Allen's Super D Gibson


Allen & His GibsonThis Super D Gibson was featured in the following article: Thompson, Glenn. "The Resurrection of a Gibson." Lawn & Garden Tractor Magazine, vol. 11, no. 2, March/April, 2017, pp. 44-50.

To view photos taken during the restoration process, click HERE.

Allen Becker has been a small-engine technician for over half a century, not counting a hiatus or two when he worked for a major airline and a company which made computer-automated drafting machines. His early work was exclusively with lawn mowers; this gradually evolved through the years to the point where he now deals with lawn mowers, garden tractors, log splitters, weed-wackers, chain saws, and occasional minibikes, go-carts and ATV’s. In other words, Allen takes on pretty much anything that comes through the door with a small engine. He repairs approximately 400 items annually, by himself.


Allen lives on the outskirts of Boerne, Texas, and each month he visits his sister and her husband on their ranch near Comfort, Texas. During these trips back and forth, he noticed a cute little tractor sitting forlornly in a field next to the road. Curiosity piqued, he stopped one day for a closer look and then went home and did a bit of research.

The tractor was a Gibson. In 1933, Harry A. Gibson formed a company in Seattle, Washington, to make railroad cars which served the lumber industry by hauling loggers and supplies to and from lumber camps. Wilbur needed something to occupy his workers during slack periods and he hit upon the idea of making garden tractors. There was a market for these after World War II, when soldiers were returning home. The first Gibson tractor was produced in 1945. When his workers indicated their interest in forming a union, Harry transferred the garden-tractor portion of his business to Longmont, Colorado, with his son Wilber F. Gibson in charge.

The Gibson which Allen Becker spotted sitting in a field alongside the road had a hood and a steering wheel, so it couldn’t be a Gibson Model A or D, which lacked hoods and were steered with levers. Likewise, it had a one-cylinder engine, so it couldn’t be a Gibson Super D2, which had two cylinders, or one of the E, H or I series, which were larger tractors with four-cylinder engines. So, that narrowed the possibilities to a Gibson SD or Super D, which were small tractors based on the D design with the addition of hoods and steering wheels. After close examination of the faded paint on the hood, the tractor turned out to be a Gibson Super D—and he wanted it!

During the next few months, whenever Allen visited his sister and brother-in-law, he stopped at the acreage where the tractor was located to see if it was for sale. On one occasion, the wife was home and she referred Allen to her husband. From her, Allen learned that she had been given the tractor years before by an uncle. Another time, only the teenage daughter was home, but she did provide a telephone number. On other occasions, there wasn’t anybody at  home. Allen never seemed to be able to reach the husband and father either face-to-face or by telephone. Finally, he happened to stop by at a time when the man of the family was available and Allen was able to give the tractor a more detailed inspection.  After a few discrete questions, Allen asked if the tractor was available for sale and tried not to show his eagerness when the owner said that it was. Allen suggested $400; the owner countered with $500 (which Allen felt was reasonable), and a deal was struck!

With the assistance of Allen’s son-in-law and a tractor with a front-end loader, the Gibson was placed on a trailer and hauled to Allen’s work area. The tractor came with a cultivator; although, it wasn’t an implement produced by the Gibson Company.

This article documents step-by-step the process Allen Becker went through to take a tractor which had been abandoned as a piece of junk and restore it to its current status as an operating tractor and a source of pride and enjoyment for its owner. It’s hoped that this will be useful for others who are faced with similar projects.

Allen’s Gibson was a Super D with the serial number SUD 31503 stamped into the side of the right rail about two-thirds of the way towards the back. The large tag on the front of the Wisconsin engine showed that it was a Model AEH, with the serial number 1103539. There are no Gibson records available which enable an owner to match a given serial number with a certain year, so Gibson tractors are normally dated by the dates in which their engines were manufactured. The Wisconsin Company maintains excellent records regarding their engines. An online search revealed that Allen’s engine was rated at 5.9 hp and was built in May, 1948, so the tractor was most likely also built in 1948.

 A quick check revealed that neither the engine nor the transmission were stuck. Both turned freely; although, there was a significant lack of compression. This was a relief, as Allen was not faced with the prospect of freeing up a stuck piston or dismantling a locked transmission—at least not until further examination determined the need to do so.

The first thing which Allen did, which is what he does to any engine, was to drain the engine oil and replace it with fresh 10W-30 oil. Next, he drained the transmission. Approximately a pint of water emerged, followed by a thick, gray substance which oozed out. Obviously, water had leaked into the transmission around the shifting-lever boot. After allowing the transmission to drain for a week, Allen replaced the transmission fluid with fresh 85W-140 oil. After the tractor was run for a short while, he planned to drain and renew the transmission grease again. 

