It’s no secret that RVs and motorhomes are often built worse than a house of cards, and that might be an insult to the playing card industry. Many companies have tried to make a sturdier, longer-lasting coach, from a builder of forklifts to countless fiberglass builds. Grumman, the company known for its sturdy delivery vehicles and America’s iconic Grumman LLV postal truck, decided to get into the RV market. What it built, the Grumman Motorhome, was designed to be luxurious and so durable that the body would outlast its own engine and transmission. Grumman was so confident in its product that it even advertised some bullet resistance.
Many motorhomes have been marketed as being able to withstand the test of time. However, I can’t recall any coach specifically noting in its own advertising materials that its body is so strong that it should outlast “several” chassis and powertrains. Grumman really expected you to own its Motorhome for so long that you’d have to repower it several times before the body fell apart. Perhaps even wilder is the fact that the Grumman Motorhome was said to be so strong that you could fire a .38 bullet at it at close range and it wouldn’t go through the motorhome’s thick metal shell.
Two of these incredible coaches are for sale for pennies on the dollar, but there’s going to be a big catch to owning these pieces of obscure RV history.
Grumman Gets Into RVs
These are motorhomes that are so surprising, just the fact that they were made by Grumman was pretty captivating in itself.
Grumman has a rich history of aircraft manufacturing and spacecraft manufacturing, but some of its other products are perhaps more interesting. As World War II began winding down, the demand for Grumman’s bread and butter aircraft began falling. Jobs were cut from around 20,000 strong to around 5,000. And while Grumman had other business units, including civilian aircraft and aluminum-bodied delivery vans, the company was looking to expand into other markets.
That is when a Grumman engineer became irritated at the weight and durability of the typical wood-and-canvas canoes of the era. Grumman chief tool engineer William Hoffman thought making a canoe out of aircraft aluminum would solve both of those problems. The Grumman canoe entered production in 1944, revolutionizing an industry along the way. In fact, you can still buy Grumman aluminum canoes today!
This would hardly be the only venture the aircraft producer would get into. The company would later team up with Flxible on a transit bus, collaborate with Giovanola on a science submersible, and of course, create the KubVan and the iconic LLV.
In the 1970s, Grumman had its hands in so many different markets that it advertised itself as a supermarket for the nations of the world. In a 1975 advertisement (above), the Grumman Corporation claimed to have been involved in aircraft, vehicle bodies, waste recycling plants, sewage plants, foundries, solar panels, data processors, switchboards, and agricultural aircraft. Of course, this is Grumman we’re talking about here, so it also wanted you to buy its F-14 Tomcat, its spacecraft, and surveillance equipment.
Something not mentioned in the text in the ad but shown in the illustration was another market Grumman had its fingers in. Grumman wanted to use the same thick aluminum bodies that Grumman Olson used to innovate step vans and apply them to the sometimes rickety motorhomes of the era.
History about Grumman’s RV venture is a little thin, but I’ve been able to piece some parts together. Reportedly, the RV venture began in 1969 when Grumman subsidiary Olson Bodies began developing a motorhome body. According to Popular Mechanics, that’s also the year when motorhome production began. Sadly, so much information from those early days has been lost to time, but I found advertisements as old as 1971 and a former owner of a Grumman Motorhome claiming to have owned a new example in 1970.
According to Grumman advertising, its Class A coaches were sold in 21′, 25′, and 28′ lengths, each with different bodies.
Each of these RVs was built around the same concept. Motorhomes in those days, much like today, weren’t really built for the long haul. Grumman didn’t like that. Leveraging its experience with aircraft construction and step vans, a Grumman Motorhome starts life as a massive shell made out of .102″ thick aluminum.
Grumman says that by going with this body, there are a number of advantages over the typical motorhome. For starters, there’s no wood to rot, siding to separate, or boards to warp. Grumman boasted the welded and riveted aluminum as being three times thicker than the aluminum used on other campers of the era. The RVs were also said to be substantially stronger than usual thanks to I-beam sections and aluminum extrusions. There’s more, as the company said its aluminum was just as strong as steel but coming in at a third of the weight. This was said to reduce wear and tear on the chassis and drivetrain while also aiding fuel economy.
The biggest advantage of the Grumman aluminum body was its longevity. Grumman points out that its greatest World War II aircraft were built out of aluminum and its Grumman Olson trucks had been known to survive more than two decades of service. Normally, this would be all marketing speak taken with a grain of salt, but the workhorse of the USPS, the Grumman LLV, is a perfect example of how long a Grumman body can last.
Grumman was so confident in the body used in its Motorhome that it said “so tough that the body will outlast several chassis and power trains. So tough that the plate was not penetrated when struck at close range by a .38 caliber bullet.”
