Category Archives: Mechanical

Reflecting upon red plastic

One thing missing from the back of my bike was a reflector. It likely had a rectangular one under the seat when it was new- that to me is not really very much in keeping with the ethos of the bike so I had a rummage and found this on Amazon:


A 1 1/4″ round reflector, metal backed, made in New Jersey. I made up a small metal bracket, painted it black and attached it below the light on the rear fender.


Ordered also a small module housing a couple switches to operate the lights and ignition- the push-button on the handlebar that currently kills the engine is going to be for a horn of some description, something a little louder than a bell.


Annoyingly, it arrived broken. I glued it up and now it’s better. Next up, dismantle, rub down and paint up handlebars… then refit all the parts.

New paint; a stark contrast, illuminated.

Decided to rub down and repaint the fenders on the bike. I had never been very fond of the gray/white color scheme and with the addition of the gloss black fuel tank it started to look out of place. Plus, the white paint was beginning to look in poor condition from being stored out in the elements for years.

DA sander

Started with some 120-grit paper on the DA sander to take the old paint down to a good surface and provide a key.

rubbed back

Once rubbed back it was wiped clean. The paint is really very thick and has protected the metal well.


Gave the fenders each a couple coats of rust-protect gloss black paint and left them hanging to dry.


Between times I decided to see how the exhaust pipe would react to a bit of polish. As it turns out, really very well.


Moved the rear light to the back of the rear fender and reassembled everything. Just needs the handlebars rubbing back now and painting up (again, black).


It’s quite a difference from how the bike started out. This is a picture of it a few years back.


Next, I turned my attention to the lights. The magneto stator was meant to come with two windings, but only arrived with one. I ordered a replacement but that arrived with one winding and two wires soldered to the output. Utter nonsense.

generator stator

Bought an extension piece to the stator that turned it from a horse-shoe shape into a full hoop with a second winding to generate power for lights.


At a fast idle it creates enough energy to light the 4.5W bulb in the headlight. I might end up doing what I did not want to and fitting an LED lamp to it instead, as it is significantly more efficient and should power from the generator acceptably from idle on up.

Computer stuff and a motor assisted bicycle

I got fed up of having a mismatched set of drives and a hole in the front of my TRS-80.

neat and tidy

This prompted me to go find some software and find a way to transfer files to and from the TRS-80. Turns out running an emulator, using it to convert binary files to hex, transmitting them across serial and converting them back works well.
Also, on a plus note, have managed to get a word processor software working and printing properly. Real proportional print on the old daisy wheel printer!


It snowed. This prompted good “out in the garage” type work, as it was pleasantly cool.

pile of parts

I decided to try a bit of a fun project. Bolted an engine to my bicycle. A few things needed a bit of ingenuity- the sprocket at the back is clamped to the spokes between two discs of rubber. That pushed it too far out and didn’t let the brake work (hub brake on the rear wheel).

rag joint

An afternoon of adjusting and tinkering and setting up and I got it to run.


50cc, 1.5hp.. geared to do about 20-25 tops. Decided it needed a speedometer. Ordered an old-fashioned mechanical one. Decided I did not like the face that was on it so redesigned it, in the style of 60’s BMC Smiths gauges.

gauge design

Printed out rough draft and compared to the one it came with.


The gears also had no lubrication, instead relying upon the nylon being inherently slippery- that only works for a short while, so added some silicone grease to try extend the lifespan of them a little.


Mounted the face, decided it looked well enough. Painted up the center of the needle with silver paint.

spray paint

Finish is acceptable. Not mirror but certainly shiny.


All finished up, looking better than it did.


Took a while to calibrate, and it’s far from accurate but it’s good enough for the job it’s doing. Also, pulled the trip reset dial off and blanked it, turning it into an odometer.

black chain guard

Painted the chain guard up, made a few adjustments to the way the chains route.


Bought a light set for it, the front lens was all hazy. Polished it up so it was a lot clearer.


All back together it looks a fair bit better.


All attached to the bike, adding to the look and usefulness.


Next up is an engine driven generator, switchable to the wheel generator. Might add a battery in there someplace but for now it’s all AC lights.

