click on pictures  Kerry Tandy- view with explorer  Chuck's Place, GMCnet Digest  Gary and Karen Sharp-forsale  Terry Doukas  Terry number 2  Richard, Macerator pumps  Charles Wood  Dave Meekhof  Erv and Emma Troyer  Dave Mumert  Alan Bredbury Shawn  Edelbach  Eric Henning--Trips and Mods  J.R. Wright  Ritch and Betty  Ritch and Betty  Pete Papas  Scott Nehoda's entry page  JR Slatten  GMC Motorhome Schematics by Edgar Kremer  Henry Davis  Forest City Convention  Dave Hilsdorf  Heinz  Dallas Jensen  Slates Motor home page  Toby Maki  Ron Keener  Chris Taylor---IA pictures  Patrick Flowers-GMCnet  Nate Chase  Zak's SMS page  Bdub's Place  Tom Henderson's Page --great links  Tim Brown  Culvers
 ORGANIZATIONS  GMC parts and deals,2736,jlkMenuID=1038,00.html  GMC Tidewater Crabs  GMC Motorhomes International  GMC International Links  GMC Western States  Home-page - Patrick Flowers  GMC Sunshine Statesmen  GMC Classics
 COMMERCIAL SITES  Mondello Performance Products  Chuck c. Picture frames  Jardine 3 inch Exhaust system  Adohen Supply Co.  Dunn's Transmissions  GMCmart  ARDEMCO GMC tanks  High Performance Fiberglass  Winterfeldt -- engines, etc  Chaparral-Maxwell, chargers,gears  EZ-STO--  Custom Instruments Panels  Ragusa accessories  TZE Plus Paget's accesssories  Gateway Motorhome Co.  Dick Paterson  Golby Motor Corporation  Alex Sirum GMC  Buskirk-Rush RV  Cooperative Motor Works (Jim Bounds)  Wheat Motorworks  AJUsa

If you have a site or knowledge of any other sites please let Gene know about them so he can add them to his list. In addition, Gene has links to many picture sites where GMC owners have posted pictures of their Motorhomes, modifications, etc.

Another site that many GMC owners are using is called GMCnet. It is a mailing list site where people can post messages and get replies from other GMC owners. If you have a problem you can usually get an answer very quickly (sometimes several answers - and many might even be the same). It has solved a lot of problems for GMC owners. You can register for free use of the site by logging onto Patrick Flower's web site for instructions. Just be prepared to get 50 or so messages per day on your email program. Warning - very easy to get addicted to the site. One wife at the Palm Desert Rally threatened to paint six wheels and a computer keyboard on the side of their house to get her husband to do some chores around the house!

If you are not currently using a computer to access the Internet you may want to get together with a friend or a GMCWS member at the Mariposa Rally to learn more about it. There is a wealth of information to help keep our "Antique Cars with Plumbing" running.

 This material is based on my personal experience and the personal experience of other club members. It is our viewpoint and does not represent authorized data pertaining to the GMC Motorhome. It is the responsibility of the readers to make their own judgment as to the validity of this material in relation to any repairs and/or modifications to their own vehicles.

 3128 Vista Sandia, Santa Fe, NM  87501-8526

 (505) 989-8157

 Please send your comments and ideas for the Tech Center to:
Emery Stora, Technical Vice President,
3128 Vista Sandia, Santa Fe, NM  87501-8526
Phone: (505) 989-8157



 Tech Info