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Off-Road Home Projects
Chevy Vintage 4WD Van
Vintage Chevy Van & 4WD Van Links ( coming )
Off-Road Homes Design Philosophy Projects Library Gallery
Vaporware Wish List - Dodge WC54 Ambulance
Chevy 4WD Traveling Van
Chevy 4WD Traveling Van - Project Plan
Project Objective: A van intended for long distance self contained travel. - fuel economy goal of 20 mpg with gasoline or mid to high 20s with diesel. Design intent is a fuel capacity of 50 gallons, yielding a range of 1,000 to 1,500 miles.
Drivetrain & Chassis
I would really like to investigate the feasibility of a mutifuel microturbine /battery/e-drive. Potentially a very desirable configuration for many reasons. However, it has no established field history and I seriously doubt this is a ready for a prime time gig. I am guessing than noise may be a big issue but perhaps this application of operating at a constant speed makes the noise suppression issue simpler, if not simple. Other questions:
- how big is the turbine lump ( this is encouraging )
- can it really digest most any fuel, solids ??
- what are the practical constraints regarding fuel
So, onto a more conventional design.
Gasoline or diesel:
diesel advantages- fuel economy, low end grunt, longevity, rationalization of fuel supplies for vehicle and household utilities, possibilities with biodiesels
gasoline advantages - lower initial expense and ongoing maintenance costs, cold weather starting, availability of fuel, especially in the outback ( only 45% of US stations carry diesel and their distribution is biased toward the highway system - Pop Science ? )
What is the relative availability of the different fuel types in Mexico & Canada
Isuzu Turbodiesel 4BD1T – 4 cylinder, 4L. By most accounts, a fine engine, anecdotally marred by reports of cylinder head issues with the later model edition 4BD2T. Significantly shorter length, bell housing to fan, than even the GM I6. It is also relatively narrow and less tall. Four cylinder is less than ideal, but anecdotal accounts claim smooth, quiet engine. Reports of 30+ mpg in a full size pickup. It is a heavy engine at well over 700 lbs., perhaps 150 lbs up on GM I6. Many thousands of these motors out and about, probably worldwide, and the support network includes Chevrolet dealers. Mating to 700R4 is a piece of cake – the aftermarket adapter has received very good reviews. I believe motor has integrated power steering and vacuum pumps. For serendipity’s sake, Isuzu and GM have long cooperative legacy, so the Chev / Isuzu hybid van seems sort of like a natural.
- fuel system mods ?
- will shorter length of Isuzu allow room for ducting/fans to exhaust heat from engine compartment
Engine, gasoline: Jeep 4.0 L EFI engine. Potentially excellent fuel economy for gasoline power, huge installed base of engines for replacement, parts, & service. Easy fit in engine compartment. However this engine might be marginal in power output, depending on final all up curb weight of the van. Unknown how aerodynamics/weight of van would impact fuel economy. What does stroked engine ( 5.0 L ? ) do to power & fuel consumption characteristics ? Supercharger ? Have heard anecdotal stories of supercharger non-impact or even improvement on fuel consumption. Adaptation of TH700 to Jeep 4.0 might be an issue, in price at the very least. Saw an article about a late Jeep fitted four speed auto with an underdrive in place of trans tailshaft, no increase in length and bolt up to NP231 or 242. Don’t know ratios of that trans.
GM small block – Spares and mods., new and used, everywhere in the US, don’t know about Canada and Mexico. Brainless choice is probably a GM 350 crate motor – no fun ! If cost is a driving issue, then perhaps a short block and reuse all else from my 350. Where it gets interesting again is possibility of a 383. Can I get a short block. Should seriously look at. TBI in any case. Should also get up to speed on small block heads and fuel economy. Can 383 be configured to return 20 + mpg or better? Well, perhaps high teens is a realistic goal. In any case, mounting a TH700 becomes a non issue.
Transmission – Auto or manual, auto or manual – the omnipresent debate. Unquestionably, it is far more likely that a manual would be a manageable field repair, the clutch probably being the weak link. Driving one daily though, what a pain in the ass, not to mention clutching in nasty low speed terrain. Adequate cooling and synthetic fluid will help with the auto immensely but if it breaks in the outback, you are probably screwed. GM 700R4 has the widest gear spread in a commonly available, not bleeding edge, auto that I know of. Internal bulletproofing knowledge is widespread and there is probably a readily available adapter to mate the R4 to most any popular t-case. I suspect that the Rockwell 221 doesn’t fall into that category. A GM TH6L80/90 has an even more useful spread of gear ratios and the physical lash up would be a piece of cake. Unfortunately, to date no one has developed/marketed an "inexpensive" stand alone controller so adapting the six speed is, for now, prohibitively expensive.