Processor and a monitoring panel (plus holiday oddments)

After the previous discovery that the -12V rail was collapsing under load, I read up on the datasheet for the 8080A processor. It states that the voltage rails must be brought up in a particular order (-5, +5, +12) and if the -5 is missing then there’s a very high chance of damaging the processor. The 8085 negated this and required a single, positive power source- the 8080 has strict requirements.
The 4116 RAM states that it should be brought up with the -5 first then the +5 and then the +12 but any of the rails missing should not cause damage to the chips. Bonus there.
So, I decided just to fling a processor at it. For $4 a pop, I decided that it was worth a shot, having fixed the power supply.


Same behavior upon power-up. At least I have a couple spares now.

repeating trash

Pulling the video RAM does show a different pattern on the screen so that at least is moderately positive- it initializes the memory in the same fashion each time it it switched on. Pulling the CPU and I/O cards and powering up the video card only liberates a solid beep, no crackling warbles.


Bought some little voltmeters from China- self-powered with internal self-regulated reference. They work from about 2.5 Volts all the way up to 30 which is impressive.


Also, bought some red transparent acrylic to serve as a mounting plate and to act as a contrast-improving device for the displays.

cut out

Marked up, cut with a hacksaw to size and sanded down smooth. Gently heated it up with my butane torch and bent it into a shape that stands up by itself.


Measured up for the meter locations, drawing the positions on the front in Sharpie.


Spread a thin layer of PVA glue on to each meter. It’s nice because it dries clear and doesn’t attack the plastics.

row of meters

Five meters stuck on and waiting for the glue to dry.

heat shrink

Trimmed the wires down to length and soldered on a length of multi-core wire, and using a spoon as a heat shield, added some heat shrink tubing to each join.


Soldered some test leads onto the other end of the cable and marked them up as to which is which.

plugged in

Got everything hooked up onto the appropriate locations on the PSU.

meter on

With a few labels to show what’s what (and a couple others because I got carried away) the output of the PSU is monitored fully. Everything is in spec, all loaded down with all boards fitted. Now that I have this set up, I’m happier in the knowledge that everything is doing what it’s meant to in terms of power.

Next up, pulling it all out of the chassis to get the analyzer clipped on properly.

new light

Back to the house, I bought a new 4′ Lithonia light fixture to replace the junky Lights of America one that refused to light one tube and barely lit the other. Wired it up, fitted the old 25W tubes and flicked the switch. Nice bright light with instant start, too.

recapped tv

Recapped a TV for someone at work. The ventilation grilles at the back had become lodged with dust due to the location it was kept in (TV stand with no access to the sides) and as such, had cooked itself. Uprated the heat ratings of the replacements (all the originals were 85C, the new ones went in all 105C with a few in really warm locations at 135C) and ran it for an evening. Worked well.


Traded the Challenger in against a new vehicle- Jeep Grand Cherokee. A bit more practical than ferrying the family around in a 2-door muscle car.

drip drip

Changed the ignition amplifier in the Renault and also a new distributor cap and arm, along with the crank position sensor. The CPS was at fault causing the non-running but the ignition amp appears to have been a bit marginal because it has a lot more torque now. Also, the power steering has stopped leaking and is holding fluid. The gearbox is leaking though, along with a weep of coolant onto the exhaust manifold that I need to find the source of because it smells when I start the car up. Other than that it is actually working moderately well.


The Renault had been making some unhappy noises from the engine bay recently, bad bearing kind of noises. I drove it to work and back and on the way home it decided to buck and jolt badly, feeling like a bearing jamming up (more on that later).

old pump

After having to purchase an 11mm wrench (not a real size, why it’s used is beyond me) I removed the water pump. Due to the design, it was impossible to remove by hand, as the bolts undo and the pump came off with a gentle tap, but the impeller got stuck in the aperture with the pulley wedged against the frame rail. A bit of wiggling and there was 1/8″ holding it back so a thump from the bottom of the mallet handle saw it liberated onto the floor.


I’m quite impressed by the coolant. It’s very clean, all things considered. This is a good thing.

water pump removed

Water pump aperture, including original gasket, which probably could have stayed, in hindsight. Note the really large space to work in (by general Renault standards, at least. I can get my hand in there and even see what I’m doing. Luxury).

gasket scraper

Spent an hour swearing at the old gasket, which was particularly awkward to remove.

no more gasket

Eventually it did come up clean. I’m just glad the block is cast iron because the angle I was forced to work at with the blade would have scratched and taken chunks out of any softer metal. Surprisingly also, the pump housing is remarkably rust free where the impeller spins, so I’m guessing this coolant does have some anti corrosion properties.

new pump

The new pump came with a new gasket (which didn’t fit very well, the holes didn’t line up properly) and has a different impeller design. Previous one was a pressed steel affair which was effective enough, had 4 vanes. This one is cast metal and has many more (and upon actually having run it now, pumps a much higher volume of coolant, particularly at idle).


