Triumph Herald
Ongoing frame-off restoration of a little British convertible
I'm a big fan of tiny cars
The Triumph Herald fits many of my desires for a project, but in factory form it is slooooooow. 1650 pounds may be extremely light, but 35 horsepower is still anemic.
The secret of the Herald is that it was designed as a sports car but detuned with a family car body shoved over it. Add in drum brakes all around and it's "just" a boring import.
This project aims to rectify the power deficit and other shortcomings with mostly period-correct modifications. No literbike engine swaps, but maybe a few microcontrollers.
Pneumatic Shifting
This is basically a fever-dream turned real project, with little justification other than it'll look cool as heck in a convertible. There are some interesting accessibility accommodations made possible by this device, though they require very specific circumstances.
2022-23 senior design project; prototype is completed and under the $350 all-encompassing budget. The end goal is a tweaked paddle-shift system that's suited for both road and race driving.
The pneumatics infrastructure adds ~5 lbs to the car, but allows for some other fun tricks, such as adjustable rear ride height and eliminating the manual washer fluid pump. And, well, I carry an air compressor already, so the weight penalty is down to the small tank alone.
Above shows an early version of the code with intentional delays, which will be cut down in testing.
In-Progress and Completed Major Components
Rebuilt 12/50 Engine
Holds 7k redline, vs 5.5k original (balance & springs)
Frame/Chassis
Bare-metal strip and repaint almost complete
Rebuilt Transmission #2
Laycock D-type Overdrive
Carburetors
SU HS2 (1-1/4"), replacing original Solex
Steering Rack
from a Mk3 Spitfire
Rebuilt Transmission #1
Standard 4-speed, traded for trans. #2
Sub-Projects
While not quite a restomod, there are a number of modernizations currently being prototyped, to be demonstrated in the coming months.
Automatic Choke
A carburetor's choke is used during startup to increase the fuel in the fuel-air mixture, and is gradually adjusted to a stoichiometric ratio as the engine warms. Contemporary American cars automate the process with thermostatic bellows, bi-metalic strips, etc, but the British Herald lacks these on every compatible carburetor.
I've began prototyping a simple system that replaces the choke cable with a servo motor and compact linkage. An Arduino microcontroller reads the temperature value of a probe on the intake manifold, associates that with a certain choke position from a lookup table, and adjusts accordingly. This is as simple as it seems, I just really hate forgetting to adjust the choke.
Starter Motor Adapter
Literally every mass produced British car of the Herald's era uses the same Bendix drive starter motor mechanism. This is a bit of a hack that forces the pinion to engage with the ring gear as the starter spins up, eliminating the need for a solenoid to engage and disengage the pinion. This mechanism is meh at best and frequently grinds gears or locks up. Conveniently, 80s Izuzu pickup trucks use a very nice Denso starter with an identical pinion gear, alignment boss, and mounting pattern as the Herald.
Problem: the steering shaft is in the way.
Solution: hacksaw the starter motor housing and machine my own adapter
Redesigned Dash UX
As with many cars of the era, the Herald suffers from a completely useless dashboard interface. Every button and cable slides a short distance in and out of the dash, providing no visual feedback from the driving position. As I'm replacing most of these cables with servo motors and integrating additional features, an opportunity is presented to fix this glaring flaw.
The current design evolution of the dashboard uses linear potentiometers and toggle switches, a bit of a 70s vibe, to provide enhanced visual feedback and a better tactile experience. All of this is tied together by an Arduino Mega and wonderfully clicky mechanical relays.
Simultaneously ahead of its time and decades behind, the Triumph Herald is as simple as "modern" cars get.
The tip-open bonnet reveals a measly 1.2 liter 4-cylinder engine, mated to a 4-speed manual transmission sending power to the rear wheels. Its sporty front suspension and steering were copied onto the reveled Lotus Elan and Europa, but the swing-axle rear end was subject to the same safety concerns as the Chevrolet Corvair.
I've had a Corvair on two wheels, and will thus pretend to be immune.