- any six speed manuals with granny 1st suitable and affordable. Solenoid shift linkage ?
- how about the manual trans/torque converter combo, what does it take
Transfer Case – Gear driven is essential. Considering the placement in the van, I suspect that selection mechanism on the top of the t-case is unworkable. The Rockwell 221 would probably be fine but I suspect there are no low gear sets available. I don’t know that the van really needs gearing lower than the 1.94 Rockwell low range but since the van may be saddled with very high diff ratios to yield reasonable RPM at pavement cruising speeds with a low rev engine, either diesel or gasoline, I suspect that in some off road circumstances, the van might benefit from a lower t-case ratio in the 4:001 range or thereabouts.
Highly preferable would be a t-case integrated with the transmission. I am sure any Dana gear driven case would be acceptable, most can be fitted with after market low gear sets, and there are very likely adapters to lash up directly to a 700R4. Only question is whether the rear output is in an acceptable position and if the t-case will fit in the available space. I think there is little question that an Atlas t-case will satisfy all of these requirements. It is rather pricey however.
- can a reliable t -case shifting mechanism be designed around electric solenoids.
Rear Axle – Highly desirable is a rear axle with a removable third member. This greatly eases the complexity of repairs, especially while on the road. Conceivably one could use the dinghy to transport the member for local repair or shipment to a repair facility or to retrieve a shipped in replacement. Perhaps one could be kept already prepared and in storage, ready for just such an eventuality. The only commonly available third member axles are probably Ford 9” and Toyota. Off these the Toyota are probably far, far more common, especially outside of the US. Are either of these full floater or convertible to such ? If not a removable third, then probably a GM 12 bolt, the heavier duty full floater.
- full floating axles ( I believe there are commercial kits to convert Ford 9" and Dana 44 to full floating )
- hub face to hub face dimension on later LC axles, particularly those with e-lockers, and do the later LC axles also use the Chevy six bolt wheel pattern
Rear Differential – selectable locker or limited slip. I think either an electric locker or a Detroit Tru Trac is the best choice here. The ARB air locker certainly has an established a reputation but the air compressor thing adds a whole new layer of complexity. investigate Eaton E Locker
Front axle – Although a removable third member would be desirable here as well, it is not as critical. Unlike the rear, front differential function is not essential to get to somewhere. Although the Toyota straight axle is unquestionably durable the question of Birfields arises, they are probably much more difficult to field repair than simple u-joints. I have vague recollection of a Toyota center mated to u-joint knuckles – hallucination ? A Dana 44 front axle is probably the wisest choice. Are there such things as cab selectable locking hubs - what are the compromises?
Front Differential – same options as for the rear. I am not sure if limited slip in the front serves any purpose as opposed to simply open or locked. Perhaps in snow/ice.
Fuel Capacity - There will, be two fuel
tanks., the O.E.M. 29 gallon main tank and an additional custom fabricated tank in the frame
cavity under the left side of the chassis. In the 90’ wheelbase van this
cavity holds a fuel tank with a capacity of 17 gallons. The 108”
wheelbase van should provide an additional 18” of longitudinal space for
a larger tank, room for an additional 10 gals. If diesel, then additional lines for fuel
delivery to the heater and stovetop house utilities. Accommodation of B100
biodiesel will be an integral part of the design.
Leave body condition as is, a little beat up. Much
easier to travel under the radar, no appearance of money. Only
the roof rack would be evidence of anything unusual at hand. The O.E.M.
white paint is perfectly suitable.
The engine doghouse will be reconstructed to allow
removal of the rear half for engine access, removal and installation. This
process is well documented.
Possibly add doghouse extension to front grill for improved air flow to radiator. Size tunnel such that doghouse end allows air flow to full width of radiator.
Can I configure a duct setup from upper rear of
doghouse to down ad/or out for heat extraction. Fan Pull. Perhaps in slow
going this would be advantageous.