Turning again to the engine, Allen discovered that the spark plug hole in the head was stripped. He could have bored out the hole and inserted a Helicoil, but when he checked his “boneyard” of old mowers in the backyard, he located a AEH engine on a junked walk-behind brush cutter. He removed the head from that engine, cleaned it and bolted it onto the Gibson’s engine and inserted a new 18mm spark plug.

Next, Allen removed part of the shroud and cleaned and lubricated the exhaust valve. Carbon from the exhaust had caused it to stick. After doing this, Allen turned over the engine and determined that it had compression.  A lack of compression at this stage would have necessitated opening up the engine and replacing the piston rings. If this had been necessary, then it also would have been wise to check the condition of the crankshaft, replace bearings showing significant wear, and grind the valves.

Allen removed the magneto, cleaned it, and filed and reset the points before remounting the magneto on the engine. By holding the spark plug wire close to the shroud and turning over the engine, he was able to determine that the engine was producing a strong spark.

The next step was to remove the gas tank and clean it to ensure that it was free of contaminants and that the pipe stub leading from the tank was open. Then he removed the Zenith carburetor, took it apart and cleaned everything thoroughly with a strong commercial cleaning fluid to make sure that all sludge and varnish were eliminated. Finally,  he reassembled the carburetor, replaced it on the engine, connected it to the gas tank and poured in a quantity of fresh gasoline.

So far, the restoration process had been amazingly easy—especially considering how long the tractor had sat in a field exposed to the weather.

With bated breath, Allen wrapped the starting rope around the sheave in front of the hood and gave it a good yank. After a couple of pulls, the engine started and ran beautifully! It was a miracle!

The engine was very noisy and inspection revealed that part of the muffler had rusted away. An inexpensive replacement was obtained from the local Tractor Supply.

After restarting the engine a few times for friends and customers, Allen faced the next hurdle—restoring everything on the rear end of the tractor. 

The universal joint connecting the Borg-Warner T-96 transmission to the differential turned loosely on the pinion-gear shaft. The front part of the universal joint had splines which matched those on the transmission shaft, but the back part was smooth—without splines—and revolved freely around the splines on the pinion-gear shaft. There was a hole through the pinion-gear shaft and there were a couple of threaded holes with set screws in the universal joint; however, none of these lined up. Allen decided that it probably would be easiest to drill a hole through the pinion-gear shaft which would line up with the holes in the universal joint, which happened to be 180 degrees from each other. By doing this, a sacrificial bolt could be inserted to lock the universal joint to the pinion-gear shaft. This turned out to be more easily said than done, as the pinion-gear shaft was hardened steel and Allen couldn’t make a dent in it. He resolved the problem by removing the set screws and machining the shoulders at the ends of the screws so that they recessed completely into the grooves of the pinion-gear shaft. This solution would not be satisfactory if the tractor were to be used for heavy work such as plowing, but it would allow the tractor to be used in parades and for display purposes. 

It turned out upon inspection that the cast-iron case containing the differential and axles was attached loosely to the frame rails. The bolts were in place, but they lacked nuts. Apparently, a previous owner had given up on the tractor and simply reassembled the parts so that the tractor looked complete. It had been abandoned as yard art.

Allen’s Gibson Super D had a hydraulic system, with a pump run by a V-belt connected to the same sheave at the back of the engine that also ran the three belts that made up the belt-tightener clutch. A check of the hydraulic system with the engine running showed that it was functioning properly. Another bonus for Allen! 

After the relatively fast and easy restoration of the tractor up to this point, the process suddenly became more daunting with the restoration of the differential and other parts at the rear of the tractor.

The adjustable hitch was in excellent condition and was simply removed and set aside.

The rear wheels were difficult to separate from their hubs after their mounting bolts were removed. Considerable “persuasion” with a maul was required. The rims called for 24 inch tires, which happened to be the same size as those for a Farmall Cub tractor and were readily available.

A bottle-jack placed against the frame was used to loosen and remove the hubs from the axles. Allen was reluctant to apply heat to the hubs and risk the possibility of heating up the axles to the point where the seals were damaged. As it turned out, the seals and axle bearings were in excellent condition and none needed replacement. 

After the rear wheels were removed, the fenders were removed, the brake pedals were disconnected and the differential and the axle housings were slid back off of the frame rails. This was more difficult than anticipated, as the cast-iron unit was very heavy. An engine hoist was used to assist with the procedure and reduce the possibility of damage to the unit or to Allen.