This is the first time I’ve seen an RV manufacturer outright saying that it expects its body to last so long that you’ll have to replace the engine and chassis “several” times before the body fails. According to Grumman’s documentation, these RVs featured aluminum reinforcement in their bodies plus an aluminum floor. Grumman was serious about having no wood to worry about rotting. There is a fiberglass cap up front that Grumman says is for styling and strength. Grumman also added insulation in the floor, walls, and roof for four-season camping.
Marketing for the Grumman Motorhome also suggests that the body was designed to facilitate the swaps of chassis and powertrain. So, while your Grumman Motorhome may have come from the factory with a Chevrolet, Dodge, or International Harvester chassis, it was intended to be modernized after the body outlived the powertrain.
John A. Linkletter from Popular Mechanics tested a Grumman Motorhome for the magazine’s March 1973 issue. In it, Linkletter says that the 392 cubic inch International V8 under the body had enough oomph for easy cruising at 60 mph or 70 mph with room to spare for passing, even on hills. Linkletter even achieved 8.29 mpg, which is pretty good for a gasser!
Apparently, the ride was about on par with other motorhomes as well. When it came time to camp, Popular Mechanics noted features including deep-pile carpet, a four-burner stove with oven, a combination gas and electric refrigerator, a water heater, a full bathroom, and more. In other words, a Grumman was pretty cushy for the 1970s.
The 21-foot Grumman Motorhome retailed for $10,750 in 1973 ($79,565 today) while the 25-footer was $14,670 or $14,880 ($108,579 today and $110,133 today, respectively) depending on if you wanted a rear bathtub or not. The flagship 28-foot Class A was $17,990 ($133,151 today). Reportedly, the 21 was built on a 137-inch wheelbase with a chassis and powertrain from Dodge, International, or Chevrolet. The 25 had the same chassis manufacturer choices but a 159-inch wheelbase. Finally, the 28 rode on a Dodge or International chassis and stretched out on a 178-inch wheelbase. Interestingly, the two shorter models were targeted toward families up to six in size while the 28 was pitched as the perfect retired couple’s RV.
Popular Mechanics went as far as to interview owners. The magazine found that most people agreed that the Grumman was “built solid” while one owner claimed unrivaled stability.
Apparently, one guy tried out 11 different other RVs before falling in love with his Grumman. Then there was another guy who had a list of 20 problems from windshields popping out and roof cracks to fuel lines burning up on the exhaust manifold and air sealing issues. But even that guy said the body was “excellent.”
So, Grumman might have sometimes sucked at the fine details, but pretty much everyone agreed that the main selling point of the Grumman Motorhome, its body, lived up to the promise.
These Grumman Motorhomes
This article is one that has been in the making for over a year. It’s unclear just how many Grumman Motorhomes were built, but production numbers are believed to be in the hundreds. Either way, they are exceptionally hard to find today. In over a year I’ve found a grand total of four for sale and only one of them was in a ready-to-camp state. That one sold so quickly that I wasn’t able to archive the ad even for informational purposes.
The cheapest of the pair is located in Ocean Park, Washington, and is just $500. It looks like the aluminum body has withstood the test of time, perhaps living up to Grumman’s aggressive marketing. The same cannot be said for the interior. Grumman used fiberglass for its motorhome roofs, which was a great idea. However, this example shows the downsides of cutting holes into a fiberglass roof to mount vents and air-conditioners. The interior has some rough water damage and it looks like the sources of the water intrusion are from those roof vents and air-conditioner.
The seller also states that the RV has been parked for several years, last ran a year ago, and the engine doesn’t run well. The brake system has also been overhauled, but it doesn’t appear that the work is finished. So, this thing will need a total overhaul, but at least the main structure should still be good.
The one in Granada Hills, California has a better-looking exterior for just $2,800, but no photos of the interior and the powertrain is in a similarly sorry state. I requested more information from the seller a while ago, but I don’t know if I will get it. Thee seller says to call them, but doesn’t provide a number.
These are the only two Grumman Motorhomes currently for sale in America that I could find. Obviously, they’re not for the faint of heart and the person who takes on these projects will almost certainly be in it only for the history rather than the practicality. That’s a shame.
It’s also a bit amusing. For all of Grumman’s marketing of these coaches as being bullet resistant and everlasting, the company sort of neglected that motorhomes are more than just bodies and drivetrains. Sure, the body might last longer than you will, but the interior will not. Still, I hope someone saves these guys because they are pieces of fascinating RV history. How often will you find an RV so obsessed with quality that its manufacturer thinks it’ll outlast its own powertrain?