Cargo Compartment - The design intent is to fabricate a bulkhead immediately behind the engine doghouse to separate the driving compartment from the cargo compartment. The bulkhead will have a pass through with a lockable door. Bulkhead frame will be fabricated from square tubing and sided with .050 aluminum sheet. The cavity formed by the tubing and sheet will be filled with rigid insulation board. The frame will be fabricated in such a fashion that in can be removed for access to the engine compartment in the case of major service.
confirm that bulkhead location does not interfere with the hinged action
radius of the dog house upper half ( preliminary check indicates all OK )
Windows, Option #1 - the only windows will be in the rear doors ( steal the flip outs from ‘67 ? ) windows will have inside steel shutters
Option #2 - additional flip out windows, in front passenger cargo door only and a matching window in a mirror image location on driver’s side
Option #3 - series of closeable, screened vent ports in upper body just below drip rails, perhaps backed by12V exhaust fans. Possible match these with similar ports along lower body or in floor to allow passive and/or fan driven convection low/high cross flow.
Option #4 – roof hatch ( or two ) fastest passive method to dump heat out and/or dump cold air in. Perhaps also double as interior access to rooftop sleeping veranda
Rear rack/ramp/deck – resurrect the design for the stretched Toyota LC toy box, feasibility of a tube frame multi purpose rack that hinges near the rear bumper and flips up to cover the rear cargo doors. Serves as holder for spare wheel assembly, hi lift jack, shovel etc and doubles as a loading ramp for the XT. As I recall, the total weight was pretty hefty ( 100lbs + ?? ), perhaps too hard to manipulate by hand. Winch or other leverage ? A reverse action “hatchback strut” which is normally in a collapsed position and you must apply force to extend it. So, when you initiate a raising of the ramp, you reinforce the strut’s “desire” to retract, assisting in raising the ramp into the up position – How to mount ? Alternative would be a cable winch to lower/raise the rack. Hand or electric ( ATV ), mounted below rack at bumper, cable up and over a pulley mounted at top of door opening and hooking into anchor point on rack. If a hand winch, spindle would have to extend to a handle outboard of rack footprint. Possible alternative is to reduce weight so rack assembly is operable by hand. Putting wheel assy. on its own pivoting rack outboard of main rack might bring main rack assy. into manageable range – need to do the math. At first glance, ATV winch seems most suitable solution.
If the ramp has an intermediate locked position that put it essentially flush with the interior floor, it might function as porch extension of the interior space. Possible a very fine mesh “floor” ( metal, other ) would support feet and furniture while permitting water drain. To allow deck deployed and door function concurrently would require a deck support method that did not utilized struts attached around door opening. Struts would probably have to use the ground for support’ likely requiring some method for adjustment to uneven or mushy ground conditions ( trailer tongue jacks ? ) Not ideal, but probably a worthwhile trade off to close the rear doors with deck deployed.
If concurrent use of deck & doors can be disregarded, then the simplest method would be rigid struts attached at deck and to body at roof line or door jambs to support weight of deck and occupants. This design would not allow closing of cargo doors – unless attachment points for struts were on a plane outside of doors in 90˚ open position - seems unlikely, and upon inspection, it is. Also appear that 90˚ open position intrudes in deck space without giving a particularly strong sense of enclosure or weather protection – large gap between upper halves of doors and body. Doors will probably be in either fully open or fully closed position most of the time.
Position cargo doors at anything from closed to wide open. Fabric awning on inertia reel attached at drip rail above rear cargo doors. A rigid bar is attached to the leading edge of the fabric. Incorporate uprights that hinge to deck and tilt upright to engage bar at leading edge of fabric awning. Short struts lock uprights in position, front to back and laterally if desirable. Perhaps pull on upright until strut drops into position locking fabric in tensioned state. Perhaps one or more tent poles on inside of fabric to form arc in material to shed wind/rain. Grommet (s) along cargo door upper edges to tension fabric and restrain doors when doors at 90˚. May need door to deck spring loaded pins to restrain doors. An option would be mosquito netting that fits perimeter of area described by deck/awning. Could also use deck/awning as off the ground platform/carport for toys when foul weather or other need suggests indoor occupancy.
Rear doors, Option #1 – stock cargo door configuration. Easiest to do –nothing,. Still allows you to have secure/weather tight enclosure while leaving windows cracked for ventilation. Should combine this with an easily deployed fabric “roof” that spans opening created by doors at 90˚open position. Perhaps inertia real on outside of one door and fabric spanning over door top edges to attaché to outside of other door. This would provide reasonable rain/sun awning overhang. Awning option: Inertia reel attached at upper drip rail above rear cargo doors. A rigid bar is attached to the leading edge of the fabric. Open doors to 90˚, pull fabric, locate bar in leading edges of doors. Perhaps a grommet/Velcro etc.or two per door to keep fabric tight over upper edges of doors. This would give a 24” overhang.
