A Project Car Without Compromise?

1955 Morris Minor Traveller. All images by author.

Project cars are inherently a compromise. For more performance, you ultimately give up something that the factory engineers spent countless dollars (or pounds, yen, marks, lira, francs, krona—whatever) developing. It takes a special kind of car-guy hubris to think that you can do something better than the factory. After all, to get the performance you want, you almost always need to give up something, be it reliability, durability, noise isolation, ride, comfort—something’s gotta’ give!

After all, the factory not only had those talented and experienced engineers and designers but typically a lot of resources to back them as well. What do most of us have? A small “shop” in a crowded garage that needs to also store a lawnmower, a handful of bicycles, some gardening tools and probably a few heavy, annoying bags of seed, soil, concrete or whatever. Those factory guys not only have a bigger pile of cash to spend, but a much nicer shop, too.

Building a project car without compromise is no mean feat. But it is doable. We think we’ve found somebody with just the right mix of experience, talent, skill and dogged parts sourcing required to create just such a car. Oh, and he’s got plenty of patience, too.

In the latest (and last) edition of Hemmings Sports & Exotic Car, we featured Zach Merrill’s heavily modified 1955 Morris Minor Traveller. Gone is the original 30-hp, sub-one-liter engine in favor of an early 1990s Toyota 4A-GE. The Japanese 1.6-liter engine shares its inline-four-cylinder arrangement with the original Morris mill, but everything else about it is different. Zach’s choice of the Toyota powerplant (used in both front and rear-wheel drive vehicles as well as the mid-engined MR2) was based on not only its output, but its packaging as well. He chose the 4A-GE because its side-mounted distributor (as opposed to the “distributor hanging off the end of it,” as Zach puts it) allowed the high-revving, twin-cam powerplant to fit snugly inside an engine bay designed for an 803-cc unit.

An engineer for Michelin in Greenville, South Carolina, Zach tends to think things through fairly analytically, so its wasn’t just a matter of stuffing the Toyota engine under the hood.  Though the JDM-spec, 130-to-140-hp engine came from a tranverse-mount, front-drive Toyota, the transmission came from a mid-Eighties, U.S.-market Corolla GT-S coupe, a rear-wheel drive car that also offered up its four-wheel disc brakes and limited-slip rear end. Along with the driveline, Zach redid the body and also the interior, with the instrument panel featuring a custom wood layout and multiple gauges.

Virtually everything about the build is custom and it also works remarkably well together. Zach’s excruciating attention to detail ensured that the build worked together as a whole. His goals, though extensive, were pretty straightforward: “enough power, enough brakes, enough creature comforts to be usable as a travel car.” In short, he wanted a cool-looking Morris Traveller that could more than get out of its own way, still turn and stop strong, with a comfortable ride and decent seats and air conditioning so his wife could enjoy the road trips. He could have bought a modern car that did all of those things like any normal person, but instead he built just such a car that had all of the modern conveniences and performance and more charm and soul than virtually every new car combined.

All of that is in our story in the magazine. What those pages didn’t allow me to tell the story of just how much work and persistence it takes to get a home-built package to work so well together. Remember that thought about compromise? Plenty of car guys have improved handling and watched ride quality go right out the window, but Zach was prepared to compromise.

When a vibration manifested itself at certain speeds, Zach wasn’t having any of that. Below, in his own words, he describes the sorts of effort that can be required to iron out any compromises when building or personalizing your car.

I work for this really good company. I work for the research arm of the company and in and around some really sharp people and that’s always very good. When I built this car, I designed the driveline. Of course, it’s all just common sense kind of work. I know how to do it. I know how the driveline should work and how important balance is.

But when I got through with this car, I had a characteristic vibration and it would just come on about 48 MPH and it would be there until about 62 and it would be gone. I couldn’t make it go away. It felt like a driveshaft vibration. It was a high-frequency, high-pitched vibration and it was also a beat frequency. It was not a steady thing; it would cycle.

I knew enough to know that it was not one thing vibrating, but there were two, where the nodes intersect. What I had was a fairly complicated vibration problem. I have friends that are the same two guys who are co-inventors of the Michelin Tweel, which is a pretty high-tech airless tire. They’re just really smart guys. One of them, his name is Dr. Tim Rhyne and he is a Ph.D. engineer. Also, he taught classes at Clemson University in vibration studies. It’s one of his areas of expertise. I asked Tim and Steve Cron, the other Tweel inventor—both of them are just brilliant—to ride in the car as I wanted to show them this vibration to see if they had any ideas of what it might be.

