Tractor Talk: WD-40, Part Deux

Still Exceeding Design Specifications at 81 Years Old

Back in the November 2015 Tractor Talk we showed you a 1935 McCormick-Deering WD-40. The WD-40 has the distinction of being America’s first diesel-powered wheeled tractor. We barely got the WD-40 photographed at the 2015 National Threshers Reunion before a deluge of Biblical proportions swamped the event. As a result, we didn’t get to talk to the owner, Chuck Lehman.

Lehman was back at the Threshers Reunion in 2016 and we caught up with him just in time see his vintage diesel on the National Threshers Association’s 1920 A.D. Baker Prony brake dynamometer. His tractor is obviously superbly restored cosmetically, but in the back of our minds we wondered if it was a trailer queen or a working tractor. Turns out this 81-year-old diesel tractor is ready to work anytime, anywhere, and can deliver more than its rated power. Since the extensive and very expensive restoration was completed in 2012, it’s been proving that at plowing days all over Northwest Ohio, Northwestern Indiana, and Southern Michigan.


We also learned more about the history of this tractor. It’s a very early one, the 230th built, wearing serial number 731. According to production lists, standard production of the WD-40 started in May of 1935 with serial number 504. Numbers 501 through
503 were preproduction units built in 1934 for testing. Number 503 is owned by noted WD-40 historian, collector, and restorer, Eric Best, who looked up some scarce information we needed for this story. The exact production date of WD-40 number 731 isn’t known but from production records we know it was built in late July 1935. The casting marks on the major structural tub back that up and are marked with a July 11, 1935 date.

The working end is simple: a drawbar and a rear PTO. The Franz family had added an on-factory hydraulic system but Lehman removed it. The current 13.5-32 rear tires are wider than the original 12.75-32s, which is a size that’s no longer available. The rubber tires were an option, with 32-lug, 50-inch diameter steel wheels standard. A 1935 WD- 40 had a retail price of $2,225, about $39,000 in 2015 dollars. The WA-40 gasser was about $875 ($15,000 in 2016) less. In the midst of the Great Depression, price was a big factor in the choice between gas and diesel.


One of the seemingly anomalous things we noted about Lehman’s WD-40 in 2015 was the red paint, which at first glance seemed incorrect. Sure, red is the color for which IH tractors are best known, but it wasn’t always so. Prior to 1937, IH and McCormick-Deering tractors were painted a dark gray. Late in ’36, at the start of the ’37 model year production, IH began implementing a color change to Harvester #50 Red. It didn’t happen immediately for all tractor lines, but sources conflict as to when the WD-40 line went red. It could be as early as the first part of 1937 or as late as November of 1937—but here’s the back story on WD-40 number 731.

About the time Lehman’s tractor was built in ’35, IH was painting some tractors red for market research to test public reaction to the red paint. According to Best, many of the first 100 WD-40s produced were red. These tractors were shipped out as demonstrators to events and dealerships around the country. According to the original owners, Lehman’s red WD-40 is one of those demonstrators; it was sent to Kansas. They were not only pitching the red paint in this case, but also the new IH D40 diesel. The diesel part of the pitch didn’t work but farmers liked the snazzy red paint because you could see the tractor from a mile away.


At that time, diesel tractors were a new idea and with the WD-40 being the first most farmers had seen, it received a cool reception all over the country. The reasons were many, the first being cost. Diesel power plants added a 30 percent price premium. Second was the lack of experience most farmers had with “them newfangled diesels” and there were some added complications in their use, such as cold-weather starting, special lubricants, complicated fuel systems, and so on. Lastly, there was a lack of supporting infrastructure. Stubborn self-reliance was the common trait of farmers in those days and diesels were a little more than many farmers could fix with the proverbial bubble-gum-and-baling-wire” so a nearby dealer with diesel experience was an important element. As a result of all these factors, it took a long while to sell the first WD-40 diesels. Those farmers willing to take the plunge in those days got smokin’ deals and the Franz family in Ness County, Kansas, walked off with a slightly used WD-40, serial number 731, in 1936 at a bargain price. The tractor remained in the family until 2010!



This is where tractors go to put up or shut up. At the 2016 National Threshers Association Reunion in Wauseon, Ohio, the event sponsor allows vintage tractors, both internal and external combustion, to hook up to a very old Prony brake dyno. This 1920s-era Prony brake dynamometer was built by the A.D. Baker Company of Swanton, Ohio, and was used to test the steam traction engines they built. Baker steamers were among the best steam traction engines built and they were one of the last companies to build them. In the late 1940s, when A.D. Baker was on its last legs (finally dissolving in 1953), they donated the Prony dyno to the newly formed National Threshers Association and it’s been a part of their annual reunions ever since. The belt-driven device, which is the flywheel from an A.D. Baker steamer, has a tachometer. There is a brake that operates on the flywheel and is attached to a lever arm. The amount of braking force is measured on a scale at the end of that lever in pounds. The brake is gradually applied and the pounds of force are measured on the scale to the right at the end of the lever, which is 63 inches according to the old formula. According to that formula, the weight times the RPM divided by 1,000 equals the horsepower. Steve Lashaway of the Threshers Association restored this dyno years ago and remains the dyno king. It takes a fine touch and experience to get accurate readings, but in 20 years, Lashaway has developed that touch and has trained others the arcane art of the Prony brake dyno.
Here is what the WD-40 looked like when Lehman got it. One of the larger issues was the front wheels. The rubber-tired WD-40s had notoriously weak front wheels and the Franz clan had repaired them many times. They were safe for use but essentially beyond restoration and very ugly at this point. Lehman was lucky to find a nearly perfect set to replace them.


