Flash of Inspiration
2006 Sprint 1050ST Rear Turn Signal Swap

One of the first mods any new motorcycle owner does is add "custom" turn signals. It's a relatively cheap and easy way to put one's personal stamp on the machine, and often involves a lot of irreversible cutting of the wiring harness plus electrician's tape. Lots of electrician's tape.

This is not that story. Rather, it is one of broader import, reinforcing the idea that those who design motorcycles have never actually worked on one, much less ridden.

The history of engineering is full of famous design flaws - the space shuttle o-ring that couldn't withstand freezing temperatures, the square windows on the original DeHavilind Comet airliner that were prone to cracks at the corners. While not nearly as dire in their consequences, minor design flaws are a part of everyday life, especially if you happen to ride a Triumph Sprint.

The Triumph Sprint 1050ST is a nearly perfect motorcycle, but from the beginning it had three annoying design issues:

  • The "projector beam" headlights, while very trendy at the time it was introduced, were, functionally speaking, utter crap, making high-beam a necessity if you had any interest at all in seeing the road ahead at night.
  • The saddlebags, while elegant and clever, will not hold a full-face helmet due to the elegant and clever latch and pop-up handle mechanism, most of which was enclosed in a bulge inside each bag that severely limited cargo space and shape.
  • Finally, the rear turn signals or as the English call them, "indicators," because they have different words for everything were placed so that when the bags were attached, they rubbed against the case and bent the flexible stalks. In addition to creating a divot in the case over time, the rubber on the stalks gets brittle and breaks.

Interestingly, the Sprint GT - Triumph's update to the 1050, still produced but no longer sold in the U.S. because we can't have nice things - has normal headlights, larger bags, and rear indicators that are well clear of any interference, so obviously they learned something.

Meanwhile, in ST land...

Here's a shot of the indicator with the bag installed.

And here's what it looks like after a few years. That's an actual crater there where the arrow is pointing.

New Triumph indicator

No-longer-new Triumph indicator

New Triumph indicators are $46.92. They will last a few years, and then break. You can find them used on ebay for $20-30 or so, but they will be used, and old, and will in all likelihood snap off shortly after they are installed. After going both routes over the years, I finally decided to try a different solution.

That's a BikeMaster mini turn signal, available from nearly any local bike shop, or Amazon and eBay if visiting bike shops make you nervous. They are $15 for a pair, give or take a buck. Yes, you can pay up to $50 - each, mind you - for Rizoma or other designer brands, but this is a workhorse, not a showhorse, so I'm not bothered what anyone thinks, as long as they know when I'm signaling a turn.

The BikeMaster lights are available in all manner of shapes, lens colours, and lighting types.  I opted for a conventional bulb over LED because fast blinkers annoy me and I'm too lazy and cheap to add a special flasher or an inline resistor to slow it down.  My hope was that the smaller indicators would not interfere with the bags.

Changing out turn signals is one of the easiest jobs there is. Doing it right - without gobs of electrician's tape and hacking up the wiring harness - is a bit fiddly, but worth it in the long run.

The first step is removing the old indicator, held on by a single bolt, which is hidden behind a cover because OF COURSE it is on the rear fender (or what the British call a "mudguard," because again, they have different words). The cover, part number 4 on the schematic below, is held on by three allen screws (part 5), two of which are hidden away in deeply recessed caves where you can't actually see them, much less get an allen key into easily. Keep trying. Even a blind squirrel finds a nut once in a while and eventually you'll get the screws out and the cover off.

In fairness, the cover is there to protect the wiring to the tail light, indicators and license plate light from all the crud thrown up by the tyre over the life of the bike. Go ahead, take it off. Surprise! It's filled with crud anyway. And wires. Clean out the crud, then unbolt and unplug the first indicator - do them one at a time, so you can differentiate the left and right sides more easily.

The first thing you notice is that the Bikemaster indicator fits the stock hole, so no drilling is required. The second thing you notice is that the stock connection will not work with the aftermarket signals. Because OF COURSE they don't. In this case, the stock plug from the harness is a male, and the plug coming from the indicator is also male. So everything is going to get neutered and we'll start again. Fortunately, I have a moderately decent kit full of connectors and covers from Cycle Terminal, who not only sell individual bits, but collections of bits as well. I went with bullet-style terminals, as that was close to stock.

The first step is to strip off about 3mm, or 1/8 of an inch of insulation. Seriously - you don't need much. Each connector has two sets of tangs to crip - one holds the bare wire, while the other holds the insulation. You only need a bit of bare wire as long as the tangs are wide.

Once you've stripped the wire, slide the insulating cover on and further up the wire. It will not go on once you've crimped the connector. Once that's in place, I set the connector in the crimper.

Note that in this case, I used my Goodspeed Motoring crimping tool, because the wires are tiny, the spaces are tight and it give me finer control over the crimp.

Lay the wire into the connector and crimp the bare wire first. Give it a tug to make sure it's secure. It may take a few tries until you get used to how to do it.

After the bare wire is crimped and you're happy with the connection, crimp the insulation. Use a larger crimp, since you do not actually want to pierce the insulating material. This is primarily for strain relief.

Once you've secured the connector, slide the cover over it. The cover for the male end will leave the plug sticking out. The female connector will be fully covered.

Here are a few shots of the process.

One wire stripped, one done

Crimping the insulation

Nearly there

Note that I have not soldered anything. Sometimes, soldering is best, but while it is certainly possible to solder the crimped connection, it's not really cost-effective here. The current is very low and there is no strain on the connection. The factory connectors were not soldered either, and they never failed, so I'm comfortable with just crimping in this application.

Here's what it looks like when everything's finished.

Note that you'll see all manner of different coloured wire used in various harnesses. The important thing is that solid black or brown are most commonly used for ground wires or, as the British call them, "earth," because, you know.

Usually the positive wire will have some sort of stripe on it. In this case, as shown above, positive from the indicator is black with a white stripe, while positive from the harness is green with a white stripe.

Thread the wires through the hole in the mudguard and tighten the indicator. On these, there is a rubber ring at the end of the stalk to allow a bit of flex. Tightening the nut too much squashes this, rendering it useless. Too little means the indicator will fall off. I went for moderately snug, with a bit of blue Loctite on the nut for good measure.

Once everything is plugged in, turn the key and make sure the inducators work correctly, then turn everything off, tuck the wires in behind the cover and bolt it back onto the mudguard.

With the new signals on and the bags installed, we now have daylight between the two.  The yellow arrow below points to the rubber grommet. This allows enough flex to install the bags, because they do not go on straight and instead must be tilted first, then slid onto a mount. Because the designers have never actually used panniers.

And the finished job, none of which would have been necessary if they had just moved the original indicators a few millimeters to the rear.


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