Randy Schultz's Triumph TR3 Plus 4 Project

Randy Schultz's Triumph TR3 "Plus 4" Project, Part 1

as published in British V8 Magazine, Volume XVI Issue 1, May 2008

by: Randall Schultz

The inspiration to undertake this conversion came from a simple idea: "Use the Triumph parts I like, don't use the Triumph parts I don't like, and use parts from other cars to produce the ultimate TR3." For me, the classic early TR3 body was the strongest styling statement Triumph ever made. It defined the spirit of British sport motoring. The TR6 chassis represents Triumph's highest development of the body-on-frame concept, featuring independent rear suspension as well as rack and pinion steering. My intention was to produce a vehicle that captured the essence of the TR3, except with better handling, brakes, and engine. I also wanted modern reliability and the ability to get service parts anywhere. From my point of view, none of the Triumph engines or electrical systems would be suitable for the project.

A TR3 body doesn't fit on a TR6 chassis. The TR3 body is narrowest just behind its doors - just where the TR6 chassis is its widest! (This corresponds to the outboard side of the rear trailing arms of the TR6 independent rear suspension.) Even with careful cutting and re-definition of the back end of the inner sill boxes, the body still needs to be at least four inches wider to fit the TR6 chassis.

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rear trailing arms of the TR6 independent rear suspension... won't fit under a standard width TR3

close-up of the TR6 trailing arm pivot   modified TR6 frame for added clearance

I took my lead from famous auto designer Alec Issigonis, the man behind the Morris Minor (and most famously the classic Mini). History documents the development and final design of the Morris Minor as a derivative of the Mosquito. Issigonis at the last minute, and in a flash of inspiration, had the Mosquito cut in half lengthwise right up the middle and added four inches! If you look at the roofline on a Morris Minor you can see the gentle curve of the roof very nearly becoming flat in the center four inches.

The great thing about history is we can learn from it. I can cut a car in half too. With the silent blessing of Alec Issigonis, and the number four as the guiding light to glory, I proceeded to "bastardize a perfectly good car".

TR3 cut in half lengthwise, up the middle

Plus 4 TR3: photo shows spare tire storage compartment.

The patient for my surgical procedure was a straight and rust-free 1958 Triumph TR3 from California. Some would say my actions are nothing to be proud of. However, I show no remorse, and stand behind my work as the only thing that could have been done to build the ultimate TR3. I'll admit there was a moment or two just before "the procedure" where I stood, zip-disc in hand, wondering if I were completely insane. Once the first incision was made, it was all business. I have never looked back or regretted my decision.

I do as much work as I can myself. I am well versed in traditional bodywork techniques, and prefer to do things the way the old guys used to. For me, every job is a wonderful journey through fields I enjoy walking. When people ask me "Don't you just want to get it done and go driving," I can honestly reply that the journey interests me more than the destination. I enjoy the process as much as the product.

I logged 681 hours of sheet metal work in this project. That includes all the cutting, widening and general fabrication of the body. For bodywork, I used oxyacetylene gas welding exclusively. Specifically, I used the traditional technique of butt hammer-welding with no filler rod to produce light-tight joints. This requires simple tools: a size "000" torch tip and a good hammer and dolly. If anyone wants to know more about this realm, just ask me about it.

next step: jigging and fixturing

getting the body into alignment with welding clamps

preparing filler strip for trunk (boot) floor

Steel filler strips were added, of course, right up the centerline of the body and even through the dashboard. Each filler strip matched the profile to its right and left in all respects including curvature, bends, ribs, etc. From the hood rearward, the strips were four inches wide, but forward of the hood I decided to add only three inches along centerline, and to add a half inch along each side. [Editor's note: It's hard to see in the photos, but this added steel is just inboard of the fender seam. It's about two inches outboard of the headlights.] Because the hood itself was widened by four inches right up its middle, some re-contouring of both hood and nose was required to bring curves and edges into alignment.

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I used an extra trunk lid to fill-in the bodywork behind the seats. I feel this space is useless for the original advertised function of occasional seating. As well, it offers no security for cargo storage. By closing this in, I was able to reverse the fuel tank and gain nearly a foot of trunk space. Rollover protection hoops project through this deck and I decided to relocate the fuel filler to this area too. The roll hoops also have brace tubes on either side of the car running from the front floor pan frame mounts, over the rear wheel arches, and into the trunk where they ties into the floor at the back. This system forms sort of a truss arrangement that really adds rigidity to the body.

Plus 4 TR3 - note filled-in rear portion of the cockpit

recessed fuel filler on the new rear deck panel

homemade dies for pressing the recessed fuel filler embossment   fuel filler door is a Ford Mustang aftermarket part

The fuel filler door is a Ford Mustang aftermarket part, with the Ford logo carefully filed-off the inside of the lid. The filler cap lives below this and is the original Nissan part connected to the TR3 tank. Since I'll be using aftermarket gauges the original Triumph fuel sender (resistance range = 0-9 Ohms) was discarded in lieu of a VDO universal fuel level sender.

Turning attention to the chassis... I welded-over all Triumph's original frame welds. In comparison to the earlier TR3 frames, the TR6 welds are much poorer. Almost all of them were "cold". After sorting this out, the frame was sent off for powder coating.

body on frame... okay, body over frame

The running gear is from a 1991 Nissan 240SX. The engine is a 2.4 liter, 16-valve OHC electronic fuel-injected design with about 168 HP through the "SX" 5-speed box and limited slip differential. That's about a 68% increase in power over the original Massy-Fergusson tractor derived power plant that used to pull the TR3 around. One of the founding concepts in this project was to run clean with good power, reliability and economy. The engine has full emission control features including catalytic converter, O2 sensors, etc. included in the installation.