Keep in mind they were probably talking about a .38 Special and those were not too powerful in their standard loading. A mild 158gr WC shot out of a short 2″ barrel revolver like a S&W J-frame would have yielded maybe 650 fps and just over 200 ft/lb. Depending on which plate you were shooting at, I could believe that statement.
This is a reason I hope a company succeeds in making reasonable PHEV truck conversions. (I’m rooting for Edison Motors – I’m not holding my breath)
An RV like this would be an awesome candidate for such a conversion.
Grumman canoes were great and did indeed last and last – at least my dad’s did for about thirty years until some crackheads stole it for scrap.
I always had a soft spot for a Cortez, unfortunately everyone I’ve looked at more soft spots from rust. I knew a family that owned a superior coach… Loved the design of the porthole window side door. And yes sadly, another rust bucket There was much innovation in the 1970’s.
I, Gru! Mortal man!
I bought a new Grumman lightweight aluminum canoe in 1981. It is indestructible. 17’ long, 65 pounds. A magnificent piece of engineering.
yeah they can be beat with everything I had one and had to sell- replacement was another brand aluminum canoe that is about 40″ wide at most with a load limit of 850kg- can haul a moose and two guys
My dad happened across a Grumman aluminum canoe when I was a kid. He nicknamed it “Kon Leaky” after the Thor Heyerdal (?) raft “Kon Tiki”. The rivets leaked a good amount of water. There would be 4-5″ of water in the back after a 2-3 hour trip. That canoe put up with lots of rock bashes on the rivers around town. Cushions were a necessity since those aluminum seats became frying pans during the summer.
Try using one hunting in Alberta at this time of year- the seats and sides are a bit umm cold
A good insulator aluminum is not.
It would be fun to find a nice shell, throw it on a new Ford chassis with the 7.3 Godzilla, and modernize the interior. An RV restomod
Agree but it would definitely have to be a labor of love. 45 grand for the chassis and countless hours of labor.
So it’s a Grumman LLMH? 😉
Love the rounded roof! Early eighties Hymers had that also, looks so good.
This finally caused me to join!
I also have a Grumman Motorhome, but built by me.
Started as a bread company auction (getting rid of their stick shifts) that I did not expect to win. It’s about 23′ long, built on a chevy P30 chassis.
6-ish years, and 3 configurations later, it’s still going… not strong, but going.
Can confirm the body is outlasting the mill. Carbureated (propane!) 350 with 380xxx miles on it and it shows. Spent last Sunday replacing the dizzy on the side of the highway.
A month the voltage regulator died and blew up my battery. 🙁
Currenty trying to save up enough cash to drop a 6.0LS in the front, but it’s slow going…
Side note memory on aluminum canoes. When I was actively kayaking back in the ’70s and ’80s, on the easier rivers we would always see aluminum canoes stenciled with the rental outfit, “W.C. Bob Trowbridge” on the bow. This was in the American River (+/- north or south) area of California. While the idea of an aluminum canoe is sound, the reality is a bit different. While they could take a lot of abuse, from experience, when they hit a rock, they would stick to the rock. Aluminum versus rock = aluminum friction against the rock. We called his outfit Water Closet Bob.
I worked for a couple of local Boy Scout councils in different capacities for about a decade between the 2000s and 2010s, I remember one camp had a bunch of 1950s Grumman canoes that had been moved from another camp in the Poconos that closed in the mid 1970s. The newer models would be junked after 5 or 10 seasons, but the old aluminum ones were still in perfect shape after 60+ years.
Much, much later, Grumman built genuine armored trucks beginning in the late 90s based at least nominally on a modified Grumman-Olson van body — just with thicker aluminum. Real aluminum armor is a thing… a rather expensive thing, compared to steel. There are engineering challenges surrounding it, though. The thicker the panels get, the more rigid they are, and constant road vibration can cause cracks to form in stress areas at welds or around rivets. The motorhome would have used the regular bread-truck panels, which are thicker than typical steel automotive panels, but still thin enough to be flexible and compliant enough last a long time under automotive stresses with little potential for failures.
As far as I can tell, the oldest use of aluminum in any quantity of civilian armored cars was the Purolator Courier, later Loomis Armored (then Loomis-Fargo and finally just Loomis…) fleet. It started as a custom fleet of all-aluminum, welded-body armored trucks for Purolator, built in-house in a wholly-owned shop. They all went to Loomis Armored when Purolator got out of the security courier business, and new ones were built along the way. They were typically refurbished and rebuilt on new chassis when the old ones wore out, but a small number were built new to handle fleet size increases and replacements for wrecked ones. After the Loomis/Wells-Fargo merger into “Loomis, Fargo & Co.” the construction was contracted out to Superior Body, a company which had also built school buses and had a fling with motorhomes in the 60s or 70s.