Option #2 – a one piece door made by welding together the outer skins of the original cargo doors and fabricate a new lightweight inner supporting framework. The one piece door hinges up, providing an awning. This might be a superb candidate for an exercise in carbon fibre fabrication.
Option #3 – Change the exterior tire/tool rack to swing away and fabricate a one piece door that hinges down, inner surface functions as a ramp.
This pole design to keep fabric under tension is a very good idea, perhaps essential. How to adapt to an easily deployed/collapsed system. Alternative would be to use inside pole support ala Bibler, easier to deploy.
Bumpers – elk guard for front
Driving lamps, back up
lamps, “yard lights”
Speaking of winches – receiver mounted winch
subassembly that fits both front and rear may be desirable. However, I
don’t recall any suitable frame members at the front of the van to hang
the winch receiver from
- how much fabrication to open up wheel wells for tire clearance
House electrical circuit – there will be a
house battery bank mounted under the cargo floor, housed in an insulated
enclosure, heated by the cargo space’s hydronic heating system. The
house circuit batteries will be chargeable through either the engine
alternator, shore power, or photovoltaic panels mounted on a rack mounted
on the van’s roof. The system will incorporate an inverter and a charge
controller. Cargo space interior lighting will be 12V L.E.D. or
fluorescent. Exterior household lighting may be 12V L.E.D. or fluorescent,
and perhaps incandescent for momentary, high intensity, security
Potable water - Stainless steel tanks will be fabricated to fill the space between the driver’s seat and bulkhead and between the passenger’s seat and bulkhead. ( battery access - perhaps shift access hatch to cargo side of bulkhead ). Given the cooler dilemma cited next, perhaps all of the water in a single tank on one side or the other, and the cooler on a floor level pass through on the remaining side would be a solution. Alternatively, one or both tanks might be placed high up against the junction of bulkhead and interior roof to provide gravity feed. Issues would be weight carried high in the van and difficulty in filling.
- exterior water level view line or filler cap float
- drain plug and drain line
Refrigeration – Thermoelectric cooler of
compressor type ? Mounting
location(s) ????. This raises a design dilemma. During relatively cool
weather, the cargo compartment would generally remain colder than the
driving compartment during travel time and the driving compartment, which
would generally remain colder during camping time. In relatively warm
weather, the opposite would likely be the case. Perhaps alternate seasonal
mounting locations. Perhaps above potable water tank between seat and
bulkhead. This might be best served by a dedicated door in the bulkhead
that allows access to the cooler from inside the cargo compartment.
Perhaps the main pass through door would suffice here. Perhaps the
dedicated access door is positioned in a fashion that allows the cooler to
be pulled through into the cargo compartment as desired.
Mount the cooler on a sliding tray that passes through the bulkhead
and is supported on either side, by a fixed support on the driving
compartment side and by a flip up/down support on the cargo side. Location
behind the driver’s seat would give easier access to the driver while in
transit but perhaps interfere with the sitting/sleeping platform when
camped. Location behind the passenger seat would eliminate the platform
interference questions and be a superior position for access while hanging
out or cooking on the “porch”. This
may also solve the battery access issue sited above. The cooler would
slide through the bulkhead, uncovering the battery access hatch.
Space heating – The design intent is to a fabricate a hydronic floor heating system utilizing the engine coolant circulation and/or dedicated diesel space heater. The space heater will also function as an engine coolant preheater for cold weather starts. Is Proheat X45 available from Kurt’s customer ?
- feasibility/wisdom of a wood burning stove, scaled to fit the van interior space. Rocket Elbow design ? How to vent it to absolutely keep smoke out of van interior. May or may not incorporate heat exchangers tied into hydronic loop. Is it feasible to operate an outside bioimass heater that incorporates a coolant circulation loop which plugs into the van coolant system. This would defer consumption of on board diesel supply when biomass fuel is available at campsites.
- feasibility of a concentrating solar mirror on a fluid to fluid heat exchanger coolant/coolant or oil/coolant circulation loop which plugs into the van coolant system.