To keep the power reliable at the stern, I used Corvair spindles running in custom-built hubs. This isn't a new idea. Back in the day, Corvair or Mercedes spindles were commonly used on racing Triumphs because the TR6 axles would break due to poor design. (The TR6 axle ends conclude in a long taper with a keyway cut along that taper. When free-play develops between the axle and the hub assembly, the axles break as the hardened key impacts its way to victory over the softer axle material.) There is a U-joint that will connect the Corvair yoke to the TR6 yoke, thank God. The inside of the trailing arms needed some slight relieving, but it all worked out neat in the end.

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half shaft assembly

wooden prototype of custom hub assembly   Corvair spindles running in custom-built hubs

The Nissan differential is the limited slip unit referred to as the "R200". After looking at Goodparts' conversion kit to mount the differential to the TR6 chassis, I decided to make my own. The Nissan driveshaft assembly was shortened to match the new driveline length. Other rear modifications include a tube shock conversion located within the spring, as well as a custom sway bar mounted from above. I have fitted in the Goodparts rear camber adjustment system between the frame and trailing arms to be able to flaunt how much rear camber the ultimate TR3 can have.

The engine sits very well in the new engine bay with no interference issues with steering, exhaust, firewall etc. I made custom frame brackets to mount the engine and was able to use the stock Nissan mounts.

custom fabricated pick-up routed to rear oil sump

Nissan 240SX has a front sump oil pan. I needed a rear sump to clear crossmember.

2.4 liter, 16-valve OHC electronic fuel-injected engine from a 1991 Nissan 240SX

The engine oil pan was, however, an issue. The Nissan 240SX has a front sump oil pan and I needed a rear sump to clear the front frame cross-member. I thought this would be easy, as the same engine was used in Nissan trucks like the Frontier with a reversed pan. However, in truck applications the front timing-chain cover is a different shape and this forms the front edge of the pan shape. I used both pan types, taking the original front sump, cutting it down and grafting it to the back half of the truck pan. I re-routed the oil pick-up to the back using a variety of piping from both set-ups welded into the correct shape.

The radiator is an all aluminum, three-row core, cross flow unit, for VW racing applications from Summit Racing. The (pusher) fan set-up is from Perma-cool. Exhaust manifold is stock, except for the removal of casting marks and the standoff bosses that the original heat shield bolted to. I had the manifold ceramic coated, with the effect of reducing the running temperature of this part by 300 degrees (and because it looks cool!)

Toyota 4-runner four piston calipers with Toyota Cressida vented rotors

front hub spacer is 1-1/8 inches thick   rear hub spacer is 3/4 inches thick

The front brakes feature Toyota 4-runner four piston calipers and Toyota Cressida vented rotors. Nissan 240SX discs were installed in the rear. The Toyota 4-runner calipers literally bolt right on with no modifications. Fitting the Cressida rotors required that the TR3 hub's outer shoulder be machined smaller by about 0.020".

Because I'm running four-wheel discs, I needed power assist. The smallest brake booster I found was from a Suzuki Swift. I connected this to a Mazda Miata master cylinder. (You should use a master cylinder designed for four-wheel discs if that's what you're running.) To keep the same mechanical pedal ratio of the Miata, I had to design and build a double-acting swing mechanism to work with the TR pedal position. This linkage allows longer lengths, without changing the original ratio. A proportioning valve allows adjustable braking bias between front and rear.

The 15" alloy wheels are from an early Nissan 240SX. I bead-blasted the anodizing off, welded-up some curbing mishaps from previous owners, and had them powder-coated. To get my wheel offsets where I wanted them, I machined front and rear spacers. The front spacer is 1-1/8" thick and the rear is 3/4" thick. The wheels are wearing Yokohama "S Drive" 195/55-R15 tires. Ultimately, I think I'll go the plus one route to fill in the wheel wells a bit more.

how often do you see an IRS (independent rear suspension) badge on a TR3?

The only Lucas electrical components left on the car are lamp housings and the windshield wiper motor. The wiper system's worm-gear drive (with spacer tubes that can be cut down, lengthened, or even replaced with 3/8" brake line) is ideal for being able to move the gearbox units four inches further apart. My friend who understands the shortcomings of British electrical systems tells me this is where the fire will start in my car!

The steering column is from a TR6, with a modified outer column tube to get the right length, and also to eliminate the column-mounted turn signal and light switches. The car will use the original TR3 center unit modified to fit on the TR6 steering wheel. The seats are from a Porsche 914. It's hard to find a good seat that's narrow enough for these cars - even if you've added four inches! (Actually, I re-designed the transmission tunnel and driveshaft cover to be a structural part of the body, so it is taller and slightly wider than the stock arrangement.)

This project is not completed. I still have hundreds of details to address. Each feature of the design begins with thought and reflection, followed by pencil sketches, measurements, and in some cases full-scale mock-ups, templates etc. As each new detail is completed, the car seems to reveal another aspect of the whole almost as if the detail were there all along - hidden from view. The resulting car is part vision, part inspiration and a lot of work! I hope you like it.

This article is part one of a two-part series! If you enjoyed this article, you'll enjoy the sequel:
      Randy Schultz's Triumph TR3 "Plus 4" Project, Part 2

A summary of the car's features and specifications appears here:
      How It Was Done: Randy Schultz's Triumph TR3

Disclaimer: This page was researched and written by Randall Schultz. Views expressed are those of the author, and are provided without warrantee or guarantee. Apply at your own risk.

Photos by Randall Schultz for the British V8 Newsletter. All rights reserved.

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