Preserving Rust Patina on a 1937 Twin City KTA Tractor

When it comes to antique tractors, fresh paint is optional but mechanical integrity is not, Welsh collector says.

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by Josephine Roberts
The tractor has received a coat of linseed oil, patina perfectly blending aged paintwork into bare patches.

Learn how this mechanic restored his 1937 KTA while still preserving rust patina using linseed oil. Patina intact, it drives like new with these covert repairs.

North Wales-based trucker and mechanic Peter Owen has come to realise that an awful lot of vintage tractors simply don’t run properly. “So many collectable tractors just get driven onto a trailer, taken off the trailer at a show, and, at the most,” he says, “they chug around the ring, and while they might run, they run often badly.”

There is a fashion these days for preserving tractors in unrestored condition, so much so that it is often rather frowned upon when someone repaints an old tractor rather than preserving rust patina. Some people think that cosmetically “doing up” an old tractor is sacrilege, believing that old vehicles should show their years and that a great deal of history lies in the worn paintwork and the dents.

However, this tendency to leave things alone can go a little bit too far, and it can mean that old tractors never get the attention that they should, and that worn parts within the engine never get replaced. A neglected old collectable might exist like this for years, failing to start properly, spluttering and stalling when it does finally start, with the owner simply shrugging and saying “that’s just how old tractors are.”

How many of us really work our tractors?

Peter, however, believes that we owe it to these lovely old machines to get them running properly, and while he is all for keeping the original paintwork, he is not in favour of leaving a tractor with mechanical problems.

I think Peter has a point. After all, how many of us really work our pre-1960 tractors? I don’t mean just run them down the drive and back, or do a few laps around the show-ring: I mean actually work them, for hours at a time. Not many, I imagine. So, all too often, owners are unaware of how their tractors really perform under pressure, because they’ve never used them often enough, or long enough, to find out.

Collectable tractors might have all sorts of faults: difficulties starting, tendencies to cut out, wonky clutches, poor brakes — and many of us put up with these issues rather than fix them, because the tractor is “just a showpiece” and it doesn’t really matter if it doesn’t work properly. Often the owner lacks the time, the finances or the expertise to sort out these problems, and given that the tractor is only fired up occasionally, it doesn’t seem worthwhile to open up what might be a can of worms.

All it takes is time and money

But some people, like Peter, love the challenge. Turning a defective machine into one that works perfectly is immensely satisfying and there’s also something wonderfully reassuring about knowing that you’ve done a proper job and that the risk of breakdown is almost zero.

up-close image of the tractor badge

“I want to be able to rely on a tractor,” he says, “and know that I can take it on a road run or just fire it up, and it will work properly and behave as it should.” That said, he readily admits that every restoration takes considerably longer than expected.

“I’ll sometimes start a little job, like looking at why there is play in the steering, for instance, and often it doesn’t prove straightforward and I could be hours fiddling with just one little part,” he says. “If I have to buy a part, then the job can run into months, and sometimes I end up having to make a part. Either way, it always goes into a far bigger job than I thought it would be!”

A closeup of the KTA engine.

It is easy to understand why many of us opt to just live with the play in the steering, especially if the tractor’s value is not impacted. But it’s a good thing there are owners out there, like Peter, who have the knowledge to get to the bottom of these little issues. Otherwise, we would see fewer and fewer old tractors that actually run and work as they should.

Self-taught restoration artist

Peter’s latest “can of worms” is a 1937 Twin City KTA, quite a rare tractor here in the U.K. The KTA is something of a transitional tractor in that it is badged both Minneapolis-Moline and Twin City, and it is neither a pre-merger Twin City tractor nor a full-fledged M-M tractor.

The KTA features a 30hp, 4.6-litre, 4-cylinder, 16-valve, liquid-cooled Minneapolis engine with a vertical head. The arched front axle gives the tractor clearance over crops, but the KTA was designed to be an all-rounder, and it was hoped that it would be as successful as tractors like the John Deere GP. Sadly, that wasn’t the case, and fewer than 5,000 were built, whereas some 30,000 of the John Deere GP were produced.

When Peter bought the KTA it would run, but only just. Peter failed to start it up when he got it home, so he decided to work his way gradually through each problem. “Even though it is a collectable tractor, I still want it to run properly,” he says, “and so many of these old tractors don’t.”

Peter works on the trucks that he drives for the family haulage firm, and he has restored several tractors over the years, but when it comes to vintage American tractors of the 1930s, he admits that he didn’t have a clue. “There is no training, and there isn’t a workshop manual,” he laughs, “so it’s just a case of trial, error and patience!” Stubbornness plays a part too. “Oh, I won’t let something beat me!” he says with a laugh.

A friend in need

A leaking petrol tank was one of the first issues he found. Peter was able to sort that out with the help of a talented radiator repair man who soldered it carefully, making barely noticeable repairs. The manifold was damaged beyond hope, so Peter ordered one from the U.S.