A tractor in the same family for threequarters of a century is bound to have a few tall tales attached to it. During his purchase and during the restoration, Lehman took the time to record a few as told by Leonard Franz, now 87. Franz remembers one of his older brothers driving the tractor home in 1936 and he gathered a lot of stick time on it over his many years of farming. The Franz family farmed as many as 5,000 acres using this tractor. It was in regular use working ground until 1954 and then spent another lifetime powering irrigation pumps. When Leonard’s father died in 1972 and the farm was sold, the family wanted Leonard to have the tractor and he kept it until Lehman came along in 2010. The WD-40 models did not have hour meters, but given the acreages, the years in use, and several major overhauls, this tractor must have an unbelievable number of hours on it.

The D40 diesel was based on a research program that began in 1916. After World War I, IH engineers went to Europe, where the development of diesel was farther ahead. They brought home some engines for study and by 1928 IH had built a prototype engine of their own. Several designs later, they finalized an IDI design in 1932 that went into production in April of 1933. It was an overhead valve, five-main engine with wet sleeves and a 4.75-inch bore and 6.50-inch stroke. It could run on the relatively poor diesel fuels of the day. Its gasoline starting system made it practical by the standards of the day. All it all, it was one of America’s first practical diesels and it was used in tractors, crawlers, and stationary power plants.
How about them four-bolt rod caps? The early D40 diesels had Babbitt-lined insert bearings but later transitioned to the copper-faced inserts as shown here. When this tractor was built, they could be either and production was mixed. Bearing wear on early diesels was a big problem due to the poor lubricating oils of the era. The first cure was Chevron’s DELO (Diesel Engine Lubricating Oil). The introduction of that oil in 1935 extended the working life of diesels by leaps and bounds.
That big “58” was the final dyno number we saw but Lehman reports it made it up to 59 hp right at the last. The 1935 Nebraska Tractor Test rated the WD- 40 48.79 hp at 1100 rpm observed and when corrected for standard temperature, altitude and barometric pressure, it had a rating of 51.81 hp. Remember when your grandpa told you that he could run a 4-minute mile in college? This number is about like you watching the old man run the mile in 3:38. The old tractor beat its 1935 rating by about 15.5 percent on equipment similar to what it was tested with back in the day. We can think of many technical reasons for that—but let’s just let the old guys bask in the glory of it.
The D40 engine was indirect injected but there were three different heads used in nearly a decade of production. The earliest (’33-36) had the injectors mounted vertically and that’s what you see here. The next type (’37-38) had the injectors canted 10 degrees. The last version from ’38 had the injectors mounted at 45 degrees relative to the piston crown. Compression ratios varied in the early days from 15:1 to 17:1 as the engineers considered what worked best and let owners do the R&D. Later, the CR stayed at around 16.9:1. What’s that third valve for, you ask? It opens a second combustion chamber for the gas side of the engine. It contains the spark plug and the extra volume to drop the compression ratio from 17:1 to about 4.5:1. The engine starts on gasoline and runs for about a minute to warm up and then switches to diesel operation.


When Lehman got the WD-40, it was in tough shape. It ran and could move under its own power… but that’s about all you could say. It was just plain worn down and worn out but it was largely complete. The WD-40s are a very advanced restoration because many parts are virtual “unobtainium.” The IH-built PT-40 injection pump and injectors are very difficult and expensive to repair, but fortunately they were in good shape. Descendants of the D40 (later called the D461) engine were built into the ’40s but internal engine parts are scarce and expensive. Powertrain parts are difficult and here is where Lehman faced a tough challenge. The input shaft, a shift rail, and one gear were damaged. He couldn’t find the parts separately, new or used, though he turned up one complete used transmission for $5,000. In the end, he found a metallurgist who could weld, re-machine, and re-heat-treat the parts, making them good as new. In all, it was a two-year restoration that was pretty much a full-time job over that period. Lehman is a “git-er-done” kinda guy.

Belt drives were still a way of life in 1935 but shaft PTOs were on the way up. The reason for the twist in the belt is to match the direction of rotation from the tractor PTO to the device. The twist reverses the direction and often helps reduce slippage as well.
You are looking at a big chunk o’ unobtainium right here! The PT-40 injection pump was one of IH’s earliest pumps and wasn’t built much past the late 1930s. As you can see, it’s as big as a lawnmower engine and probably heavier. Judging by the serial number, this one was built in late May of 1935. It was simple, robust, and reportedly very reliable. The D40 diesel could run on #3 furnace oil, also known as #3 fuel oil, which is an obsolete fuel grade whose specs were rolled into #2 diesel.

Now you know the rest of this story. The ’35-40 WD-40 is a historically important milestone tractor but Chuck Lehman’s has even more going for it. Sure, the unusual red paint adds to the collector interest, but for Lehman, it’s the human history that makes the tractor important That a family would keep a tractor for 75 years and that he could be handed the keys by someone who was there when it was bought new makes it special. This tractor has a lot of stories to tell, and working it like he does, Chuck Lehman, and anyone nearby to watch, is there to hear them. DW



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