The Purolator/Loomis design was very durable, but also very rigid which isn’t always a good thing. The outside panels had a continuous weld running along a piece of 90-degree angle aluminum which attached it to the sides and roof. Square-section aluminum tubing made up the inner bracing, which was welded at intervals to the outside panels and along the interior corners, and then the interior aluminum panels were screwed to the bracing. All the shocks taken up by the exterior body structure would get transmitted to those screws, and they’d eventually crack, leading to loose, rattling interior panels that the local shop crew would have to replace or drill new holes for new screws. Later versions used thicker screws, which lasted longer. The original bodies rarely had issues with welds. The first run from Superior had some problems with weld quality, but eventually they got the hang of it.
I worked at Loomis in the 90s, and through the Wells-Fargo merger when we got their steel-body trucks added to the fleet. They were a little quieter and rode a little better due to their weight, but the rust was unstoppable and all in all, they were junk compared to our aluminum trucks — they were all on their last legs even though the truck chassis were fine. (The most annoying problem being the doors no longer aligning, which made them a pain to close and latch properly.) Our aluminum trucks just ran on and on through engine and drivetrain rebuilds.
Also, for our Rust God, David, if you’re ever tempted to find an armored truck for the Autopian fleet (Why not??), stay away from the steel ones! They rust! Badly! Enough that doors have fallen off of them because the hinges rust, and then the door falls off! (I recall a report of that happening. The door was recovered with the latch still locked to the latch pins which had ripped off of the rusty door frame…)
so the real question is what is the unknown weakness in an armored truck?
I wonder if they ever experimented with epoxy bonding the panels together like they do for aircraft? I’m not an engineer but my first instinct would be to address the biggest point of failure…
Lotus built Elise’s with glued aluminium parts, and I wouldn’t be surprised if they still use that technique.
Granada Hills, CA. Hmmm. That’s not too far from where esteemed leader David lives. (closer to him than me, anyway) Too bad it’s not an old Jeep, or he might take a look!
May I point out Gruman didn’t build the motor and tranny. Also the average warranty on a vehicle of that age was 12 months or 12,000 miles. So a body that would last longer than 12 months when it was parked for 11 months is nothing. We not only need a economic expert here but a history expert or just an old guy.
I never said Grumman made the engine and transmission. There are multiple notes in the story that the body was by Grumman, but what was underneath was not. Here’s one:
“Marketing for the Grumman Motorhome also suggests that the body was designed to facilitate the swaps of chassis and powertrain. So, while your Grumman Motorhome may have come from the factory with a Chevrolet, Dodge, or International Harvester chassis, it was intended to be modernized after the body outlived the powertrain.”
Elsewhere, I note the Popular Mechanics review and how that coach was powered by an IH V8. I never said the powertrain was from Grumman, only that the body was designed to outlast the powertrain.
I’m not sure what you’re talking about with the warranty portion of your comment. Grumman’s advertising suggested this should last way longer than the warranty.
I think his point was that even the manufacturer wouldn’t guarantee past a year of lifetime on the drivetrain and chassis. Grumman saying it could last three chassis swaps could mean 3 years, or charitably 10 years. It didn’t mean dozens of years as you might expect now for multiple chassis.
This comment is a little bit of a head-scratcher. Mercedes doesn’t just pump out articles that are not thoroughly researched. You just have to read it to appreciate that she does her homework. You also didn’t need to point out something that is described in the article more than once.
I try and read all of Mercedes’ articles and I have yet to be disappointed. It helps that we share an affinity for RVs, too.
Why does the warranty on the chassis/powertrain running out after a year mean that it would need a new chassis/powertrain that soon. As you point out the 12/12 warranty was pretty standard in that time frame but we certainly didn’t see cars getting scrapped after a year unless they were totaled due to a collision.
Ex RV powertrain dealer mechanic here, circa 1993-4.
Our dealership was located in the county in the US with the highest proportion of elderly retirees in the entire US at the time; we had a big and busy shop and did a lot of motor and trans work on the full line, from Mark III conversion vans to Class As, Bs and Class Cs.
Class A front engine gassers with 454s often only got about 60K miles out of an engine from new in that era. But that could mean 3 years for the few retirees that lived aboard and drove a lot, or 20 years for working families that took it out 18 days a year, or 10 years for snowbirds that wintered in Florida and summered in the Northeast.
So having a body that would hold up over a decade or two was a lot more important to some buyers than others depending on their particular use case, but every experienced buyer wanted to avoid roof leaks and water damage.