- need to contemplate
alternative hydronic floor designs. First thought is a contiguous layer of
rigid blue foam with a coolant line pathway “milled out of the foam (
router ? ), but shallow enough to leave sufficient insulation between the
coolant lines and the van floor. Perhaps an intermediate layer is
unnecessary or even unwise. Foam layer might be underlain with perhaps ¼
“ plywood, or perhaps sandwiched by same, with coolant lines in close
proximity to upper layer. Entire sandwich must support tied down
motorcycle and normal foot traffic without sustaining damage. Perhaps
sacrifice section of hydronic floor for a narrow track for MC wheels.
Might feel really bizarre under foot when moving about empty compartment.
One drawback of this design is loss of standing interior height in cargo
compartment. How thin can
hydronic sandwich be ? How to accommodate front wheel chock.
Cooking – Two burner diesel stovetop.
Perhaps a very small microwave oven as well. The intent is to design a
“Murphy Bed” style cooktop that folds up against the starboard
interior wall to reduce the footprint when desirable. Alternatively, the
option of placing the cooktop at a convenient working height when in the
porch kitchen might argue for a removable cooktop on a long fuel line or
quick disconnect line with optional outlet ports, say kitchen porch and
back deck, so it can be removed from the van interior working height and
placed at porch or deck working height. Perhaps a location in the rear
side cargo door would solve both interior and kitchen porch needs.
Sink basin – Murphy sink, also along the
starboard wall. The basin could be of a flexible material that would
expand to shape when filled with water and fold up for storage when empty.
Water spigots could be affixed to van wall.
Washing – In addition to the sink, there
will be an external shower stall, either at the side cargo door or the
rear cargo door. Intent is to straddle the open doors with a ”hula
hoop” ring from which hangs a shower curtain and a shower head. The
shower head will be gravity fed from a roof mounted bladder, The design
intent is that the water in the roof bladder be warmed passively by the
sun. The bladder will be filled via an electric pump with an intake hose
long enough to reach a surface water source within ____ ft. of the van.
The ”bladder” may be of flexible or rigid construction. If flexible,
it would also double as a rooftop sleeping pad. If rigid it may also
double as a rooftop sleeping platform or sitting deck. An alternative to
the gravity feed shower is to utilize the pump by reversing the direction
of flow. The shower stall “floor” will be a grate, perhaps a flip down
grate hinged to the cargo floor or perhaps a slide out from a purposely
built subframe structure. ( does a 12V insta – heater exist )
Sleeping – A Murphy sleeping platform that
folds up against the port interior wall. Integral foam padding.
Hammock - strung inside van or on porch or deck or from trees at
Communications – A laptop computer would
probably suffice and be considerably more space efficient than a desktop
case. However, for long term sessions, it would be desirable to also have
a large flat screen monitor, external keyboard and mouse. An external hard
drive would also be advisable. Wireless data transfer would probably be
the most useful in urban locations and satellite data transfer for ex
urban. Best location for these components would probably be dedicated
space in the bulkhead wall, perhaps on Murphy trays for the input devices.
The monitor might swing out on a gimbaled arm but otherwise retract flush
into a cavity within the bulkhead. A sliding or flip down door(s) that
hides the components would probably be a desirable security measure.
GPS /mapping display mounted on dash
Porch – The design intent is to live out of rather than in the van. The side cargo door opening would allow integration of the van interior and exterior spaces. The roof could be fabric sheeting, on a retracting spool, that pulls out to span just the gap between the side cargo doors or, alternatively, extends along the entire length of the van. The roof could rely on the cargo doors for support and/or on poles that run to either the ground or to anchor points on the van body. Alternately, the roof function could be served by the PV array, the rack sliding out to serve as roof of the porch. Typical PV modules are in the neighborhood of 60” in length ( plus or minus a few inches), which may or may not extend far enough from the van’s body to suffice as an adequate roof. Perhaps the fabric take up spool could be mounted to the starboard edge of the array framework and then be used in conjunction with, or independently of the array as roof. The roof, whichever it is, must overlap the van body drip rail sufficiently to prevent water from dripping into the area of the cargo door opening. Mosquito netting that is installed as needed Simply hanging from the perimeter of the roof, would probably be adequate.
The “kitchen” could be mounted in a cabinet that is hinged vertically to the van body just interior to the rearmost side door. The cabinet would normally stay stowed against the van’s interior wall but in the “camping out” position. it would swing out to face the open.. This porch - kitchen function encourages mounting the thermoelectric cooler behind the passenger seat.