Gave the gasket a coating of sealant and installed the bolts, which were held in place by the gasket (useful side effect of the holes not lining up well).

pump in place

There was a moderate period of jigsaw/Jenga type thought and experimentation that occurred before the pump went in. In the end, the bolts had to be in place, the pulley had to be on the shaft but not attached so the pulley could wobble about enough to allow access to put the pump in place. Thankfully there’s enough room to see one bolt past the frame rail and also space to stick a locking rod so the pulley bolts can be tightened.

alternator bracket

Then it was time to put things back on! Alternator and aircon compressor bracket assembly first.


Alternator with top adjustment bracket.


Finally, aircon compressor and belt, which took a while to remember which way round all the pulleys it goes.


Finally, the battery tray and battery went back in. Filled up the coolant and let it burp as best it can with the engine off.


Been a while since I’ve had grubby hands, made a change from moving boxes and furniture.


Finally, all buttoned up, topped up and running. Aircon even works still, which is nice. There howling bearing noise is gone, but initially it was still bang thump, kangarooing and running intermittent badly on the test run. This was traced back to a rubber bungy that had split and fallen off one of the big spigots on the brake booster. Replaced that with a short length of pipe with a wire nut stuffed in the end because that shouldn’t split now. Normal, smooth running resumed. This fuel injection system really doesn’t do well with vacuum leaks at all.

It’s nice to have it back on the road, even if the front brakes are now sticking because they’ve not been used. Next job, that.

Wipe and wait

My car has a 4-position windshield wiper stalk; off, intermittent, slow, fast.

While the motor needs to be pulled and serviced because there’s little difference between slow and fast, the intermittent wipe had always been somewhat pathetic.

Selecting intermittent would make the relay click, and as soon as the wipers returned to the parked position, click again and they would almost immediately wipe again.

Pulled the dash shroud down and located the clicking box at the top left. (Top right is the key-in/seatbelt buzzer, bottom left the cruise control stalk, above that with the finned heat sink the dashboard dimmer control).

relay delay box

Took the circuit board out and drew up the circuit diagram by following the traces, to get a better understanding of the circuit and its method of operation.


Culprits were most likely the electrolytic capacitors. One had a high ESD and the other was meant to be 22uF, it measured in at about 100nF. Replaced them both. Now the wipers wipe and wait about 5 seconds before wiping again on intermittent, and added bonus, they now wipe 3 times after spraying screenwash onto the screen. Not bad for 45 minutes’ work and spares I had in stock.

Odds and ends

Been busy with Scouts events lately. First off was the Raingutter Regatta, which is an event where you build a boat from a kit and then race against other people with boats by blowing at the sail through a drinking straw.

Didn’t win any races but the boats were decorated that morning with Sharpie permanent markers. We have the Cheshire Cat from the latest edition of the Alice In Wonderland films, and Edvard Munch’s “The Scream”.


That was a bit of fun. Next up was the Space Derby, which is basically elastic-band, propeller driven craft that fly along a zipline. Furthest wins, or first to the end of the run, which is about 30 feet or so of fishing line, held taut.


We went for a heavier design which won it first place in the races (not the fastest but it managed to gain the most momentum and coasted on by faster but shorter-traveled competitors). Designed after the P52 Mustang.

wheel off again

Took the wheels off the front of the car again, and changed the brake pads for new ones. The brakes had good pedal but offered little actual braking effort.


The pads were so glazed I could almost see my face. Plenty of friction material but all cracked up. In the bin they went. The brakes now work properly. That’s better.


I recently fitted some LED bulbs to my reversing lights because LED and because they weren’t very bright. Unfortunately, the addition of LED’s didn’t really help. Most of the light was going back through the plastic of the reflector.

splish splash

Began by taking the worst lamp unit out and gave it a bit of a clean up in the sink. (Read: gave it a thorough clean with q-tips and soap and lots of water).

flash on

Taking a picture with the flash on shows that the reflector now reflects better because the plastic inside isn’t covered in grime and the reflective surface is a bit cleaner. However, the reversing light is still very dull.