Closeup of the KTA serial plate

The manifold would take two months to arrive. In the meantime, Peter looked at the brakes, which are housed in the rear axle and can be accessed only by inspection hatches on the top and bottom of the axle. “Somehow a load of dirt had gone up into the axle,” he says, “and the brakes in there had filled up with muck and it had turned into a tar-like substance. It was a nightmare to clean out! The brakes were worn down to the rivets and they were quite fiddly to re-fit, especially with me having to work through the hole in the axle.”

When the manifold arrived, Peter found that it would only fit if he removed a couple of lugs with a grinder. “It’s not nice having to pay a few hundred pounds for a part only to have to take a grinder to it,” he says, “but if you have to, you have to.”

closeup of the area of the breaks that has been cleaned

Peter found that the seals were corroded beyond recognition. “A lot of the seals are made of a sort of waxed cord,” he says, “and of course these perish and all have to be replaced, which is all very time-consuming.” Peter spent many evenings in the company of his friend, Les, working away on this seemingly never-ending restoration. “It can be lonely, boring work sometimes,” he says. “It’s much nicer if you have someone to discuss ideas and options with, someone who will give a hand. It makes the job much more enjoyable.”

Hands-on experience is essential

Peter learned more about the KTA as he went along. “It seems you can get parts for the ‘red nose’ Minneapolis-Moline, and they have similar engines, also some Allis parts, like those on the Allis U, cross-reference to KTA parts,” he says, “but you just have to learn all this as you go along.”

The only way to really learn anything about a tractor is to work on it and with it, and Peter now feels that he knows this KTA quite well. There are things of wonder — like the hub reduction, for example — which Peter finds quite remarkable, and the funny plate on the side of the tractor that opens to provide access to the clutch.

Closeup image of the inspection hatch.

Other features, however, Peter found quite annoying, like the fiddly hole to fit the brakes into, and the design of manifold, which caused a few grey hairs. Dealing with an antique, he tried avoid fitting any shiny new parts onto the tractor, but sometimes there was just no other way as both functionality and tractor safety had to be considered. “Some bolts were so seized up that they broke being removed,” he says, “and then I had to try to find or make something similar to replace them.”

When he replaced the worn bushes on the front axle, for instance, the only bolts he had were new, so he ground them down to make them look like the old ones. Both the mudguards and the bonnet had damage where the tin had become thin and torn, so Peter had the underneath of both parts repaired and reinforced, in the hope of leaving the outward appearance unchanged. “There were a couple of weld marks I had to try to age so that they blended in,” he says, “but now at least the mudguards are strong and secure.”

Maintaining an original look by preserving rust patina

The Prairie Gold paint on the KTA has faded and worn to a muted, darker tone, which blends seamlessly with glimpses of bare, weathered metalwork. The paint issue is complicated. Pete tells me that the earliest KTA examples were painted Twin City grey, but the last of these tractors were painted in the new M-M colours.

Just to make things a bit more complicated, it is said that there was more than one shade of M-M Prairie Gold, and which shade is correct for which date of tractor is something that experts argue over. Peter is getting around the minefield of paint colours by leaving the tractor just as he found it, as far as appearances go anyway.

A shot of the KTA tractor from the back, highlighting its short hubs with the seat sticking out beyond them.

“I’ve tried to make sure that any repairs to the tinwork are done discreetly,” he says, “and I’ve wiped it over with linseed oil. I like the look of it as it is now, so I’m going to leave it.” The long, sweeping mudguards have dents and nicks here and there, as one would expect from 80-plus years of work, but if they were painted up in the shape they are in, the paint would certainly draw attention to the flaws, like shiny paint on a lumpy bumpy wall.

Young at heart

As it is, the tinwork has a lovely, well-used look, and the irregularities in the mudguards are a pleasant reminder of the years of use that the tractor has endured. This is a tractor that looks old, and according to Peter, it feels a little archaic to drive, too.

“I have to stand up to drive it,” he says. “If I don’t stand up, I just can’t reach everything I need to reach!” (At 5’1″, there would be no hope for me then, so I don’t even ask for a ‘go’). The driver steps onto a rear platform in order to drive the tractor, and while this certainly allows for easy access, it does take some time to become accustomed to the “sitting behind it all” driving position.

hand holding out an old oil filter that has been used for too long.

Peter has taken the tractor for a 30-mile drive, so he is well and truly acclimatized to the KTA now. “It went really well, actually,” he says, “better than I thought it would.” An incorrect exhaust pipe makes things a little noisy, but it’s better than going without, and a good warm-up and workout provided just the test drive that the tractor needed.

One could say that after restoration, the tractor looks little changed from when it first arrived in Peter’s yard. But that was the whole point: Peter’s aim was to restore the tractor and get it working perfectly, by preserving rust patina and allowing it to remain looking like an 85-year-old tractor. The result of all of Peter’s work is a tractor that shows its age gracefully but underneath, it is without doubt fitter than it has been in many years. It’s like an 85-year-old with the heart, lung and joints of a 40-year-old! FC

Josephine Roberts lives on an old-fashioned smallholding in Snowdonia, North Wales, and has a passion for all things vintage. Email her at

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