A kitchen table(s) might be hinge mounted on one or both of the cargo doors and flip down when the porch kitchen is in use. Table position retained by cable/straps attached to the doors.
Chairs would be simple,
commercially available, fabric on folding frame, perhaps lounging style
would be preferable most of the time
Roof rack – Very multipurpose. The design
intent is to roof mount a water “bladder”, photovoltaic panel array,
canoe rack, and a sleeping platform. The bladder would be the closest
layer to the van’s roof, constrained by the framework of the rack that
is affixed to the van’s body. The leading and trailing edges of the rack
would be raised to accommodate padded contact points for mounting a canoe.
Resting on the longitudinal rails of the rack would be a sliding subrack
that carries the photovoltaic panels. The design intent is that the
subrack slide on tracks to either port or starboard and then tilt down at
the leading edge, providing a, more optimal angle of incidence to the
sun’s rays. Alternatively the rack might only extend to starboard and
also serve as a porch roof . The slide function serves additional
purposes; to expose the water bladder to the sun for heating, and to make
the bladder available as a sleeping pad/platform for roof overnighting.
The rack also might incorporate anchor points for the poles of a tensioned
fabric shelter for inclement weather
- problem #1: during travel time, the panel rack in the stowed position will prevent the bladder from receiving radiant solar input. Possible solution – use the type of PV panel that allows light thru intended to bounce to backside of panel. Give that up for heating water.
- problem #2: the heated bladder may be too warm for comfortable sleeping. Perhaps the panel array/rack could be designed in a manner that would allow it to suffice as a sleeping platform without suffering debilitating damage. Possible solution – a fabric insulating pad, used between bladder & body in warm conditions and use as blanket in cold conditions.
- problem #3:
roof access – rope ladder, rigid ladder, steps in cargo door, roof hatch
cargo retaining rail for the
motion sensor activated recording of really vicious dog snarling and barking ?
min cams for exterior views ?
combination locks for access to cargo compartment
Where to put everything ?
Valuables storage ( hidey hole – false floor
behind driver’s and or passenger’s seat ?, access from cargo
compartment thru bulkhead)
mountain bicycle (Foes 2:1 FXR )
- Grumman 17” canoe or collapsible “skin on frame”
The cargo compartment will easily accommodate both the XT and the bicycle, perhaps also a collapsible watercraft. The Grumman would have to mount on the roof
1969 Chevrolet 4WD Van - Project Log
This is the first and longest running off-road home
project in our collection. Fitting, perhaps, since it is also the oldest
vehicle we use as a foundation. We were attracted to the late 60s vintage
GM platform for a few reasons.
- we just like the way they look, no justification beyond a simple matter of personal aesthetic taste
- they run about 1,500 pounds ( scan & link CR data sheets ) lighter in curb weight or about 30% less than, the later generation of GM vans introduced in 1971.
- The overall external dimensions are smaller than the later models. This is a mixed bag, less internal volume for carrying stuff, but the van should slip through both the air and a narrow off-road track with less interference
- We think the weight distribution is better with the engine/transmission package located closer to the center of a van's wheelbase, which should be more suitable for off-road
- for most routine maintenance and engine service, the earlier models generally offer better access and with a simple modification to the engine “doghouse” offer superb access. The drawback here is that the engine/doghouse location compromises the interior volume available for carrying stuff
- we also like the forward seating position for picking lines off-road. Yeah, we know forward position doesn't offer much crash crush protection but we tend to look at this in the same way we look at riding motorcycles. You pick the design for the riding, not the crashing.
This project, even from the earliest conceptual stages, was intended to be 4x4. We deem this mandatory for an off-road home. Real wheel drive vans, especially when empty, are notoriously difficult to keep straight and moving forward in poor traction conditions. Although a selectable locking differential and a winch would certainly help, the most flexible solution really is four-wheel drive. Mix that with lockers and a winch(s) and you can’t do much better.
Our first candidate for this project was a 1969 Chevrolet 108” wheelbase, no windows, model. The long wheelbase version was most appealing because it allowed room to install a bulkhead between passenger and cargo compartments while still allowing room to fit a full-sized dirt bike or two.