The Gibson UnrestoredWhen Allen acquired the Gibson, the rear wheels would not turn—probably because the brake bands were rusted to their drums. The brake drums on the Gibson were mounted on the axles inside of the differential case, so  servicing them required that the differential case be opened. Once this was done, an attempt was made to remove the axles from their housings. However, this proved impossible. Each axle in its housing was placed in a press and up to 30,000 pounds of pressure applied without success. Allen was concerned that additional pressure would break the housings and present a whole new set of problems. So, he resorted to a make-shift solution. He inserted a file in the gap between the two ends of each brake band and by rotating the axle and the brake drum, he was able to clean off much of the rust on the drums. Although new brake bands are available, Allen decided to use the existing bands, as they did not show signs of extensive wear.

On any of the A or D series Gibson tractors, each brake band is activated by a lever which extends through a hole in the front of the differential case. A considerable amount of dirt and grease enters this hole and accumulates on the bottom of the case. Water gets into the case, as well, and the grime tends to harden over time. Some Gibson owners drill a hole in the bottom of the differential case under each brake band/drum assemble to allow water to escape. Whenever the differential case is opened, it is necessary to scrape out the residue in the bottom. Allen carefully cleaned each brake band/drum and the surrounding differential case.

It was time to reassemble the differential. The pinion gear has to be centered in the housing. Gaskets between the differential case and the axle housings serve as shims which determine the sizes of the gaps between the gears. The gasket on one side was intact and could be reused; however, that on the other side required replacement.

Allen laid layers of 3M Post-It notes in three places on each differential flange and then placed the axle housing in place and checked the gap between the gears. By inserting and removing individual Post-It notes, he determined the thickness of the gasket necessary to produce a desirable gap of between .002 and .003 of an inch between the gears.

Allen then went to WalMart and purchased a large tablet of construction paper—the kind used in elementary schools. He determined that each sheet was .003 inch in thickness. He laid sheets over the flanges and cut around the number necessary to produce a gasket of the proper thickness. Twelve layers of construction paper were needed to produce a gasket of the proper thickness.  The gaskets for both sides had to be of equal thickness to ensure that the pinion gear was centered. The gaskets were held in place with Permatex gasket seal while the differential case and axle housings were reassembled with the aid of the engine hoist.

Slipping the differential and axle assemblies  over the frame turned out to be more difficult that expected, as the two channel-irons that make up the frame were a bit too far apart. A “farmer’s jack” was used to exert enough pressure on one side to permit assembly.

 The old tires were easily removed from the front wheels; however, the tires on the rear wheels were a different story. Allen first cut off most of the rear tires with a Sawzall and then cut through the remaining bead using a die-grinder with a cutting wheel. When cut through, the beads fell off the rims readily. Allen wire-brushed the rims thoroughly and coated them using a spray can of Rustoleum red-oxide primer.

Front and rear tires were purchased locally. The front tires cost approximately $40 each; the rear tires were approximately $200 each. Allen mounted tires on the front wheels himself and replaced the wheels on the tractor; the rear wheels and tires were taken to a dealer who mounted the tires on the rims for $25 each.

After the rear wheels were retrieved from the dealer with the new tires mounted, the fenders were reattached to the tractor and the rear wheels attached to the hubs. The old tires were size 7x24; the new tires were size 8.3x24. The additional width placed the sidewalls too close to the fenders, so each hub was moved out approximately 1 inches.

The universal joint was fastened to the pinion-shaft, the brakes were adjusted and the tractor taken for a test drive. With everything seemingly OK, the floor board was fastened down, the brackets for the gas tank were tightened, the hitch attached and the hood replaced. The front bumper was removed to allow the hood to be slipped into place. The bolts which held the bumper brackets also held the motor mount in place and it turned out to be difficult to realign the bumper brackets, the frame and the motor mount. Allen used a tapered punch to assist with this.

The old clutch spring was broken, so Allen made a new one. The V-belts used in the clutch needed to be replaced, so a matched set was ordered at a local auto-supply store. Allen requested belts with matching mold numbers.

The steering wheel was intact and usable but had many cracks. When time permits, a product such as Flex-Seal will be used to fill the cracks and smooth-out the wheel.

Allen Becker’s restoration of the Gibson Super D was a labor of love. His pleasure in ownership and his anticipation of driving the tractor in parades and showing it at tractor shows fueled his perseverance. His wealth of experience allowed him to deal with each of the many problems methodically and identify solutions.

Allen does not plan on painting the tractor. He is one of a growing number of collectors who enjoy keeping tractors “in their working clothes.” This may change in the future, but for now the Gibson will remain as is. If increased rust seems to be a problem, the tractor may be coated with one of the clear coatings available which are formulated to maintain the patina.

Thanks to Allen Becker’s enthusiasm, knowledge and skill, this 1948 Gibson Super D has been brought back from the grave and will likely be around to generate interest and enjoyment for many years to come.