Out with the Dremel.

lamp unit off

A bit of smoke and hot plastic later and the reflector housing is off. Indeed, the plastic is made from this kinda tan colored ABS which isn’t very reflective. You can just about see the remains of the silver paint that used to be on it at the bottom. Heat and age have made it all flake off.

taped up

Cleaned out and taped up the sections I didn’t want to paint. Stupidly I forgot to take a picture of the afterward, but I used shiny aluminum paint which, although not as shiny as the original chrome, is a lot better than how it was.

epoxy mix

Mixed up some “5 minute epoxy”, using the traditional matchstick and random piece of card.


With a combination of cynoacrylate and the epoxy glue, I fixed the reflector back onto the lamp assembly.


After a quick polish with some plastic polish, the result is visible.

light on the right

The light on the right is brighter than the one on the left now; before it was the other way around.

all bright

After going through the same rigamarole with the left light cluster, it looks a bit better than before.

buffed up

Machine polished the left lens because it was very scratched, particularly over the reflector. Looks better now, the white marking is where the plastic has crazed in the sun.
I think I’m going to be on the look for Renault 9 rear lights, because those actually line up with the rear swage line. For now though, these ones are working better.

Sensors and an unfortunate incident of unplanned ingestion

I’d planned for a while to change the intake air temperature sensor on the Renault because it had been reading a little “odd”- erratic and not really reflective of the world in general.
I ordered a replacement part- the closest I could get in terms of fitment is for a 1991 Jeep. The thermistor curve is the same as mine, as is the physical fitting. The only difference is the wiring connection.


I don’t have a 19mm crow’s foot so slight tool abuse saw the old sensor undone.

old sensor

The offending article. Rather grubby (not that it really affects it) from being in the flow of fuel and air.


Closer inspection shows that the thermistor bead is cracked. That’ll be why the readings have been a bit strange.


Comparing old versus new. Same, barring the socket.


Head inside into the warm to get set up with the tools required- I don’t have the proper Jeep socket so I decided that the heat of the engine in the location shouldn’t be so high to melt solder, so I would reuse the original connector.

chop chop

A quick spin of the Dremel later and the connectors are exposed.

trimmed and soldered

Trimmed the lugs down and soldered the old wires on.


I’d added a couple pieces of heat-shrink tubing to the wires before soldering them on. Fired up the propane torch outside to warm them up to shrink them down to the wires.


A little bit toasted but shrunk down nicely.


Inserted the new sensor and connected it all up. Noticeable difference now on cold start, before the oxygen sensor warms up and begins to give trim readings.

computer monitoring

I took the car for a drive and it was a lot better. When I got back I popped the hood to check on things and in doing so, leaned on the airbox, which was stone cold- that’s wrong for this kind of weather as the preheat damper valve should open up and draw warm air in from around the intake manifold. Took a bit of a looksee at what was going on. The vacuum operated valve was working when vacuum was applied to it. I took the throttle body hat off and found this:


That’s about one-third of a thermostatic vacuum valve that controls the intake preheat damper flap. The rest of it is… gone. That will likely be the bad misfire the other day and the reason for the plugs being covered in dirt and having closed up, with bits of the valve being drawn into the cylinders and bashing about at the insides.


I borrowed the 1979 Edmund Scientific fiber boroscope from work to have a look inside to see if there was anything left in the manifold that needed to be removed or any damage to the inside of the engine.

intake poke

Pushed it down the intake and had a look inside the manifold.

air sensor

It’s a bit difficult to get pictures from but that’s the new intake air sensor down the intake towards no.1 cylinder.

Took the plugs out and had a look in the bores.


Top of one of the piston crowns. They all looked good. Put the mirror back on and took a look at the valves.

exhaust valve

Exhaust valve- looking good. A few signs of chips in the deposits in pots 1 and 2 but nothing substantial, thankfully. Looks like it broke up and was ejected in pieces out of the exhaust.

5 volts

Took a few readings from the throttle position sensor as it was acting a bit weird. Measured OK, and came up better after having been reconnected, so probable cause is a bad connection at the device. Back up and running, but I need to go to Dodge to see if they have the thermostatic valve.