But even before we started rounding up components for the conversion, we happened across a 1967 GMC, 90” wheelbase, fully windowed, model had already been converted to 4WD and with a completely finished interior. The owner/fabricator had done a tremendous amount of work on this conversion and kept complete documentation of all the components installed. The conversion looked pretty sound and the entire asking price for the van and spares was far less than even a rudimentary cost calculation for components to fit the 69 yielded, not to mention the labor hours involved. So we thought we would look at this as an inexpensive proof of concept prototype. We would use it for a while, decide what features and characteristics we liked and didn't like, then pursue our original 108” concept. We made a few changes over the years, complete instrumentation, transmission oil cooling system, supplementary engine water cooling, interior modifications, and conversion for hauling dirt bikes. In general the GMC performed well but there are certainly some things we would change, partly to take advantage of more contemporary components now available and partly to make it more suitable for our off-road home/toy box concept. The most glaring problem with the GMC, and one we deem unfixable without extraordinary outlay of cash and labor concerns the body. The van spent most of its life in the Puget Sound area of Washington State. Every body panel and door eventually developed serious, perhaps terminal rust damage from living so long in a water saturated environment. The body filler has also cracked and lifted in a number of places. All in all, I am inclined to think the condition of the GMC's body will seriously inhibit getting a decent price for the van as is and the thought of the time and expense to correctly repair the body damage is frightening.
images of dash, solo bed, wheel chock, spares storage and trans cooler
system, and aux. water rad )
Which brings us to our current project. We recently acquired another 1969 Chevrolet 108”, not windowless, but none of the windows are in the body panels so replacing the windowed doors with un-windowed is relatively simple. The van remained in one family’s ownership since driven off of the showroom floor. After 40 years, much of that time as a commercial vehicle, it is a little beat up with dents, dings, and creases in just about every body panel, but having spent its entire existence in New Mexico and Southwest Colorado, it is completely free of any rust of consequence. Our plan is to convert the 69 into an off-road home/toy box, incorporating the lessons we have learned with the 67 GMC and the design ideas we have accumulated over the years. We have decided that the most cost/time effective plan is to simply gut the GMC and install the bits on the 69 Chevy, but with the intent of eventually upgrading many of the components to more desirable, contemporary replacements. We are at some advantage here in that, other than the wheelbase, the two vans are essentially identical so most anything on the GMC will transfer easily to the new project. This approach will yield a functional van while we search for our ideal components over time rather than having to gather them all up before we can begin the project. It will also allow us to concentrate sooner on the auxiliary systems and the interior configuration, which are certainly the most design and fabrication intensive aspects of the build in trying to optimize the off-road home and toy box attributes of the new rig.
So, in the first iteration of the 69 Chevy build, the will utilize the following major components from the 67 GMC:
- The engine is a 350 small block currently fitted with HEI ignition, a two barrel Rochester carburetor, an “RV” camshaft of unknown specification, and tube headers routed into a single tailpipe and muffler. This engine has a little over 100,000 miles on the clock, starts reliably and runs OK but, not surprisingly, consumes a wee bit of oil. Unfortunately, it was last rebuilt with .040” oversize pistons so the block isn't really suitable as a core for another rebuild. On the other hand, this allows us to have a running van for testing other aspects of the project while we are building a new engine.
- The transmission is a TH400 three speed automatic. This transmission was rebuilt approximately 30,000 miles ago and at the time I designed and installed an external fluid cooling and filtering system which has been problem free. I will transfer the entire transmission package intact.
- The transfer case is a Rockwell 221, all gear construction and a very heavy-duty piece. Perhaps the only drawback, although probably not serious for our application, is that there are no lower low range gear sets available in the aftermarket. The Rockwell does have one advantage for our setup. Because of the van’s mid-engine design, the distance from transfer case to the rear axle is relatively short and the Rockwell rear output is dropped, putting it very close to being on the same plane as the rear axle input, and minimizing driveshaft angle - a good thing.
- The 4WD modified GMC doesn't exhibit any peculiar handling traits like bump steer. We think the original owner pretty much had any steering component issues sorted out, so we will start out by simply transferring the rear suspension, rear axle, front suspension, front axle, and steering components to the 69 Chev. The rear axle is a limited slip GM 12 bolt and the front is a Dana 44, both perfectly fine for this application. We intend to retain the current 3.08 differential gear sets, at least until the new engine transmission package is in place and some testing completed.
There are two aspects of the
front axle that we intend to change at the time of the swap.
- replace the front drum brakes with this disc brakes. It takes quite a bit of pressure on the brake pedal to slow the 67. First experiences on steep mountain roads were downright unnerving at times. Early on I had occasion to pull the GMC’s TH 400 for a rebuild so I took the opportunity to install a low stall speed torque converter. This helped immensely in retarding the van’s speed on down hills and made the drum brakes tolerable in those situations.