They both rode in the car and I got it doing it and Tim started asking me questions. They asked the final-drive ratio, what’s the tire revs per mile, what’s the transmission overdrive ratio, what RPM range is this happening, etc., etc. He’s looking at his watch and he’s trying to determine the frequency of this. He said, ‘I got an idea of probably what’s going on. Let me model it for you.’ The next morning—they had stayed late that night, I guess—they had built a mathematical model based on the information I had given them. They said, ‘Come on in and we’ll show you what’s going on.’

So, he had an animated mathematical model that showed that the probable thing was that the rear axle was vibrating in torsion, if you can imagine it rocking back and forth on its axis, at 61 Hz, and that’s the frequency. He said, ‘What is happening is that you’ve built a system that has a natural frequency in torsion of 61 Hz. So, it’s like a tuning fork—it’s looking for a reason to vibrate at its frequency. You give it one and it will start its motion. Apparently, it’s getting stimulated between those roads speeds.’

‘Well,’ I said, ‘how do I fix it?’ ‘You can retune it so it’s got a different natural frequency, at which point you gotta hope you don’t intercept that somewhere. Or you can build a passive damper that’s tuned for 61 Hz and that’s got enough mass to also vibrate at 61 Hz, but just out of phase with the vibration of the axles.’ ‘Great,’ I said. ‘How do you do that?’ ‘Well, I’ve never actually done it. I just tell you how it works.’

At that point, I knew what I wanted to do but had no clue how to do it. But also I look at cars all the time, so I see all of these passive dampers on production cars. Those guys didn’t design a car to need a passive damper. They designed a car and discovered it needed a passive damper. Their solution was to put this passive damper and make the problem go away rather than start over and redesign it.

Again, using some connections, I called another friend who also works for Michelin who works with Ford because I see those things on Fords all the time. I asked him, ‘Have you got anything that happens to be a 61 Hz passive damper?’ The guy said, ‘Hmmm, that’s a pretty high frequency. Actually, you must have really small tires or a really high axle ratio if you need that.’ I got all of that: a 4.30:1 ratio with 23-inch tire. ‘The highest thing we’ve got is 48 Hz.’

I went crawling through junkyards pulling passive dampers off of things. Fifteen dollars apiece will buy all you want of them. I bought one, studied it, figured out how it worked and then figured out how to tune it and then figured out how to make it work on the car.

It’s magic! Once you get there, it absolutely works. But when it’s supposed to be 61 Hz, and it’s actually tuned for 63 Hz or something, it doesn’t work at all. It’s got to basically mimic what’s going on and vibrating out of phase to cancel it.”

So, it was like the most out of my element I was during the whole construction of this car for that silly piece right there. It was an awesome thing, an awesome learning experience. Basically, it’s a big, firmly mounted weight that’s suspended in rubber. It, essentially, is a tuning fork, just a big, massive tuning fork. I made a big, heavy bracket and mounted it forward of the leading edge on the driver’s side relative to the driveshaft. It’s basically a big, 10-pound weight on a bracket. But, it’s magic.

A lot of things were tuned for noise, vibration and harshness, but that was the biggest one. The exhaust system, I worked on that several times. I’m probably on the fifth iteration of that exhaust system before I got it sorted the way I wanted it, the sound I wanted with enough isolation so that it didn’t transmit harshness into the vehicle.

The first exhaust system was basically hung just like the Morris exhaust system. It would just light up that rear-view mirror because that rear-view mirror is mounted on the center post of the windshield. And that’s also like a tuning fork—just looking for a reason to vibrate. I had to isolate the exhaust system and make a tuned mount for the rear-view mirror.

So, there you have it. Even after solving the drivetrain problem, the man made a passive damper for his rear-view mirror to iron out the exhaust vibrations rattling through the car—even after working out those kinks in the exhaust as best he could. When it comes to carefully ironing out such details on a build, I suppose it helps when you work in the research arm of a Tier 1 auto parts supplier at one of their major research and development centers and can call on two certified geniuses in the field of vibration science, but Zach still had to figure out the ultimate solution on his own, a solution that involved scouring through a junkyard, which most of us end up doing on a build or restoration anyway.

While there are some who might see what Zach has done as sacrilege, what with converting his sluggish Minor Traveller into a pretty spirited—and comfortable—tourer, we’d beg to differ. Rather than sacrilege, how about inspiration?

Still, his achievements on the Morris are notable, from the reliable performance of the Toyota 4A-GE driveline to the sharp handling to the properly isolated noise and vibration. It takes a pretty special sort of patience—and access to some talented engineers, of course—to create a project car seemingly free of compromise with updated mechanicals that still has all the charms of the original. We salute Zach Merrill for a job well done.