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Sunday, February 08, 2015

Fifth vehicle - 1969 Triumph TR-6

Possibly one of the coolest cars I ever owned was a Triumph TR-6.  There was a lot to like about the Triumph.  It had a 2500cc inline 6 cylinder pushrod engine that had a ton of torque, and developed 125 horsepower.  The car had wonderful handling and was pretty reliable, in spite of the Lucas electrical system.

Part of the reason the little TR-6 handled so well was because it had independent rear suspension. Most rear-wheel drive cars have a solid rear axle and a differential.  The solid axle means that whenever one of the rear wheels hits an irregularity in the road, part of that force is transmitted across the axle to the opposite rear wheel, and this does nothing for handling.

Below, a typical solid rear axle with differential.  These are tough and strong, but they don't have great handling.

An independent rear suspension (IRS) has two half-axles, connected to the differential through a pair of universal joints.  Each rear wheel can move up or down with the road surface, and not impact the other wheel's up/down motion.  This reduces chassis roll whenever one wheel hits a bump or a dip, and contributes to a huge improvement in the vehicle's handling and road grip.

Below is a video of a guy driving his later TR-6 through his neighborhood (It has the fugly federally-mandated 5 MPH rubber bumper guards).  At about the 5:25 mark he gets on the gas a little and the inline 6 makes that awesome sound.

My first TR-6 (I have owned three of them now) looked just like this.  Notice the bumper doesn't have the goofy rubber things that you saw in the video.

The TR-6 has a nice open and simple engine bay.  Front is right.

The car had some serious electrical issues, as British cars usually do.  When I first bought it, I didn't notice that the ammeter constantly was showing a slightly negative current flow.  After I had owned it for about a week, the car died suddenly, and I was clueless as to the reason.  I got a buddy to bring me some gas.  It started, but only ran for a little bit before dying when I turned on the headlights. That's when I figured out the charging system had an issue.  After getting a spare charged battery, I was able to drive it home.

The charging system had two issues:  A fried rectifier and a fried solid-state voltage regulator.  A very knowledgeable friend helped me identify and then correct both issues without having to buy expensive parts.  The rectifier we replaced three diodes on, and the voltage regulator we replaced with a Chrysler mechanical type that cost $3 at the junkyard.

The Chrysler regulator is simple and rugged.  As the voltage gets too high, an electromagnet pulls a contact open, which de-energizes the alternator field winding.  When system voltage drops back to normal, a spring pulls the contact closed, re-energizing the alternator.  This happens several times per second, and you get a fairly constant output voltage.  Tabs to adjust the spring tension adjusts the 12V output voltage.

With that fixed, I had many years of happy motoring in the TR-6.  One thing it always did was pull to the right a little bit, and clunked when I turned hard right.  I never understood why this was until after I had sold it.  The guy who bought it came back and told me that the upper A-Arm mount was broken off from the frame.  I honestly didn't know what he was talking about, because I didn't know anything about suspension at the time.  Hopefully he got it welded for cheap.

Another time one night, I went to go somewhere in the TR-6.  As soon as I turned the key in the ignition, massive amounts of smoke started pouring of the dash.  I shut off the ignition and checked under the dash, but could still see wiring glowing red-hot under there.  I quickly popped open the hood and disconnected the battery before the car could burn to the ground.

The following day I looked under the dash and found a few burned up wires, and wrapped them in elecrical tape, so they could not touch one another.  Crossing my fingers, I re-connected the battery.  Happily there was no further smoke, the car started fine, and everything electrical still worked.  It was just a weird isolated electrical event.

Below is the international warning symbol that the TR-6 contains British electrical components.

One of the things I liked about this car was the cool fuel filler - the design was right out off the race track.  It was spring-loaded had a quick-release lever, so that when you moved the lever with your thumb, the cap would pop open.  Also, it was located in the middle of the rear deck of the car, so you could fuel from either side.

None of these pictures give you an idea how small and nimble these cars are, so here's a perspective shot.  I'm not sure what's going on with this guy's hand - maybe it's slipping into another dimension...

I loved that little car.  It had enough torque that if you were decelerating in first gear and then stomped on the gas, the car would squat down in back and chirp the rear tires.  After I sold it, I missed it so much that after a couple of years I bought another one.  And later on, I bought a third.  I may get another one at some point.

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