- existing axle has 0° of castor which we suspect is left over from the previous owner prioritizing the transfer case and front axle U joints angles. Our intent is to modify the axle to achieve a caster angle more in keeping with that typically found in this type of vehicle. This is a relatively simple matter of cutting the axle housings and rotating the knuckles with respect to the differential.
- engine and transmission package. We never seem to find ourselves in any particular hurry when on a road trip in the van so we don't need lots of horsepower, nor high rpm . Our concerns are a broad spread of torque in the lower rpm ranges and minimizing fuel consumption. We suspect that a correctly designed engine and drive train package may yield both. On a good day, the 67 GMC can get 14 mpg but 10 mpg is more typical for all-around usage. Our design goal is to see consistent 20 mpg on the highway so most of our attention will be focused on selecting an optimal combination of the engine, transmission, and axle gearing to meet this goal while still having sufficient power to cruise and pass at the speeds we prefer. After the 69 Chevy is up and running using the 67 GMC components, building a new engine/transmission package will be the first priority on the list of planned upgrades. We think that there are significant gains to be had in both performance and fuel mileage with a correctly built small block, equipped with TBI fuel injection, and backed by a TH 700R four speed automatic or a GM six speed automatic. We would really like a TH 680L or 690L six speed automatic but as yet there is no off the shelf system to convert these transmissions from fully integrated with the vehicle’s computer to a standalone shifting mechanism. In most other ways, the six speed appears to be preferable to the four.
- axles. Once we have settled on differential ratios, we will install a Ford 9” rear axle. The motivation for this change is the removable third member, a highly desirable feature for an outback traveling van. This greatly eases the complexity of repairs, especially while on the road. Conceivably one could use the dingy to transport the member for local repair or shipment to a repair facility or to retrieve a shipped in replacement, perhaps even a spare already prepared and kept in storage, ready for just such an eventuality. Converting the Ford axle to a full floating design that matches the GM six stud hub pattern appears to be reasonably well-documented. We will give serious consideration to installing rear disc brakes at the same time. We will also equip both front and rear axles with selectable lockers or Torsen limited slips such as the Detroit Tru Trac.
- wheels and tires. The GMC is currently equipped with 30 x 9.50 – 15 B.F. Goodrich All Terrains. Considering our intent for plentiful outback travel, we would like to fit 31 x 10.50-15. We strongly suspect this is about as commonly available a size as there is so finding a replacement off the beaten track should be comparatively easy. On the GMC the front tires rub at full lock when the front suspension is also compressed so fitting 31s will probably require a wee bit of surgery to the van to eliminate any rubbing. We think the hassle is probably worthwhile. An option is to drop back to 235/75R 15, perhaps the most commonly available size and completely free of interference issues, but we would prefer the additional ground clearance provided by the 31s.
- The vast majority of design and fabrication time will likely be spent with the auxiliary systems and interior configuration to balance the requirements of both off-road home and toy box in one package. The interior of the van will be separated into two compartments, passenger and cargo, with a pass thru between them. A wall to wall, floor to ceiling bulkhead, located immediately behind the engine doghouse cover will separate the compartments.
Requirements for the passenger compartment are relatively straightforward, to make driving and passengering as comfortable as possible. Requirements for the cargo compartment are much more complex and must serve two, often conflicting, purposes. It needs to function as a foul weather live-in shelter and storage space for the “household” essentials and the toys ( although in reality toys are quite essential to the whole point of this design exercise ).
- seating ( heated ?)
- snoozing ( passenger only one hopes )
- task lighting
- security ( bulkhead mounted camcorder with view(s) of cockpit glass )
- sound deadening
- food and drink access
- small item storage
- moderate bulk storage ( warm clothing, blanket, pillow, small packs, etc. )
- hydronic floor heating system
- passive high/low cross flow ventilation system
- modify existing bench/sleeping platform to fit 108” body
- Murphy kitchen for starboard side
- house electrical systems
- house electronic systems
- hidey holes
- security systems ( motion activated recording of vicious dog noises )
- rear deck/rack
- roof rack/PV array/water bag
- retractable awnings
- side door Murphy countertop
- shower stall
- design and fabricate an auxiliary fuel tank- design and fabricate an underfloor storage box